November 22, 2012
A Penton Media Publication
Tune in to EngineeringTV.com
Reengineering
the
SNOWMOBILE
page 34
HANDLING EMI
WITH INDUSTRIAL
FIBER OPTICS,
page 38
ENERGY-EFFICIENT
CASTINGS,
page 42
BETTER HEAT
SINKS WITH
MULTIPHYSICS,
page 45
APPLIANCE WIRE
GETS A ROLE
IN MACHINE
BUILDING,
page 48
RS# 101
RS# 102
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VOLUME 84
ISSUE 18
NOVEMBER 22, 2012
ELECTRICAL/ELECTRONIC TECHNOLOGY GUIDE
Safety standard
gives
Appliance wire
is back, but
regulations may
limit its use.
AWM and NFPA compliance
APPLIANCE WIRE
a new lease on life
High-end AWM-style cables are
making a comeback in machine
wiring providing over 20 years
of reliable performance.
FEATURES
Authored by:
Rick Orsini
Senior product manager
Lapp USA
Florham Park, N. J.
Edited by Robert Repas
[email protected]
Key points:
• NFPA-79 outlines electrical standards for
industrial machinery to protect operators,
equipment, and facilities from fire and
electrical hazards.
• Banned in 2007, AWM may now be used in
machine wiring, restrictions permitting.
34
• New permissions may let MTW products that
carry a UL TC-ER listing slash installation costs,
even over AWM.
Rethinking the
snowmobile
Resources:
NFPA 79 Standard, bit.ly/Rbblbv
UL Wire and cable flammability testing, bit.
ly/TxHTv2
economics for
38 Better
industrial fiber optics
Plastic optic fiber is a better option
than copper wiring for applications
plagued by electrical noise.
with quartz
42 Casting
The casting of synthetic-quartzcomposite mixtures to tolerance uses
less energy than casting iron.
For a white paper on the NFPA 79 electrical
code, scan this code or go
to: http://machinedesign.
com/whitepaper/
understanding-theelectrical-code-to-becompliant-0501
48
MACHINE DESIGN.com
Appliance wire OK’d
The key change to NFPA-79 for 2012 involves the ability to use appliance
wiring material (AWM), which had been banned since 2007. AWM can be an
economical wiring choice compared to higher-performing UL-listed machinetool wire (MTW). But there were several sound reasons behind the AWM ban.
For one, some contractors were using AWM incorrectly as part of the building infrastructure. The NEC does not recognize AWM for this type of use.
Also, not all AWM products are created equal when it comes to the quality
of their insulation layer. The insulation thickness of low-quality commodity
cabling varied such that the wire, while meeting its electrical insulation requirements, was not sufficiently flame resistant for use in industrial machines.
It’s important to stress that not all AWM suffers from these quality issues.
Lapp and other reputable cable manufacturers can and do produce AWM products whose insulation wall thickness is both consistent and adequate for the
voltage rating of the cable. High-quality AWM can pass the specified vertical
flame tests (FT 1) and can safely be used in industrial machines. Keep in mind,
however, that AWM lacks the extra layers of PVC-nylon insulation found in
Lapp USA, www.lappusa.com
Technology borrowed from
motorcycles, snowmobiles,
mountain bikes, and snowboards
leads to a lighter, more-nimble
Personal Snow Vehicle.
If you find electrical safety standards confusing, you’re not alone. Many
machine builders recently grappled with an ambiguous round of changes to
NFPA-79. This is the National Fire Protection Association code that outlines
electrical standards for industrial machinery that protects operators, equipment, and facilities from fire and electrical hazards. NFPA-79 is cited extensively in the National Electrical Code (NEC) that governs the electrical wiring
of industrial machines.
The standard cuts a broad swath across the industrial machinery landscape.
It applies to a comprehensive range of machines — everything from machine
tools and injection-molding presses to testing machines and packaging lines. It
encompasses all of a machine’s electrical and electronic elements operating at
600 V or less. This means that a vast majority of machine power, control, and
lighting circuits fall under the scope of NFPA-79.
Machine builders complied with the dictates of NFPA-79 for years. But earlier this year the standard underwent revisions that make it more difficult to
specify compliant electrical cabling.
