Tài liệu Mold Cost, Mold Price and Delivery pptx

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5 Mold Cost, Mold Price and
Delivery
5.1 Mold Cost and Records
Some of the following may be obvious to the reader, but it is surprising how
many mold makers and their staff do not keep proper records. The decision
makers must be aware of the methods used by mold makers to arrive at a
mold cost and mold price. They will then better understand what is involved
when negotiating the purchase of any mold or special equipment used to
increase production and to improve productivity.
The mold cost is the total of the actual costs incurred to make a mold, which
include general plant overhead, but does not include any addition for risk
and profit as will be discussed later. It is the sum of all moneys spent for raw
materials, hardware, and services, plus the total of the time (hours) used by
designers, machinists, assemblers, and other technicians involved in building
a mold and any additional equipment required for this mold, multiplied by
the hourly wage (or salary) rates, which will include all employee benefits
provided. Added to this is the plant overhead rate. Hourly rates and/or
overhead rates used in these calculations can be different for different
employees or groups of employees and for different equipment used; or, there
can be a single, plant-wide rate.
Overhead costs can also be included in the hourly rates, so that the actual
rate used to arrive at the mold cost consists of, for example, $18.00 (actual
hourly pay to the employee), plus $12.00 (employee’s benefits), plus $25.00
(overhead rate) for a total rate of $55.00 per hour to be used when calculating
the mold cost.
In order to arrive at an accurate mold cost it is therefore important
(1) To have a complete and clearly understood Bill of Materials (BoM),
and component drawings,
(2) To record all the funds spent for purchased items and services,
(3) To have a method of recording conscientiously the actual times spent

on this job by each employee, e.g., by filling out time cards, and
(4) To have clearly defined hourly rates
The old-fashioned method was to have the BoM shown on the assembly
drawing. This used to be satisfactory with simple dies or molds, but is not
practical for today’s molds, which often consist of many components. It is
also not convenient for a buyer or accountant to work with an often unwieldy,
large drawing.
Major costs to make a mold:
 Raw materials
 Direct labor (hours)
 Machining costs (hours)
 Purchased components
 Equipment depreciation
 Testing costs (hours)
 Overhead
 Plant costs
Keep proper records of any job!
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5 Mold Cost, Mold Price and Delivery
The mold maker must make sure that only materials and times necessary for
the mold as designed (originally planned) are included in the actual mold
cost. Neither time, nor materials required to make changes to correct any
design or manufacturing errors while building the mold, nor any costs which
were found necessary to be added after the mold was tested before shipping
should be included in the actual mold cost, if these costs were not anticipated
when estimating.
These additional costs will unfortunately eat into the profit margin, because
they cannot be billed to the customer. These changes and corrections, as well
as their reasons, must be properly recorded, so that they will be remembered

when using this record for a repeat order of the same mold or for future
estimates of similar molds.
All mold makers should keep a special “job file” for every mold built, in
numerical order of jobs, by subject, and possibly also by customer, and keep
it in one central location rather than in the memory or in the files of individual
employees. Changes in personnel are unavoidable and it is quite common
that much important data is lost when an employee leaves. These records
must include the original cost estimate, a copy of the purchase order or sales
contract, the confirmation of order, the BoM, the actual cost data, and the
test report of the mold (or the system). Any significant information gathered
about the performance of the mold at the molder after delivery and any
complaints or changes that were necessary to make and any other information
that could be valuable for future, similar molds can then be added to the file
at later dates, as they occur.
5.1.1 Spare Parts for the Mold
This is an often-overlooked area. Today, especially with high production
molds, there are some delicate, easily damaged mold parts such as mold pins.
Other parts, such as gate inserts, stripper rings, ejector pins and sleeves, and
other moving parts are subject to wear. In addition, there are electrical heaters
and thermocouples that may have a limited service life. It is also a good idea
to have the proper size O-rings on hand when dismantling and re-assembling
a mold, to make sure there won’t be any water leaks.
Mold spare parts will be much less expensive to make while the mold is being
built in the first place than to have them built when needed. It is good practice
to have such spare parts on hand when buying a mold and this should always
be included in a mold order. While they add to the mold cost, the will save
much time when the mold needs repairs and ensure minimum downtime.
It is up to the mold maker to suggest the spare parts to be recommended to
the buyer at the time of the mold order.
Always create job files for every

project (molds, etc.)
For multi-cavity molds, a rule of
thumb is to order 5% spare parts
and round up
It is always a good idea to order
spares at the time of the mold. The
cost to produce another piece will be
much lower
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5.1 Mold Cost and Records
5.1.2 The Basic Elements of the Mold Cost
The total mold cost consists of a number of costs directly attributable and
necessary for the making of a mold, as detailed in the following sections.
5.1.2.1 Designing the Mold, Including Checking of Drawings
Design of a mold can sometimes require considerable time. The time required
is not necessarily related to the size, but always to the complexity of the
product and to the performance features expected of the mold. Design time
can range from 10 to 15% of the total hours estimated for the mold, but
could be as high as 20% or even more. But this time is not wasted: always
remember it is easier to change the designs at an early stage than to change
the steel once cutting has started.
CAD (Computer Assisted Design) has revolutionized design practices, but is
really most useful when applied in conjunction with standardization of
designs of mold details. The more hardware, mold features, or entire molds
are standardized and in the memory of the computer, the less design time
will be required. But this does not imply that there is not ample room for the
ingenuity on the part of the designers and it must be understood that there
is no progress without change. It may be necessary to deviate from established
standards and sometimes to change them partly or altogether, if a better

design can be found. But the overall target must never be forgotten: While a
proposed design change could improve one area, e.g., the mold performance,
it could negatively affect another area, such as mold life or the manufacturing
process, so that the final cost of the product could increase.
Another area that must not be overlooked is delivery time. Mold deliveries
are always urgent and critical. Molds are usually required “as soon as possible”
and for this reason alone it is often better to stick with existing, reliable
standards. They assist not only during the design phase but also in machining
operations that may also have standard procedures, and even specially
equipped machines and fixtures to facilitate the making of mold parts.
Checking of drawings is often overlooked or ignored, but it is very important;
at least 10% of the design time should be dedicated for checking. Checking
is much simplified with CAD, because the computer performs most calcu-
lations, but it is important to make sure that the data input was correct.
Checking for dimensions is only part of the process. The checker must also
make sure that the final mold design covers all design features required by
the product design, all fits and clearances for the mold, and much more. Any
error can be very costly. Having a responsible checker, preferably another
experienced designer (never the original designer!) looking at the drawings
before they reach the manufacturing phase will be much less expensive than
having to fix errors later.
Figure 5.2 shows the various design and manufacturing steps in relation to
the time needed for completion (usually weeks). The description on the graph
is self-explanatory.
Figure 5.1 Mold designer working at a
CAD station
From experience, it is practically
impossible to check one’s own
designs and drawings
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5 Mold Cost, Mold Price and Delivery
5.1.2.2 Materials
The cost of material is usually about 10–15% of the mold cost, and may be as
high as 20% or even more, in large but otherwise simple molds.
Raw Materials
The deciding factor when selecting steels for mold shoe and stacks is usually
a policy matter, whether to make mold shoes or plates in house or purchase
them from a mold maker supply house, either as (listed) catalogue items or
have them made to order. It is essentially a simple question of economics:
there are considerations, such as the shipping distance and time from a steel
supplier and the need to carry steel inventories and invest much money in
them.
Time step
QUOTING
Obtain project information (part drawing, etc )
Develop rough concept
Quote
ORDER CLEAN UP
Order received
Send out order confirmation
Obtain complete design information
Finalize concept
Quote any modifications to original concept
DESIGN
Stacks or inserts
Mold Shoe
Hot runner
Assemblies
BOM

