Machine design, tập 84, số 16, 2012

October 18, 2012
A Penton Media Publication
Tune in to EngineeringTV.com

Special issue
on MOTION

CONTROL

A

Robot

Revolution
page 20

OFF TILT: WHERE
INDUSTRIAL MEMS
GYROSCOPES EXCEL,
page 34
SIMULATION HELPS
CALCULATE TRAJECTORIES,
page 40
PROTOTYPING WITH
SPRINGS, page 44
CLOUDBASED HELP
FOR MOTION SYSTEM
DESIGNERS,
page 50

[ MOTOR TRUTH #7 ]

Can I save
energy by using
a VFD (inverter)?
YES

NO

MAYBE
The truth is that it depends on your
application. If you have a high-cycling
application, a VFD can reduce the
starting current on each cycle.
If you have a hoisting application, a
VFD can provide energy regeneration.
If you have an oversized motor on a
small load, a VFD with flux control can
maximize the motor efficiency.
Otherwise, a VFD is a load and
actually consumes energy - especially
if you use a high carrier frequency.
Visit sewmotortruth.com/truth7 to
get the whole story on VFDs and
energy-efficient drivetrains.

sewmotortruth.com/truth7
864-439-7537
RS# 101

www.theleeco.com

Go ahead, push us to your limits.

RS# 102

We love a good challenge.
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how extreme, talk to The Lee Company. We’ve been solving complex
fluid control problems in all kinds of industries for more than 60 years.
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• Miniature Solenoid Valves
• Fixed and Variable Volume Pumps
• Atomizing and Dispense Nozzles

We’re not just talking about off-the-shelf solutions, either. A Lee
engineer will be happy to discuss your application, and develop
a custom design if needed. From managing nanoliter droplets to
creating fully integrated fluidic systems, we’re unsurpassed in breadth
and experience to deliver the precise, reliable performance you require.
Whatever problem you face, make the solution easy.
Contact The Lee Company today.

Innovation in Miniature

• Micro Dispensing Valves
• Integrated Fluidic Manifolds

• Custom Engineered Designs
See us at MD&M Minneapolis, Booth #636

The Lee Company 2 Pettipaug Road | Westbrook, CT 06498-0424
Tel: 860-399-6281 | 800-533-7584 | www.theleeco.com

Westbrook • London • Par is • Fr ankfur t • Milan • Stockholm


VOLUME 84
ISSUE 16
OCTOBER 18, 2012

CAE

CAE

Building a

BETTER
SPACECRAFT

FEATURES

CAE software tests
hypersonic-reentryvehicle designs

The European Space Agency
launch of Thales Alenia Space’s
Intermediate eXperimental

Vehicle aboard the Vega
small launch vehicle is
planned for 2013.

Authored by:

Kyle Indermuehle
Aerospace Lead
Simulia
Providence, R. I

robot for the rest of us
20 AA relatively
low-cost factory-floor robot
that can be trained or programmed by
a factory-floor worker.

Edited by Leslie Gordon


Key points:
• Process-automation software can link design and simulation
models to automate the execution of hundreds or even
thousands of simulations.
• The software can help designers improve designs by
improving them in terms of performance or cost variables
through statistical methods.

Resources:
Simulia, www.simulia.com

For more on simulation software, scan this
code or go to: />article/software-automates-the-executionof-thousands-of-simulations-0609
40

MACHINE DESIGN.com

As CAE software becomes increasingly sophisticated,
engineers can now refine designs to their nearly final
form. This lets engineers test physical prototypes later
in the product-development cycle. The use of CAE software is critical in the space industry, where it’s difficult
to create test settings that simulate real-world conditions. Vacuum chambers and wind tunnels help, but they
cannot account for all conditions at the same time. That’s
why spacecraft producer Thales Alenia Space Italia
(TAS-I) in Italy used CAE software in the design, testing,
and building of its hypersonic reentry vehicles for the
European Space Agency.
Head of aeromechanics and propulsion at TAS-I,
Cosimo Chiarelli helped design and test the vehicles. He
explains that the physics of atmospheric reentry are complex, so vehicle analysis required a multidisciplinary optimization (MDO) approach to account for all the variables.
Variables include aspects of the spacecraft structure
such as geometry (length and shape), as well as the di-

mensions and material attributes
of the shell and thermal-protection
system. Other variables include the
trajectory (comprising the vehicle’s
speed, altitude, and angle of attack),
the thermal conditions for the vehicle’s windward, leeward, and nose
zones, and the thermal loads the vehicle encounters. The final design
accounts for all variables, with a focus on the 150 sec that make up the

most-critical portion of reentry.
To improve designs, engineers
conducted separate simulations for
each of the physics disciplines. They
used a collection of software packages and divided the analysis into
seven major computational tasks
and 40 subtasks, many with their
own input and output file types. Engineers used Isight process automation software from Simulia, Providence, R. I., to organize the tasks,
manage the execution of TAS-I’s dif-

