Questions about coatings via CVD Vacuum Chamber 1

[bigmark1972]

I am a toolmaker for my family owned business. I have an opportunity to purchase a nice heated CVD vacuum chamber for a low price.

I know very little about the process or how it actually works, but I would like to.

We perform a lot of tube cutting via the supported shear process. Our tooling is typically a-2 or d-2 standard hard. Wear is an issue and increasing time between sharpening would reduce my workload considerably. I'd like to be able to coat this tooling in house to avoid potential delays in having it done elsewhere.

How difficult would it be to learn how to make this work? What coating would be the easiest to deposit and have the best wear characteristics. Is this something that is best left to trained personnel or could I learn how to do it myself?

I'd like tin, tialn or something even harder if possible. I believe tin and tialn are via the CVD process. I'd need to know what gases are required, what materials to use for the reaction, vacuum levels etc.

Is this black magic or is it worth pursuing? I'm a decently intelligent guy and I don't mind cracking a book or studying anything to learn whatever I have to.

Could someone point me in the right direction to obtain this knowledge or offer their opinion on the feasibility of learning the process?

I'd appreciate any input.

Thanks,
Mark

Heritage Systems

 

[kenvlach]

You probably want to stay away from CVD, which often involves streams of toxic expensive gases which (generally) thermally decompose upon the heated substrate part.

TiN is most commonly deposited via reactive PVD; the titanium is evaporated or sputtered from a metal source in a vacuum containing nitrogen.

http://en.wikipedia.org/wiki/Titanium_nitride

http://en.wikipedia.org/wiki/Physical_vapor_deposition

Maybe check the Society of Vacuum Coaters

http://www.svc.org/

and process descriptions on vendor sites. E.g.,

http://www.brycoat.com/resource-pvd.html

'CERAC Coating Materials News' may be useful although mostly oriented toward optical coatings:

http://www.cerac.com/pubs/CMNarchives.htm

As with all coating processes, precleaning is essential; both prior to loading and then within the chamber.
Another thing not mentioned upfront is that you will need some means of chemical stripping poor deposits.

JTreglio is perhaps the Eng-Tips expert on these coatings. Read his responses to other posts.

 

[JTreglio]

TiN was originally deposited by CVD, and is still used on many tool inserts. However, the deposition temperature is quite high, so one generally does not coat high speed steel tools by CVD. The preferred method is by PVD. TiAlN is deposited by PVD. Other good tool coatings include ZrN and TiCN.

PVD is certainly easier to bring in-house than CVD, in that the process does not involve any hazardous materials. However, most PVD equipment is pretty expensive. I do know of a small unit that is available for under $100 K, but otherwise systems typically run over $300 K. Operating costs are low.

The easiest coating to deposit is TiN -- almost impossible to mess up. Easy to tell if you've done it right -- a good TiN has a bright gold color. ZrN is a better coating, not much more difficult to deposit, and has a light gold color. TiAlN is quite difficult to deposit, as is TiCN, so I would stay away from either of those.

The simplest PVD systems to operate are cathodic arc units. They are also cheaper, and produce in general very good tool coatings.

Because both PVD and CVD are bulk processes, unless your needs are quite great it is generally better to send the parts out for coating. Where are you located? Many of the PVD houses are able to give you pretty good turnaround on tools, particularly in the Detroit area.

Jim Treglio

Jim Treglio

 

[bigmark1972]

Thanks so much for the info, I am in the Grand Rapids area. I could live with a short turn around but I have sooooo many things I'd love to be able to coat. I'd actually like to build my own unit. I am a machine builder if I had some good plans I'd like to look into that. I was thinking possibly using plasma to evaporate the titanium but I'll research your suggestion.

 

[JTreglio]

Even if you build your own unit, you'll still need some expensive pumps, gauges, and power supplies.

Jim Treglio

 

[bigmark1972]

I am not at all against sending stuff out, It would just be so nice to have one in house. I know the components are not cheap, but I'd still like to try if I could figure out how to do it.

Sometimes, I can get good equipment on Ebay for pennies on the dollar.

 

[JTreglio]

If you want to go the route of building it yourself, you should hire a competent consultant. While you could learn much of it from the literature, in the long run it will save you a great deal of time and money to bring in someone who knows what to do.

Jim Treglio

 

[bigmark1972]

Jim,
Could you recommend any good coaters in the GR or Detroit area?

Also, if you could offer your opinion on what coating would be the most cost effective? I'd like the shear dies we use to cut stainless steel tubing coated for wear and gall resistance.
I use hardened A-2 and D-2 pretty exclusively.

Thanks!

 

[unclesyd]

You might want to take a look the the TD coating, Vanadium Carbide. We used this coating on D2 in a very high wear environment with very good results.

http://www.tdcoating.com/

 

[JTreglio]

Three companies that come to mind in your area are Goldstar Coatings, Balzer's, and IonBond. If the tools aren't seeing much in temperature, either TiN or TiCN should suffice. If they get very hot, TiAlN would be the coating of choice. TiN is the cheapest, so I would start there.

Jim Treglio

 

[adamant]

They might also provide help:

http://www.ccl.fraunhofer.org/working_areas/technologies/technology_03/e_surface.php

(at Michigan State University, East Lansing, Michigan 48826-1226)

 

[bigmark1972]

Thanks for all the help, that TD coating is very interesting also.

 

[mlt6ba]

For outside vendors to use, I have one more you will want to contact ~ Richter Precision. For the 3 companies mentioned above they all provide a great product. What we have learned over the years with PVD - CVD coatings it's price and customer service as they all put on the same coatings. Don't want to debate here on whom the best is, as I have never ever had a complaint about anyone of them ~ but cost ~ go to Richters.

 

[JTreglio]

Just looked up PVD coating services on the Thomas Net. There are 33 listed, of which about half are in your area.

Jim Treglio

 

[gfansher]

"they all put on the same coatings"

i picked up on this while reading through the thread. the answer to this is yes and no. TiN is in fact titanium nitride and it's the most common pvd coating out there. however, the structure of everybody's coating is different (as is the preparation, cleaning, handling, etc.) and you will get a slightly different coating from just about every vendor you use for coating. and don't get caught up in a trade name; "SuperSmith 2000 N" may very well just be Smith Coatings version of TiN.....it's not the end all/fix all, it's just their version of TiN.

 

[JTreglio]

gfansher is correct on the variations of TiN. In addition, there are at least three variations of the PVD process, depending on how the metal is vaporized: sputtering, e-beam evaporation, and cathodic arc.

Jim Treglio

 

[PISA]

i found adresses in vacuum-guide.com,

equipment manufacturers:

http://www.vacuum-guide.com/vacuum_coating/equipment/vacuum_coating_america.htm

and experts:

http://www.vacuum-guide.com/vacuum_coating/services/vacuum_coating_services_america.htm

hope it helps