MANUFACTURE
Inserts
Process planning
Programming
Rough machining
Hardening
Final machining and polishing
Shoe and Hot Runner
Process planning
Programming
Machining (Gun drill, mill, bore and grind)
ASSEMBLY
TESTING
Adjustments
Re-testing
Acceptance
Prepare for shipping
Shipment
Sample Mold Project Timeline
Figure 5.2
Time line
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When selecting mold materials, there are many considerations: for the mold
to last a long time and to perform best, the following characteristics must be
considered for suitability:
 Compressive strength
 Wear resistance
 Corrosion resistance
 Toughness (against impact)

 Thermal conductivity
 Resistance to high temperature
In addition to the above, the following are also very important:
 Machinability
 Hobbability
 Polishability
 Dimensional stability in heat treat
 Weldability
 Nitriding ability
 Cost of the raw material
 Availability
Materials must be selected to prevent galling and seizing; materials which
slide across each other should have different molecular structures (unless
one of the materials is nitride plated).
As a general rule of thumb, material suppliers recommend that even for dis-
similar materials in a contacting condition, the difference in hardness should
be 6 Rc if possible. For similar materials the difference should be 10 Rc.
When selecting material for a mold, there are several material properties to
be considered. The following list contains the most important properties:
 Ultimate and yield strength
 Impact strength
 Modulus of elasticity
 Hardness
 The effect of temperature on these properties
 Thermal conductivity
 Thermal expansion
 Wear resistance
 Corrosion resistance
The quality of the materials (cleanliness) is an important consideration.
5.1 Mold Cost and Records

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5 Mold Cost, Mold Price and Delivery
Some mold makers (usually larger operations) prefer to keep a selection of
steels for the mold plates and for stack parts in plates and bars in their stock;
this may require heavy lifting equipment, large machine tools, a large
inventory, and much plant space. Other mold makers, with easy access to
steel suppliers, can contract with them to supply small and large plates already
cut to size, rough finished, or even ground to size. Still other mold makers
(usually smaller operations) specialize in making only the stacks and to buy
the completed mold shoe from mold supply houses and then to assemble
and test the completed mold. In all these cases, standardization to a limited
number of sizes can have a significant influence on the mold cost.
Contracting large annual volumes of steel can lower the price of steel
significantly. The larger the pieces of steel, and the larger the annual quantities
committed to purchase from the supplier, the lower will be the cost per mass
(kg). In the case of very large mold parts, it is often worthwhile to buy the
steel in forgings, with only little machining allowance. The forging process
incurs separate cost, but saves not only on steel costs but also on machining
time.
Other raw materials used in molds are BeCu, aluminum, bronze, plastics
(for wear), among others. When buying BeCu, it is important to inquire
before ordering how the blanks will be made. Blanks cut from rolled bars are
usually free from enclosures or voids but are not available in larger sizes. If
larger pieces are required, they should be pressure-cast to ensure homogeneity.
It is not unusual for small voids inside the work piece to become visible after
many hours had been spent on machining BeCu parts and the pieces have to
be scrapped at high cost to the mold maker.
Standard Hardware
Today, no mold maker even thinks of making hardware items such as screws,

dowels, and others. However, it is important that hardware items are used as
they are provided by the supplier. Any modification can diminish their rated
strength characteristics, and therefore they must not be modified for safety
reasons. If they absolutely need to be modified, they must be called up in the
BoM as a special part, so that they are easily identified as “special” in assembly
and service.
Mold Hardware
Mold makers used to make many mold hardware items, such as leader pins,
bushings, ejector pins, and even hot runner parts, among others. Today, it is
often much less expensive to use standard hardware as supplied from mold
supply houses and other specialists. They are also easier to replace for service.
They are made in large quantities, on special equipment and with specially
selected materials, heat treatment, and surface finishes, and are usually of
much better quality than the homemade varieties.
The cost of standard and mold hardware in a mold (not counting any hot
runner systems) could be estimated as about 5% of the total cost.
When buying steel, contract for large
quantities (e.g., estimated annual
requirements) for lowest price
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5.1.2.3 Production Planning
Cost for production planning is usually included in the overhead. It includes
the costs of deciding the best way of routing the work piece through
production, the selection of the appropriate machine tools, cutting speeds,
the need to prepare jigs, fixtures and gages for the job (and to design them),
and the cost of programming software for machining each of the required
mold parts. Obviously, standardization will be of great advantage. In some
CAD/CAM system, some of the programming is done as the mold part is
designed. At smaller mold making enterprises, it is usually the boss or the