OCTOBER 18, 2012

The MDO workflow
for the reentry vehicle
in Isight comprised
several analysis tasks
such as grid generation
and trajectory
computations. It used
a variety of commercial
and proprietary codes
and input and output
file types. Engineers
used the software to
tie together separate
simulations and
automate the analysis.

OCTOBER 18, 2012



40

aim with MEMS gyros
34 Taking
Superaccurate MEMS gyroscopes

ferent codes, and aide in the understanding of results from all of the
tasks. “The software helped us create flexible simulation workflows
and automate the exploration of solutions for the large design matrix,”
says Chiarelli.”
To conduct a feasibility study of
their new MDO approach, engineers chose a theoretical hypersonic
reentry vehicle and applied simplified assumptions. Further streamlining the process, they decided to
optimize globally for all variables
combined, rather than locally for
each individual variable. To minimize costs, engineers applied the
process-automation software’s adaptive simulated annealing algorithm,
a statistical technique that searches
the envelope of design solutions.
Isight performed 200 iteration cycles in only a day, assembling several
designs that satisfied requirements.

simplify the motion-sensing tasks
of industrial robotics.

a better spacecraft
40 Building
CAE software tests hypersonic-

MECHANICAL

Working

reentry-vehicle designs.

Here are some tips when using
springs for prototyping and design.

with

STOCK SPRINGS

44 Here are some tips when using springs
Working with stock springs

Mechanical equipment and related hardware routinely
include springs in their designs. And in a perfect world,
knowing the load and travel, an engineer can adjust the
mating parts so that the design can use a stock spring.
However, that is usually not the case, and springs are frequently an afterthought.
Often this is because springs are well-engineered and

for prototyping and design.

design gets
50 Motion
help from the cloud

proven components. Springs operating within their design
parameters will last a long time. And they come in thousands of different sizes and versions. Most common are
compression and extension springs, made from various
materials, with or without a finish.
Stock springs are often used for applications requiring
less than 500 springs per year. Generally, however, it is not
only better but more cost effective to
contact spring manufacturers with
specific requirements. From there,
the manufacturer may recommend
a new design and make a customized
spring for little or no cost premium.
One cannot emphasize enough
the importance of discussing design requirements with a spring
manufacturer. Stock springs are
great for prototyping, but their use
in production often compromises
other aspects of a design.
This article is meant to help size
springs for prototyping, prior to seek-



Authored by:

Norman Ellis
Ellis & Associates
Laguna Hills, Calif.
Edited by Kenneth J. Korane

Key points:

Free and simple cloud-based analytic
tools help designers quickly analyze
motion-system performance in both
the time and frequency domains.

• Stock springs are generally intended for
prototyping, and their use in production
can compromise designs.
• Experts recommend discussing specific
design requirements with a spring
manufacturer.

Stock springs are useful for
prototyping, but altering mating
parts to accommodate a stock
spring can compromise other
aspects of the final design.

44

MACHINE DESIGN.com

Resources:
Spring Manufacturers Institute, www.
smihq.org. The SMI is a good source
for information on spring design and
capabilities, as well as for locating spring

manufacturers.

OCTOBER 18, 2012

44
Access our Reader Service
Web site to quickly find and
request information on the
products and services found
in the pages of MACHINE DESIGN.
www.machinedesign.com/rsc

2

MACHINE DESIGN.com

OCTOBER 18, 2012

MACHINE DESIGN.com

41












We’ve got the pneumatic parts you need, and they ship
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individually, or multiple valves can be assembled on
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Manual control valves are designed for non-electrical
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Air Pilot Valves
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Foot pedal valves with guard are 5-port spool valves with
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Solenoid Valve Cables & Air Valve Connectors

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Quick-disconnect Air Couplings
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Pneumatic
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Fittings and
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RS# 103


ON THE COVER
Baxter, a robot from
Rethink Robotics.

