Machine Design 7 March 2013
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (18.89 MB, 102 trang )
March 7, 2013
A Penton Media Publication
Tune in to EngineeringTV.com
What does the
FUTURE
HOLD?
FUTURE
TECHNOLOGY
ISSUE
page 46
CARBON FIBER COMES TO
3D PRINTING, page 52
DRONES THAT CAN MOVE
MOUNTAINS, page 58
ELECTRIC VEHICLES
THE REAL ACTION IS
IN BIKES, page 73
ROBOTS GO OPEN
SOURCE, page 80
They save you a bundle.
The engineer’s choice
Talk about a bundle of advantages! EC technology from ebm-papst not only gives you more control options for advanced
applications than AC technology, but its high efficiency also saves a whole lot of energy. Furthermore, it prolongs the service
life of air-conditioning and refrigeration systems and makes their operation much quieter. The electronics are completely
integrated into the motor, making these truly “plug and blow” fans. One more thing: our EC technology enables you to create
an energy-saving bundle of several hundred fans and control them from a single workstation.
For a whole bundle of information, visit www.ebmpapst.us/hyblade
RS# 101
• Designed Specifically for Thermal
Benchtop Testing Applications
• Compact, Rugged and Lightweight
• Plug-and-Play Compatibility
• Fast Data Transfer
Visit omega.com/osxl-sc_series
*OSXL-SC Series
Starts at
$
2450
Bench Top Thermal Imaging
Camera Kit Real-Time Thermal
Imaging and Analysis
Images/content are for illustration purposes only
®
omega.com
®
© COPYRIGHT 2013 OMEGA ENGINEERING, INC ALL RIGHTS RESERVED
Process Measurement
Instrumentation
*Note: Not for Export - US only
Because of transmission frequency regulations, these wireless products
may only be used in the United States, Canada and Europe.
Miniature Non-Contact Infrared
Temperature Sensors with
Separate Electronics Modules
Visit omega.com/os-mini
*OS-MINI Series
Starts at
iBorescope for iPad
®
/iPhone
®
for WiFi-Enabled Real-Time
HHB-ISCOPE
Starts at
$
299
Visit omega.com/hhb-iscope
IR2 SUPERMETER
®
Ultra High
Performance 2-Color Ratio
Fiber Optic Infrared Temperature
Measurement and Control System
Visit omega.com/ir2
®
Powered
By
302
$
Video Capture and Display
on iPad
®
/iPhone
®
Platforms
iR2 Series
Starts at
$
2995
RS# 102
FEATURES
FUTURE TECHNOLOGY
The Lit Motors
C-1 will be a
motorcycle
built with
automotive
unibody
construction
when it
goes into
production,
hopefully
next year.
You can thank the Japanese for fostering the birth of the modern electric
motorcycle, but not in the way you might think. “The big four motorcycle
companies — Honda, Kawasaki, Suzuki, and Yamaha — are all very conser-
vative. Rather than come up with their own e-bikes, they sat back and watched
events unfold. That let a bunch of guys in their garages on low budgets use cre-
ativity to demonstrate e-bikes that were at parity with gas bikes,” says retired
electric motorcycle racer Chip Yates.
Yates is in a position to know what he’s talking about. In the first-ever orga-
nized race between an all-electric motorcycle and beefy, twin-cylinder, 1,150-cc
gas bikes, Yates collected third-place honors on a bike carrying 102 lithium-ion
polymer pouch cells and a dc permanent-magnet motor. He and his team also
set the world-speed record for electric motorcycles in 2011, hitting 190.6 mph
during a one-mile, standing-start run in the California desert.
The accomplishments of Yates and his crew personify the role garage entre-
preneurs have had in advancing e-bike technology. E-bikes are now a hotbed
of development dominated by independent inventors and small start-ups. One
reason is that for someone set on producing an electric-powered vehicle, it’s
far more manageable to bring a motorcycle to market than anything with four
wheels. “In some ways bikes are a natural platform for innovation because they
are easy to get your head around,” says Yates. “An e-bike is relatively inexpensive
to build. It is a much simpler undertaking than a car. You can spend more of
your time on new technology rather than on building a giant platform.”
In Yates’ case, some of that innovation went into coming up with a patent-
A speedy pace of
innovation could make
electric motorcycles and
scooters more viable for
consumers than electric
four wheelers.
Authored by:
Leland Teschler
Editor
Key points:
• Electric motorcycles are much easier to
produce than electric four wheelers, a fact
that has attracted numerous entrepreneurs.
• The tough part: Kinetic-energy recovery
during braking because the front wheel
loads much more than
the rear.
Resources:
Chip Yates Bonneville World’s Fastest
Electric Motorcycle Video, http://youtu.
be/W_UlRWRfU88
Current Motor, www.currentmotor.com
EngineeringTV.com Current Motor
interview, />video/Electric-Scooter-Cloud-Communic;Only-
Engineering-TV-Videos
Lit Motors, www.litmotors.com
Lit Motors C-1 on YouTube, www.
youtube.com/
watch?v=VkvvsRBSroA
Swigz.com Pro Racing
(Chip Yates)
For another feature on
electric motorcycles,
scan this code or go
to />racing_bike_121410/
Your first
e-vehicle
could be an
e-bike
MARCH 7, 2013MACHINE DESIGN.com 73
FUTURE TECHNOLOGY
Researchers at
Volvo Construction
Equipment are
developing
excavators and
wheel loaders that
handle simple
digging and loading
tasks without an
operator. Shown
here is a concept
model of its
futuristic SfinX
excavator.
The idea of using robots for arduous tasks like mining probably dates from
the dawn of the industrial age, and it’s long been a mainstay of science fic-
tion. Isaac Asimov, for one, wrote of autonomous asteroid-mining robots in
the 1940s.
The concept is now reality, with robotic haul trucks hard at work at several
mines around the world. Many experts expect their numbers to grow substan-
tially in the coming years, potentially changing the face of the mining industry.
Equipment manufacturers began discussing autonomous mining in the
1970s. But commercializing it took numerous technology breakthroughs,
along with developments that slashed hardware costs. Among these are GPS
for navigation, high-speed wireless communication networks, and so-called
“perception” technologies: laser, ultrasonic, radar, and other sensors that can
detect nearby stationary and moving objects.
There have also been advances in hardened electronics, processing speeds,
and control algorithms. And the acceptance of innovations such as electro-
hydraulics — where electrical signals command powerful actuators — play a
key role in “drive-by-wire” steering, braking, and work functions.
Even with all this, autonomous mining is only in its infancy and, today,
it centers around massive “ultraclass” dump truck trucks that carry several
hundred tons of ore. They run predictable routes in open-pit mines, loading
in one place and delivering the material to another.
Autonomy’s benefits
Fueling commercialization of these driverless trucks are the potential ben-
efits they bring. For example, they make production more efficient by letting
mine operations run consistently around the clock. There are no operators
who need coffee and lunch breaks, and grow fatigued near the end of a shift.
The vehicles eliminate the productivity lost during shift changes from one
crew to another, when conventional trucks sit idle.
Another benefit is consistent performance. Trucks can be programmed to
Authored by:
Kenneth J. Korane
Managing Editor
Key points:
• Autonomous mining boosts productivity,
cuts operating costs, and enhances safety.
• Driverless haul trucks are currently working
at several mines around the world.
Resources:
Autonomous Solutions,
Caterpillar, />command-for-hauling
Flanders Electric, www.flandersinc.com
Hitachi Construction Machinery,
www.hitachi-c-m.com
Komatsu,
www.komatsuamerica.com/mining
Leica Geosystems Mining,
www.leica-geosystems.com/en/Mining-
Solutions_96237.htm
Rio Tinto, www.riotinto.com/
ourapproach/17203_mine_of_the_future.asp
Volvo Construction Equipment,
www.volvoce.com
Drones
come
down to Earth
Driverless trucks foretell
the future of mining.
MARCH 7, 2013MACHINE DESIGN.com58
VOLUME 85
ISSUE 3
MARCH 7, 2013
Access our Reader Service
Web site to quickly find and
request information on the
products and services found
in the pages of
M
ACHINE
D
ESIGN
.
www.machinedesign.com/rsc
73
58
Drones come
down to Earth
Haul trucks that drive
themselves offer a
glimpse at the future
of mining.
Your first e-vehicle
could be an e-bike
Because they use smaller
battery packs and less-
power-hungry motors,
e-bikes could become
practical for most people
before an EV on four
wheels.
Motion Focus
• Ensuring quality control at America’s
largest steel mill
• Machine vision boosts productivity on
bottling line
A project to perfect prosthetics
A DARPA-funded effort pushes the state of
the art in biomedical engineering.
The future of additive
manufacturing
Companies, government agencies, and even
tinkerers are using additive manufacturing to
make production parts.
The future of robotics:
Crowd-sourced code
Open-source software is giving rise to
emerging breeds of quasicommercial,
prosthetic, and industrial robots.
52
38
80
46
MARCH 7, 2013MACHINE DESIGN.com2
&20081,&$7,216
Get the PRO in
Watch the bar code scanner
tutorial and other informative
videos to learn why ...
We make it easier to communicate
Communicating to ASCII devices can be a hassle
with some control systems, but the Productivity3000
controller’s user-friendly design makes that job easier.
Follow along in this example to set up communications
with a bar code scanner:
v &RQQHFWWKHVFDQQHUWRRQHRIWKH3URGXFWLYLW\
&38VHPEHGGHGVHULDOSRUWV
v &RQoJXUHWKHSRUWWKURXJKWKH)5((3URGXFWLYLW\6XLWH
SURJUDPPLQJVRIWZDUH,QWXLWLYHGLDORJER[HVOHW\RXVHW
SDUDPHWHUVVXFKDVEDXGUDWHVWRSELWVDQGWKHSURWRFRO
LQWKLVFDVH$6&,,&XVWRPXVLQJVHOHFWLRQPHQXV
v &RQoJXUHWKHODGGHUORJLFLQVWUXFWLRQk$6&,,,1yGHoQH
QXPEHURIFKDUDFWHUVDVVLJQWKHGHVWLQDWLRQPHPRU\
DQGXSGDWHWKHSURJUDPLQWKHFRQWUROOHU
v <RXUHUHDG\WRUHDGGDWDIURPWKHVFDQQHU,WVWKDWHDV\
/>3HUIRUPDQFH
9DOXH
ZZZSURGXFWLYLW\FRP
RS# 103
DEPARTMENTS
March 7, 2013
A Penton Media Publication
Tune in to EngineeringTV.com
What does the
FUTURE
HOLD?
For customized article reprints and permissions,
please contact: Wright’s Media, 877-652-5295, or
e-mail at
Editorial content is indexed in the Applied Science
Technology Index, the Engineering Index, SciSearch
and Research Alert. Microfilm copies available from
NA Publishing Inc., 4750 Venture Dr., Suite 400, Ann
Arbor, MI 48108, Ph: 734-302-6500 or 800-420-6272.
Permission to photocopy is granted for users registered
with the Copyright Clearance Center (CCC) Inc. to
photocopy any article, with the exception of those for
which separate ownership is indicated on the first page
of the article, provided that the base fee of $1.25 per
copy of the article, plus
$.60 per page is paid to CCC,
222 Rosewood Dr., Danvers, MA 01923 (Code No. 0024-
9114/13 $1.25 + .60).
Subscription Policy: M
ACHINE
D
ESIGN
is circulated to
research, development, and design engineers primarily
engaged in the design and manufacture of machinery,
electrical/electronic equipment, and mechanical
equipment. To obtain a complimentary subscription
see our Web page at submag.com/sub/mn. For change
of address fill out a new qualification form at submag.
com/sub/mn.
Printed in U.S.A., Copyright © 2013. Penton Media, Inc.
All rights reserved. M
ACHINE
D
ESIGN
(ISSN 0024-9114) is
published semimonthly except for a single issue in
January, February, April, June, July, August, and October
by Penton Media, Inc., 9800 Metcalf Ave., Overland Park,
KS 66212.
Paid subscriptions include issues 1-16. Issue No. 17
(OEM Handbook and Supplier Directory) is available at
additional cost. Rates: U.S.: one year, $139; two years,
$199;. Canada/Mexico: one year, $159; two years, $239;
All other countries: one year, $199; two years, $299.
Cost for back issues are U.S. $10.00 per copy plus tax,
Canada $15.00 per issue plus tax, and Int’l $20.00 per
issue. OEM Handbook and Supplier Directory, $50.00
plus tax. Prepaid subscription: Penton Media (M
ACHINE
D
ESIGN
), P.O. Box 2100, Skokie IL 60076-7800. Periodicals
Postage Paid at Shawnee Mission, KS, and at additional
mailing offices.
Can GST #R126431964. Canadian Post Publications
Mail Agreement No.40612608. Canada return address:
Pitney Bowes, P.O. Box 25542, London, Ont., N6C 6B2.
Digital subscription rates: U.S.: one year, $69; two years,
$99;. Canada/Mexico: one year, $79; two years, $119; All
other countries: one year, $99; two years, $149.
POSTMASTER: Send change of address notice to
Customer Service, M
ACHINE
D
ESIGN
, P.O. Box 2100, Skokie,
IL 60076-7800.
EDITORIAL
Living on a jet plane
EDITORIAL STAFF
LETTERS
SCANNING FOR IDEAS
See-through housing enables visual check of filter and fluid
Electronic access for new and old enclosures
REPORTER’S NOTEBOOK
LOOKING BACK
COMMENTARY
Who’s to blame for bogus mpg?
VANTAGE POINT
Curbing the engineering knowledge gap
TAVENNER ON SAFETY
Will OSHA’s Injury Illness Prevention Program
give you a headache?