NOVEMBER 22, 2012
A Krones technician documents the use of AWM in
compliance with NFPA-79.
One company successfully navigating the shoals of the recent
NFPA-79 revisions is Krones Inc., Franklin, Wis., a manufacturer
and integrator of packaging lines for food and beverage companies. The company’s engineering team recently found that compliant AWM usage does require a bit of extra effort compared to
the automatic compliance found with UL-listed MTW.
“Whenever you must implement changes because of an electrical-code change, there’s definitely an engineering-labor factor,”
says Mike Nelson, the Krones engineer charged with NFPA-79
compliance.
Some of that engineering labor went into researching specific AWM products to see whether they meet the compliance
restrictions. Even proper jacket labeling doesn’t answer every
compliance question regarding AWM. “You can’t tell whether a
product complies just by looking at the cable,” says Nelson. And
even more engineering labor went to NFPA-79’s documentation
requirements.
In all, Nelson estimates that Krones has spent more than 150
engineering man-hours complying with the requirements related to AWM use. And that figure represents just the work done to
formulate a compliance strategy. It does not include the technical
documentation and drawing changes needed to incorporate the
wire into each and every machine.
NFPA restrictions. In the case of extremely large machines
MTW. This extra insulation allows some types of MTW to
such as bottling lines, machine builders and installation
pass flame tests (FT 4) more rigorous than those for even
contractors can spend dozens of engineering hours and
the best AWM.
thousands of dollars complying with the documentation
Reversing the AWM ban reflected the realities of the
requirements.
global machinery marketplace in which AWM remains a
These documentation needs, while not insurmountwidely used cabling choice. The restrictions imposed by
able, must be factored into the cost of wiring the machine.
the new NFPA standard attempts to negate the potential
In some cases, the added documentation costs can erode
drawbacks of AWM.
the minor price advantages of some AWM cables.
The first restriction states that the AWM must be idenOne way around the concern of documentation is to
tified as suitable for the application at hand and must be
favor listed MTW. Because it inherently complies with
used in accordance with the machine-manufacturer’s inNFPA-79, MTW cabling alleviates the documentation
structions. Other restrictions detail cable construction inrequirement and eliminates any residual confusion over
cluding minimum conductor count, flame resistance, and
whether a given AWM product is approved and properly
wall thickness. Compliant AWM cable must carry a jacket
labeled. MTW also has a host of technical advantages that
print legend that spells out the AWM style number, voltderive from its superior flexibility and resistance to flame,
age, temperature rating, and flame rating.
The reversal on AWM
usage also requires more
documentation. For exampl e, m anu f a c tu re rs
Certain UL-listed cables meet exposed
Another change in the 2012 NFPAmust provide field-instalrun (-ER) specifications, which provide an
79 standard allows exposed cable runs
lation information related
additional level of protection for these
along the structure of the equipment or
to the AWM wire with
types of applications. Cables meeting -ER
in the machine chassis. As long as the exeach machine’s technical
requirements are subjected to the same
posed cables closely follow the surface
documentation.
Exposed cable runs for fast installation
Easy compliance
Given all the cable runs
on and around today’s complex industrial machines,
the need to do cument
AWM usage for each and
every machine represents
the most onerous of all the
and structural members of the machine,
the installation does not require conduit,
raceways, or any special hardware. Thanks
to reductions in installation time and labor, exposed cable runs can reduce costs
dramatically compared to traditional installation methods that need conduit or
special mounting hardware.
crush and impact tests as armored-type
or metal-clad (MC) cables, that lets cables
leave the machine area and enter a cable
tray without conduit.
Keep in mind, though, that not all ULlisted cables meet NFPA requirements,
especially lower-priced commodity and
rigid products.
NOVEMBER 22, 2012
48
Safety standard gives
appliance wire a new lease
on life
CAD/CAM/CAE/FEA
builds a
better heat sink
How Toyota designed
a small, efficient heat
sink to cool electronic
components in its
future hybrid vehicles
Multiphysics
software builds a
better heat sink
Authored by:
Ercan (Eric) Dede
Principal Scientist
Toyota Research Institute of North America
Ann Arbor, Mich.