DEPARTMENTS
8 EDITORIAL
Antidote to innovation … Six Sigma

10 EDITORIAL STAFF
12 LETTERS
16 SCANNING FOR IDEAS
Going big with ultrasmall ball screw
Rotary motion with speed and precision

20 REPORTER’S NOTEBOOK
24 LOOKING BACK
31 COMMENTARY
So much for the idea of putting a hex on your boss
— Stephen J. Mraz

33 INDUSTRIAL DESIGN
Making “cheap” products look expensive

63 ORR ON ENGINEERING
What’s New?

64 SOFTWARE PRODUCTS
66 PRODUCT SPOTLIGHT
Hydraulic & pneumatic cylinders

68
74
76
77
78
78
79

4

PRODUCTS
DATA FILES
BUSINESS INDEX
AD INDEX
CLASSIFIEDS
BUSINESS STAFF
BACKTALK

MACHINE DESIGN.com

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Printed in U.S.A., Copyright © 2012. Penton Media, Inc.
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OCTOBER 18, 2012

POSTMASTER: Send change of address notice to
Customer Service, MACHINE DESIGN, P.O. Box 2100, Skokie,
IL 60076-7800.


Secure your operations

with proactive maintenance
Imagine the conditions in the North Sea. They take their
toll on all types of equipment. Bearings are no exception.
At one of the major production platforms, failing motor
bearings used to cause gas compressors to break down
as often as every third month. Each time, that meant
25% lost production for several days.
Jim Marnoch and his team provided SKF ProActive
Reliability Maintenance services. After thorough analysis
of the vibration signatures and the damaged bearings,
they found a long term solution. SKF NoWear bearings
along with a new sealing arrangement made all the
difference, allowing the compressors to run 6 times
longer than before.
At today’s high oil prices, for every breakdown that
can be avoided, the platform operator saves tens of
million dollars. On top of that, these improvements
also reduce health, safety and environmental risks.
It’s another great example of knowledge engineering
at work. Find out more at www.skf.com/poke

The Power of Knowledge Engineering

Gas Export Compressor

SKF ProActive Reliability
Maintenance

® NOWEAR is a registered trademark of the SKF Group.

Jim Marnoch, SKF

RS# 104


What’s new online machinedesign.com
Free Webcasts:
Designing Effective Safeguarding for Machines
Thursday, October 18, 2:00 p. m. ET
Attend this Webinar to learn how to design effective machine safeguarding.
Experts from Schmersal will discuss types of hazards, various options for
separating guards and devices, different levels of circuit design, and how to
engineer a complete safety system.

Making 3D Printed Parts “Real”
Thursday, October 25, 2:00 p. m. ET
Rapid prototyping — now called additive manufacturing — has had a profound
impact on the product design/development process across many industries.
This presentation from GreatBatch Medical and Objet will explore recent
advances and benefits of AM, including:
• Materials that range from rigid to flexible, high temperature, and clear.
• Time and cost savings using Polyjet technology.
• Example applications.
• A Q&A on equipment and capabilities.
Learn more and register for these events at />
Environmentally safe cryogenic machining

EDITOR’S WEB PICKS

The chief technical officer of MAG IAS explains the benefits of using

cryogenic machining on composites and ultrahard metals, and how
environmentally safe cooling fluids
eliminate waste-disposal problems
manufacturers face with traditional
coolants. View it at www.engineeringtv.
com/video/Cryogenic-Machining-UsingEnvir;International-Manufacturing-Tec.

6

RS# 105
MACHINE DESIGN.com

OCTOBER 18, 2012

Actuators and drives App
Bosch Rexroth’s GoTo Products apps for
iPhone and iPad provide quick access to
information on more than 3,500 linear
motion, hydraulic, pneumatic, electric
drive, and control products. Content
includes technical data, dimension
and specification tables, and product
visuals, as well as video clips explaining
key features of various motion and
control technologies. The iPhone version
takes advantage of GPS and autodial
features to simplify ordering from the
nearest distributor. Learn more at www.
boschrexroth-us.com/gotoapp.

Simulation Hall of Fame
Do you consider your simulations
prize-worthy? The Ansys Hall of Fame
competition showcases eye-popping

simulation images and striking videos
that illustrate real-world multiphysics
applications using the company’s
software. Winners will be selected based
on the project and resulting benefits,
with Apple iPads as the top three prizes.
Deadline is November 23. Learn more and
view previous winners at www.ansys.com.

Elastomers and
thermoplastics for vehicles
Minnesota Rubber and Plastics has a
new brochure on molded components
and assemblies for motor-vehicle
applications. Charts list a wide range of
products, compare the performance
of amorphous and semicrystalline
polymers in relation to cost, and provide
selection criteria for high-temperature
thermoplastics. Get a copy at www.
mnrubber.com.