PRODUCTS
BUSINESS INDEX
AD INDEX
BUSINESS STAFF
BACKTALK
10
12
16
20
28
34
8
35
36
88
89
90
93
94
ON THE COVER
The most current version of
DARPA’s Modular Prosthetic Limb
4 MARCH 7, 2013MACHINE DESIGN.com
Facts about Blowers
Energy conscious plants might think
a blower to be a better choice due to its
slightly lower electrical consumption
compared to a compressor. In reality,
a blower is an expensive capital
expenditure that requires frequent
downtime and costly maintenance
of fi lters, belts and bearings.
Here are some important facts:
Filters must be replaced every one to
three months.
Belts must be replaced every three to
six months.
Typical bearing replacement is at least
once a year at a cost of nearly $1000.
t Blower bearings wear out quickly
due to the high speeds (17-20,000
RPM) required to generate eff ective
airfl ows.
t Poorly designed seals that allow
dirt and moisture infi ltration and
environments above 125°F decrease
the one year bearing life.
t Many bearings can not be replaced
in the fi eld, resulting in downtime
to send the assembly back to the
manufacturer.
Blowers take up a lot of space and often
produce sound levels that exceed OSHA
noise level exposure requirements. Air
volume and velocity are often diffi cult
to control since mechanical adjustments
are required.
To discuss an application, contact:
EXAIR Corporation
11510 Goldcoast Drive
Cincinnati, Ohio 45249-1621
(800) 903-9247
Fax: (513) 671-3363
email:
www.exair.com/14/423a.htm
See the Super Air Knife in action.
www.exair.com/14/akvideo.htm
Compare these Blowoffs
ere are a variety of ways to blow the water from the bottles shown in the photo below, but which method
is best? To decide, we ran a comparison test on the same application using four diff erent blowoff methods:
drilled pipe, fl at air nozzles, Super Air Knife (each using compressed air as a power source), and a blower
supplied air knife (using an electric motor as a power source). Each system consisted of two twelve inch
long air knives. e following comparison proves that the EXAIR Super Air Knife is the best choice for
your blowoff , cooling or drying application.
e goal for each of the blowoff choices was to use the least amount of air possible to get the job done
(lowest energy and noise level). e compressed air pressure required was 60 PSIG which provided
adequate velocity to blow the water off . e blower used had a ten horsepower motor and was a centrifugal
type blower at 18,000 RPM. e table at the bottom of the page summarizes the overall performance.
Since your actual part may have an odd confi guration, holes or sharp edges, we took sound level
measurements in free air (no impinging surface).
Drilled Pipe
is common blowoff is very inexpensive
and easy to make. For this test, we used (2)
drilled pipes, each with (25) 1/16" diameter
holes on 1/2" centers. As shown in the test
results below, the drilled pipe performed
poorly. e initial cost of the drilled pipe
is overshadowed by its high energy use.
e holes are easily blocked and the noise
level is excessive - both of which violate
OSHA requirements. Velocity across the
entire length was very inconsistent with
spikes of air and numerous dead spots.
Flat Air Nozzles
As shown below, this inexpensive air nozzle
was the worst performer. It is available in
plastic, aluminum and stainless steel from
several manufacturers. e fl at air nozzle
provides some entrainment, but suff ers
from many of the same problems as the
drilled pipe. Operating cost and noise
level are both high. Some manufacturers
off er fl at air nozzles where the holes can
be blocked - an OSHA violation. Velocity
was inconsistent with spikes of air.
EXAIR Super Air Knife
e Super Air Knife did an exceptional
job of removing the moisture on one
pass due to the uniformity of the laminar
airfl ow. e sound level was extremely
low. For this application, energy use was
slightly higher than the blower but can
be less than the blower if cycling on and
off is possible. Safe operation is not an
issue since the Super Air Knife can not be
dead-ended. Maintenance costs are low
since there are no moving parts to wear out.
The Super Air Knife is the low cost way to
blowoff, dry, clean and cool.
If you think compressed air is too expensive and noisy - read this. The facts will surprise you!
Blower Air Knife
e blower proved to be an expensive, noisy
option. As noted below, the purchase price
is high. Operating cost was considerably
lower than the drilled pipe and fl at air
nozzle, but was comparable to EXAIR’s
Super Air Knife. e large blower with
its two 3" (8cm) diameter hoses requires
signifi cant mounting space compared
to the others. Noise level was high at 90
dBA. ere was no option for cycling
it on and off to conserve energy like
the other blowoff s. Costly bearing
and fi lter maintenance along with
downtime were also negative factors.
The Truth About Compressed Air!
Blowoff Comparison
Comp. Air
Horsepower
Required
Sound
Level dBA
Purchase
Price
Annual
Electrical
Cost*
Approx. Annual
Maintenance Cost
First Year
Cost
Type of blowoff PSIG BAR
SCFM SLPM
Drilled Pipes
60 4.1 174 4,924 35 91 $50 $4,508 $920 $5,478
Flat Air Nozzles
60 4.1 257 7,273 51 102 $208 $6,569 $1,450 $8,227
Blower Air Knife
3 0.2 N/A N/A 10 90 $5,500 $1,288 $1,500 $8,288
Super Air Knife
60 4.1 55 1,557 11 69 $534 $1,417 $300 $2,251
*Based on national average electricity cost of 8.3 cents per kWh. Annual cost reflects 40 hours per week, 52 weeks per year.
RS# 104
Visit www.rollonnews.com
for technical papers and
application help or call
1.877.976.5566
75D
61CD
Don’t let defelction slow
you down. Telescopic Rail
won’t yield to heavy loads –
even when fully extended.
s
RAPID DELIVERY
s
ONLINE DESIGN
s
LIVE SUPPORT
EDITOR’S WEB PICKS
What’s new online machinedesign.com
FREE WEBCAST: PIEZOMOTOR TECHNOLOGY
BASICS AND PRACTICAL APPLICATIONS
Thursday, March 14, 11:00 a. m. ET
In this Webinar, engineers with PiezoMotor AB will discuss the basics of
piezomotor technology and provide examples of a wide range of practical
applications for the devices. Piezoelectric motors fit applications in numerous
markets, such as medical, optics and photonics, instrumentation, and aerospace
and defense. The discussion will cover how the motors offer stiff and stable
performance in precision-positioning applications, have a high force to size
ratio, are economically manufactured in large quantities, and use simple drive
and control electronics. Learn more and register at />training.
Formula Hybrid racer
The Formula Hybrid design competition has students
building high-performance race cars that are also efficient
hybrid-electric vehicles. Entries are judged on acceleration,
braking, and handling qualities as well as endurance, cost,
and reliability. Engineering TV takes a look that the Univ.
of Michigan’s hybrid race car
at www.engineeringtv.com/
video/University-of-Michigans-
Formula;Only-Engineering-TV-
Videos.
Aluminum design
competition
Students studying engineering,
design, architecture, or a related
field can win a scholarship through
the 2013 International Aluminum
Extrusion Design Competition.
Hosted by the ET Foundation and
the Aluminum Extruders Council,
the goal is to promote the under-
standing and use of extruded alum
i-
num profiles, highlight innovations,
and recognize design excellence.
