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Cable, Wire and Harness
Acceptability Standards
to Provide New Industry Tool
A new standard just published will give cable, wire and harness fabricators
and buyers common ground to establish quality and acceptability levels. Titled
IPC/WHMA-A-620, the 278-page standard with over 500 full-color illustrations
was developed in a three-year process by an 86-member committee and represents
a consensus among these industry leaders.
The standard was prepared by the ITGC Industry Technical Guidelines
Committee of the Wire Harness Manufacturers' Association and the
Wire Harness Acceptability Task Group of IPC-Association Connecting
Electronic Industries.
"The core group included members from the supplier, cable fabricator,
military and aerospace, and commercial communities, with representation
both from domestic and international firms," said Jack Crawford, IPC
director of assembly standards and technology.
Vernon Judy, president of Qualastat Electronics, Inc., based in Pennsylvania
and spokesman for WHMA for the A-620 development, said the standard
is a living document and one that will invite industry-wide feedback for
improvement and fine-tuning.
"This is not a design guide. This is an acceptability standard; every copy
includes a feedback form with encouragement to provide constructive
comments for future revision," Judy said.
He said the need for the standard has evolved rapidly as electronics makers
have developed other standardized practices.
"It's the first time anybody has made an effort to put together an industry-wide
consensus standard. I would guess that many companies have developed their
own workmanship standards for harness and equipment. Now, with the
generation over the years of standards for many areas of electronics, it's
driving companies to do things the same way. The harness is probably the
last area that gets hooked up: Most companies develop their product and then
remember they need to order a harness or a cable assembly to hook it together,"
Judy explained.
Crawford said: "Historically, cable and wiring harness fabrication has been
done to military standards. There are some automotive standards out there,
as well, but not a true industry (peer consensus) standard. That's why this
is the first true consensus beyond internal workmanship standards."
He said the standard is not an enforcement action or a requirement of any kind.
"We don't ever tell anybody they must use the standard. We say 'Here is a
standard your peers have developed, and you and your customers may
find it a useful tool," said Crawford.
"What the A-620 document does, is give suppliers and customers common
ground to discuss acceptable quality levels. The standard is also a measuring
stick against which bids from varying suppliers can be compared.: If one
supplier stipulates the acceptability standard as the basis for quality, and
another supplier gives a lower bid without reference to a publicly available
standard, a buyer could factor the industry standard in to ensure that the
needed quality level and overall value are received.
"It becomes a marketing tool when a manufacturer can say they don't know
what their competitor builds to, but can hold up the A-620 requirement to
demonstrate the acceptability levels the manufacturer will meet. The buyer
can look at it and see that it really means something," Crawford said.
"People that aren't used to working with standards sometimes don't realize
the value — it levels the playing field between users and suppliers. When a
user brings in a defined standard that establishes the minimum quality level
they will accept, every potential vendor vying for their business has to agree
they will build to this acceptance requirement," he said.
Judy said he believes the standard will be picked up quickly in the industry.
"A lot of the members of the committee are already IPC members, and they're
already using the earlier IPC-A-610 standard for assembled printed circuit
boards (PCB). They know that standards work, and that this is the next
step of the process," Judy said.
The IPC has a series of acceptance documents in place, with at least two
more to come. In addition to IPC-A-610, the association's IPC-A-600 standard
covers bare PCB acceptance. A proposed IPC-A-630 standard would establish
consensus on "box build," or the assembly of circuit boards, cabling and controls
in a device's chassis and installation of the chassis in the final vehicle -- such as
a television assembly in its casing. The proposed IPC-A-640 standard,
meanwhile, will provide fiber-optic assembly and acceptance criteria.
"There has been some crossover between standards development committees
such as terminal soldering requirements in IPC-A-610 and IPC/WHMA-A-620,
with a very concerted effort to avoid conflicts between standards by preserving
knowledge within the process," said Crawford.
At their heart, the acceptance documents represent basic, commonsense
approaches to uniform industrial processes, both men said.
"It's what's worked in the past, and some of it is definitely left over from
the military standards. A lot of the information we have is what we found as
consensus between company workmanship standards that were offered a strawman
documents for development of A-620. For the most part we're not creating
something new. In a way, anybody that's signing up to this standard is signing
up to get on the board with recognized Best Manufacturing Processes," said Judy.
