Developing a Leak Test - Housing part for an automotive customer

We are molding a housing part for an automotive customer. The housing gets filled with 300degrF Epoxy at the customer, and should, of course, not leak thru the housing.

We inherited a leak tester from the previous molder, but no information on what settings we need to use to test the part on leaks (the tester was set to 3seconds at 5 psi, but we found many rejecxts that shouldn't be rejects.

Does anyone have any advise on where I can find information of how to determine the leak tester settings (in seconds at a certain PSI or kPa). The tester is only using air pressure. How can we re-create the condition of hot epoxy by using airpressure.

Also looking if I can add an additional confirmation test. By filling the part with some other liquuid. Any ideas where I can find table that translate certain epoxy viscosities into oil types.

Any help, please!

S.

[CarolX]

Does the equipment bear the name of the manufacture? Contact them and see what product literature is available. Perhaps they have a technical rep that could give you some guidance.

You might want to try a search on Google. I have pretty good results with this search engine.

Ragrds,
CarolX

[Jim Biz]

I agree Carol ---

mboeto - I might add - would the customer have any information on what their "expected" specifications are for this leak test??

Originally posted by mboteo

We inherited a leak tester from the previous molder, but no information on what settings we need to use to test the part on leaks (the tester was set to 3 seconds at 5 psi, but we found many rejects that shouldn't be rejects.
S.

How did you determine that they weren't leakers? Visual, magnification? Did the machine indicate leaking? Is the part capable of being static leak tested?

[HFowler]

Energy,

You might consider a hydrostatic test for leak determination. This involves pressurizing the cavity with water instead of air. It's a lot safer and more forgiving than air which sounds like what you're looking for. I've used both, and you're right about air rejecting potentially good parts.

Hope this helps.
Hank Fowler

The customer's only requirement in this case is that the housing won't have voids that can cause leaking. The houses are filled with epoxy and cured at 140degrC (don't know yet what type of epoxy yet). The leak testing is part of a test dial (5 other test in following station are done on the parts).

I guess the leak test was the previous molder's choice of test to ensure 100% testing on the parts as part of their process controls (read detection method) in their PFMEA.

So pressures and times have never been set by the customer; we just try to get a comparable test towards what the conditions are at the customer.

We found that rubber pad that seals of the part during the test is prone to wear, and might cause false leakers. Also found when decreasing the pressure and time, leakers might pass (applying a more severe Water leak test on one part).

The goal is to find out how I should translate the customers conditions into the pressure and time variables of my test station. The supplier of the test station has only been able to supply me the specifics of how to set, maintain and calibrate the test station.

I might want to dig into my old schoolbooks of "Fluidomechanica" to calculate the correct formulas, etc. But maybe somebody has some lists of websites to refer to me to make things easier.

Thanks anyway,
S.

Above message was mine. Forgot to log in.

[Bob Stevens]

We perform a Pressurized Air test on a Vacuum Motor used on 4-wheel drive vehicles. The test machine was designed and develop by by J. C. Boudreau of Colony Hill Electronics and measures leaks in Pascals. If interested, you can contact J. C. at (800) 421-8903 and he may be able to help you resolve some of your problems.

Bob