foreman who does the production planning.
5.1.2.4 Machining Costs
Machining costs includes the total of all costs incurred when transforming a
“blank”, i.e., a raw piece of steel, into a finished mold part, ready for assembly.
These transforming methods may include:
Rough machining. Cutting blanks from rough plates, sizing and squaring these
blanks, and machining these or purchased plates by milling, drilling, deep
hole drilling, boring, rough grinding, or other methods.
Rough turning. Rough turning from rods or cut blanks.
Stress relieving. This is often required after large amounts of material have
been removed (cut) from a pre-hardened work piece, which may cause it to
shrink and/or warp. Stress relieving will ensure that the finished part will
retain its shape after the final machining.
Finish machining. Milling, drilling, turning, finish grinding, jig boring, jig
grinding, honing, lapping, EDM, etc.
Heat treating (hardening) (see Section 5.1.2.9)
Hobbing of cavities. The method of producing cavities by hobbing is rarely
used today. For details of this technology see [5].
Finishing, engraving, texturing, polishing (see Section 2.1)
5.1.2.5 Cost of Special Gages
This includes the cost for any gages, fixtures, or other devices that are required
to assist in machining and/or checking of this particular mold. It includes
the cost of gages required to check special tapers and the cost of any special
tools used to facilitates machining, which will save significant time when
making any number of identical mold parts. If the cost is included in the
mold cost, the customer should have the right to these manufacturing aids,
but they could also be kept at the mold maker for future use for similar
molds for this customer.
5.1 Mold Cost and Records
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5 Mold Cost, Mold Price and Delivery
5.1.2.6 Cost of Electrodes for EDM
Electrodes to produce the necessary shapes are usually machined from special
carbon compounds or longer lasting, special copper alloys. For a large number
of identical shapes, electrodes can also be molded or cast from special alloys
by specialists in this field.
Which type of material to use, or whether to use machined, molded, or cast
electrodes is a question of economics and the required accuracy. In any case,
the cost of making or buying the electrodes must not be overlooked; in
addition, the cost of the special wire for wire EDM must be included in the
mold cost.
5.1.2.7 Cost of Plating
Hard chrome, flash chrome, or electroless nickel-plating and other surface
finishes are best left to specialists. The cost is considered part of the mold
cost.
Note that if any change to a part already chrome-plated is required, the plating
must first be removed (by a method similar to the plating) before re-
machining. After the changes, the part must be plated again before assembly.
Plating and other surface treatments are rarely done in-house. The time delay
and the transport costs can be substantial and the decision maker should
consider selecting a different mold material, even if it is more expensive or
more difficult the machine. Typically, chrome-plating can be avoided by
choosing a suitable stainless steel.
5.1.2.8 Cost of Transportation Between Shop and Service
Providers
Include the cost of transportation to and from specialists of any of the
machining operations subcontracted by the mold maker. Operations and
services performed by outsiders may include any job beyond the capacity of
the mold maker’s equipment, or not within his expertise, or they may be less

costly than doing them in-house. Also, the shop could temporarily be
overloaded and it would be preferable to purchase the necessary service
elsewhere to avoid delaying the job. The cost of transport is easily overlooked.
Some mold makers consider this cost as overhead, but it should really be
charged to the mold.
5.1.2.9 Cost of Heat Treatment
Many mold makers use outside sources for heat treatment of the mold parts.
Most heat treatment shops have regular (often daily) pickup and delivery
services and this cost is usually included in the price for their service. Because
the heat treatment for most mold or tool steels is different from each other
and varies to achieve different hardness and toughness conditions of the
steel, it is good practice for the mold designer to specify (wherever possible)
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only a carefully selected, small number of different steel types and range of
hardness.
Occasionally, the designer can select from a small number of most frequently
used “standard” steels, which can be treated to a condition almost as good as
the most suitable but rarely used steel. This allows simplifying the handling of
the heat treatment and shortening the time for the work pieces to be returned.
Some mold makers do their own heat treatment on a selected, relatively small
number of steels and subcontract only those parts that are outside the
capability of their own facility, e.g., if the parts are too large for their furnaces
or because it is a steel for which they have no facilities or experience in heat
treating.
5.1.2.10 Cost of Inspection
Inspection of mold parts between the various manufacturing steps and after
completion of a part is essential. The more often the work pieces are inspected,
the less is the likelihood that a “spoiled” part continues through more
operations on its way to assembly, where it will be discovered to be defective.

However, inspection can be very expensive. Most mold shops have their own
methods and practices to minimize the cost of inspection; some have
inspection stations located near certain machine tools or between the various
groups of machine tools; some have central inspection stations, to avoid
duplication of the usually very expensive testing equipment; some educate
the machinists to check their own handiwork, some depend on independent
inspectors. There is high cost incurred with checking; this could be charged
to the mold cost, but it is often considered part of the general overhead.
5.1.2.11 Cost of Assembling
In some mold making shops, a “lead mold maker” will do the assembly himself
or supervise the assembly process by technicians or the machinists themselves,
but in larger mold shops, the mold assembly is mostly done independently
of the manufacturing of the mold parts.
Ideally, if all drawings are correct and the parts are made to specifications,
assembling a mold should not be more difficult than assembling any clean,
delicate machine or apparatus. The parts are supposed to fit and nothing
more than standard or torque wrenches, a soft hammer, and lubricants should
be required to assemble a mold. The ancient method of fitting mold parts by
filing or grinding should not be used. If parts do not fit as they should, they
must be returned to the design office, to establish why they don’t fit and who
was at fault: the designers, the machinists, or the suppliers. Any corrective
action must originate with the responsible mold designer and be properly
recorded for the future, especially if repeat orders are expected.
To make changes to mold parts without this practice will only perpetuate
the error. Any costs incurred should be charged against the department from
which the error originated and not recorded as part of the mold cost.
5.1 Mold Cost and Records
Standardize on the types of steel
selected if possible
Figure 5.3 Mold assembly area

(Courtesy: Topgrade Molds)
Inspection is expensive but saves
money in the long run
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5 Mold Cost, Mold Price and Delivery
5.1.2.12 Cost of Mold Testing
Today, many mold makers have at least one molding machine for mold testing.
If the machines in-house are not suitable for the mold to be tested, the mold
maker will have to test the machines at the molder who ordered the mold. If
this is too difficult because of distances and possible need for crossings of
national borders (with all the problems of custom duties, paper work, etc.,)
or because the customer does not want to interrupt his production just for
testing a mold, the mold maker could buy machine time from a (close-by)
molder.
One way or another, testing a mold adds to the cost of the mold. Where and
how the mold will be tested must be discussed at the time of ordering and
testing time and machine time should be included in the mold cost. The
actual cost of testing, i.e., the time of mounting the mold in the machine,
startup, getting the mold on cycle and running it “hands-off” (i.e., without
any further adjustments) for a specified length of time (typically 2–4 hours,
sometimes more) and then shutting it down and removing it from the
machine is only part of the test. The molded products from each cavity must
be inspected for visual defects, measured for accuracy, and possibly tested
for their intended performance. This of course takes time, and the mold
maker may have to wait days or even weeks until the product, and the mold,
is accepted.
But there is also another, very important, purpose of testing: can the
productivity be improved by changing molding parameters or even by
changing some features of the mold or its auxiliary equipment to reduce the

