haulinkraut

If you can find a metal with the same insulating properties as Zirconia Oxide ceramic that is more durable and reasonably priced i'll buy some. Another direction to consider as well if insulating properties of metal don't work is machining Zirconia. You can buy it in machinable rod.

haulinkraut

Also, I have access to a rockwell hardness tester. So if you have a broken sacrificial zircon puck I can tests it's hardness for your research.

Ed@Demonspeed

Thanks for the offer. We have as well. We are actually well equipped on the testing side. Tensile testing, proof load, charpy impact, XRF and OES metal identification, Skidmore machines, ...

It looks like, based on the charts that I am looking at, the ceramic zircon has better properties than the rod. There are several other alternatives that appear to be better. I am going to pull a slug of each and try them out. We are also researching the thermodynamic behavior of the pads. We have good ties to Hawk Brake, which is in our neighborhood here, so we are looking to get some education from them.

Thanks
Ed

haulinkraut

Great. Glad to see you are not just another garage fab guy who makes "performance" parts and doesn't collect data to prove effectiveness. I am willing to bet you are going to find any other equally effective thermal insulating materials to be either cost prohibitive or a not as effective compromise at the exchange of durability. For as much headache as the zircon pucks are to source, they do their job. And i would imagine that with bird cage retainers to hold them on the pistons in place so they don't fall and break, the wear is next to non-existent. Might be as simple as machining an aluminum mold. The rest of the process is pretty much the same as pottery. Although the strength goes up if the zirconia powder is pressed into the mold then water impregnated.

uscarrera

MarcD147

I am looking for pucks...

uscarrera

Ed@Demonspeed

Well, we ran our heat transfer real world testing on the different metals that we had anticipated would give us good results.

The results were favorable for one material.

Here is the testing that we did.

A heated and stable surface of 250 degrees F. with a layer of oil to promote conduction to the test sample.
10 material samples with the same approximate size and shape to the ceramic disc.
Timed experiment (temperature increase over a period of time)

The idea behind this test is that the ceramic disc is to isolate the caliper and the fluid from the high heat of the pads during braking.
Data was taken at 30 seconds, 1 minute, and 90 seconds.

The ceramic disc for example after 30 seconds of exposure had a temperature reading of 115 Deg F on the opposite side.

The best material that was trialed heated to only 123 Deg F on the back side.

This was a very good result (relatively speaking). Considering the worst result was heated to nearly the same 250 Deg of the heating element in that same time. Titanium, which we had thought was going to be a front runner actually was in the bottom 3. It may be the grade of Ti we used, but based on the book, this should have been a good one.

So, the good news is that we have a material to use and the material is not the most expensive. It is rather exotic, but less cost than Ti or some of the others we trialed. Now we are down to having some samples produced.

We are also talking to coating suppliers to see about coating the parts with a thermal barrier which, if we are good and lucky, might even do better than the original.

Our normal design path would be to have samples made and then test them on our car in real life. We would do some caliper temperature tape or paint to measure what the caliper is getting up to (before and after the change). If anyone would like to participate in the beta test, maybe we can set that up too.

Thanks

Ed

dherring

Cool! (pardon the pun)... What about specific heat or heat dissipation? If you have multiple brake applications w/o siffcient time to cool, how does that affect things? How does this material rate w/r to mechanical properties? Can it withstand repeated application of pressure at high temps?

haulinkraut

Ed,

I would like to second the previous question. Also, why did you only heat to 250f? Seems these brake are seeing over that and different material may not see the same results as a linear curve. So at say 500f that material may very well may not isolate heat as well. Also, what about thermal expansions and structural integrity at higher temps?

Ed@Demonspeed

The heat dissipation of the ceramic puck was actually much slower than any of the other samples. It held more heat. (much like a brick oven). Using 30 seconds in a quite extreme condition. Some track have entire lap times at or around 1 minute and we do not spend that amount of time on the brakes. Typical heavy braking zones are less than 5 seconds of braking. This is a carbon based wrought material (machined from bar). It has much stronger properties than even the backing plate material of the pads.

250 degrees F was used because we used oil to promote conductivity between the heated surface and the sample. We were concerned that the surface finish would play a part in the testing. As you know, 250 is about the reasonable limit for oil before it starts to loose its properties. And, we were looking for a temperature delta, not an absolute. Heat transfer rate is a relatively linear relationship, so there would not be an appreciable change to the experiment at a higher temperature.

This portion of the testing was intended to narrow our choices, not be an absolute decision making factor. As I had said, our next step would be real world track testing with temperature paint to measure the temperature at the caliper in each case. We have also spoken to the coating specialists, so we will be trialing two different ceramic coatings as well for the real world tests.

I posted the details of the testing to show progress and that we are taking a scientific approach to the solution. There are plenty of other details and observations and details that I had held back because they are either boring or we would like to keep them to ourselves as trade secrets.

Thanks

Ed

dherring

It is terrific that you are doing this Ed, especially in such a systematic manner. Any comments from me are merely curious ponderings from a non-engineer... I think the question about the coefficient of thermal expansion may be another issue that is relevant for fit of the puck in the caliper piston shaft. I beleive that different metal alloys can can considerably different thermal expansion properties.

haulinkraut

Sounds like you did your homework. Any idea on what the price point will be?

Ed@Demonspeed

Thanks guys,

We have the sample size and the production part quantities out for quote right now. It will really depend on the coating cost, which we will not approach until we know if the coating adds value. I am anticipating the sell price to be favorable.

Thanks

Ed

MarcD147

LOL

For whom :-)