The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Powder Coating C-Hooks Opening Under Load

2007

Hello,

Ron here from Scranton, Pennsylvania. What has been causing me great distress is a simple C hook. The hook is used in a powder coating operation to hold multiple parts (pipes) on a monorail as they travel through the powder coating operation (wash, dry off oven, powder application, curing oven). After being used several times the hooks are burned off to remove the multiple layers of powder coating. The burn off oven temp. is roughly 1,400 F. I've been experiencing C hook failures (hooks are opening) regularly which causes the parts to fall from the line onto the ground causing rework or scrap.

Does anyone have any suggestions on the best type of material to make C hooks out of which will resist opening? Simply moving to a thicker C hook is not an option since there are space limitations involved.

Very Sincerely,

Ron Faraday
Job Shop - Fences - Scranton, Pennsylvania, United States

---

2007

I'd say that your burnoff oven is doing the damage. The rate of cooling of the hook after burning will impact the softness of the steel after burning off.

You could try chemical stripping. Its cheaper (for us anyway), less messy, kinder on the environment, and less hazardous. Best of all, it doesn't make the hook soft. The chemical is non-toxic and can be put to foul sewer after use, but we re-use continuously.

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

1400° F is grossly too hot. Get a heat treating book and look at hardening cycles. you are basically in an annealing (softening) cycle unless you do a quench as soon as it comes out of the furnace. 500F will take a bit longer, but your hooks will not fail. NO higher!

James Watts
- Navarre, Florida
2007

Stripping is the right way to recycle the c hooks many solvent based strippers are available which would not affect your hooks also.

Kuldeep Singh
Wet process engineer - Pantnagar, Uttrakhand, India
2007

finishing.com is possible thanks to our supporting advertisers, including: