Chemically accelerated super finishing on knives?

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mitch8

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Oct 11, 2010
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I don't know how much you guys follow the gear industry but there is a process called chemically accelerated super finishing, that can give gears a mirror finish(or pretty close anyway). As far as I understand the chemical softens the steel on the very surface so that it can be wiped away like a layer of microscopic mud. The steel only gets wiped away on the peaks sence the part is being tumbled in a non abrasive media. This is all happening in a vibratory finishing machine.

My question is, would this work on knives? Could I use some of this chemical to aid a wet sanding process? Or could I use it instead of polishing compound? If any of you have experience with this process or something similar let me know. It is also called isotropic superfinishing if that helps.
Thanks, Mitch
 
Would probably work on some designs like full flat grinds, but it would probably muddy your clean bevel lines right?
 
Unless this is a different process, it is done in an industrial tumbler with various acids and burnishing compounds. Not really useful for the normal knifemaker.
 
I cut in with 36 grit belts. Then all my blades go for a ride in the vibratory tumbler with ceramic media. The large surfaces on the ceramic triangles just knock the tops down like you described. I use no chemicals other than wd-40. I come back in and clean up lines with files or grittier belts for sharp lines. Then step on up to 120 etc etc.
I have noticed doing this lessens the effort I have to expend getting up to 120-220. I would imagine its similar, just mechanical vs chemical...
I also use polishing compound on corncob media for some stuff. I can just let it ride while I go do something else.
 
Oico, it wouldn't mess up your bevels and that's why the gras industry likes it, very little dimensional change.
Stacy, why don't you see this being practical for most makers?
1shot1kill, I'm talking about the REM process.
 
Oico, it wouldn't mess up your bevels and that's why the gear industry likes it, very little dimensional change.
Stacy, why don't you see this being practical for most makers? To much chemical storage?
1shot1kill, I'm talking about the REM process.
 
Sounds like you have it all worked out. Let us know what it costs you, the equipment you had to get, and show us some photos of the knife blades you finished this way.
 
If someone offered it as a service and it were cheap enough, I would probably spring for it just to save some wear and tear on my hands. Especially if it worked out close to or cheaper than the price of abrasives.
That's from the point of view of someone who hates final finishing sanding, some may love it ;)

As a hobbyist though who makes one knife at a time, shipping would likely make It less than economical.
 
thats why i came here, i don't have any of this figured out. i can't seam to find any of the stuff for sale. even birchwood casey has relatively small portions of their industrial chemicals priced out online but i can't find the REM chemicals anywhere.
and i wasn't planing on on getting a vibrotory tumbler and all that, i was just planning on getting the chemicals to and use them pretty much like you would a lapping compound. i have no idea if this would be effective though. maybe i should post this on a machinist or manufacturing forum too.
 
mitch8 said:
thats why i came here, i don't have any of this figured out. i can't seam to find any of the stuff for sale. even birchwood casey has relatively small portions of their industrial chemicals priced out online but i can't find the REM chemicals anywhere.
and i wasn't planing on on getting a vibrotory tumbler and all that, i was just planning on getting the chemicals to and use them pretty much like you would a lapping compound. i have no idea if this would be effective though. maybe i should post this on a machinist or manufacturing forum too.
Click to expand...

Lapping compounds are simply abrasives. Vibratory media tumbling is exactly the same process you described minus the chemicals. The chemicals only accelerate the process, and I would bet only slightly. Using just the chemicals would probably not achieve the desired result. Honestly, if you hate finish sanding that much get a tumbler and some standard media. I have used tumblers for ages with gun parts and the like to either knock off edges (with stones) or even polish out (corn cob and compound). Adjusting the media and the grit of the abrasive allows you to achieve a specific result. You do have to account for and sharpen detail to some degree, but the tumbler is working while you are zzzzzzz....

If you just want to cut away at the metal chemically, just use acid, or vinegar if you want a milder touch... And is manually (like, with your hands...) using a chemical that will eat metal and dealing with the health and environmental costs better than a little elbow grease in the long run? I know I don't particularly even like playing with the FeCl more than necessary.
 
i know that lapping compounds are just abrasives, i was just saying that i would use the REM chemicals in a similar way. the tumbling media in the rem process is non abrasive (plastic pellets) so i was thinking all i need to do is slop on some compound, scrape across it with a ruler and repeat. the reason i'm looking for alternatives to hand polishing is because i do a cryogenic treatment on my blades that ups the wear resistance. you have to temper the blades after cryo meaning that i have to sand of the temper color. hand polishing isnt that bad until you get to broad blades that have been cryogenically treated and have a flat grind.

anyway, i sent a message to REM surface engineering and we will see if they think this is a practical method of shining up a blade.
 