Entries should demonstrate the
benefits of aluminum extrusions
and show creativity, practicality,
product/process advantages, and
market/impact potential. In addi-
tion, a sustainable design award,
sponsored by Sapa Extrusions
North America, will go to the stu-
dent whose design best addresses
societal and/or environmental con-
cerns, in addition to meeting the ba-
sic criteria. The competition is open
to high-school and college students
around the world. Deadline for sub-
missions is April 12. Download the
entry form at www.ETFdesign.org.
Bearings catalog
igus has released its 2013 bearings
catalog for plastic bushings, self-
aligning bearings, plastic ball bear-
ings, and linear bearings and guides.
All run without lubrication. The
catalog contains extensive product
details and engineering data, up-
dates and specifications for bearing
materials, and info on applications
ranging
from agricultural and con-
struction machinery to bikes and
medical devices. Request a copy at
www.igus.com/quickorder.
App for hydraulic filters
Bosch Rexroth’s Fit4Filter smart-
phone app helps users replace and
upgrade existing hydraulic filter
elements from a job site or factory
floor. It cross references thousands
of filter elements and lets users up-
date the app with new data. It also
gives availability and delivery de-
tails. The app is suitable for filter ele-
ments on hydraulic power units in
virtually any application, including
plastic injection-molding machines,
offshore-drilling equipment, and
machine tools. Learn more at www.
boschrexroth-us.com/filter.
RS# 105
MARCH 7, 2013MACHINE DESIGN.com6
IRUWKHORFDWLRQQHDUHVW\RX
0RWLRQ,QGXVWULHVFRP
0RWLRQ,QGXVWULHV,QF
2YHUORFDWLRQV0RUHWKDQPLOOLRQSURGXFWV
,QGXVWULDOPDLQWHQDQFHWUDLQLQJFRXUVHV&DOO&OLFN9LVLW
:LWKDIRFXVRQDGYDQFHG
WHFKQRORJ\9LFNHUV
VFUHZLQ
FDUWULGJHYDOYHVHDVHV\VWHP
GHVLJQE\GHOLYHULQJFRPSOH[
DSSOLFDWLRQVLQDFRPSDFW
DQGVLPSOHSDFNDJH&RPELQH
PXOWLSOHFDUWULGJHYDOYHV
LQDFRPPRQPDQLIROGIRU
VXEVWDQWLDOFRVWVDYLQJV
$QG\RXFDQILQG9LFNHUV
VFUHZLQFDUWULGJHYDOYHVDW
\RXUORFDO0RWLRQ,QGXVWULHV
ORFDWLRQ2XUORFDOVDOHVDQG
VHUYLFHVSHFLDOLVWVDUHH[SHUWV
LQDSSOLFDWLRQDQGWHFKQLFDO
VXSSRUWSURYLGLQJWKHSDUWVDQG
WKHNQRZKRZ\RXQHHGWRVWD\
XSDQGUXQQLQJ
7KHEUDQGV\RXFRXQWRQIURP
WKHSHRSOH\RXWUXVWªWKDW¶V
(DWRQDQG0RWLRQ,QGXVWULHV
RS# 106
3UHFLVLRQJURXQG2'PDLQWDLQV
FULWLFDODOLJQPHQWZLWKLQ
P
$
PVXUIDFH¿QLVKDQGZHOO
GH¿QHGFKDPIHUVSUHYHQWVKDYLQJ
RUVFUDSLQJGXULQJLQVWDOODWLRQ
5ROOIRUPHGGHVLJQ\LHOGV
VXEVWDQWLDOFRVWVDYLQJVRYHU
*URXQG6ROLG'RZHOV
+ROORZIHDWXUHRIIHUVZHLJKW
VDYLQJVRYHU*URXQG
6ROLG'RZHOV
63,52/6HULHV
*'*URXQG
+ROORZ'RZHOV
DUHGHVLJQHGWREH
GLUHFWUHSODFHPHQWV
IRU*URXQG6ROLG
'RZHOVSHU,62
IRU$OLJQPHQW
$SSOLFDWLRQV
:K\8VH
6ROLG
*URXQG
'RZHOV"
63,52/DOVR
SURYLGHV,QVWDOODWLRQ
7HFKQRORJ\
EDITORIAL
If you happened to read a news item about a company that wanted to be
Chinese, you might logically think that company was headquartered in
Asia. You’d be wrong. This is the strategy of network-equipment maker
Cisco Systems Inc. as articulated by its CEO John Chambers in 2004.
Chambers’ comments are indicative of attitudes found among those
heading multinational companies. And those attitudes have become a
hot button in this era of big corporate bailouts and sending U. S. jobs to
foreign countries.
There is no question that company managers have changed their
views over the years about where they owe allegiances. Corporate lead-
ers were once expected to fulfill obligations to society and particularly
to the country in which they resided. But globalization has eliminated
any such sense of duty. In fact, it has increased the chance that heads of
U. S. companies are advocating policies that aren’t in the overall interest
of Americans.
The situation is illuminated by Clyde Prestowitz, a one-time U. S. trade
negotiator in the Reagan administration. He points out that U. S. CEOs
may be influential in the U. S., but have no political clout in authoritarian
countries like China or Russia. CEOs who do business there must main-
tain good relations with the powers that be, which often means being
more responsive to the wishes of authoritarian countries than to those
elsewhere.
Prestowitz says this is why in 2009 a group of big-name American
CEOs advised against including any “buy-American” provisions in the
economic-stimulus package then being voted into law. (All of which
would have been allowed under World Trade Organiza
tion rules.) The
irony was that China, Japan, and many European countries were in the
process of enacting buy-domestic policies themselves. “The CEOs were,
in effect, arguing for sending more of our stimulus money to help create
jobs overseas, while our trading partners
were doing the opposite,” he
writes.
No wonder, then, that people who have been paying attention to these
events increasingly distrust corporations. “We must be alert that when
American CEOs advise the president or lobby Congress today, they may
unwittingly be acting, in effect, as emissaries of foreign governments. In
any case, we cannot be sure that they are speaking on behalf of America’s
overall prosperity,” says Prestowitz. Participants in the Occupy Wall
Street movement couldn’t have said it any better.
Epitomizing the kind of cockeyed view of the world many CEOs have
today
is a comment from one who Prestowitz declines to name. The man
opined that he ran an international company that just happened to be
based in the U. S. Its headquarters, he claimed, could as easily be situated
in a Boeing 747, from which he could comfortably run the company while
circling the globe.
This is the kind of remark U. S. legislators should keep in mind the
next time a multinational company comes looking for favors. There are
increasingly few reasons not to drive the same kind
of hard bargains as
countries less “enlightened” about trade. One bargaining point that im-
mediately springs to mind is that companies wishing to sell goods in the
U. S. had better figure out how to make them here.
— Leland Teschler, Editor
Living on a jet plane
RS# 107
MARCH 7, 2013
Clippard Instrument Laboratory, Inc.
