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Coe Precision Straightener
Slashes Scrap Rate, Secondary
Rework while Increasing
Productivity for Critical
Automotive Engine Control
Module Part
Flatness
was critical for an automotive engine control module that Perfection Spring
and Stamping Corp. (Mt. Prospect, IL) was producing. Continuous surface
cleanliness was also at issue to the end result. It took an unusual piece
of straightening equipment (and know-how from Coe Press Equipment) to
finally solve the problem.
Perfection
Spring and Stamping Corp. is a full-service metal stamping facility in
business since 1955. Today it focuses on three different manufacturing
areas: slide forming manufacturing, coiled springs, and metal stamping.
They make a variety of parts from wire and strip coil. Their expertise
in fourslide and spring work allowed them to grow into a full-service
contract manufacturer serving industries as diverse as automotive, automotive
electronics, power tools, and appliance producers.
 VP
of Operations Kenny McLaren said, “We ship locally and internationally
for a variety of manufacturers who have plants worldwide. We’re
attempting to grow our markets even further with our diverse manufacturing
abilities.”
Perfection
Spring & Stamping produces parts from coil steel and aluminum strip
up to 24” coil widths and up to .300” thick and wire from
.004” to .312” in diameter. They manufacture a variety of
different types of springs in their coil forming area, such as torsion,
compression, and extension springs. Their production is split with coil
and conventional springs at 15%; fourslide and multislide work at 25%;
and the balance in punch press and sub- assemblies.
 The
“Rigidizer” Challenge
“We
were having a major problem with production of a rigidizer that is part
of an automotive engine control module (ECM),” said McLaren. “It’s
a flat aluminum-alloy plate or a flat steel plate (3-mm thick) with a
printed circuit board laminated to it. Electronics are added to the laminated
board, and then it’s formed into a finished control module.”
McLaren
added, “We manufacture these rigidizers for several different companies
that supply OEM’s around the globe. A key requirement of this part
is that it is extremely flat without surface imperfections. Any presence
of nicks, mars, or tool marks, etc. on the surface will interfere with
the quality of the finished component. It is very important that these
control modules work in extreme environmental conditions, whether it’s
at sea level in the western US or below sea level, or in the tallest mountains
or the most extreme conditions that either summers or winters give us
on the globe.”
“There
is the equivalent of a double-sided adhesive tape laminated on the flexible
circuit board to hold it to the stamped backing. Our customers populate
various electronic components to the circuit board, solder it, test it,
and form it into a shape around some type of metal body or housing. Once
this is done, the flexible circuit board is flat. When it’s folded
up, it’s generally in a sealed unit that makes it impervious to
the outside environment.”
 He
added, “Flatness for the surface mounted electronics is absolutely
critical. When the circuit board is mounted and has the various electronic
components added, it’s very important for them to solder and only
solder where required. Any voids or imperfections on the metal surface
or rolling in the stamping will cause the solder to puddle and, especially
with the size of some of the circuitry, allow it to puddle in ways that
can cause the whole board to short circuit. These ECMs range in size from
5” x 7” to 8.5” x 17”. Some of the overall panels
are 11” x 15” or 11” x 18” laid flat before bending
operations. We have a five-station progressive die that stamps them. Total
overall flatness after all of the manufacturing processes is roughly 0.5
mm, which is 0.020”.
“We’ve
managed to punch holes of various shapes and configurations in these panels
and form ridges. In some cases we’ve even drawn bubbles in the parts.
So there’s the overall panel flatness of 0.020” that is still
expected. But on a square inch basis, our customers are looking for a
total flatness condition of approximately 0.05 mm or 0.002”. All
this is important because consumers driving modern cars have these ECMs
in them, and we all know how imperative it is that these modules don’t
fail.”
Improving
the Process, Quality Levels
McLaren
remarked that the company needed to make some aggressive improvements
in producing ECMs, because they had unacceptable defect rates and downtime
issues when they first started manufacturing them. Primarily, the problems
they had were getting the material flat, secondary part rework, and downtime
due to die adjustment to make up for the inadequacy of their coil straightening
equipment. These problems were costing them thousands of dollars per month
in scrap.