I tried ferric chloride acid in an attempt to reduce the (hours) of hand finishing needed on a hardened blade in d2. Results? Ungood. In fact, I had it in a satisfactory (mostly satin) state when I started, now I need to start all over again.

I'd bet that the plastic pellet agitation is a key component to the process you describe. If it wasn't totally necessary they wouldn't do it. I work in an efficient manufacturing plant, nothing that isn't absolutely necessary happens.

I have doubts, not that it wouldn't be awesome for knife makers, but that it'll be feasible, either due to cost or necessary equipment. I hope you're onto something though. Be sure and let us know what you find out, and don't give up. :)
 
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mitch,
I am not trying to be argumentative, but you asked if anyone knew about the method. You even said it was done in a vibratory tumbler.

I responded that the use of it I was familiar with would not work as you planned, and would not be useful for knife blades.
You said that you didn't see why it would not work.

Someone else said it would not be a good method.
You responded that you didn't plan on using a tumbler, just wiping off the surface with the chemicals.

This method uses chemicals that are only licensed by REM, and specialized equipment. It takes a lot of money to do this. The results may or may not be of any use to a knifemaker anyway. It is not a wipe-on....wipe off process.


Here is an excerpt from REMs own data:
The REM (R) procedure is not a polishing process but rather a finishing process. The REM procedure involves two steps. The first step, referred to as the "Refinement Process", involves a chemical interaction on the surface of the part. A soft, thin (one micron) film is formed on the surface of the part. The part then interacts with the ceramic media in a special vibratory bowl. During this interaction the film is physically removed from the "peaks" of the processed part and the "valleys" are unaffected. The chemically induced film re-forms only at the peaks that are interacting with the vibratory media, and the process repeats itself. Over time, the peaks are removed, leaving only the valleys, producing the improved micro finish. The second step is referred to as the "Burnish Process." After the required micro finish is achieved, a mild alkaline mixture is introduced. After a relatively short period a polished, chrome-like finish is produced. In addition to the polishing effects, this step effectively removes all traces of the film formation from the refinement process.

Also:
We hold the exclusive license from REM Chemicals, Inc. to offer Isotropic Finishing in Georgia. "PCMC" is the only Company in Georgia, and will be the only Company in Georgia, Licensed to provide this unique gear finishing service. We have obtained REM Chemicals State-Of-The-Art Equipment, Chemicals and Media.


CRYO-REM (R) IS A TRADEMARK OF EVANS PERFORMANCE PRODUCTS, LLC AND USED UNDER LICENSE BY PROFESSIONAL CRYOGENIC METALLURGY & COATINGS
 
Dang, I didn't know that they were that exclusive. I thought that they would be like most companies and just sell to anyone that is willing to buy. Thanks for doing that reaserch Stacy. And I could have sworn that REM used non abrasive plastic tumbling media which led me to believe that the surface could be rubbed with just about anything and it would still remove the peaks. Going back and looking at my post I noticed that some of them read a bit rude and I'm sorry for that, I was just worried that people would shoot down this procedure a little to quickly because its the classic way of doing things. Clearly that is not true and people here have researched this specific process quite a bit.

On the topic of ferric chloride, I do like the look of very small pits from a light rust after the rust has simply been polished off with compound and leather. So my question is, what do you mean by unsatisfactory? Was it a lightly pitted and textured surface? Cause I find that quite nice looking on some blades.
 
I actually don't mind some pitting either. I have a blade in cpm m4 that pitted from removing the Cerakote finish. An acid finish (even gray/orange peel) doesn't look nice to me the way a nice patina does, even if neither, or both, cause pitting.

I can't say that I won't acid and stone wash another blade, because I like the look when I do it right. For use in accelerating scratch removal, and as a finish in and of itself, the acid didn't work the way I had hoped.

It's possible that, under the right circumstances, it would work as I had hoped given the right jump off point and expectations. I imagine that I'll try again with a different steel and adjusted idea of what to expect. Part of the fun for me is in the experimenting. ;)
 
I use a heavy FeCl etch to eliminate most sanding on my damascus knives, the peaks are more exposed than the valleys. Haven't tried it on plain steel but I have a couple of rough blades so I might

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