Design and maintenance of the fixtures that hold the parts as they
travel through the coating system is frequently a source of quality defects.
In order to provide the highest possible level of efficiency and
quality a rack should be thought of as a tool.
Issues to Consider in the Design & Care of Parts Racks
- Racks will be used in an industrial environment; make them sturdy.
- If
the parts can swing on the rack, they may hit each other n the oven
- and cause a blemish in the coating.
-
Tubing used for rack frames can trap water in the washer;
- if it boils out in the cure oven it will stain the coating.
-
For electrostatic application, contact points must always be clean
- to provide good ground.
- Coating build-up on racks can crack and create dirt defects.
-
Coating build-up on contact points will interfere with electrostatic
- attraction.
To maintain a low level of defects on the coated parts, the tooling
must have a low level of defects. Good original design and good rack maintenance will contribute to yield.
Electrostatic contact points should be designed to make sure they provide a certain ground to the parts.
Missing contacts should be replaced and bent frames straightened so that the work package is consistent in relationship to the application equipment.
Heavy build-up on racks should be avoided by a planned
schedule for stripping racks and by making sure that there are enough racks to manage production while racks are in the strip cycle.
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