cycle time? This can take much longer than the planned original testing. In
some cases, the customer or molder will make these tests in his own plant,
after receiving the mold.
An unfortunate but quite frequent result of testing is the discovery that one
or more dimensions of the product are outside specifications, either in all
cavities (design or concept error), or in only some of the cavities (manu-
facturing or concept error). In this case, the mold needs to be removed from
the machine and dismantled, the “offending” mold parts altered or replaced,
or in the worst case, the mold design needs to be changed. This also means
retesting of the mold.
Part of a proper testing program is the issuance of a setup guide, detailing
all molding parameters used for the final, nonstop test run, which pro-
duced the test samples. It should be mandatory that the responsible mold
designer be present during all testing procedures of “his” or “her” mold to
see first hand and learn from any problems as they show up, during the
installation, and the running of the mold. This person is then also respon-
sible for any remedial action, for recording any problem, and to make sure
that they do not occur again in the future, not only in this type of mold,
but in any other mold having similar features. Even if several identical
molds are made at the same time, for the same customer, they all must be
individually tested.
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Molds are often tested several times before the mold is finally accepted. While
the first (and sometimes the second round) of testing are expected and often
included in the mold cost, additional testing is probably the fault of the mold
maker, not of the customer. Retesting is expensive, but is not really part of
the mold cost; rather, it must be charged to the learning experience of the
mold maker and should not be added to the mold cost. If the same mold will
be required again later, the error causing the trouble should not be repeated,

if good records have been kept of all the errors and the remedial actions.
In some cases, a representative of the customer is present at the tests and can
accept the mold right then and there. More often, the product samples must
be shipped to the customer for approval, which means that, while waiting,
the mold will have to be removed from the machine to make room for other
uses of the machine.
5.1.2.13 Cost of Errors
Costs incurred after testing because of necessary adjustments and rework
due to mold maker’s or designer’s errors or inexperience must never be
charged towards the mold cost; however, they can be foreseen in the “risk
factor” used in determining the mold price (see Section 5.3.1).
5.1.2.14 Cost of Product Design Changes
Product design changes while the work on the mold progresses are, un-
fortunately, quite common. It is important to establish (estimate) any
expected cost increases caused by such changes at the time the change is
requested and to have the customer to agree to pay for it.
A simple change while the mold is still being designed could have a negligible
effect and its additional cost could be ignored. A more complex change could
be quite significant, even requiring redoing one or more mold parts. It could
even affect the planned mold design, the estimated mold cost, performance,
and any quoted delivery time. The further the job has progressed, the more
expensive can even a small change, such as the diameter of a core pin, turn
out. Many unpleasant discussions or arguments between a mold maker and
a customer can be avoided, if the effect of a change on the quoted mold cost
is discussed and clarified at the time of the request for a change and not
when the mold is already finished and approved by the customer.
5.1.2.15 Cost of Crating and Shipping
Depending on the sales contract, costs of packing and shipping are often
borne by the customer; if not, they must be included in the mold cost. These
costs can be substantial, especially if the mold must be packed in a seaworthy

crate or shipped by air. This point must also be clarified at the beginning and
confirmed in writing.
If the mold maker makes a mistake,
he cannot increase the mold price
but must absorb it. Similarly, if the
customer made a mistake in the
product drawing or changed his
mind regarding a feature of the
product after the mold job is started,
he too will be responsible for any
costs caused by the requested
changes
Note that everything agreed upon
must be confirmed in writing
5.1 Mold Cost and Records
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5 Mold Cost, Mold Price and Delivery
5.1.3 Cost of the Preparation of a Mold Manual
When buying an automobile, a kitchen stove, an electronic appliance, or an
electric shaver, we always expect to receive an instruction manual to tell us
how to properly use it, even if we know how to drive or how to use any of
these gadgets. Every user expects from the manual to explain safe use, the
necessary upkeep and maintenance schedules, how to trouble shoot it, and
where to get help, and so forth. The same applies when buying a mold.
A proper mold manual is expected not only to describe the mold (mold
drawings, bill of materials, wiring diagrams, timing sequences, etc.) and how
to operate and maintain the mold properly. It will also contain data on
products used in the mold that were supplied from vendors (valves, actuators,
etc.). It should also contain a test report from the final testing at the mold

maker that should give the optimal settings and conditions at that time. This
does not mean that the molder will not have ample opportunity to change
the suggested settings to further improve the mold’s productivity, but it means
that the suggested conditions and settings were optimal, at the time of testing,
and give a good starting point for the customer starting up the mold.
A table of contents of such a mold manual is shown in the Appendix. It is
obvious that to assemble a good, comprehensive mold manual as suggested
is time-consuming and costly, but it will serve the customer well, especially
when operating the mold for years to come.
5.2 Overhead
This is not meant to be a book on accountancy practices and we are not
presuming to suggest how to determine the overhead rates that will be used
in the calculations of the mold costs. Each plant has its own management
and accountancy methods and will decide how to arrive at an appropriate
overhead rate.
Here, we would like to show what is usually included in overhead:
 Buildings and land: rent (mortgage), heating and air conditioning,
cleaning, maintenance
 Power, water, other supplies not attributable or chargeable to a project in
progress
 Interest on moneys owed
 Insurance (public liability, fire, etc.)
 Indirect labor: salaries and benefits required to run the offices and plant,
except for those whose time is directly chargeable to the customer
 Cost of administration (management, personnel, accounting, purchasing,
sales, security, etc.)
 Communication (telephone, etc.)
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 Transportation (cars, trucks, travel, etc.)

 Office computers, furniture, and supplies
 Plant supplies, oil, cutting fluids, small tools
 Production planning
 Investment in checking (inspection) equipment, usually spread over
several years
 Other costs associated with the smooth running of the plant
The total of all these expenses over each year is divided by the number of
hours of all those employees (engineers, designers, machinists, assemblers,
mold testers, etc.), whose time is charged directly against the project they are
working on, and which in turn will be paid by the customer.
By increasing the productivity and the quality of the shop equipment, e.g.,
by buying better (or newer) machine tools, the overhead will go up. However,
the time required to make a mold part should decrease, for example, by being
able to cut more steel per hour, or by reducing the setup time of the work
piece, or by having one machinist operate two or more (automatic) machines.
This can greatly reduce the direct labor portion of the mold cost.
However, this type of investment in plant and machinery will only be
economical, if the new machines will work enough hours per year so that
the hoped-for savings in labor are greater than the increase in overhead.
5.3 Mold Price
Mold “price” is the amount quoted by a mold maker to the prospective
customer, either directly, but quite frequently indirectly, through the molder
who will (possibly, but not for sure) make the products. The problem for the
mold maker is that in many instances, a customer will approach three or
more different molders, who in turn will then approach three or more mold
makers, so that it is quite possible that nine or more mold makers will be
requested to quote for the same job! I remember a time, when within one
week inquiries for molds for the same product from three different molders
landed on my desk. It is obvious that in such a case, only one mold maker
will get the job, but it is also possible that none of them will get the job,

