[cordvision]

I got two questions:

1. I'm trying to find out if carbon fiber or stainless steel is stronger on a volume basis. If I make the exact same part from carbon and from stainless steal, which one will be stronger? I tried re-searching it online, but the comparison is usually done by weight (two parts of the same weight) and not by volume.

2. I'm worried about milling carbon fiber plates on my Tormach because the dust is a health hazard. I also don't like the idea of using flood coolant or a vacuum cleaner because chances are that the dust will find it's way into the air one way or another. Looking for a solution, I came up with the idea of creating a fixture that is submerged in coolant in a flat tray. I basically would do all the milling submerged in coolant. Once I'm done, I can just dump out the tray and I don't have to worry about the dust. Does this sound like it would work? Am I missing something?

[SCzEngrgGroup]

The answer to question #1 depends on the specific part, and how it is loaded. There is no "carbon fiber will ALWAYS be stronger if....". To get the "best" design requires designing FOR the material, not just re-making a part designed for one material using another material.

Regards,
Ray L.

[cordvision]

The answer to question #1 depends on the specific part, and how it is loaded. There is no "carbon fiber will ALWAYS be stronger if....". To get the "best" design requires designing FOR the material, not just re-making a part designed for one material using another material.

Regards,
Ray L.

In this case, I can't design it specifically for carbon fiber. This part is just one piece in an assembly, and the design is given and can't be changed (assembly would have to be changed as well which is out of question). The part basically looks very similar to a wood saw blade with just one tooth on it. "The tooth" is about 5mm long and 3mm wide. The prototype was cut from a 0.8mm stainless steel sheet. The "tooth" has to be quite strong, and I'm wondering if there is a chance that it would be strong enough if made from carbon fiber instead of stainless steel.

[tmarks11]

1. Is there any side loading on the "blade"?
2. How is the "blade" stressed? Any part in compression (carbon fiber doesn't do so well in that application).
3. Does the "tooth" have to interact with anything? i.e., will it be subject to any rubbing?
4. Is any of this a moving part that would be subject to vibration that can lead to fatigue?

The problem is that you really answer this you need an ME to run some structural analysis of it (assuming this is a critical part). Why are you thinking carbon fiber instead of stainless?

[cordvision]

1. Is there any side loading on the "blade"?

No side loading.

2. How is the "blade" stressed? Any part in compression (carbon fiber doesn't do so well in that application).

The tooth just catches on a metal ridge and is loaded/stressed in the same direction as a tooth of a saw is when it is cutting.

3. Does the "tooth" have to interact with anything? i.e., will it be subject to any rubbing?

No rubbing or abrasive movement. Just a static load on the tooth.

4. Is any of this a moving part that would be subject to vibration that can lead to fatigue?

No.


I want to use carbon just for aesthetic purposes. It is a highly visible part and carbon would be very fitting. (Yes, I know that there are carbon decals, but that won't be a solution). I guess I just have to get some carbon and make a prototype. I was hoping that I could just get a ballpark figure just to get a feel if it even has a realistic chance to possibly work.

[adamvs]

No side loading.


The tooth just catches on a metal ridge and is loaded/stressed in the same direction as a tooth of a saw is when it is cutting.


No rubbing or abrasive movement. Just a static load on the tooth.



No.


I want to use carbon just for aesthetic purposes. It is a highly visible part and carbon would be very fitting.

Make it out of carbon, and when that fails make it out of stainless.

If the part has a lot of 'latching' action, against this metal ridge, the resin in carbon-fibre will break down over time. Stainless would be much tougher.

[tmarks11]

If the part has a lot of 'latching' action, against this metal ridge, the resin in carbon-fibre will break down over time. Stainless would be much tougher.

+++1

[warrenb]

No side loading.


The tooth just catches on a metal ridge and is loaded/stressed in the same direction as a tooth of a saw is when it is cutting.


No rubbing or abrasive movement. Just a static load on the tooth.



No.


I want to use carbon just for aesthetic purposes. It is a highly visible part and carbon would be very fitting. (Yes, I know that there are carbon decals, but that won't be a solution). I guess I just have to get some carbon and make a prototype. I was hoping that I could just get a ballpark figure just to get a feel if it even has a realistic chance to possibly work.

In this application you don't want to go with CF. It is not made for loads against the end grains.

But if CF is required for visual aesthetics put a precured sheet on top of the part. CF is tough to get a shiny finish. (15 years in the CF aircraft business and still make LOTS of SS parts)

But you're a metal worker. Hone your skills for mechanical decorative metal finishing. Do some spotting or brushing or graining.

[pickled]

Start your google searches with material science aspects to better understand what type of specified "strength" that you are looking for. It can be quite dangerous to put this kind of question out there for the masses. Only you and your customer truly know the environment and forces potentially involved with intimate detail. Omit a fact like, "the design may be outside for extended periods", or "the temp of this application can be below freezing at times" and you could have a bad situation on your hands. Even unplanned excessive UV exposure can make failures out of otherwise perfectly suited materials. Good luck, but proceed with caution as you move forward!

[CadRhino]

+1 there are lots of cool ways to finish metal.

In my early days I worked quite a bit with composited. I had some serious health compromises from it and only work in metal. If you do go down the cf route, be overly cautious with what you are exposed to.
Good luck.

In this application you don't want to go with CF. It is not made for loads against the end grains.

But if CF is required for visual aesthetics put a precured sheet on top of the part. CF is tough to get a shiny finish. (15 years in the CF aircraft business and still make LOTS of SS parts)

But you're a metal worker. Hone your skills for mechanical decorative metal finishing. Do some spotting or brushing or graining.

[tbev]

Just a cutout of cf sheet and lay, glue, whatever, stick, it to the visible side of of ss part, you can cut a logo or design in the cf so it will cover and ss will show thru the cutouts...easier looks and durability of ss where it counts.

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