Transmission Component Alternatives

[GrantR]

It has been asked of me to decide on alternative materials and redesign existing Aluminum components that we manufacture for GM, that would make the product cheaper, and lighter. My current focus is on a Servo Assembly Cover that we make, this particular cover protrudes outside on the transmission body, and would go on the Z71, Corvette, and various SUVs. Before any testing or final prototypes have even been made, my concern is the Exhaust Manifold from the engine which is approximately 2 inches away from the servo cover. I expect that in certain operating conditions, such as a traffic jam on some black paved highway on the hottest day of the year this area on the vehicle will become pretty hot.

Our focus so far has been on replacing the aluminum with various engineering plastics. The only plastic, we have found, that the gives us adequate mechanical properities is Dupont Zytel HTN51C35HSL NC010 high temperature nylon resin, but even this plastic does not behave well under high heat. To date, plastics have been considered because of the Net Shape/Near Net Shape parts produced by the injection moulding process, which would require very little secondary machine operations as opposed to the current Diecasted Aluminum parts.

So with all this said,I have two questions:
1) I was wondering if anyone knew of other plastics/composites (or any other material) that could be used for this type of application that would give us the thermal and structural properities of aluminum and be cheaper and lighter than Diecasted Aluminum?

2) What would be an reasonable external temperatures that the cover would be exposed to, which would be present in the worst case scenario mentioned above(if indeed this is the worst case scenario)? If this is not the worst case scenario please enlighten me.

Thanks to all that take time to answer these questions.

 

[ivymike]

Sorry, I don't have the mat'ls experience to recommend any for you, but I was wondering if there's any chance you could integrate a thin reflective heat shield at the surface of affected areas, eliminate your heat problem, and still have an overall cost advantage? (I know, it sounds like a stretch)

 

[GregLocock]

How about magnesium alloy? It's lighter, if not cheaper.

Your manifold is probably running 700 C, and most engineering plastics give up at 80-150, so if you can't shield it (as mike suggests) you are going to be in a world of hurt.

Typically the trans oil itself can hit 110 C, so you need to watch out for that as well.


Cheers

Greg Locock

 

[seek]

You might like to look at PEEK or PPS (to a lesser extent). Again, like the others, I don't have direct experience with these materials in this environment, but I would say that temperature will be a problem. I have designed a couple of auto trans servos in my time and the pressures and cyclic nature of the loads, combined with the temperatures would be an interesting problem. Have you seen the ceramic coatings given to magnesium components through the Keronite process? The ceramics might help insulate the alloy. I don't know if it can be applied to plastic. Good luck

Joe Sasso