because it could be just an early inquiry to find an approximate mold cost to
assist in establishing the cost for a new product, which may or may not,
come into production. There are exceptions to this, if, e.g., a customer needs
a few identical molds in a hurry and could ask several mold makers for quotes
and then lets some or all of them build these molds.
There is another serious problem with this method of approaching many
mold makers for the same quote. Although this should not be the case,
unfortunately, the mold maker with the lowest bid often (probably) did not
have the experience with this type of product or mold and has greatly
5.3 Mold Price
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underestimated the work to be done. This could be bad for the buyer, who
may then get an inferior mold, but also for the mold maker, who will probably
lose money on the job. A conscientious mold maker will try to build a good
mold, even if he or she will lose money on it. After a number of under-priced
mold orders, a molder who keeps losing money will eventually go out of
business. On the other hand, deliberately quoting high is not helpful either,
because there will be no buyer to purchase at the quoted high price.
There is, however, a leveling influence in the trade: a shop that always bids
low will get a lot of jobs, which will fill the shop and require extended deliveries
for new prospective orders. Because there are only a limited number of mold
makers that are easily accessible to a molder, shops with higher prices will
then also get busy, and the shop with the lowest prices will gradually learn
from the gained experience to make better estimates in the future.
A short but significant story from an earlier experience: In the 1950s,
I was designing mostly tools and dies for metal parts, but also plastics
molds, at a large electrical manufacturer. We had our own large tool room,
but sometimes there was so much work that we had to subcontract the

excess. At one occasion, we needed 35 blanking and forming dies for a
rush project very quickly and had all designs detailed and ready. To get
sooner into production, we planned to place orders with several suppliers.
I invited twelve tool and die makers to quote. We had previously worked
with nine of them; three we did not know. I told them that nobody was
going to get all 35 jobs and grouped them so that each group was for one
specific product. Everybody picked up the already prepared drawings and
within days, most quoted on just two or three groups according to their
preference, but all 12 die makers quoted on one specific group of 6 dies.
Before, I had already estimated the cost for this group at $6,500. The quotes
came in as follows: $2,650, $4,000, eight were between $6,200 and $6,800,
one was $8,500, and one at $10,250!!! (Note that at that time, $1,000 was
a lot more money than it is today). I went to see the lowest bidder whom
I did not know. He was a farmer, outside the city, who had in his barn a
lathe, a small milling machine and a small surface grinder, all second hand,
with virtually no overhead. He told me he wanted to become a tool and
die maker, but had so far only experience in jigs and fixtures. I also talked
to the boss of the firm that quoted $10,250, whom I knew quite well, and
asked him how he arrived at such a high price. The answer was that he
had lost money the last time he built some dies for us, and wanted to
recuperate his loss! Needless to say that neither of these two got the job.
The moral of this little story is that
(1) Experience is needed when quoting
(2) One can never recuperate in one job losses suffered on a previous job.
(3) It also points out the importance of knowing the suppliers you work
with, by visiting them, and by getting references, if possible.
Buying on price alone is a very risky
proposition
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Our company had a policy that stated that when letting a contract we must
make sure that the supplier had not made a mistake in quoting and that we
must never select a supplier based on the lowest bid alone. This is mainly in
the company’s interest. If the supplier loses money, he will go under; if he
makes money, he could become be a good and reliable supplier. Unfortunately,
many buyers, often at larger companies, used to place all their orders with
the lowest bidder, regardless of other considerations. And all too often, the
lowest bidder was the one that made mistakes in estimating or was not familiar
with the subject. The result was that many tool and die makers (and this
applies to mold makers as well) always lost money with these customers, and
in future just refused to bid for them at all, or only quote jobs where they
expected not to get into trouble.
Once the proper mold cost has been estimated, we must add profit to it, to
arrive at the mold price to be quoted. Never forget that in order to stay in
business, the mold maker must make a profit, or he will eventually be forced
to close down.
5.3.1 Risk Factor
When quoting any new mold, it is very important to consider the possible
risk taken, based on our familiarity (or lack thereof) with the product or the
type of mold; however, there are other factors, which are all purely business
decisions.
The first question must always be: is the product similar or, better yet, identical
to one for which we have built molds before? In this case, there should be
little or no risk.
If the product is similar, but a different number of cavities is required or,
possibly, the runner system is different from one we have done before, or if
the wall thickness is smaller than we had experience with, or if there is some
other point where there may be need for some (costly) learning experience,
it may be wise to add a risk factor of approx. 10–25% or even more to the
estimated cost. This depends on how certain we are that the planned mold

will work as expected.
If the product is different but still within the range of products for which the
mold maker has already built molds, the same or even more “risk insurance”
may have to be added.
If we believe that we are entering unknown territory, we should consider
either to decline quoting at all, or adding a high enough risk factor so that, if
the quote is accepted despite a high price, there will be enough money to
learn on the job and build a good mold.
Most customers understand that there is nothing gained if the mold maker
is not familiar with the type of mold required. I have often refused to bid
and suggested to the prospective customer some other mold maker more
familiar with the type of products for which he wanted a mold, not because
5.3 Mold Price
There is a risk with every quotation
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we could not have made it, but because the customer would be better served
by a specialist in that field who could provide not only a better mold but
probably at a lower price and with shorter delivery. Such customers were
always grateful for this approach and came back when they had a job in our
line of expertise.
5.3.1.1 Development Design
Sometimes, a mold maker may consider a new or unfamiliar product and/or
mold as a challenge. If technologically solved successfully, it could open up a
new field of expertise with the potential for manyfuture, profitable sales. In
this case, the mold maker could just add his ordinary markup to a relatively
low, “guesstimated” cost, and absorb any cost above this as the cost of “learning
experience” and consider it as “product development cost”.
There is also another approach when “charting unknown waters”. It works

well if there is a good relationship and trust between customer and mold
maker and if the mold maker has a reputation for making good molds and
for developing new, or improving existing technology. In such case, the
customer will readily agree to pay a quoted price for engineering and design
time to develop a new mold design (or molding method) and even for any
costs of prototypes and experiments, in order to arrive at a mold price based
on such preliminary work. The customer can then, depending on the terms
of such a “research” program, retain ownership of the tentative designs and
hardware. If the job goes ahead, the finally estimated cost of the design time
for the mold or project will be reduced by the amounts already paid. In my
own experience, most such design contracts have resulted in orders. The
molds and any connected equipment could always be reasonably well
estimated and quoted and the customer was better off this way. If a job did
not proceed it was mostly because of economical rather than technical
reasons.
In injection molding, there are very few things that are impossible to do and
if a project was dropped, the reasons were usually either very high mold and/
or system costs or the final cost of the product could not be economically
justified.
5.3.1.2 Deliberately Low Quoting to Get a Job
This is sometimes done if business is slow, so that rather than laying off and
losing skilled, hard-to-find workers, the mold maker could decide to forego
adding profit to the estimated mold cost or even go below cost just to keep
the operation busy until more work comes in. This, however, can be risky: at
the time, it may appear to be a good move and the mold maker may be able
to fill up the shop with marginally profitable or even money-losing jobs, but
the shop may not be able to accept (for reasonable delivery time) other,
profitable jobs.
When working on new
developments, have the customer