Edited by Leslie Gordon
[email protected], Twitter @
LeslieGordon
• Engineers designed a smaller and moreefficient heat sink to thermally regulate the
electronic components in future Toyota hybrid
vehicles.
• Numeric simulations generated an optimal
cooling channel topology with fluid streamlines
in branching channels.
• The dual configuration prototype provided
higher-performance cooling in an ultracompact
package.
Resources:
Toyota Research Institute of North America,
http://tinyurl.com/8kdkq3r
It’s no secret that
These
carmakers are under
isometric
a lot of pressure to reduce
views show the
the number, size, and weight of
derived hierarchical
engine components for better fuel
microchannel cold plate
economy. In one case, we were tasked with
without a jet plate (top)
designing a smaller and more-efficient heat
and with a jet plate
shown transparent for
sink to thermally regulate the electronic
clarity (bottom).
components in Toyota hybrid vehicles.
Instead of using typical analytical design
methods and trial-and-error physical prototyping, we first used multiphysics software to design and test possible prototypes.
Hot under the hood
Toyota hybrid vehicles have sophisticated electrical systems in
which many power diodes and power semiconductors — such as insulated-gate bipolar transistors — handle power conversion and other
applications. These components are standard planar silicon devices
measuring a few centimeters on each side. The devices mount on aluminum heat sinks, or cold plates, with channels in which a water-andNOVEMBER 22, 2012
MACHINE DESIGN.com
Toyota used multiphysics
software to build a better
heat sink for its future
hybrid vehicles.
45
45
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products and services found
in the pages of MACHINE DESIGN.
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MACHINE DESIGN.com
NOVEMBER 22, 2012
49
Appliance wiring material, banned
in 2007, is now back in service owing
to the realities of today’s global
machine marketplace. But, its use
comes with restrictions.
MULTIPHYSICS SOFTWARE
Key Points:
2
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RS# 103
ON THE COVER
DEPARTMENTS
An SR-85 Snow Runner
from Sierra Snow
For customized article reprints and permissions
please contact: Penton Reprints, 1-888-858-8851,
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8 EDITORIAL
Silliness at 40 below
10 EDITORIAL STAFF
12 LETTERS
16 SCANNING FOR IDEAS
Spindle drive moves with accuracy
Filter vent equalizes pressure inside and out
20 REPORTER’S NOTEBOOK
26 LOOKING BACK
33 COMMENTARY
What’s up with model-based engineering?
51 ORR ON ENGINEERING
The death of e-mail?
52 SOFTWARE REVIEW
SolidWorks 2013 makes 3D modeling easier
54 PRODUCT SPOTLIGHT
Adhesives & fasteners
56 PRODUCTS
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RS# 104
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© Allied Electronics, Inc 2012. ‘Allied Electronics’ and the Allied Electronics logo are trademarks of Allied Electronics, Inc.
An Electrocomponents Company.
What’s new online machinedesign.com
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Rapid technological innovation, demand for customized products, and requirements for more reliably maintained systems
are spurring the rise of smart machines. This eBook from National Instruments discusses the different approaches used to
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New technology for control-panel design
This eBook from Eaton offers insights on how to simplify control panel wiring and design. Topics include an overview of
traditional panel design; key industry standards; protocols used in industrial networks; and how the SmartWire-DT system
speeds commissioning of next-generation machines and control panels.
Download these eBooks at http://machinedesign.com/ebook.
Simple, low-cost robot
The CEO of Rethink Robotics gives an overview of the Baxter robotic platform. The
inexpensive, easy-to-use robot is designed for small manufacturers who do short production
runs of many different parts. It can be programmed
by shop-floor workers and offers humanlike speed,
precision, and strength. Learn more at www.
engineeringtv.com/video/The-Baxter-RoboticPlatform-for;Only-Engineering-TV-Videos.
Selecting potting compounds
Electronic and electrical equipment needs potting
compound to secure, protect, and insulate components.
A Fabrico site, www.fabrico.com/markets-electricalequipment.htm, looks at considerations for evaluating
potting materials, including device characteristics,
environment, adhesive cure time and expansion rates,
and overall costs. It also discusses benefits of materials
such as epoxy, polyester, urethane, and silicone.
EDITOR’S WEB PICKS
Actuator-sizing software
6
A new online sizing program from Tolomatic helps
engineers design and specify electric actuators based
on motion requirements like length, velocity, and
acceleration, as well as orientation, loads, and applied
forces. It also lets users select a motor based on
parameters such as continuous/peak torque and speed,
and add features to the actuator like mounts and switches.
It’s compatible with PCs, tablets, and smartphones. Learn
more at http://sizeit.tolomatic.com.
Oil-cleanliness booklet
More than 75% of all hydraulics problems can be linked to
dirty oil. Bosch Rexroth has published a 44-page booklet,
on oil-resistant paper, that outlines common contaminant
sources, the basics of contamination control, key filter
properties, tolerances of hydraulic components, and
recommended oil-cleanliness levels according to ISO 4406.
It also covers monitoring and maintenance strategies to
proactively diagnose problems before a failure. Order a
free copy at www.boschrexroth-us.com/filter.
Enclosure selector
Rittal’s Web site (www.rittal-corp.com) helps engineers
quickly design, size, and quote enclosures and climatecontrol products. The SmartSelect tool lets users select
MACHINE DESIGN.com
NOVEMBER 22, 2012
the type of product and then specify dimensions, ratings,
materials, and other parameters. Results include exact
matches and close alternatives, along with product
details, drawings, installation videos, and related info.
The company’s QuickQuote application creates a bill of
material and price estimate. Users can also access the
tools on most smartphones and mobile devices.
Controls catalog
OTTO has published an interactive, 226-page magazinestyle PDF catalog on its switches, grips, joysticks, and
control panels. Content includes product data, technical
specs, drawings and photos, and a comprehensive
military cross-reference. Download a copy, or request a
print version, at www.ottoexcellence.com.
Structural simulation
Ansys will host a free, 1-hr Webinar on November 29 on
how to improve simulation processes. The discussion
covers large and complex model performance, modeling
3D-composite shapes, customizing processes for
structural mechanics, crack modeling, mapping of
external data, and contact modeling, as well as better
ways to handle finite-element models. Learn more at
http://tinyurl.com/cknkp9x.
Fastener app
PennEngineering has launched the PEMspec app for
iPhones and iPads. It lets users access critical installation
dimensions for self-clinching, flaring, broaching, surface
mount, and weld fasteners. Data includes mounting-hole
size, minimum sheet thickness, and installed height above
sheet, among other criteria. Users can search by fastener
parameters or part number, and the app also contains
pertinent links and contact information. Learn more at
www.pemnet.com.
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© 2010 ZERO-MAX
RS# 105
EDITORIAL
Silliness at 40 below
Many years ago a college classmate of mine told a funny story
about his summer job testing communications gear for a defense
contractor. He spent his time alternately freezing the radios to
–40°C and heating them to 85°C, while operating them to make
sure they’d work at these extreme temperatures.
Trouble was, most of the radios wouldn’t pass this test. To fix
the problem, the contractor had to go through a redesign, which
took more than a month, putting the project behind schedule.
Once the electronics had been fixed, my buddy drew a lot of overtime running radios in temperature chambers, trying to catch up.
In fact, the pace was so hectic that nobody bothered to check the
radios at room temperature.
You may be able to guess what happened. It was only as things
slowed down that QA discovered the revamped radios often sputtered out when operating in ambient temperatures.
With that situation in mind, I was amused at a tale told in the
memoirs of former General Motors Corp. Vice Chairman Bob
Lutz to illustrate some of the whacky design practices he encountered when he joined GM in 2001. He discovered the ashtray of a
new Cadillac STS had a lot of spring pressure. When opened, it
shot out as though launched from a cannon, and once deployed,
was tough to push in with just one finger. This was in contrast to
the ashtray on an Acura, which glided open and took a single effortless push to close.
Lutz figured the ashtray design in the Cadillac had to be a mistake, so he was flabbergasted when a senior interior-trim engineer
said it operated that way on purpose. The reason: So it could meet
an internal GM standard that dictated ashtrays had to function
after a night spent at –40°F.