IT’S MOTION
CONTROL VERSUS

MOTHER NATURE
ON CENTRE COURT.
©2010 Moog. All rights reserved.

RS# 106

WHEN IT COMES TO HIGH PERFORMANCE MOTION CONTROL, MOOG EXPERTS ARE THERE.
When design engineers sought the best way to control the new retractable roof at Wimbledon’s famed Centre Court, they turned
to Moog. The result was an innovative all-electric installation that provides 148 axes of control via high performance electric
actuators, servo motors, servo drives, closed-loop controls and software. Now, more than 1,100 metric tons (1,212 tons) of steel
and 5,200 square meters (17,060 square feet) of fabric move swiftly and safely to prevent rain delays.
Moog’s combination of motion control expertise and world-class solutions
can make the difference for you too—no matter what industry you’re in.
For more information call 866-580-7610.

How can we improve your machine design?
View our Wimbledon video at />
WHAT MOVES YOUR WORLD

moog.com/industrial


EDITORIAL
Antidote to innovation
… Six Sigma

Reliability
in a Clutch
...a clutch, brake or power
transmission part for that

matter. Since 1903 Carlyle
Johnson has solved some of
history’s toughest motion
control challenges – it’s what
we love to do. Our precision
electrical, mechanical, air and
hydraulic power transmission
products consistently prove
reliable and dependable in
every application. Underwater,
on the ground and in the air,
CJM is everywhere.

Standard and Custom Clutch, Brake
& Power Transmission Solutions

291 Boston Turnpike • Bolton, CT 06043
Phone: 860-643-1531

www.cjmco.com
8

RS# 107
MACHINE DESIGN.com

There has been a lot of soul searching in the U. S. about a perceived lack
of innovation among domestic manufacturers. One sign U. S. manufacturers have trouble innovating comes from the management consulting
firm Booze & Co.’s annual report on the 1,000 companies that spend
the most on research and development. Last year, only one company
among the top 10 R&D spenders (Microsoft) made the list of the top-10

most innovative companies. In a nutshell, Booze points out that a lot of
companies spend piles of money on R&D that don’t result in innovative
products.
In the quest for things to blame for this poor performance, Six Sigma
programs seem to be one of the latest scapegoats. The case for Six Sigma
as a cause of mediocre research is made by Navi Radjou, Jaideep Prabhu,
and Simone Ahuja in a book called Jugaad Innovation, which outlines
ideas for innovating more frugally.
What convinced these three business consultants that Six Sigma kills
the innovative spark was 3M’s experience applying Six Sigma processes
to its R&D labs in the early 2000s. By 2005, 3M’s share of revenues from
new products had dropped from the 30% it had seen for decades to
21%. The reason: 3M engineers became risk averse and played it safe,
the consultants say. The situation turned around when 3M rolled back
the program and reinstituted an old practice of giving employees 15% of
the their paid work time to pursue pet projects without worrying about
whether such efforts could be immediately commercialized.
But Six Sigma is just a symptom of what ails R&D in most companies, the consultants insist. It is a manifestation of an approach to R&D
structured so that it lacks flexibility and is insular. Companies that run
R&D under rigidly structured schemes like Six Sigma seem to think that
innovations can be scheduled, say the consultants.
Another problem: Western companies often measure innovation the
wrong way, by the number of patents they file. Big mistake, the consultants claim. The patenting process costs a lot, is time consuming, and
often mires the patent holder in lawsuits. Better to not bother with patenting at all. Instead, focus on commercializing developments fast rather
than trying to erect barriers around them.
Maybe so, but having heard these arguments, I am convinced the real
obstacle to innovation in many companies lies elsewhere: In the ranks
of top management. Even when an innovative product gets developed,
bottom-line oriented managers are likely to axe it before consumers can
venture their opinion. That’s because ivory-tower managers often don’t

know their own customers, so the only thing that can convince them an
idea is good is a spreadsheet full of data. But there won’t be any such data
for something that is a real innovation. (After all, the market for MP3
players was microscopic prior to Apple’s invention of the iPod.) And by
the time there’s enough evidence to justify an innovative project, it may
be too late to commercialize it.
Radjou, Prabhu, and Ahuja seem to agree. They say top management’s
overreliance on formal data shows why 90% of all consumer-product
R&D goes into tweaking existing offerings, and why big R&D spenders
leave the door open to competitors with truly innovative ideas.
— Leland Teschler, Editor

OCTOBER 18, 2012


air cylinders
More Sizes • More Styles • More Accessories
Performance that Engineers havee Learned to Trust.
40”


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For the past 50 years, Clippard has been providing
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RS# 108

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EDITORIAL STAFF

EDITOR
Leland E. Teschler


GRAPHALLOY
BEARINGS CAN
TAKE THE HEAT.