Providing innovative solutions for today’s engineering challenges
877-245-6247 • www.clippard.com
+XQGUHGVRI2SWLRQV0RGHOV
$SSOLFDWLRQV2SSRUWXQLWLHV
:D\
:D\
2[\JHQ&OHDQ
6HULHV
+LJK)ORZ
/RZ)ORZ
1XPHURXV
0RXQWLQJ
2SWLRQV
6HOHFW
2ULILFH
6L]H
9DULRXV
&RQQHFWRUV
)OXRURFDUERQ
(35).0DQG
6LOLFRQH6HDOV
Minimatic® Electronic Control Valves
)UDFWLRQDO
:DWWDJH
:D\: \
VVV
)DVW
5HVSRQVH
++LJK+
Standard &
Custom Designs
HFWHFW
FH
HH
t L bt I
H
1RUPDOO\2SHQ
1RUPDOO\&ORVHG
)XOO\3RUWHG
FREE 360-Page
Catalog
&\FOH/LIHLQ
WKH%LOOLRQV
RS# 108
EDITORIAL STAFF
1300 E. 9th St. Cleveland, OH 44114-1503
EDITOR
Leland E. Teschler
MANAGING EDITOR
Kenneth J. Korane
SENIOR EDITORS
Elisabeth Eitel
Stephen J. Mraz
ASSOCIATE EDITOR
Lindsey Frick
INDUSTRY COVERAGE:
AUTOMOTIVE, PACKAGING,
MEDICAL
Stephen J. Mraz
CAD/CAM, MANUFACTURING
Elisabeth Eitel
Lindsey Frick
FASTENING & JOINING,
MATERIALS
Lindsey Frick
FLUID POWER
Kenneth J. Korane
MECHANICAL
Elisabeth Eitel
Lindsey Frick
Kenneth J. Korane
EDITORIAL PRODUCTION
Denise Greco
Editorial Production Manager
Randall L. Rubenking
Art Director
RS# 110
RS# 109
MARCH 7, 2013MACHINE DESIGN.com10
DŽƟŽŶdĞĐŚŶŽůŽŐLJͮ&ŝďĞƌKƉƟĐƐͮůĞĐƚƌŽŶŝĐ^LJƐƚĞŵƐ
нϭͲϱϰϬͲϱϱϮͲϯϬϭϭဒϬϬͲϯϯϲͲϮϭϭϮ;h^ͿŵĐŐΛŵŽŽŐ͘ĐŽŵ
ǁǁǁ͘ŵŽŽŐ͘ĐŽŵͬĐŽŵƉŽŶĞŶƚƐ
^ƵƌǀĞŝůůĂŶĐĞƐLJƐƚĞŵƐƌĞƋƵŝƌĞŚŝŐŚƉĞƌĨŽƌŵĂŶĐĞƐŽůƵƟŽŶƐĨŽƌƚƌĂŶƐĨĞƌƌŝŶŐƉŽǁĞƌĂŶĚ
ĚĂƚĂĂĐƌŽƐƐƚŚĞƌŽƚĂƟŶŐŝŶƚĞƌĨĂĐĞƐŽĨǀŝĚĞŽĐĂŵĞƌĂƐ͘DŽŽŐŽīĞƌƐƐůŝƉƌŝŶŐƐƚŚĂƚ
ŚĂǀĞďĞĞŶĚĞǀĞůŽƉĞĚĨŽƌƚŚĞƌŶĞƚĚĂƚĂĐŽŵŵƵŶŝĐĂƟŽŶŶĞƚǁŽƌŬƐ͘DŽĚĞůƐ
ĂƌĞĂǀĂŝůĂďůĞŝŶĐĂƉƐƵůĞĂŶĚƚŚƌŽƵŐŚͲďŽƌĞĐŽŶĮŐƵƌĂƟŽŶƐ͘
ZĞůŝĂďŝůŝƚLJŝƐďƵŝůƚŝŶƚŽĞĂĐŚƉƌŽĚƵĐƚ͘džƚĞŶƐŝǀĞůŝĨĞƚĞƐƟŶŐŵĞĂŶƐŽƵƌƐůŝƉ
ƌŝŶŐƐĂƌĞƉƌŽǀĞŶƚŽƉƌŽǀŝĚĞůŽŶŐůŝĨĞĂŶĚůĞƐƐĚŽǁŶƟŵĞ͘
>ĞĂƌŶŵŽƌĞĂďŽƵƚDŽŽŐ͛ƐƐŽůƵƟŽŶƐĨŽƌƐƵƌǀĞŝůůĂŶĐĞ͘^ƚĂŶĚĂƌĚƐůŝƉƌŝŶŐĚĞƐŝŐŶƐĂƌĞ
ƌĞĂĚLJĨŽƌƋƵŝĐŬĚĞůŝǀĞƌLJŽƌĐĂŶďĞƚĂŝůŽƌĞĚĨŽƌƵŶŝƋƵĞƉƌŽũĞĐƚƐ͘ŽŶƚĂĐƚƵƐƚŽĚŝƐĐƵƐƐ
LJŽƵƌĂƉƉůŝĐĂƟŽŶ͘
>ŽŽŬŝŶŐĨŽƌŵŽƌĞ͍
^ĐĂŶƚŽǀŝĞǁƐůŝƉƌŝŶŐƐƉĞĐŝĮĐĂƟŽŶƐ͘
ƚŚĞƌŶĞƚ^ůŝƉZŝŶŐ&ĞĂƚƵƌĞƐ
͗
ͻ ŽŶƟŶƵŽƵƐϯϲϬΣƌŽƚĂƟŽŶ
ͻ DĂŝŶƚĞŶĂŶĐĞͲĨƌĞĞŽƉĞƌĂƟŽŶ
ͻ ZŽďƵƐƚƉĞƌĨŽƌŵĂŶĐĞ
ͻ ŽŵƉĂĐƚƐŝnjĞ
ͻ WůƵŐͲĂŶĚͲƉůĂLJƚŚĞƌŶĞƚĐŽŶŶĞĐƟŽŶƐ
RS# 111
LETTERS
only felt pens and a few overhead
projectors — that seemed to be the
norm for all levels of education in
the U. S. A. just a few decades ago.
Now our personal computers have
taken over and left us with instant
gratification but little reward for
thinking the problem out first. We
are all guilty of using the best and
greatest — MathCad, CAD/CAM,
and CNC — and need to use these
tools, but it sure makes a difference
if we had learned what it felt like to
cut a piece of metal or wood with
a file or saw somewhere along the
line in our education.
James Johnson
Anecdotally, this is nothing new.
Feynman wrote about this from
his time at MIT in the 1940s. Some
students were astounded when he
showed them that certain classes of
curves always had a horizontal tan-
gent at their lowest point. Is it getting
worse? I am skeptical, but I’d like to
see some data comparing students
now with students of yesteryear.
Carl Herrmann
My best professor in college, who I
was lucky enough to have for both
statics and dynamics, structured
most of his exam problems in a way
that didn’t require students use a
calculator to solve them. Instead,
the problems contained similar tri-
angles, 3-4-5 right triangles, and
simple ratios
and sums. He wanted
us to focus on the concepts and
not get bogged down in the math.
