Tools for Electrocoating

Question:

We are starting a custom electrocoat operation and are wondering what should be considered in the design of tooling. Can you make some suggestions? J.K.

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Answer:

Tooling (racks, hangers, hooks, carriers, or whatever you call it) is critical for a custom coater but also important for OEM operations. I will try to give you some generic ideas for tooling from my own experience and a lot of operations that I have seen. Some major considerations to be made and the reasons are as follows:

1. Electrocoat only or electrocoat as a primer
   1. Part density will be significantly reduced if the same tooling is used for adding a topcoat (liquid or powder)
   2. Cleaning of tooling will be significantly increased if used for electrocoat and topcoat
2. Part density vs. flexibility—the biggest challenge
   1. High part density provides more efficiency and profit
   2. Flexibility reduces the time required to change tooling as parts are changed
   3. With proper design, a good compromise between density and tooling flexibility can be reached
3. Grounding of parts is essential
   1. Lack of a good/consistent ground will produce “light coats” that are expensive to strip
   2. Using the weight or design of the part to improve consistent grounding helps
   3. Using wedge-shaped “pins” for part hanging and/or tooling assembly helps to get/maintain contact
   4. Using square stock for hooks gives better contact points
   5. Designing hooks with sharp “V” forms keeps the part from moving and losing contact during coating
4. Cleaning methods
   1. Burn-off seems to be the most efficient method of removing electrocoat from tooling
   2. Grinding or wire brushing are labor intensive and remove sharp edges that help maintain contact
   3. Blasting can be efficient but also removes sharp edges
   4. Designing tooling that can be easily disassembled can increase the racking density for burn-off
5. Assembly methods for flexibility and design
   1. Welding is the least costly method of initial assembly, but provides less flexibility and is costly to repair
   2. Bolting together allows for some flexibility, but bolts are very hard to dissemble after many times through the system; design with minimum or no threads extending beyond the nuts or tapped holes will make disassembly easier
   3. Using wedge-shaped “pins” for assembly allows for assembly and disassembly without tools or a hammer
   4. “Snap-on” type hooks look good but are not as easily changed as it appears, and ground contact is not always established unless the contact area is clean
6. Storage of tooling
   1. Building carts or using a simple conveyor system for storing unused tooling can be expensive but reduces damage and decreases labor
   2. Designing with easy disassembly can significantly reduce storage space; again racks for components reduce damage and can also be used for burn-off cleaning
   3. Designing with flexibility can reduce the amount of tooling to be stored and labor to change tooling for different parts

While there are other considerations in tooling design, almost all designs require some compromise. Building and testing prototype tooling can be very helpful, if time permits. As with most projects, getting input from multiple sources (both internal and external) is important.