®

MANAGING EDITOR
Kenneth J. Korane


SENIOR EDITORS

HANDLE HIGH TEMPERATURE AND HARSH
OPERATING CONDITIONS WITH EASE
GRAPHALLOY® bushings,
bearings and components:
• Survive when others fail
• Run hot, cold, wet or dry
• Excel at -450°F to 1000°F
• Corrosion resistant
• Self-lubricating
• Non-galling
• Low maintenance
• Ovens, dryers, pumps, valves,
turbines, mixers, conveyors

Leslie Gordon

Stephen J. Mraz


ASSOCIATE EDITORS

GRAPHITE METALLIZING

CORPORATION
Yonkers, NY 10703 U.S.A.

Lindsey Frick

Robert J. Repas, Jr.


ISO 9001:2008
H06a

TEL. 914.968.8400 • WWW.GRAPHALLOY.COM/MD
RS# 109

INDUSTRY COVERAGE:
AUTOMOTIVE, PACKAGING,
MEDICAL
Stephen J. Mraz

CAD/CAM, MANUFACTURING
Leslie Gordon

ELECTRICAL, ELECTRONICS
Robert J. Repas, Jr.

FASTENING & JOINING,
MATERIALS
Lindsey Frick

FLUID POWER

Kenneth J. Korane

MECHANICAL
Lindsey Frick
Kenneth J. Korane

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EDITORIAL PRODUCTION
Denise Greco
Editorial Production Manager
Randall L. Rubenking
Art Director

1300 E. 9th St. Cleveland, OH 44114-1503
10

MACHINE DESIGN.com

RS# 110
OCTOBER 18, 2012


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RS# 111

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LETTERS

An engineer is
an engineer . . .
Having run an engineering and
design business for over 40 years,
I have followed with amusement
t h e “C A D J o c k e y ” d i s c u s s i o n
(“The Attack of the CAD Jockey?”
Aug. 23). We design and build
commercial products and production machinery, and I find
that a person’s title or degree
doesn’t matter. It is what comes
out at the end of a project that’s
impor tant. We let people do
whatever they can and benefit
from their experience.
Harold Parks
A good engineer must be both
a good engineer and a good designer. A good designer is not an
engineer (and is not expected, or
required, to be one).
Dayle D. Winnie
Anybody can learn CAD and create geometry. But not all people
can design. Designers have creativity and some sense of what
will make a product work. I’ve

been on all sides of this designer/
engineer debate for many years
and have met many design engineers who could not design
something as simple as a pin. On
the other hand, I’ve worked with
designers who understood basic principles and could engineer
and design products.
In companies, there is a mix of
people. There are those who can
analyze things once they are designed, those who can take something from concept all the way
through manufacturing, and those
who create geometry from concepts sketched out on napkins.
It is not incorrect to state that
design is simply creating geometry. I realize that in some places,
CAD jockeys are called designers, but nothing could be further
from the truth. It takes someone
with engineering-design knowledge to create designs.
Jaime Robledo
12

MACHINE DESIGN.com

Job-title controversy
Readers are still hashing
out the meaning of
the terms “designer”
and “engineer.” And
although they have
no problem defining
ethical behavior,

they also think
ethical behavior is
disappearing.

Over the last 25 years I have gone
from a technical illustrator to an
automation design engineer
without an engineering degree.
However, it is important to note
that at some companies I would
not be considered an engineer
without an engineering degree.
Prior to the meltdown of 2008,
I was a special projects engineer
at a company that was growing
and letting HR control titles. As
a result, HR personnel would not
consider anyone without an engineering degree for any engineering positions and were forcing people with 10 to 15+ years
of experience but no degree out
of engineering positions.
At another company, I was
given the title mechanical designer because I do not have an
engineering degree. Those with
engineering degrees were called
mechanical engineers.
My experience indicates that
the term “designer” has two basic definitions. The one used in
the editorial refers to the person
responsible for the look, touch,
and feel of the product. The second is the person who does the

same functions of an engineer
without an engineering degree.
The second definition is the one
most of your readers are most
familiar with. Another way to
look at it is that the first definition refers to industrial design,
while the second refers to me-