participate and share the
development and design costs
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5.4 Mold Cost Is Absorbed by the Molder
In the following, we will consider the question: Who pays for the molds?
Ordinarily, a customer buys a mold from the mold maker, either directly or
through the molder, at previously established price and delivery terms. But
there is a notable exception to this: whenever the molder has control over an
in-house mold making operation, but also, if the molder must purchase the
mold from an independent mold maker, the molder could decide to absorb
some or all of the mold costs, particularly if there is a contract for a large
production run at stake, possibly spread over several years. In such cases, the
mold cost per unit of the product could be negligible. However, a problem
could arise with the ownership of the mold. This should be settled at the
time of the contract for the product order. It is very tempting for the customers
not to have to spend much or any money up front for a mold, but the mold
is then locked in with the molder and the customer cannot remove the mold,
e.g., when planning to change the molder. Also, if the molder goes into
receivership, the customer must be able to prove that the mold belongs to
him before being able to get possession of the mold.
Another, somewhat similar, scenario is when the molder has universal mold
shoes and buys or makes a suitable number of stack inserts, which are
probably only suited for the mold shoe for which they were built. This
arrangement is less expensive for the customers but could also lock in the
stack inserts with the molder.
5.5 Arriving at Mold Cost and Delivery Time
Over time, experience has taught mold makers (and this applies mainly to
those for whom the business is to build molds as their product) that only a
fraction of inquiries for mold prices and requests for quotations will ever

result in an order. The problem is therefore how to arrive at a reasonable
estimate – not too high and not too low – and with a reasonable delivery
time, without spending too much time on estimating. In the following are
some hints about how to go about this issue.
To my knowledge, there is no definite or perfect method of estimating a
mold cost. Don’t forget that the very term “estimate” implies an uncertainty
and risk, both for the vendor and the buyer.
The least risky case is when the mold maker specializes in only one or just a few
selected types of products and mold sizes and can standardize them to such
a degree to be able to even make a sales catalogue and a published price list for
these molds, for example, by size of (similar) products and a certain, limited
number of cavities. In this case, there is virtually no risk involved at all.
There are many mold makers who specialize exclusively in certain molds
and research ever better methods of molding to assist the customer in getting
5.5 Arriving at Mold Cost and Delivery Time
Ownership of the mold must be
clearly established
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better productivity. They invest in better and more economical methods to
manufacture the mold components with shorter deliveries. These mold
makers specialize, e.g., in molds for bottle caps, disposable thin wall con-
tainers, toys, large pails, pallets, crates, PET preforms, small gears, and many
more. It is very difficult for a “general” mold maker, who builds any kind of
mold for any shape of product, to compete successfully with the specialists.
5.5.1 Calculating the Mold Cost
It is possible to calculate correctly the machining times required for any and
each (mold) part by breaking it down into the various elements (steps) of
manufacturing from raw material to the finished part, including all handling,

setups, machining, checking, and so forth. This is done quite commonly in
any industry where large numbers of the identical or similar parts are made,
such as in the automotive industry, using time study methods and by
determining for every operation the optimal machining methods, thus
arriving at an accurate manufacturing time (and cost) for each part. Ob-
viously, such method requires a lot of time and is based on the availability of
detailed part drawings.
5.5.2 Estimating the Mold Cost
Typically, at the time of estimating,
 We don’t have detailed part drawings for every mold part,
 Even if there were detail drawings, economically we could not devote
that much time to estimating by breaking manufacturing down to its
single step operations and timing, and
 We would still have to guess assembly times and all the other times, such
as designing and testing.
In fact, at the time of estimating, usually, we don’t even know how the mold
will look or how large it will be, to determine the cost of materials, hardware
items, and other costs. Proper estimating is based on past experience. Without
experience (records, personal memory, and understanding the facts), every
estimate is just a guess.
As an oversimplified example, let us examine the case of a mold maker with
enough money not to go out of business after building a number of molds
that were underestimated because of lack of experience. The first mold was
estimated much too low, resulting in a large loss. The next one was estimated
too high and no sale resulted. When the next mold (for a similar product as
in the first mold) is quoted, this time, already prepared with some experience
from the first molds quoted, the mold maker arrives at a better estimate. The
mold could be quoted deliberately low to get a better chance of getting the
Calculating the mold cost accurately
is impossible

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job. After building this mold, the mold maker has now gathered more real
experience, but just in this type of mold, and hopefully begins to establish
some reputation of building good molds in this line of products.
This could lead to more lucrative mold orders. But if a new inquiry for a
mold for a different type of product arrives, the same uncertainty will repeat
itself. Slowly, over many months and even years, the mold maker will get to
the stage where he can refer to a fairly large number of precedents and his
estimating becomes more accurate. The problem was (at least in the past)
that many mold makers have jumped from job to job and have accepted just
about any mold inquiry that came their way, regardless of their familiarity,
or lack thereof, with the product. They had to “guess” many times and
probably lost money on many of these molds.
The trend today is to specialize in a limited field of products and refuse jobs
outside one’s expertise. This benefits both the mold makers and their
customers. There is no substitute for trust and good, positive relationship
and cooperation between the mold makers and their customers. Once the
customers are aware that the mold maker is on their side and helps them to
reach their goals by improving the quality of their products and the pro-
ductivity of their machines, there is usually little objection, even if the mold
price is higher than that of competitors who are just interested in selling a
mold. After all, as we have stated earlier, in mass production, the mold price
per unit represents only a very small component of the cost of the product.
5.5.2.1 Past Experience
We always learn from our mistakes, as well as from our successes; but we
must never believe that because the last (similar) job seemed to have worked
well, we should blindly repeat that design. When looking at an older design,
we should always ask ourselves:
 Was it really the best we could have done?