Lutz says loopy situations like the Cadillac ashtray were not at
all uncommon in those days. They arose because GM had a habit
of engineering its vehicles for extreme situations. That was a noble
idea, but it came at the expense of alienating thousands of GM
owners on a daily basis.
You might wonder what happened to the –40°F ashtray spec.
Lutz says his team eventually eliminated it and 90% of the other
sacred but silly engineering do’s and don’ts that had somehow become embedded in GM culture. He also opined that the existence
of these disconnected-from-the-real-world practices was a “testimony to a culture that was inwardly focused in pursuit of its own
goals, with the customer left out of the equation.”
I would put it a little differently than Lutz did. Both in the case
of the bad radios and with the ashtrays that operated superbly
only at –40°C, the designers had lost sight of the trade-offs they
were making. There is a lesson here for any engineer who’d like
to avoid having something they designed be the butt of jokes, or
who doesn’t want their work to wind up as a humorous incident in
someone else’s memoir.
— Leland Teschler, Editor
RS# 106
NOVEMBER 22, 2012
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RS# 107
VISIT US AT IMTS BOOTH #E-4351
EDITORIAL STAFF
EDITOR
Leland E. Teschler
[email protected]
MANAGING EDITOR
Kenneth J. Korane
[email protected]
SENIOR EDITORS
Leslie Gordon
[email protected]
Stephen J. Mraz
[email protected]
ASSOCIATE EDITORS
Lindsey Frick
[email protected]
Robert J. Repas, Jr.
[email protected]
RS# 108
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
Does your gear drive mesh properly? Not all do.
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MITRPAK features include:
• Stainless steel shafts • Double-shielded ball bearings • Factory optimized gear mesh
• Hardened spiral
• Adjustable locknuts in place of • Completely sealed
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spacers and retaining rings
• Lubricated for life
U.S. and metric right angle, three-way, and counter-rotating gear drives in stock and
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For complete specifications and CAD files, log onto www.mitrpak.com, or call
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RS# 109
EDITORIAL PRODUCTION
Denise Greco
Editorial Production Manager
Randall L. Rubenking
Art Director
MITRPAK
Power Transmission Products
38 River Road, Uxbridge, MA 01569
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10
Lindsey Frick
Kenneth J. Korane
MACHINE DESIGN.com
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NOVEMBER 22, 2012
TM
micro
fasteners
Ideal for today’s compact electronics
f*DPLQJ+DQG+HOG'HYLFHVf1RWHERRNV
f&HOO6PDUW3KRQHVf7DEOHW&RPSXWHUV
1(:
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DQGFDSDELOLWLHVJRWRRXUZHEVLWHDQGFOLFNRQWKH
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+5%+%
7DSHUHGDQGLQWHUIHUHQFHILWPLQLPL]HKROH
WROHUDQFHLVVXHV
Locating pins
Surface mount
nuts/spacers
*RWRZZZSHPQHWFRPDQGVHOHFWWKHSURGXFWOLWHUDWXUHWDE
WRYLHZPLFUR3(0706HOI&OLQFKLQJ7DFN3LQ70EXOOHWLQ
Standoffs/spacers
Inserts for plastics
Low profile head screws
70 YEARS
OF EXCELLENCE
www.pemnet.com
1942-2012
RS# 110
382R
©2012
LETTERS
Anyone for ethics?
Unfortunately, ethics went out the
window in the U. S. many years ago
with the advent of our “instant” society (“Where Did Ethics Go?” Sept.
6). Everyone wants everything they
can possibly need and dream of
without waiting or working for it,
all at the expense of others.
This problem is more prevalent
here in the U. S. than in Europe,
Asia, or the Caribbean countries.
It is most likely the fault of parents
who let others raise their kids and
advertising wonks.
And it doesn’t matter what the
profession is, it is all about greed.
Randy Scott
I have worked in the engineering
field for more than 40 years. I am
now in business for myself as a
forensic mechanical engineer doing accident reconstruction for attorneys and insurance companies.
Part of my job involves testifying
in court on civil and criminal cases
where I have been amazed at what
some engineers will say under oath
to prove a case for their clients.
Sometimes they testify to accident
scenarios that violate the laws of
physics. Some engineers testifying
are registered professional engineers and are theoretically bound
to follow the “Engineers Code of
Ethics.” But they don’t. How can
they look in the mirror and not
cringe at what they see?
