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2

Starting New in the Mold Design
Field

The only prerequisite for the beginner is some knowledge of mechanical
drawing delineation, whether it is done electronically on a computer (with
programs like Autocad) or on the drawing board with pencil. Of course, the
designer must also be familiar with some areas of basic arithmetic and
trigonometry; both are required to put dimensions on the mold parts so they can
be machined. Some of the advantages of electronic drafting are the following:
(1) Designs of entire, or portions, of earlier built molds can be easily used
again by simply copying or modifying some existing design features
from the program's memory, without the need for tedious redrawing.
(2) An up-to-date library of standard mold components and hardware can
be established, which can be easily and quickly accessed and
reproduced in new designs without the need for redrawing them every
time they are needed.
(3) The quality of the drawings produced by a computer printout does not
depend on the skilled hand of the designer.
(4) The computer permits easy transmission of designs to other locations,
such as in-house manufacturing centers or manufacturers at other
addresses.
Note the computer is only a tool to the designer; ultimately, the quality of a
design depends entirely on how well the designer understands what is required
and what can be made. Also be aware that even the most experienced designer
will not always come up with the best design on the ®rst attempt, but will try out
different ideas in the course of the design job. This often necessitates sketching,
erasing, and redrawing part or all of the picture, which is much easier to do

electronically. There is a saying about the difference between a draftsman and a
designer: ``the draftsman uses the pencil, the designer uses the eraser.'' In the old
days, the designer made his drawings on paper without much care for the


6

Starting New in the Mold Design Field

appearance of the resulting picture; it was then usually left to draftpersons to
produce a good, readable drawing.
The important thing is the thought that goes into the design of the mold, to
ensure the best possible design. Different solutions are always possible to
achieve the same end; in fact, all mold designers have their own ideas on how to
solve certain design problems. To take advantage of various ideas, and to arrive
at the best mold, it is good practice for the designer, after creating a mold layout,
to consult with a colleague, or to arrange a design meeting of peers to discuss
the proposed design. In many cases it is even better to provide two or more
different layouts. These alternatives should then be discussed, and the best
design or a composite of the various ideas should then be agreed upon.
This procedure is standard practice in all major design of®ces around the
world. It may appear to be time-consuming, but the time (and emotions) invested
in such peer critique are usually outweighed by the bene®ts of arriving at a better
mold. Since, in general, mold designers (especially beginners) may not be
familiar with machining and assembly practices, someone who is familiar in
these areas should be included at such design meetings; this prevents a design of
mold parts that may be dif®cult (or even impossible) to produce economically or
to put together at assembly. It is also bene®cial to have someone who knows the
actual molding process look at a new layout. It is much less expensive to catch
an error while it is still in the designing stage, than to ®nd out about it later when

steel has been cut or, even worse, when the mold is completed.
Time and money can be saved by spending more time during the design
stage to consider alternatives and to get the designer involved in the
manufacturing process of the mold, than by rushing a job through the design
of®ce to save a few hours there. When estimating the total time to build a mold,
allocate approximately 15±20% of the total time for designing and detailing,
about 60±70% for machining, and 15±20% for assembling the mold. (This, of
course, depends on the shape of the product and the complexity of the mold.)
And remember that the better the drawings are when given to the shop (or an
outside source), the less time is wasted during machining and assembly of the
mold.