 Were there any problems with it?
 Could we improve on it?
 But, even if we could change the design for a better mold, is it worth the
risk?
Over the second half of the 20th century, the plastics molding technology
has advanced in great strides. A large variety of new plastics have given us
the choice of many new molding compounds, some of them requiring new
molding techniques, as well as new molding machines with more and better
features, thus resulting in new approaches to mold design. A mold, which
was on the cutting edge of technology only a few years ago, probably would
not be built today the same way. But considering the stack parts or the mold
shoe, there could still be many similarities with an older mold. Machining
times have also much improved over the years, with the use of CNC and
5.5 Arriving at Mold Cost and Delivery Time
There is nothing that replaces past
experience, especially if the
experience was bad
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automated machine tools. Even though standardization and CAD/CAM has
reduced the design and work preparation times, we can still use at least some
of the old machining times as reference for an estimate.
5.5.2.2 The Importance of Accurate Records
The most important assets of a mold maker are his records of earlier molds.
These records, kept in the “job file”, consist not only of the drawings and
Bills of Materials (“BoM”) of a mold made earlier, but also any records
showing the actual times worked on the various steps, such as designing,
machining, assembling and testing, and any test reports generated at the
time. It is still better for these records to be also kept in computer files, because

it will be easier and faster to retrieve old references for estimating, without
the need to go manually through filing cabinets, and the danger of losing
hardcopy in the process, or misfiling when returning the files after use.
5.5.2.3 Anticipated Mold Design
Before proceeding with any estimate, we must have some idea how the mold
will look. This is easy if we have a good precedent. In this case, we will probably
also have good data of the cost of the precedent mold(s) and there is not
much risk involved when quoting the new mold.
If we have no precedent, or just similarities with an earlier mold, it will be up
to the estimator (maybe with the help of a mold designer) to make a few
sketches, primarily of the stack and then of the overall mold. The sketch of
the stack can often easily be imposed on top of a significant cross section of
the product drawing, provided we have such drawing to work from. We can
then also check how any specified tolerances will affect the mold cost. If
working from a sample or model, a sketch of the significant cross section
will have to be made by the estimator before starting to plan the stack believed
to be most suitable for the job.
There is never just one possible solution in mold design, but unfortunately,
an estimator usually does not have enough time allotted to an estimate to
come up with several ideas, and to select the most promising one. In addition,
if two or more estimators work on the same project, each one will probably
come up with a different layout. This is the risk of estimating. Only if the
job results in an order, the designer eventually assigned to the job, will have
enough time to consider the product from all angles, before arriving at a
suitable mold design. This may ultimately look quite different from the
design sketch used to estimate the mold cost. It is good practice to have the
sketches made by the estimator passed on to, and discussed with, the mold
designer.
5.5.2.4 Times and Materials Required
Once a reasonable design for a stack (with all its appendages such as actuators,

ejectors, etc.) and the overall sizes of the mold has been sketched, the estimator
There is always a great risk when
working from a sample or model,
because of the absence of
dimensions and, more importantly,
specified tolerances
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can proceed to determine the approximate times required to make one stack
and any special features and the mold shoe and the expected time for
designing and mold testing, based on identical precedents or on similar jobs.
In the case of multi-cavity molds, the estimate for one stack can usually be
multiplied by the number of stacks, while allowing for any possible savings
(cost reduction) by using fixtures etc. or other mass production helps, so
that making N pieces will usually cost less than N times the cost of one piece.
These estimates assume the time (hours, days, or weeks) required for
designing, machining, assembling, and testing of the whole mold. The planned
mold, for which there are no precedents, can also be broken down into smaller
entities such as cavities, cores, the ejection mechanism, the separate mold
plates, and so forth.
To this must now be added the cost of raw materials, hardware items, standard
mold components, such as hot runners, heat treatment, and any other
foreseen subcontracted costs. The more detailed the records of previously
made molds and mold parts are, the closer will the estimate be. After
multiplying the hours with the plant rates and overhead rates as they apply
(at the time of the estimate) and adding the estimated costs of materials and
all other costs, the risk factor should be considered and must be factored in,
if deemed necessary. This estimates the total cost of the mold, (labor and
materials) ready for quoting, but before any profit has been added, which is
usually outside the responsibility of the estimator, but rather in the hands of

a sales organization or the management of the mold maker, who will consider
all other factors to arrive at the mold price, as already discussed earlier.
Most mold makers use this method. In smaller organizations, a top mold
maker or designer may be involved. Larger plants often employ one or more
dedicated estimators, usually experienced mold designers or machinists,
whose full-time job is to estimate any mold inquiries that could result in
orders. Obviously, this can result in higher overhead.
While some estimates could require less than one hour, e.g., with a perfect
precedent, others could take several hours or even days to arrive at a
reasonable cost. In some operations, it is practice to have management
involved even before the estimator gets a chance to see any inquiry, to establish
if it is worthwhile to spend time on it. Large manufacturing companies often
send out inquiries for molds just to find out how much they would cost.
They often have their own mold making facilities and have no intention to
place any order with somebody else. It could be a complete waste of time to
estimate such jobs. Also, inquiries could come from companies with poor
credit ratings, or poor payment records, and management could decide not
to waste valuable time on them.
5.5 Arriving at Mold Cost and Delivery Time
An estimator makes or breaks
a mold-making business
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5.5.3 “Guesstimating” the Mold Cost
Because accurately calculating the mold cost is practically impossible, most
mold makers use the method of estimating described in Section 5.5.2.
However, there is another method that is simple and inexpensive, but quite
risky, and should not be used unless with ample, long experience in the type
of mold to be estimated. It requires essentially two people, both with good

experience. Both estimators visually inspect the sample or drawing to evaluate
its complexity (shape, size, accuracy required) and jot down on a slip of
paper their estimate of the cost to build the mold. This may take maybe five
minutes or even less.
They then compare these figures; if they are in agreement, a mold price will
be quoted. If there is little difference, the higher one will be selected. If there
is a substantial difference, they will discuss the reason for their lower and the
higher estimate. It is possible that one estimator saw something that the other
overlooked. If both agree on a new figure, the quote will be on this basis. If
there is still a doubt, sketches will be made as explained in Section 5.5.2,
which of course takes much longer.
5.5.4 “Ball Parking” the Mold Price
Quite often, a customer asks the mold maker for a “ball park estimate”, i.e., a
preliminary, approximate estimate for a mold or a whole project. “Ball
parking” should never be given without a written understanding that it is
not a binding quotation. It is meant solely to give the customers an idea for
a mold price that they in turn can use for estimating a product cost. A ballpark
estimate can be arrived at the same way as a guesstimate (see above) and it
only means that the final (quoted) mold price could be somewhere around
± 20% of the “ball ballpark” quote. Most mold makers ball park high to make
sure the customer will not be shocked by the final price.
5.5.5 Mold Price Catalogue
The easiest method of estimating, with the smallest risk, is associated with
specializing in one narrow range of products so that there are established
mold prices, which can be used and priced by any sales person, even without
mold or estimating experience or it can be determined by the customers
themselves. As long as the new product fits within a listed, usually limited
range of sizes and for a specific, listed number of cavities, regardless of the
actual dimensions and shape of the product, a mold price is listed. This
method is used by mold makers specializing in a number of different products,

