Fabrication Shop - PLC Programming, Industrial Controls, Machine And Tool Design

Resistance Welder Quick Change Tooling

Kenneth did this project while he was an employee at an after market and OEM auto parts manufacturer in Oklahoma City. It is included to show some of the variety of projects that he has worked on during his career. At the manufacturer's chassis products plant, they make a variety of aftermarket and OEM chassis parts for automobile and light trucks. Kenneth worked as a Manufacturing Engineer in the light chassis area. The light chassis area was divided into three work cells, one of which was the welder cell, which produced welded ball joints. The welder cell was a very efficient work area with the exception changing over from part to part on the welder. The actual welder was an Atomic brand resistance welder that used a set of very heavy copper blocks for tooling. These blocks weighed approximately 25 to 40 pounds apiece. During each change over both the upper and lower blocks would have to be changed. Before a good part could be produced the blocks had to be aligned. Because each set of blocks were of differing heights, the knee of the welder had to also be adjusted. The process of changing the blocks and adjusting the knee usually took an average of 45 minutes.

SCOPE: Kenneth's assignment was to develop new tooling that would achieve the following goals:

a.) Reduce the set-up time of the welder tooling to under 5 minutes

b.) Incorporate existing alignment pins on the tooling that had ensured product quality

RESULTS: Kenneth accumulated the appropriate dimensional data from every part that was welded in the cell. After doing this and studying both the machine process and existing tooling, he decided to use one set of blocks for every part. The only thing that would have to be changed would be the plates that mounted on the face of each block. These plates were bolted on using socket head cap screws. He decided that instead of using screws pins could be used to keep the plates in place. The existing plates had two alignment pins that helped align each half of the ball joint case. He added two addition pins. This ensured even better quality and increased the life of the replaceable plastic pins. Occasionally the plates would have to be faced and de-burred because of wear. Kenneth added replaceable electrodes that could be easily removed and replaced with new ones. This eliminated the need to send the plates to tool and die for rework. The result of this project was a change over time of 2 or 3 minutes, increased tooling life and better quality ball joints. Below are pictures of the welding cell and weld tooling.

Welding cell

Welder blocks

Quick change plates