OCTOBER 18, 2012

chanical design.
As a side note, I found the definitions for “designer” frustrating
during a job search. A thorough
and specific list of job duties and
responsibilities is much clearer
than just a title with generic
qualifications.
By the way, I have continued
my education by earning Associates degrees in technical illustration and math, a BA in Family
Studies, an MBA, and a graduate
degree in accounting. It would
be nice if engineering classes
were offered in the evenings like
so many other programs.
John E. Melton
CAD jockeys are computer-age
draftsmen and draf tswomen.
They are not designers unless
they have additional training in,
knowledge of, and aptitude for

one or more of the numerous
fields of design. Even sketching
or drawing free hand requires
talent not necessar y for good
CAD jockeys. Indeed, I am a CAD
jockey and I can’t draw a pretty
picture to save my life.
Bob Vanstone

Farewell ethics
Our societ y has gone from a
Christian-based one in the idealistic past to the “if it feels good
do it” attitude in the 60s, to our
current and cynical “get it while


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RS# 112
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LETTERS

you can” mood today (“ Where
Did Ethics Go?” Sept. 6).
There is a tendency to push
morals to the side when it comes
to personal responsibility in society. Why are we surprised to
find out it carries over into professional careers? Or, if we take

the Darwinistic approach of survival of the fittest, instead of taking care of the least among us,
did Madoff actually do anything
wrong other than get caught?
Mike Bartle
Ethics went to the same place
morals and principles went. Our
nation has been in a state of decline for many years now as we
stand idle watching entertainment, and political and other
institutions raise our kids to be
what we see today. This will not
stop until we get off the sidelines

and get involved. Thanks for your
words of wisdom, I was feeling
like a loner in this new world.
Felix Ronmint

Curing the U. S. blues
More engineers, greater encouragement of the entrepreneurial spirit, and most importantly,
fewer MBA’s (“Made in America?”
June 14). This is what we need for
manufacturing to thrive in this
country.
Joe Bonasses
This is one of the best and most
encouraging articles I have seen
in a long time regarding the state
of American manufacturing. We
need more forward thinkers like
the folks mentioned here. Buy

American. Be American.
Bill White

RS# 113
14

MACHINE DESIGN.com

OCTOBER 18, 2012

LETTERS TO THE EDITOR
Please include your name, address, and
daytime phone number. Letters may
be edited for brevity and to focus on
essential points.
Mail: Letters, MACHINE DESIGN,
1300 E. 9th St., Cleveland, OH 441141503, Fax: 216-621-8469
E-mail, Editorial:


Conversion error
If the Super Draco can develop
150,000 lbf of thrust, then the
metric equivalent should be
670,000 N (“Spacetruckin’ with
SpaceX,” Sept. 6).
Dennis McKee
Good catch. The correct figures
for the Super Draco should be
15,000 lb of thrust or 67,000 N —

Stephen J. Mraz


RS# 114


SCANNING FOR IDEAS
Edited by Stephen J. Mraz

Going big with

ultrasmall ball screw
Wiper
Return

Screw shaft

Ball bearings

Engineers at Steinmeyer Inc., Burlington, Mass.
(www.steinmeyer.com), recently added a new
Nut
device to its line of precision balls screws, the
Ultraminiature, which the company claims is the
“world’s smallest commercially available ball
screw.” Its diameter can be as small as 3 mm and
have a pitch of 1 or 0.5 mm. This makes the device well suited for medical applications such as
dispensing exact amounts of liquids.
The ball screw can be ordered in several sizes
ranging up to 16 mm in diameter with a 30-mm

pitch. The screws come with one of four types of
ball nuts and with or without preload. The actuators are made of precision-ground,
hardened tool steel. Stainless steel is
For more information on rolled and ground
ball screws, scan this
an option. The screws can meet ISO
code or go to: http://
tolerances from P0 to P5.
machinedesign.com/
RS# 401
article/how-rolled-andground-ball-screwsstack-up-0708

r
formation via ou
Request free in Web site at
Reader Service
c
design.com/rs
ww w.machine

16

MACHINE DESIGN.com

OCTOBER 18, 2012


N OW I T H I N K I N 3 D.
AND MY DESIGNS JUST KEEP GET TING BET TER.
With our Dimension® 3D Printer, I know my model will represent my idea exactly.