The voluntary standard will be certified by the American National Standards
Institute (ANSI), meaning the standards organization has assured the
development process has been open — that fundamental steps have been
properly followed. Additionally it shows that a balanced group of users,
suppliers, and a general group including training, test and consulting
companies were involved in development and the consensus process.
ANSI certification also gives the U.S.-based industry an avenue to
international standards associations, such as ISO or IEC, which must be
coordinated through ANSI.
Adherence to the acceptability standard will also smooth the manufacturing
entry of computer-based process control, said Crawford.
"The concept of process control is used somewhat haphazardly but is not a
widely-used terminology within the industry, we learned during the development
process for the A-620 standard. Companies were doing it, and it was in place,
but they really didn't identify it as such. Our acceptability document introduces
'process indicators' that can help process and quality managers identify when a
process is going out of control. If you plug that data into software, at some
point it sets off an alarm. If the number of process indicators is high enough
that you're about to be running scrap, you'd like to know, right?" Crawford said.
As an example, explained Judy, a crimping operation using fixed-die equipment
could learn that dies are starting to wear, based on crimp-height measurements.
Use of process control data will help manufacturers develop reasonable schedules
on how often to make such measurements to assure guaranteed good equipment.
"A lot of people think it costs money to set up a quality checking system, but
it isn't nearly as costly as running scrap," Judy said.
The new acceptability standard also puts a clear system in place to help
manufacturers and customers understand the exact chain of precedence for
determining responsibility in the event of a dispute. The chain of documents
stretches from the procurement agreement determined between customer and
vendor back to specific documents specified by the customer. It also sets out
various classes of acceptability based on end-use environment and criticality of
performance, specifying what an acceptable part is, what a defect is, and what
might be process indicators that fall somewhere between the two.
By reducing what has been an industry practice to a documented process,
the A-620 standard crystallizes accepted process and makes it available to all
participants.
Development of the standard has also brought together industry groups to
share knowledge and broaden participation, Crawford and Judy said.
Among the knowledge sources are a series of training videos for subjects
including wire harness assembly (IPC-VT 56), introduction to wire crimping
(IPC-VT 58), wire preparation (IPC-VT 59) and a future video on fiber-optic
cable fabrication (to be listed as IPC-VT 65).
Sharing technical knowledge and documentation can only make the industry
stronger and more dependable, they said. Just developing the collaborative
process for standards creation has shown strength can come from such sharing.
"WHMA, as a group of people with a strong will and desire, were limited in
their standards development experience. As a relatively young and small
association they were also not yet members of ANSI. IPC members were
requesting a standard for cable/wire harness acceptance, so it only seemed
logical to do this as a team effort," said Crawford.
Judy concurred, saying: "If I were to assess the way this thing has grown,
I think that IPC has definitely given the committee management experience,
and also the technical ability to put this information together. We at WHMA
were more useful in adding the raw manufacturing information; IPC has
definitely taken more of a leadership role in the technical and publishing parts."
During the standards development process, WHMA has seen a boost in
membership and a more diversified mix of industries, including representatives
from the communications, medical, automotive aftermarket and marine industries.
Crawford said the 45-year-old IPC, originally an association for PCB design,
then PCB assembly still has a large number of original equipment makers
involved in the development process.
"They had been pinging on us for some time, because there are no box
build standards and these companies couldn't identify cable harness
standards they wanted to use," said Crawford.
For both organizations, the IPC/WHMA-A-620 process that began in
1998 finally establishes industry consensus will satisfy a true industry need.
Copies of the IPC/WHMA- A-620 Requirements and Acceptance for
Cable and Wire Harness Assemblies, which includes 510 illustrations
in 18 chapters, may be purchased by contacting either
IPC
2215 Sanders Road,
Northbrook, IL 60062-6153
Phone: (847) 509-9700;
Fax: (847) 509-9798
Internet: http://www.ipc.org/bookstore
or
The Wiring Harness
Manufacturers Association
3335 N. Arlington Heights Rd.
Suite E
Arlington Heights, IL 60004
Phone: (847) 577-7200
Fax: (847) 577-7276
Internet: http://www.whma.org
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