Looking for a plastic I can use in the engine bay, more specifically as a spacer/insulator for the throttle body. So what I need is something machineable, with a high strength and tolerance to heat. So far just by looking at specs Nylatron seems to be a good but I don't have much experience with plastics. I would use aluminum but I want something to act as an insulator but more importantly it's easier for me to machine plastics. Thanks in advance.

I think Phenolic would be a good material of choice.

just a newbie-- But
I second the above. Avoid breathing the dust, ah very bad for you.:D

I actually took a whole class on plastics a semester or two ago. I still have some of my notes and sweet book from that class. I will do some research and see what I can come up with. Some other considerations you will have to take into account is that the plastic that you will be using has to be petroleum resistant.

Well, after doing a quick looksee in the book, it looks like the above mentioned Phenolic would be a good choice, but another one would be Polyamides, a.k.a.-Nylon. The only disadvantage to Nylon would be is that it is hydroscopic. But that shouldn't affect it too much. One disadvantage of Phenolic is that it is pretty hard to machine from what I can gather.HTH

Phenolic isn't too bad to machine. I made a carburetor spacer a few years ago for my boss :D

This type of Phenolic is an irritant only. I studied it in my Material Selection class.

Machineable teflon would be the best choice but $$$....It's very easy to machine and comes in a variety of thicknesses. A 6"x6"x2" piece would run about $40+/-....

Polyvinylidene Flouride(PVDF) would be my vext choice but is a very hard material and difficult to machine.
Both plastics are highly chemical and temprature resistant.

I've been working with industrial plastics for 6 years and never heard of "Phenolic" does anyone have a cut sheet on it?...where do you get it?

I would think the temp would be to high for a thick piece if teflon?

Originally posted by BossGrip
I've been working with industrial plastics for 6 years and never heard of "Phenolic" does anyone have a cut sheet on it?...where do you get it?

I don't think phenolic is a plastic, it's more of an all purpose composite (honestly it looks like rags presed into resin), very hard, sands and grinds well. It's also a great heat insolator and wears fairly good too. It is used EVERYWHERE in aviation. They use it to make pulleys, spacers, rub strips, heat insolatiors etc.....

You can also buyt phenolic gasket scrapers that are very nice, they are hard, keep and edge and can be resharpened...and they do not mar even the softest of metals.

If anyoen knows a source for phenolic please speak up, I would love to get some to make a new set of scrapers.

I work in the aviation field and as dug said it is widely used in the industry and we get ours from http://www.mcmaster.com/

I built a carb spacer about 6 years ago out of phenolic and it is still going.

hth

rich

Thanks for the responses, sounds like phenolic is the way to go. When working with it, would a generic dust mask be all that is needed to keep on the safe side? Do you pretty much machine it as you would aluminum then?

Originally posted by DUG

If anyoen knows a source for phenolic please speak up, I would love to get some to make a new set of scrapers.

check here

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1769942501

rich

When working with it, would a generic dust mask be all that is needed to keep on the safe side?

The only way to do it is to get the WMHIS / MSDS sheet and check...you need to be sure, especially with composites

Originally posted by BillaVista


The only way to do it is to get the WMHIS / MSDS sheet and check...you need to be sure, especially with composites

Agreed....I'll get an MSDS sheet on Monday

Originally posted by ItsaCJ6
I would think the temp would be to high for a thick piece if teflon? Teflon would work even if your engine got up to 400*;)

the hydroscopic properties of nylon will screw you up. we used it in some machined parts for underwater use. it swelled and would no longer work.

There are several types of Phenolic. Canvas, linen and paper are common. Linen would be the choice for a carb spacer only because it's texture will be best for thin sections. It sounds like you might be using somewhere between 1/8 and 1/4 thick. I have machinded lots of this stuff and a regular mask will do for your one time job. Use an old bit or Endmill. Slow spindle speed and a fairly high feed rate, not like aluminum at all. More like steel but a higher feedrate.

Scott

Also PVDF is attacked by acetone so if your girlfriend is doing her nails anywhere near your spacer......Lookout:eek:

Ultimately what you are going to want to look for is some sort of reinforced phenolic "composite". Using a reinforcement like fiberglass (either chopped strand mat or a "woven" or "stitched" fabric) or a cellulose (cotton, linen, paper) will be what you want. Phenolic along is VERY brittle, and, depending on the reaction process (novalak vs resole) will crack from the condensation reaction of the polymer. The papers, cottons or linens should work just fine for you. The best strength, however, will come from the woven or stiched glass composites, but unless you plan to structurally load your intake, don't bother (save a couple bucks).

Check out www.mscdirect.com for phenolics. They have everything you would want.

For personal safety, we like to use positive air displacement (stand with your back to a fan between the composite and the fan). This alone will help keep a lot of the crap out of your face. Wearing a good Home Depot dust mask is also a plus. The phenolic is already cured, so chemically it is not a huge problem, it is more of a dust control/inhalant irritant at this point. Eye protection needs not mentioning of course. Like cruzila said, slow spindle speed will give you good results. This stuff will chip if you work it too fast. Wear some nitrile gloves to keep bits out of your skin as well (just to be safe).

And don't forget to have fun :D

Use a chunk of 30% Glass Filled Nylon 6/6. As someone stated before, it is a hydroscopic material. But who cares?, when you run your motor the material will dry.

Many intake manifolds are being molded with this material. Anyone have a 99-03 Chevy truck with a 5.3? If so, go and look at the intake. You will see it is a tough black plastic. This is 30% GF Nylon 6/6. The material is machinable, however, it does not machine like metal. As with most plastics, it needs to be cut FAST with a SHARP cutter. Preferably a 2 flute. This minimizes warpage in the material. This material is commonly chosen for replacing metal parts.

Look up the material at www.matweb.com for properties.

90% of the autos will probably be built this way in the next 10 years.