And that makes it easier to improve my design with each iteration. Our Dimension
is right here in the office, and that helps us get our
products to market faster. And, with the Dimension Print
TM

Pack we got everything we needed to start printing immediately.
The Dimension models we create are made in ABS, so they’re
also tough and durable. Overall, Dimension gives me an amazing
sense of freedom—and creativity.
Find out more at www.dimensionprinting.com/macd4

RS# 115

©2012 Stratasys, Inc.


SCANNING FOR IDEAS

Rotary motion
with speed and precision
Dial-plate
mounting holes

Gear teeth

Large central opening
for mounting equipment
or cabling

Gearbox

Pinion

Precision Ring Drives from the
Nexen Group Inc, Vadnais
Heights, Minn. (www.nexengroup.com), combine a rolling
pinion with a precision-grade
bearing and gearhead. There
are four drives in the series
with ratios ranging from 64:1 to
220:1. Peak torque goes from
563 to 1,936 Nm. And accuracy

ranges from ±11 to ±35 arc-sec,
with repeatabilities of ±4.2 to
±1.2 arc sec. The drives can handle peak-torque inputs at any
time, which lets it index at twice
the speed of traditional camdriven systems.
The rolling pinion is 99%
efficient, while the gearbox is
96% efficient, making the rotary

device an energy saver. And the
bearing-supported pinion rollers
move smoothly across the face
of each tooth, so it generates less
noise and vibration than conventional rotary devices.
The drive mounts on a table
supported by cross-roller bearings rated for 1,575-kN loads.
RS# 402

The new 955 eBrik linear displacement transducer.

Price and performance
so well balanced,
it just might displace
potentiometers.
At last, there’s a purely electronic solution to position sensors. Our new
955 eBrik uses magnetostrictive technology so there’s no contact, no
moving parts, nothing to wear out. No erratic position signals. Available
in 1" to 72" stroke lengths, it’s economical and versatile enough for
many applications, field-programmable, and the perfect replacement
for old-style potentiometers. Learn more at our website.

ametekapt.com
18

MACHINE DESIGN.com

OCTOBER 18, 2012

RS# 116


These new generation CD® Couplings feature zero
backlash precision and high torsional stiffness.
They answer today’s demanding servo motor
applications with high reverse loads and
positioning requirements. New clamp style
hubs handle increased torque on shafts
without using keyways. Manufactured of

RoHS compliant materials.
Now, size, select and see the right
CD coupling solution for your coupling
application with Zero-Max 3D CAD files.
Check our FAST deliveries.

www.zero-max.com 800.533.1731
© 2010 ZERO-MAX

RS# 117


REPORTER’S NOTEBOOK

A robot for the rest of us
An industrial robot can cost hundreds of thousands of dollars just
for the hardware. It can cost three
to five times more to add it to an
assembly line and get it working.
That’s why industrial robots are
typically only used by large, wellcapitalized manufacturers. That’s
also why Rodney Brooks, one-time
robotics professor at Massachusetts Institute of Technology and
Director of its Computer Science
and Artificial Intelligence Laboratory, founded Rethink Robotics
in 2008. He wanted to develop a
relatively low-cost factory-floor
robot that could be trained or
programmed by a factory-floor
worker.

That $22,000 robot, Baxter, is
now rolling off the U. S. assembly
lines and is ready to go to work.

Baxter’s basics
Baxter is equipped with two
arms on a turnable torso. Each arm
measures 41 in. from shoulder to
wrist and has seven degrees of
freedom (dof). The arms move at
up to 3.3 fps empty and 2 fps when
loaded. They come with two interchangeable hands or end effectors
that can pick up 5-lb payloads.
Electrical parallel grippers
with interchangeable fingers of
different lengths, as well as interchangeable fingertips, can be
customized to pick up and handle
specific objects. The grippers add
1 dof and open or shut within
1 sec. They include a force sensor,
which detects when an object is in
the robot’s grasp and how much
force it is exerting on that object.
Vacuum-cup grippers work
on smooth, hard-to-grab objects
such as mirrors, plastic sheets,
and larger packages. The cups
come in a variety of sizes and an
air-pressure sensor detects when
they have “grabbed” an object. The

cups reduce the risk of marring an
20

MACHINE DESIGN.com

Baxter can be set up and trained by factory workers to help them load and unload
boxes one day, then rolled to another workstation to sort and align products the next.

