Cheaper mini cylinders replace die springs, nitrogen cylinders.

Press tooling that runs without failing is what every stamper wants. Especially when the runs are high volume.

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Logghe Stamping Co. (Fraser, MI) is an award-winning supplier to DaimlerChrysler producing types of parts few other companies want to even consider: extrusion metal stampings and deep-drawn precision components.

Tooling design for these type parts is difficult because of the precision required. And because these parts are often vehicle safety-related, manufacturing tolerances are critical. They are found on every vehicle produced.

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DaimlerChrysler, like other assembly companies, orders parts from vendors when needed. And it expects delivery promptly. Parts are not inventoried. Production must start almost instantly when the call comes, and tooling at the vendor must be set up quickly and accurately. Precision parts shipped on time is an essential requirement of work for the Big Three, according to John Logghe, vice president of the company.

Small Lot Sizes

But the orders are for smaller lot sizes, often requiring frequent press tooling changes, according to Mike Blaszczak, Logghe tool room supervisor, "so you are in and out of the press with a greater frequency than used to be the case. Dies must run efficiently, otherwise Logghe could not make its ship dates to the customer, which would result in an assembly plant stoppage, costing thousands of dollars an hour. What happens in the tool room is the key to meeting the part shipping requirements and part quality requirements."

Automakers are constantly striving to improve overall vehicle quality, which, in turn depends on the quality of each component. To produce extrusion stampings to the tolerances required requires superior tooling. That's where the new nitrogen cylinders come in.

Extrusion stamping puts great stress on cylinders, and cylinder life was not as long as Logghe wanted. So, the company has begun replacing nitrogen cylinders and die springs with an improved minicylinder from Moeller Manufacturing. According to Blaszczak, these nitrogen cylinders cost less and last longer than throwaway-type cylinders provided by another source.

At Logghe, steel travels through a 110" progression across a die and it must come out within spec. Tolerances are tight because deep drawn features may require a secondary operation, such as tapping, to permit assembly to another part. With the Moeller cylinders installed, press tooling can run much more efficiently and produce more parts without unscheduled downtime, according to Logghe.

Cylinder Performance

"The Moeller cylinders hold up better in our fluid because their seals last longer. We are getting about 300,000-500,000 more hits than other ones I have tried," said the experienced Blaszczak. "Self-contained minicylinders from any vendor are said to be good for about 1 million cycles, but the oil-based fluid we use in the press destroys seals, causing the minicylinders to lose pressure and fail, resulting in expensive press downtime and tooling repair."

Obviously, cylinder performance can vary according to operating conditions and proper application, but the Moeller minicylinders at Logghe have been a much longer lasting die component and resist leakage when side-loaded.

These cylinders, with body diameters from 1.00" (25mm), are a single-piece tight tolerance construction with two seals rather than just one to prevent fluid from getting in--almost doubling the life. A rod wiper and polyurethane rod seal completely protect the interior of the cylinder. Another feature of the patented self-contained cylinders is an extremely hard single-piece rod, lapped for smooth operation, minimum friction, and lower operating temperature, thus minimizing seal wear. A self-lubricating guide for the rod also reduces friction and minimizes side loading, contributing to more accurate part ejection.

According to the company, there are more than 100 cylinders installed at Logghe, all of which are lasting many more cycles than expected, saving cost compared to the previous type.

"They say cheaper isn't better, but in this case, it is," asserts Blaszczak. "On just two cylinder sizes we installed, the savings was $15,000 alone compared to another type of nitrogen cylinder. In our experience, Moeller's ISO standard cylinders cost less and last longer. Although the minicylinders are designed to be repaired or rebuilt and recharged, if needed, Logghe has found that it is less costly to get a new one.

"Plus we are eliminating mechanical die springs where we can--due to maintenance advantages--as we refurbish the dies. Also, nitrogen cylinders deliver more spring force in less space than do die springs and provide the same deflection as a die spring in a shorter height," Blaszczak said.

Moeller Manufacturing, a full-line press tooling detail supplier, is ISO 9001-certified. It produces standard and special pierce tooling, including ball lock retainers, punches, die details, die buttons, piercing and trimming tools, and die sections. Moeller Manufacturing Company

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