OFFSHORE RETURNS ONSHORE

ZF Commercial Suspension Systems & Components, LLC (Lancaster, SC) is a Tier 1 supplier of chassis components for Class 8 trucks, recreational vehicles and military vehicles. The company is a business unit of ZF, a worldwide supplier of driveline and chassis technology for the automotive, commercial vehicle, off-highway, marine, rail, and aerospace industries.

Among their many products in the U.S. are inline ball joint assemblies which, until 2008, were being imported from a ZF facility in Europe. Following a feasibility study, production was moved to Lancaster to service the North American market.

Ball joint assembly involves a cell consisting of two hydraulic presses. Engineers determined that high-quality production of these safety-critical components could take place in North America by incorporating the latest production methods. The specifications for ram position control were tightened to ±.0015 in and bids were solicited from domestic suppliers.

The order eventually went to Multipress (Columbus, OH) for custom configured 100-ton and 50-ton floor mounted C-frame presses. Each unit features a number of electronic and mechanical sub-systems to ensure the specified accuracy on a consistent basis. A Delta motion controller in concert with an Allen-Bradley PLC divides the speed of the downward ram stroke into three stages, with the maximum deceleration occurring within 0.10 in of contact with the part.

Dwell time and ram reversal are determined by the combined action of an electronic timer and a pressure transducer that ensure that both time and pressure on the work piece are within pre-programmed limits. A linear transducer built into the hydraulic cylinder controls the contact position of the ram within the ±.0015 in specified tolerance.

Multipress provided other features, including a touch screen operator interface, storage of multiple recipes for various ball joint sizes and shapes, and light curtains and hard guarding for operator safety.

The presses were installed at ZF?s South Carolina plant in July of 2008. Peter Meca, the lead manufacturing engineer for the cell, says ?We have other Multipress equipment here, but nothing approaching the tight specs of these two units. Compared to the previous cell, I feel we?ve gotten twice the press for less money, and we?re pleased to once again be able to offer a competitive American product to our American customers.?

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Multipress, Inc., 1250 Refugee Lane, Columbus, OH 43207, 614-228-2358, www.multipress.com.