I remember him saying, when
showing us how to solve the prob-
lems after the exams, things like,
“Four equations, four unknowns,
you’re home free.” If you had got-
Math? We don’t need no
stinking math
Your blog on the prevalence of cal-
culators in math classes (“We Are
Turning Out Engineers Who Don’t
Understand Math,” Nov. 14) and
how they were dumbing down en-
gineering students struck a chord
with me. It reminded me of a cal-
culus professor who was asked if
calculators would be permitted for
exams. His response was, “Yes, but
I will accept no approximations of
pi or e.” This forced some people to
look at the problems and discover
they could frequently be reduced
to a fairly simple complex number
and a function — the correct an-
swer — without using a calculator.
The other classes which forced
you to really understand the princi-
ples were materials courses where
atomic distances were frequently
less than 10
-99
m, the limit of cal-
culators at that time. There were
a number of students who wrote
on the exam that problems could
not be done. The professor simply
replied: “Incorrect, your calculator
cannot do the problem.”
Don MacGregor
Knowing math and having a “feel”
for it are two different things. Rote
learning can give you a knowl-
ed
ge of math, enough to solve
most common problems using a
calculator. But in engineering you
need more than just rote knowl-
edge. You need a feel for the math
involved, especially in design. And
the only way to get that feel is by
solving problems, lots of problems,
applying the math knowledge you
have learned in different ways to
suit the information you have to
work with. Hand calculations and
aids such as a slide rule, trig tables,
and log tables help develop the
feel for the math in engineering
problems.
This has always been an issue in
engineering education and always
will be.
L. Gradwell
No chalkboards, protractors, com-
passes, or even graphite pencils,
ten that far on the exam, he would
give you almost full credit.
Still, there would be many stu-
dents frantically punching away at
their calculators as they scrambled
for an answer. Prior to going to col-
lege, I had only used a slide rule and
trig tables. Five years later it was
all different, but I think that back-
ground stood me in
good stead
both in college and ever since. I still
do estimating and calculations in
my head and usually arrive at the
answer before my coworkers can
find their calculators.
Jim McKim
This is worrisome. I was in col-
lege during the slide-rule age and
learned to know a long list of math-
ematical relationships very well.
Calculators are only as accurate as
the information keyed in, and the
answers have to be understood,
not just accepted as correct. We
need people who can estimate,
reason, and discern, not just mind-
lessly enter garbage. The old say-
ing garbage in/garbage out was
never more apparent.
Tom Kenfield
This is nothing new. My dad told
me a s
tory about how, back in the
1950s, his employer did not want
to hire any more unqualified con-
tract help. It was decided to make
up a simple math test to screen ap-
plicants. Nobody could pass the
test. Then they started giving it to
the people that already worked
there. The less-than-stellar results
explained a lot of problems they
were havin
g getting things to go
together.
Mike McGinty
Math spoken here
Leland Teschler blogged about the wide
use of calculators in engineering colleges
and the lack of math knowledge in engineering
grads. Readers see the connection and bemoan
the disconnect between solving engineering prob-
lems and what is taught in colleges. Meanwhile, one
reader asks for more math, not more calculations, to
explain a problem.
MARCH 7, 2013MACHINE DESIGN.com12
RS# 112
TM
LETTERS
I r
i
2
(1)
i
r
i
2
(in.
2
), (1)
i
represent points
(no unit), r
i
moment arms (in.)
Therefore the reaction module of the
group of points, which is equivalent
to the section module in the bending
stress problem, is:
Z
I
max(r
i
)
r
i
2
mas(r
i
)
(in.)
For moment load M in (in-lbf), the
maximum reaction force in the
group of points is:
F
M
Z
in.-lbf
in.
lbf
— Moo-Zung Lee
Maybe we need some math
I am working on a tank problem
that relates to a recent article
(“How Bolt Patterns React to Ex-
ternal Loads,” Sept. 8). In doing so
I have seen the formula: F = 4M/
ND numerous times and wondered
how it was derived. Your article has
shown me this and I appreciate
that.
However, I do have a question:
how F = M/Z comes out in pounds?
Typically this is stress (psi). For
some reason I am not seeing this.
Michael Weyand
Thank you for your interest in the ar-
ticle. Engineers use the term moment
of inertia loosely for convenience.
Generally, it means the second mo-
ment of something. Or the moment-
arm-square multiplied times some-
thing. It could be a moment of iner-
tia of masses, areas, lines or points.
In treating bending stress in a
cross section, moment of inertia ac-
tually means the “moment of inertia
of the cross-sectional area,” which
consists of A
i
elements.
I r
i
2
A
i
(in.
4
), A areas (in.
2
),
r
i
moment arms (in.)
And the section module of the cross-
sectional area is:
Z
I
max(r
i
)
(in.
3
)
For moment load M in (in-lbf), the
maximum reaction stress in the cross
section is:
b
M
Z
in.-lbf
in.
3
psi
In the article, we were interested in
the reaction of bolts as a group of
points. The points have no physical
unit. Therefore, the second moment
or “the moment-of-inertia of the
group of points” is:
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, M
ACHINE
D
ESIGN
,
1300 E. 9th St., Cleveland, OH 44114-
1503, Fax: 216-621-8469
E-mail, Editorial:
RS# 113
MARCH 7, 2013MACHINE DESIGN.com14
Print your
prototypes and
models right at
your desk.
5 Cylinder
Radial Engine
MAKERBOT
®
REPLICATOR
®
2 DESKTOP 3D PRINTER
$2,199
• Choose the easiest, fastest, most aordable desktop tool for
making professional-quality 3D prototypes and models.
• Cut costs and streamline product development and production.
• Get the best price/performance 3D printer on the market.
MakerBot is leading the Next Industrial Revolution.
Thousands of engineers, industrial designers, architects, and
creators are using MakerBots to make the world a better place.
AFFORDABLE
RAPID PROTOTYPING
AND MODEL MAKING
The New Standard in Desktop 3D Printing
Buy now or get
a free sample print.
Call 866.613.3471 or
visit makerbot.com/md
RS# 114
SCANNING FOR
IDEAS
Clear
window
Air fitting for emptying
fluid out of the filter
Mounting
fasteners
Filter
top
Reusable
filter
element
Mounting
studs
Filter
base
Filter-element
bypass valve
Fluid
outlet
Fluid
inlet
Machined
slots
Edited by Stephen J. Mraz
See-through housing
enables visual check of filter and fluid
Request free information via our
Reader Service Web site at
www.machinedesign.com/rsc
Engineers at Clear View Filtra-
tion, Spokane, Wash. (www.
clearviewfiltration.com), designed
their patent-pending fluid filter so
that race teams can visually check
the fluid pumping through the
filter. This lets them quickly deter-
mine the fluid’s condition. A quick
blast of compressed air or CO
2
into a convenient inlet valve clears
away the fluid and lets the team
inspect the filter element and
what it has collected, which can re-
veal excessive engine-component
wear. These two checks cannot be
made with conventional filters.
The filter’s housing is machined
out of 6061 T6 aluminum for dura-
bility. The sight window is a high-
grade plastic that resist
s chemi-
cals, heat, scratches, and impacts.