Why do people try to beat the
system? Do they really think the
“easy way” is the best way? It’s pretty
simple, and somewhat trite, but
honesty is always the best policy.
Harold A. Schwartz
Smaller can be better
Yes, small sample sizes have more
outliers, but there is more to the
story (“Bad Math for Fixing Bad
Math Scores,” Aug. 23).
Home schooling represents the
smallest of schools, and homeschooled kids have average scores
in the 88th percentile on standard12
MACHINE DESIGN.com
Ethics are dead?
A couple of readers bemoan the lack
of ethics in practically every facet
of American life. Others debate
whether Steve Jobs’ management
style would work at NASA. And
one reader wonders about our
privacy and cloud computing.
ized tests without the enormous
budgets of public schools and in
spite of (or perhaps because of )
most parents lacking education
degrees.
Not all home-schooling parents
are in it just to get their children a
good education. Some parents are
more interested in religious indoctrination and some appear to be
ducking the responsibility of getting their kids to school every day.
I became a home-schooling parent
when I saw that children in many
overseas schools, especially in Asia,
were about two years ahead of
American kids in math by 4th grade.
I figured that my children were going to have to compete with those
kids when they grew up, so I took
on the rather large responsibility of
teaching them at home. I remember
asking a public-school teacher why
they didn’t assign more homework.
The response was that the parents
would complain.
Funding ever more assistants
and fewer students per school is
not going to fix the problems of
public education. Plus, it ignores
two extremely serious problems:
The lack of parental involvement,
which would change if all parents
paid part of the cost out of pocket;
and the cultural sense of entitlement that everyone deserves an
easy, effortless life courtesy of the
government.
When the government subsidizes something we get more of
it. Subsidizing idleness, teenage
motherhood, and recreational degrees that don’t lead to produc-
NOVEMBER 22, 2012
tive jobs erases the work ethic that
made this country great.
Karl Oberstramm
Get off of my cloud
I’m concerned over privacy in “the
cloud.” I am no expert on this topic,
just someone who has seen Facebook, Google, and other e-mail
providers “data mine” everything
that passes through their hands.
Supposedly no personally identifying data is ever mined, but how
many pieces of a jigsaw puzzle
have to be present before the final piece can easily be deduced?
It’s already frightening how much
Google knows and what advertising clout they have attained. I
use Google as an example, but the
same principle applies to similar
online organizations and to governments. If I have heard correctly,
the U. S. government, for example,
is building an ambitious project to
record everything in the U. S. that
goes on in the Internet. So am I
right to be downright frightened of
storing my employer’s engineering
information in “the cloud”, where I
will have no real control over who
might see it?
David Rensle
Running NASA Apple-style
By your example, Steve Jobs let
the project run off the rails and
then chewed out the development team after development
had reached a crisis (“If Steve Jobs
RS# 111
LETTERS
Had Run the Mars Rover Project,”
Sept. 20). Only then did he take
corrective action.
The NASA results might have
been the same with Steve Jobs present. It depends on how much micromanaging (or project oversight)
Jobs was capable of. NASA made its
decisions and lived with the consequences. Managers there thought
they had managed the risks.
It takes proactive checks to prevent projects from running off the
rails. Even Steve Jobs didn’t do that.
I think your analogy is faulty.
Stephen McDonald
A wise manager taught me early in
my career that if you fire everyone
who makes a mistake you are soon
left with only those folks who are
not doing anything at all.
David Leahy
I agree with whoever said Steve
Jobs was the last American busi-
nessman who knew what he was
doing, so I doubt he would have
any interest in landing an SUV on
Mars. But if he did, he’d have the
right people in the right places at
the right times.
You don’t keep underachieving
employees on your payroll. Get
rid of the people who do it wrong
and promote/hire those who do it
right. The replacements automatically learn from their predecessors
mistakes. Or they, too, become predecessors.
Frank Blankenship
Curing those ethanol blues
My problem with ethanol started
out with my RV and some equipment I store for winter. The 10%
ethanol/gas blend attracts water in
the atmosphere. This fact was hammered home as I pumped 2 gallons
of water from my 200-gallon fuel
tank on my boat. It was also evident
in the Spring when I found that
the float valve on my lawnmower
rusted, even after draining it for the
winter.
