Smart Station Five

Automotive Manufacturing & Production,  Nov, 2000  

• E-mail
• Print
• Link

A nonsynchronous light truck locking differential assembly system that Owen Machine and Tool (Jackson, MI) has built for Eaton Corp. includes several hydraulic manual presses, which is pretty much the norm for systems of this type. To help assure that the difs are built at they should be, there is in-process gaging, and pallets are fitted with radio-frequency ID tags.

And then there is Station Five.

This one is different. It is a CNC electromechiancal press.

At Station 5 two bushings are pressed into place. These are comparatively critical bushings inasmuch as they are the ones that are used to control the torque transfer from the slipping wheel to the one with traction. If the bushings are off--too tight or too loose--then the locking doesn't occur. Which means a trip back to the dealer for the driver, and a warranty claim.

This press, designed and built by Promess (Brighton, MI), features what is called "signature analysis." What is involved is, basically, that a good operation is profiled; force and distance curves are determined. Variation limits are set. Then, during the assembly operation (the press uses an encoder-equipped servo motor that drives a ballscrew ram that is instrumented with sensors) force and displacement are monitored so as to help assure that the appropriate parameters are attained in the assembly. This means that assemblies are made as they should be--and if they aren't, that's known, too, so it doesn't take until the final test at Station Seven to know that the assembly isn't what it should be.

GET IT OUT

As manufacturers think more about using plastic in light truck beds, the issue of making the process as smooth as possible is key...which is why one automaker ran mold release trials for producing beds with a rigid polyurethane elastomer to determine what material would Facilitate getting the parts from the mold.

As this was a test, only a test, chromed steel tools measuring 72 [ft.sup.2], 18-in, deep with a 2% draft (which is about 1/3 the size of an actual tool set] was used. In the operation, a 10-mm glass perform was placed over the textured plug, or A-side, of the tool. The RIM process then was initiated; the material is compressed to 3 mm; the polyurethane sets in 15 seconds at 180[degrees]F; the cycle takes 2 minutes.

Getting the parts out of the mold proved to be easy when a mold release material, XTEND 19W, From Axel Plastics Research Laboratories [Woodside, NY], was used; 20 parts per application were released, as compared with 12 from the next-best material.

Details: write in 122 on the Reader Service Card.

COPYRIGHT 2000 Gardner Publications, Inc.
COPYRIGHT 2008 Gale, Cengage Learning