And the filter is a stainless-steel
mesh (60 or 115-micron holes)
that can be easily cleaned and
reused. The filter base has 12 ma-
chined slots. If contaminants clog
one or more of the slots, the oil
or other fluid can still pass freely
through the remaining clear holes.
If too many of the
se slots or the
filter element gets clogged, a relief
valves opens, letting unfiltered
fluid pass through. This prevents
motor failure due to a completely
clogged filter.
The filter withstands work-
ing pressures of 150 psi at 200°F.
The company builds five differ-
ent types o
f filters for use with
engines, transmissions, hydraulic
units, and other fluid systems. The
company can also adapt filters
for custom applications to handle
specific pressures, volumes, or
types of fluids.
The filter measures 6-in. long
and 5-in. wide, w
eighs 3.5 lb, and
costs about $385.
RS# 401
MARCH 7, 2013MACHINE DESIGN.com16
TM
F OR A 3D W ORLD
/HDUQPRUHDW6WUDWDV\V)RU$':RUOGFRP
6WUDWDV\VLVDUHJLVWHUHGWUDGHPDUNRI6WUDWDV\V/WGUHJLVWHUHGLQWKH86DQGRWKHUFRXQWULHV
, !+,
6
,
5!-
(*,+
b
(YHU\GD\PRUHDQGPRUHRIWKHWKLQJVZHVHHDQGXVHHYHU\GD\VWDUWOLIHDVDSURWRW\SHSULQWHG
RQD ' SULQWHU,W¶V DWHFKQRORJ\WKDW LV FKDQJLQJ WKH ZRUOGLQVRPH DPD]LQJ ZD\V
'HVLJQHUV
DQG HQJLQHHUV DUH XVLQJ LW WR SULQW DPD]LQJO\ DFFXUDWH SURWRW\SHV EHIRUH WKH\ JR WR SURGXFWLRQ
0DQXIDFWXUHUV DUH XVLQJ LW WR SULQW DPD]LQJO\ GXUDEOH HQGXVH SDUWV DQG GUDPDWLFDOO\ LQFUHDVH
SURGXFWLRQ HI¿FLHQFLHV
$QLPDWRUV HGXFDWRUV JDPH GHYHORSHUV DQG PHGLFDO DQG GHQWDO
SURIHVVLRQDOV DUH DOO XVLQJLW WR WUDQVIRUP WKH ZD\ WKH\ ZRUN
' SULQWLQJ LV WKH QH[WLQGXVWULDO
UHYROXWLRQ$QG6WUDWDV\VLVKHUHWROHDGLW
:HOFRPHWRD':RUOG
RS# 115
+DFNHQVDFN1-86$ì
ìPDLQŴPDVWHUERQGFRP
ZZZPDVWHUERQGFRP
have an open mind
…and fill it with info
on epoxies
ìZKLWHSDSHUV
ìYLGHRV
ìHQHZVOHWWHUV
ìWHFKQLFDOWLSV
Visit our resource
library for:
KNF Neuberger
Trenton, NJ •
www.knfusa.com
609/890-8600
Pump Selection Guide
Rugged Liquid Solenoid Pump
advanced diaphragm pump technology - why settle for less?
FREE!
Dispenses from 30 to 80 μl/stroke of liquid volume
Compact size, lightweight, it mounts in any position
Operated from 0-10 Hz with flowrates to 48 ml/min.
Flowtight at rest in both directions to 14.5 psi
Small quantities available for OEM prototype evaluation
•
•
•
•
•
KNF applied its 20 years of diaphragm pump experience to bring you a
new, solenoid-driven pump. It is designed to accurately dispense a
repeatable, adjustable volume using a variety of corrosion-resistant
materials and head connections, including manifold mounting.They run
quietly, and patented construction ensures .
over 500,000,000 cycles
Compact • Adjustable Dose • Long Lifetime
DiaphragmType • Quiet Operation
Model FMM80
SCANNING FOR IDEAS
RS# 117
RS# 116
Thermoplastic
housing
Fasteners
Electrical
connection
for power-
control
and output
signals
Electromechanical
drive includes
controls and
communications
Spring-loaded slide
bolt replaces existing
striker/keeper
Mechanical drive can be rotated
for installation flexibility
Electronic access
for new and old enclosures
The EM Electronic Keeper from Southco, Con-
cordville, Pa. (www.southco.com), lets compa-
nies put electronic access and push-to-close
features on new or old enclosures, both large
and small. The remotely actuated electronic
keeper replaces existing frame-mounted static
keepers (or strikes). A signal causes the keeper
to release and unlatch the door. And the door
can still be pushed closed and locked. Wiring to
the keeper is routed in the frame, so repeated
opening and closing of the enclosure does not
put wear on the wires.
More than one E-Keeper can be installed on
larger enclosures and operated from a single
remote, numeric keypad, RF keyfob, m
ag-
stripe card, or networked security network.
When installed, the device can be used to moni-
tor and audit when enclosures are opened, or
to activate alarms when a specific enclosure is
opened. The device can use a 12 or 24-V power
supply. RS# 402
Well-connected.
Newark element14 makes it easy to fi nd all your electronics products and solutions – fast. newark.com
RS# 118
REPORTER’S
NOTEBOOK
To save energy, engineers mount
pneumatic valves as close as pos-
sible to the actuator. This reduces
the length of tubing between the
valve and actuator, so it takes less
compressed air for
each actuator cy-
cle. This can
cut com-
pressed-air
consump-
tion by up
to 20% in some
applications.
Unfortunately,
common pneumatic valve
s are
usually too large and heavy to
mount near actuators in handling
applications, where cylinders, grip-
pers, or suction cups sit on mov-
ing arms or gantries. The added
mass of a valve bank could reduce
the arm’s speed and load capac-
ity, and possibly affect position-
ing accuracy. Or it might require
more-powerful drives and beefier
structures. This would increase
energy consumption of the overall
machine and negate the benefits
of decentralized pneumatics.
Engineers at Bosch Rexroth,
Charlotte, N. C., have reportedly
overcome these issues with a
valve called the AV03. The AV03
offers high flow rates in a package
that is lighter and more compact
than traditional air valves. This
makes it well suited for handling
equipment and other applications
where the pneumatic hardware
moves.
The new valves have about half
the weight of conventional valves,
and are about 45% smaller thanks
to the use of high-performance
polymers, fewer parts, and orient-
ing the spool at an angle within
the housing, explains Marchelle
Forish, a senior product specialist
at Bosch Rexroth Pneumatics,
Lexington, Ky.
The valve housing is glass-fiber-
reinforced polyamide, which is
substantially lighter than alumi-
num and other common valve ma-
terials. The polymer also improves
chemical resistance, compared to
aluminum manifolds.
Mounting internal components
on a diagonal makes
better use of
internal space,
says Forish. Engi-
neers can, thus,
pack more func-
tions into a smaller
space. Working
ports are only on the
side where needed,
and the valve has a
smaller footprint for base-plate
mounting.
The design also uses fewer
parts than previous versions. For
example, it needs only a single tie
rod for manifold assembly, and
a single screw for
valve mounting.
This eliminates
one or two tie
rods, depend-
ing on the series,
as well as one
fastener for each
valve. It also
speeds installation
and replacement.
The AV03’s built-in
pilots further re-
duce the amount of
mounting hardware.
Despite the smaller size, the
AV03’s flow capacity actually
matches or exceeds that of most
competing valves. That’s because
arranging internal components at
an angle let developers streamline
the supply and exhaust channels
and reduce flow losses.
The angled design enables
larger air channels, which permits
more flow in less space, explains
Forish. “Every return, throttle, and
constriction reduces pressure. And
the sharper a return, the greater
the reduction in working pressure.
“Improved channel geometry
helps avoid turbulent flows and
p
ressure losses, as it uses only the
pressure needed. As a result, a
lower work-
ing pressure
can be set up-
stream of the
valve,” says
Forish. Users
get the same cylinder force yet
enjoy flow improvements of 40%,
letting them substantially lower
the supp
ly pressure and boost ef-
ficiency, adds Forish.
The AV03 is a zero-overlap spool
valve with soft sealing, and the Series
includes 2×3/2-way, 5/2-way, and
5/3-way versions. Users can custom-
ize the number and type of valves to
meet specific requirements. With a
25-pin D-sub connection, manifolds
can be configured in increments
of one after the second valve and
after the fourth valve with 44-pin
D-sub and fieldbus connections. The
AV03 controls up to
24 coils with a 25-pin
D-sub connection, up
to 40 coils with a
44-pin D-sub, and
up to 128 coils
with a fieldbus
connection. De-
signers can also
opt for different
pressure zones
within a single valve
mani
fold.
Users can electri-
cally connect the valve blocks using
multipole or fieldbus connections,
with integrated I/O modules, de-
pending on the configuration. And
because sensors can directly con-
nect to the valve electronics, fewer
cables have to be fed back to the
control cabinet.
Maximum nominal flow is
300 lpm, with operating pres-
sure ranging from –0.9 to 10 bar.
Medium/ambient temperature
is –10° to 60°C, and valves run on
standard compressed air filtered
to 40 μm. Protection class rating
is IP65.
The AV03, currently available in
Europe, will be released in the U.S.
in the 3rd quarter of this year.
MD
A new angle on valve design
Resources:
Bosch Rexroth, www.
boschrexroth-us.com
RS# 406
For additional details
on the AV03, visit www.
advanced-valve.com/en/
index.html
Users can customize AV03
manifolds with different valves,
pressure zones, connectors, and
communications networks.
Mounting internal components
in the AV03 at an angle makes
efficient use of internal space,
cutting valve size nearly in half.
MARCH 7, 2013MACHINE DESIGN.com20
Regulations in many coun-
tries now mandate a mini-
mum energy efficiency for
electric motors that are at
least 1 hp. But does it make
sense to replace motors
smaller than 1 hp in the in-
terest of energy efficiency?
That was one of the
questions a German
wastewater-treatment
plant tried to answer with
some recent tests. Work-
ers there took measure-
ments to gauge the eco-
nomics of replacing an or-
dinary 0.37-kW (0.55-hp)
induction motor with a
more-efficient design for
powering a disc thickener,
a rotating sieve that filters
water from sludge and
mud. In use, the motor
rotates the sieve with a
constant torque because
the sludge has a constant
consistency. The new motor, a
synchronous permanent-magnet
design, ended up using about 40%
less energy than a conventional
induction motor.
The original induction mo-
tor created 2.62 Nm of torque
at 1,350 rpm and operated with
61.5% efficiency, and dissipated
0.26 kW/hr. The new motor, fro
m
Bauer Gear Motor, Somerset,
N. J., created 3.5 Nm of torque at
1,500 rpm and operated with an
efficiency of 87.7%, dissipating
0.16 kW/hr. Both motors operated
from an inverter from Danfoss,
Baltimore, and used the same
Bauer 381:5 gearbox which was
94% efficient.
Estimates are that over four
years, the induction motor would
consume 2,657 kW-hr compared
to 1,635 kW-hr for the synchro-
nous PM motor.
Bauer personnel involved in
the test note that there are more-
efficient induction motors avail-
able and that comparisons with
one of those motors would not be
as dramatic. Nevertheless, the syn-
chronous PM motor would have
still saved energy and been less
expensive to boot. An induction
motor with premium efficiency for
this application would have dem-
onstrated at least 82.5% energy
efficiency, weighed 88 lb, and cost
about $905, say Bauer personnel.
The 87.7%-efficient synchronous
PM motor used in the test weighed
55 lb and cost about $879.
MD
Minutes
Kilowatts
Energy consumption
Induction motor
Synchronous PM motor
0
15
30
45
60
75
90
105
120
150
135
165
180
195
210
225
270
285
300
315
330
0.325
0.3
0.275
0.25
0.225
0.2
0.175
0.15
0.125
0.1
0.075
0.05
0.025
0
The synchronous
PM motor in place
in the wastewater
treatment plant.
A look at the
instantaneous
power
consumption of
the induction
motor and
synchronous
PM motor
reveals
different power
levels of the
two when
rotating a disc
thickener. Both
were driven by
an inverter.
Field tests show energy efficiency
not just for integral-horsepower motors
Resources:
Bauer Gear Motor, member of the
Altra Industrial Motion Group,
www.bauergears.com/
RS# 407
Danfoss Group, www.danfoss.com
RS# 408
The difference between
a synchronous and an
asynchronous motor,
machinedesign.com/article/the-
difference-between-asynchronous-
and-synchronous-motors-0103
MARCH 7, 2013 MACHINE DESIGN.com 21
Thousands of enclosures
Hundreds of sizes
Next-day shipping
REPORTER’S NOTEBOOK
A magnetic sensor turned
out to be a useful replace-
ment for a simple
limit switch that
prevented over-
travel in screw
jacks.
ActionJacs
made by Nook
Industries in
Cleveland, Ohio,
once incorporated heavy-
duty bolt-on limit switches
as a means of keeping the
worm-gear-driven jacks from be-
in
g driven too far. Recently, the
company replaced the switches
with magnetostrictive sensors
which detect ring magnets fixed
to the translating screw to note
its position. The sensors, along
with a patented electronic detec-
tion circuit, make up what’s called
the Nook Sensor System.
Sensors on the NSS are manufac-
tured using polypropylene overmold-
ing which also seals them. The sensors
slide into a profile on the
side of the screw housing.
If need be, several can be
positioned in the profile
for sensing the screw as it
passes various points in
its housing. This permits
such actions as slowing
the screw as it nears an
end point.
The small magne-
tostrictive sensors,
measuring 28-mm long,
are made by Turck in Min-
neapolis. The sensors come
with a quick-mount tab
that helps seat them in
the cylinder’s groove
for easy single-handed
mounting. Operators
tighten a screw to keep the
sensor in place.
MD
Magnetic sensors
beat limit switches for
positioning screw jacks
Resources:
Nook Industries, www.
nookindustries.com
RS# 409
TURCK, www.turck.us
RS# 410
Sensors