from small bottle caps to large industrial pallets.
The risk for the mold makers is that the mold prices, which are ordinarily
kept confidential, are open to everyone, which makes it possible for an
aspiring competitor to underbid. On the other hand, the customer should
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know that buying from an established specialist means usually getting the
benefit of long experience, better quality molds, higher productivity, and
faster delivery.
5.6 The Quotation
Any quotation (“quote”) to a customer should contain at least the following
details
1. Date of quotation
2. Specification of the quoted mold, and any other specifications applying
to the use of the quoted mold, such as the type of molding machine and
ancillary equipment. It should also indicate certain details about the
planned mold, e.g., type of gating, estimated cycle, responsibility for
shrinkage, and so forth (explored in detail in the foregoing text)
3. The quoted mold price (explored in detail in the foregoing text)
4. Time period, for which the quote is valid (important, especially, if there
is much activity, many inquiries and heavy shop loads) so that any long
delay in accepting the quote could seriously affect the quoted delivery
time
5. Delivery data to testing the mold, from receipt of order and complete
drawings (will be discussed in Section 5.6.1)
6. Shipping method (subject to negotiation between customer and supplier)
7. Payment terms and conditions (subject to negotiation between customer
and supplier)
8. Warranties and disclaimers (will be discussed in detail in Sections 6.1
and 6.2)

9. There could be other items included in the quotation.
See sample of a quotation in the Appendix.
5.6.1 Delivery Time
Delivery time is an important part of any quotation. To determine a delivery
time, the estimator uses the same data as for the costs, the time that is required
to perform the necessary work (designing, machining, assembling, and
testing); however, a delivery promise is also dependent on the available time
in any of these areas and on how soon the job can be started. It is common to
quote “delivery to testing” rather than “delivery to shipping”, to make the
customer is aware that testing could reveal unforeseen problems, which will
have to be solved before shipping.
5.6 The Quotation
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Plant loads and conditions change constantly. Everybody could be busy today
but may be looking for work in a month or two. Quotations usually indicate
deliveries that would be possible, if the order is placed now or within a short
period of time. The delivery is based on the shop load at the time of quoting
or expected to be within the next few weeks. Because the shop load changes
continually, every quotation must clearly limit the time during which the
quotation is valid.
However, this also bears a risk for the mold maker, who is continuously
submitting quotations, usually in the order as they are requested, but knowing
full well from past experience that only a fraction of them will ever result in
purchase orders. While it would appear to be a great success for the mold
maker, if the backlog of orders increases, i.e., when more orders are received
than can be shipped, the wishes of the customer (for early delivery) must
not be ignored.
The obvious answer would be to increase the number of hours available for

design, manufacturing, etc., but this is not a practical solution, because more
space, capital for equipment, and most of all, more skilled personnel would
be required to make use of such an immediate expansion. Working overtime
is usually a simple solution, but in some localities, the number of overtime
hours is legally limited. Adding shift work in some areas could help, provided
the necessary qualified personnel could be found in time. One solution
available to the mold maker is to subcontract some of the work. It is quite
common with smaller mold making operations to subcontract their design
work and many mold makers subcontract some machining and finishing
operations, as has been discussed earlier.
5.6.2 Confirmation
Any quotation should always contain the cautionary phrase “subject to
confirmation”. With these words, the mold maker reserves the right to have
another look at the quotation and to see how it will affect the shop load,
before finally committing to a delivery time with a formal “confirmation of
order”. The formality of confirmation also gives the mold maker another
opportunity to look at the quoted price: since the customer is now obviously
serious about ordering the mold, it is wise to make sure that the price was
quoted properly. At this time, there could be some serious discussions between
mold maker and customer, if an extension of the originally quoted delivery
time, or even a higher price should be asked by the mold maker, but it is
better to have an argument now, even risking to lose the order, rather than
losing money on the job or having unpleasant arguments, or even law suits,
later. Once the customer accepts the confirmation, the mold maker must do
everything to ensure that the delivery date is kept. There is nothing worse
than promising a delivery date that cannot be kept. It is good practice for the
mold maker to keep the customer regularly informed (weekly or monthly)
about the status of an ordered mold and the mold maker must advise the
customer as soon as something occurred that could affect the delivery date.
There is nothing worse than

breaking a delivery promise
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The mold maker must never forget that the customer too has a responsibility
to the people who expect the molded products.
Every mold maker would be happy if the volume of work passing through
the shop were constant. Unfortunately, this is never the case and it is usually
“feast or famine”. Mold work is always seasonal, e.g., much work in Fall and
Winter and then tapering off towards Summer, but there are also other factors
affecting these fluctuations, which makes it always difficult to accurately
forecast the shop load. No mold maker wants to lay off skilled personnel when
there is little work; many workers, and especially machinists, prefer to work
overtime during “feast” periods and regular or even shortened hours during
a “famine”. The best way for planning has always been to have a good backlog
of orders of a few months, usually from customers who don’t mind waiting
longer, because they know from past experience that they will get a good job.
At the same time, the mold maker should always keep some shop time open
for unforeseen problems. See sample of a confirmation in the Appendix.
5.7 In-House Mold Making Operations
There is really little difference between independent mold making operations
that make their living from making molds and an in-house mold making
shop, which is part of a molder’s operation or at least under his control.
Today, almost every molder has some facilities (a few selected machine tools
and some skilled mechanics) to service molds and fix minor mold problems,
often right in the molding machines; some also can make major repairs and
perform regular and major maintenance functions on the molds. From there,
it is only a small additional step to make use of these facilities and the mold
maintenance personnel, especially during periods when they are not otherwise
busy, to build stack parts, stacks, or even complete molds. Over time, some
additional equipment may be installed and mold designers are engaged, so

that the molders could eventually be in a position to build their own molds.
These are usually molds similar to those that are in operation in their molding
plants and with which they are familiar. These molds will then often not be
estimated or valued on their real cost, but much lower, because the machining
and assembly times are not considered at all, or maybe only partly, because
the machinists and technicians are there anyway and would be idle if they
would not be working on a new mold. In addition, the molder could save by
accepting shortcuts in mold design and construction, which otherwise would
not be acceptable. This can (and often does) permit a molder to quote to a
customer prices well below those quoted by an independent mold maker.
Problems with this approach are:
 These molds will be more or less copies of existing technology and there
will be few new ideas or improvements over the old methods so that the
molder loses out on any advances in technology, which are constantly
developed by independent mold makers.
5.7 In-House Mold Making Operations
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