EZ10 torque failure?
EZ10 torque failure?
(OP)
I am working on an EZ10 adapter project. Customer requires that the EZ10 metal shell, which is adhered to the plastic base by a loctite E-60HP glue and cured, passed torque test at 1.2nM. We tested the adapters with a torque wrench at 1.4nM (we increased the requirement as a safety net) as a part of the QC process and they passed. However, when the parts got to Japan, the customer tested them and there was a lot of failure. What could have caused the failure?





RE: EZ10 torque failure?
Nor have you told us the nature of the failure.
Is the plastic part molded? Is mold release used? Is it cleaned? Was it cleaned for your internal test pieces, but not production?
Is there a plasticizer that is migrating with time to the bond line?
How hot does the thing get in use? Notice that E-60HP strength falls off rapidly with temperature.
RE: EZ10 torque failure?
Below is more details about my problem.
The plastic is molded from CoolPolymers D5110 resin, a thermally conductive PPS. The mold release was used and the part was cleaned from the agent.
Nature of failure - The EZ10 metal shell did not adhere to the plastic when re-tested at 1.2nM.
E-60HP adhesive was used and cured according to the mfg's spec. The adapters are to be attached to MR16 LED lamps so i don't think it will get really hot. Note that the adapters were never used on the field. They failed torque test at the customer's incoming inspection.
RE: EZ10 torque failure?
Ok.
But WHERE in the joint did the failure happen?
Did the epoxy not adhere to the plastic?
Did the epoxy shear?
Did the plastic fail?
Did the epoxy not adhere to the metal part?
etc.
RE: EZ10 torque failure?
RE: EZ10 torque failure?
Mold release not really cleaned. Cleaning not done at all, cleaning process is not effective, cleaner is contaminated, before an after cleaning parts handled by the same people....
RE: EZ10 torque failure?
PPS is used in other applications for it's high operating temperature and it's chemical resistance, which would indicate it is a material very (if not impossible) to bond.
Then you have the problem of differential expansion rates of two dissimilar materials possibly causing bond failure during thermal cycling (maybe during transport?).
Mould release, especially if silicone based, will require mechanical means (abrasion) to get it off.
H
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
RE: EZ10 torque failure?
Long ago, we used a Dow Corning pliable epoxy potting material in a stainless steel (SS) tube. The instructions called for cleaning the tube with solvents and applying a certain model of Dow primer in order to adhere to the SS. Neither was being done.
Without the prep, only the expansion of the epoxy at curing time made a good seal. The SS did not expand as much, so there was pressure all around the interface. Stick the tube in cold water, though, and the epoxy shrunk more than the SS. A nice gap all around, large enough to wick water, and the potting could easily be pulled out of the tube. Proper cleaning and priming of the SS eliminated the issue.
If you're shipping your part to Japan in the cold cargo bay of an airplane, your two parts may be temporarily separating during the flight. Combined with the poor adhesion to that plastic, I would expect a failure.
Best to you,
Goober Dave
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RE: EZ10 torque failure?
Where did you see the epoxy's poor performance on a range of plastic? I looked at Loctite E-60HP spec and did not seem to see any reference on it.
Thanks
RE: EZ10 torque failure?
http://tds.loctite.com/tds5/docs/HYSAE-60HP-EN.PDF
The strength with nylon and acrylic is lousy, but moderate for PC, ABS and PVC.
RE: EZ10 torque failure?
Regards,
Mike
RE: EZ10 torque failure?
RE: EZ10 torque failure?
Best to you,
Goober Dave
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