 “Now
we have all but eliminated these issues,” McLaren remarked. “
We went from extremely unacceptable scrap quantities, which made it almost
undesirable to make these parts via stamping (originally, they were die
cast and machined), to producing a quality part.”
Perfection
Spring solved these problems by purchasing a Coe Press Equipment (CPPS-
250-24) power straightener that employs 11-rolls (rather than the five
to seven rolls found on a conventional unit) along with a pulloff (CPR-PO
8024) coil reel. These were added to an existing Verson 300-ton press
line.
McLaren
remarked about the problems before buying the new Coe equipment, “We
were running two shifts a day just to keep our head above water. We were
probably running at a 5-6% scrap rate typically on multi-thousand runs.
We could be in and out of tolerance very quickly depending on the coil
size, which affected coil set and material flatness. So we were only getting
a third of the way into the coil, and we found that we weren’t getting
flat material anymore. We tended to constantly check the material flatness
and had to readjust the previous straightening equipment, which also added
labor to the part.”
 “We
were making ongoing improvements from the time we ordered the Coe equipment
to the time we got it. However, in less than a week after we received
it, we were able to settle down the manufacturing process to the point
where our downtime went from many hours a day to just a portion of an
hour a day. What the Coe equipment has allowed us to do is run a wider
variety of products on the same piece of equipment, because our uptime
is greater. Also we were able to consolidate the production for ECM parts
and other products on one press line and open time on our other presses
for different work. This equipment has really allowed us to get a tremendous
amount of throughput. We’ve at least doubled or tripled the amount
with it.”
Perfection
Spring runs the material with a very slight loop and uses a Sonotrol to
monitor the loop. What they don’t want to do is re-induce any coil
set into the material from the loop, and the company has found that the
amount of coil set in aluminum is variable depending on where the coil
is on the reel. Coe’s straightener uses a variable drive and performs
like a precision leveler. It was specially made, because Perfection Spring
needed more rolls in it to get flatter material. With a variable drive,
as they start and stop the press, it allows the rollers to slow down at
a very even rate and accelerate smoothly. The type of marks that can be
associated with coil stops and starts on soft materials like aluminum
are virtually non existent now.
 Cleaner
is Better
The Coe
straightener also has an opening head that allows for easy cleaning. Most
other straightener heads are designed in a sandwich construction and are
not built to open. The only way that rolls can be cleaned on most conventional
straighteners is by using a Scotch Bright abrasive mat that is run through
the rolls to remove any blemishes or material pick up on them. But Perfection
Spring needed more insurance…and Coe delivered. “This unique
design allows us to open up the head and clean all the rolls so we don’t
impart any picked up dirt from them to the stamped material. We also ordered
the straightener with hard-chrome and polished rolls, because these give
the least amount of pickup,” added McLaren. So the company performs
a daily cleaning (wiping down the rollers with a simple alcohol solution)
and does so quickly…simply opening it up by loosening two screws,
completing the entire operation/cleaning process in a matter of minutes.
McLaren
remarked, “These parts can be rather large, even though they are
aluminum, they weigh close to one pound each. With 3-mm thick aluminum,
we go through a 55” coil quickly. We don’t want to be adjusting
the straightener all the time to get the flatness we need. As a job shop
we must have the capability to process these rigidizers in aluminum or
steel. We wanted to have a system that dialed back to the straightener
settings that we originally ran. Coe equipped the straightener with digital
indicators on each upper roller that show us what our exact heights are.
Once we worked out the heights for each roller to give us successful straightening,
it was easy to get back to these settings with this feature. We were spending
upwards of five hours per week on adjustments to our previous equipment.
Now we’re able to run within minutes once we have the die successfully
set up. Using digital indicators with this equipment allows us to take
the craftsmanship out of the settings and apply some real science for
material deflection.”
The bottom
line: improved quality, reduction of secondary finishing operations, and
increased throughput level that has been doubled or even tripled, at times.
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