object’s finish, but they do require
that users hook the robot to an airpressure supply.
The arms can be “trained” or
programmed to work together, or
they can each carry out tasks independently of what the other arm
is doing.
The torso can be bolted to a
table or other stable surface, but
can also ride on a 141-lb pedestal
from the company. The pedestal
has two adjustable heights and
is sized to fit through standard
doorways. It lets the 165-lb robot
be rolled from workstation to
workstation on industrial-grade
casters. The casters come with legs
that lock it into place and adjust to
level and stabilize the robot.
For safety and to carry out tasks,
Baxter has 360° sonar and machine
vision with one main “face” camera and access to four others. The
wrists, for instance, carry a camera

so Baxter can closely monitor what
its end effectors are doing. Each
wrist also carries a range finder.
Baxter operates in temperatures from 32 to 104°F and is rated

OCTOBER 18, 2012

IP50, which means it is protected
against dust but not water and
other liquids. It runs on 120 Vac
and 10 A, and is rated for 6,500 hr.

What makes Baxter
different
Baxter is different from other
industrial robots in that it uses behavior-based intelligence, a concept Brooks developed throughout the 1980s and 1990s. He used


What Baxter
can do
Rodney Brooks tells
of how his team
regularly takes
Baxter out of its
packing crate at a
customer’s facility
and has it set up and
working on a line
they’ve never seen
before within an hour. But what

kinds of tasks does Brooks believe
Baxter will be widely used for, at
least at first?
• Material handling: Moving
objects from one location to another, counting, and reorienting.
• Loading and unloading lines:
Putting parts on or removing
them from conveyor belts or
fixed surfaces.
• Inspecting, testing, and sorting: Checking parts for weight
or shape, evaluate them against
a criteria, and perform different
actions depending on results.
• Operating machines: Watching machinery and performing
sequences of actions based on
input or alarms. For example,
it could insert a part into a machine, push a button, then remove the part.
• Packing and unpacking: Picking up an object, bag, box, or
tray and arranging them in an
array for packing. It can also unpack containers.
• Light assembly: It can be
quickly trained to align and snap
fit parts together and insert
them into containers.
• Finishing: Grinding, polishing,
and other finishing operations.

Resources:
Rethink Robots, www.
rethinkrobotics.com

RS# 406

Baxter’s computerized “eyes” do more than try to humanize the robot. The robot will
first “look” in the direction it will be reaching with its arms, and workers quickly pick
up on those cues. The eyes never looks angry, but can look puzzled if you don’t fully
explain what you want the robot to do. And the eyes will close when the robot is off
the job or “sleeping.”

the concept for all the robots developed and built at his previous
company, iRobot (makers of the
Roomba). “You program in a collection of parallel behaviors, each
running independently, that look
at the environment and input conditions, then decide if they have an
action to perform.”
Conventional robots come with
little or no programming, so users
have to define and program all error
conditions. Baxter comes preprogrammed with certain “instincts”
right out of the box that always run
in the background
when Baxter is
working. This lets
users program
tasks rather than a
string of repetitive
Baxter is
motions.
already
For example,
handling

if
you
show
simple tasks
Baxter an object
at companies
and position its
supplying
gripper so that
parts to
Rethink
it can pick the
Robotics. So, in
object up, the
effect, robots
robot builds a
are helping
visual model of
build robots.
the object and
stores this data.

Later, Baxter will be able to visually
identify the object, even if it’s in a
different orientation and amidst
other objects and clutter, and pick
it up.
Another one of these basic instincts is self-preservation, “For example, the arms never collide with
one another, thanks to the preprogramming,” says Brooks. “Even
if you grab both arms and try to

bring them together, you will feel
a force, one that gets stronger the
closer the arms get to one another,
resisting you. This behavior keeps
the robot safe from itself.”
“Another built-in behavior is
that Baxter knows it can’t put
something down if it doesn’t
have something in its hand,” says
Brooks. “So if the robot picks up
an object to place in a box, and a
worker grabs the object from its
gripper, the robot doesn’t try to
put that object in the box. Instead,
the robot goes to the designated
area to pick up another object.”
“To get the robot to pick up an
object, a worker simply takes its
gripper and places it over the object,” says Brooks. “Pushing a button on Baxter’s sleeve closes the
gripper on the object. The worker

then lifts the arm. The robot now
knows it is supposed to pick up
one of these objects in this area.”
“And if you’re training the robot
to pick up an object and put it in
a box, you can first train it to put
the object in the box, then where
to pick it up,” explains Brooks. “You
don’t have to do it in order. Baxter

OCTOBER 18, 2012

Continued on page 26
MACHINE DESIGN.com

21