Fortunately, I found a station that
sells ethanol-free gas. These can be
found at www.puregas.org. And
Washington state now lets marine
stations sell only ethanol-free gas.
The real surprise came when
I started using ethanol-free gas
in my car and truck. The truck (a
2005 F 150) was getting 13 mpg
around town and the spark plugs
were black. In Feb. of this year,
I started using ethanol-free gas
in the truck. Within two tanks, it
was getting 14.5 mpg, and the
new plugs are running tan. Since
then, the mileage has been 14.5
to 15 mpg, which is an 11 to 15%
improvement.
This might be an isolated case,
but it seems a rigorous test needs
to be done.
Erik A. Larsen
TM
14
MACHINE DESIGN.com
NOVEMBER 22, 2012
RS# 112
A n atomy of the
HUCK 360
®
®
PROBLEM:
CONVENTIONAL THREAD
BOLT
NUT
TRANSVERSE
VIBRATION
TRANSVERS E
V I BRATION COMPARISON
Gap between the threads allows
for transverse movement.
CLAMP (LBF-THOUSANDS)
25
20
H U C K 3 60
15
O T H E R V I B R AT I O N R E S I S T AN T
NUT DESIGNS
10
5
0
0
50
100
ti m e
150
200
SOLUTION:
HUCK 360
250
(SECONDS)
BOLT
Once vibration begins,
clamp load quickly
decays with nuts and
bolts, while it holds
constant with the Huck 360.
RS# 113
NUT
No gap exists.
Threads are locked
preventing any
movement.
SCANNING FOR IDEAS
Edited by Stephen J. Mraz
Spindle drive moves
with accuracy
The BS22-1.5 spindle drive from
MICROMO, Clearwater, Fla. (www.
micromo.com), a member of
the Faulhaber Group, uses ball
screws to generate highly accurate
linear motion. The stainless-steel
drive is accurate to within 5 μm
or less over its entire length of
travel. The motor connects to the
ball screw through a backlash-free
coupling that is part of the ball
screw.
The screw is 126.5-mm long,
and the standard stroke measures
94 mm. Pitch is 1.5 mm. Axial load
capacities are to 519 N (dynamic)
and 475 N (static). The device
can handle input speeds up to
5,000 rpm and still maintain its
accuracy.
RS# 401
Motor
Motor flange
Clutch housing
with duplex ball
bearings
Spindle thread
Spindle nut with
fastening screw
thread
For a white paper on
gearhead construction
and use, scan this
code or go to: http://
machinedesign.com/
whitepaper/gearheadconstruction-and-use-0911
16
MACHINE DESIGN.com
NOVEMBER 22, 2012
r
formation via ou
Request free in Web site at
ice
Reader Serv
c
design.com/rs
ww w.machine
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RS# 114
SCANNING FOR IDEAS
Filter vent equalizes pressure inside and out
Electronic enclosures are often sealed against
water and contaminants, but this can lead to
pressure differentials between the interior and
exterior that cause problems. For example,
lower pressure inside the enclosure can pull
water and air in, damage the seals, and wreak
havoc on the electronics. To prevent this problem, engineers at W.L. Gore & Associates Inc.,
Elton, Md. (www.gore.com/protectivevents),
developed a protective vent, the PolyVent D3,
that lets air pass in and out, but keeps water,
dust, insects, and debris from getting in.
The vent has a press-fit width of 2.5 mm
and gas-flow capacity of 7 ml/min. The housing is polypropylene and contains an ePTFE
membrane. This membrane lets gases pass
through while keeping out contaminants. The
vent works in temperatures from –4 to 212°F.
The vent takes up no space inside enclosures
and its low-profile exterior portion reduces
the risk of damage from technicians who service the enclosure.
RS# 402
18
RS# 115
MACHINE DESIGN.com
NOVEMBER 22, 2012
Liquid and
particles kept out
Polyester backing
Polypropylene
housing
Air and gas
molecules pass in
and out through
the membrane
ePTFE membrane
RS# 116