supertanium bolts 9

[klyde]

Does anyone have any test data on Supertanium bolts?

 

[klyde]

unclesyd,CoryPad & Screwman. You guys have been a tremendous help and provided an education that I needed. The helo that I'm flying was designed by a good aerospace engineer back in the 50's. The manufacture of the kit is currently being done by 4-5 guys in Canada and Florida. None of these guys are degreed professional engineers. They are pretty darn good wet thumbers, but I haven't caught them with any indepth engineering yet. In spite of that they have a fairly impressive record. What bearing failures we've had to date have been fairly well predicted and have not caused any major damage or failures. Lucky?? I guess so. But this bolt thing just bothered me. Something like Supertanium just sounded like "Unobtanium" or something like that. I have received a brochure from Premier Industrial Corp. indicating that they are using a sacrificial and barrier type coating which they claim far surpasses any elecroplating. They further claim that the process does not embrittle the steel when applied. They have a picture showing the results of 1,000 hr of salt fog cabinet on a quartet of bolts. The supertanium is the only bolt that appears useable. I don't know, but it looks good.
I've also acquired some data from SPS on AerMet 100 alloy fasteners. They are claiming a diffused NiCad plating with Chromate treatment. Per AMS 2416. I don't know how this compares with the 1,000hr Salt Fog, but it does sound like some of the corrosion treatment that I think Screwman wasn't too fond of?
Again I want to thank you guys for taking the time to produce what I think is an excellent thoughtful discussion
Stu Fields

 

[Screwman]

Klyde,
The diffused NiCad is a very good finish. It is vapor deposited and has a very low likelyhood of embrittlement. The Aeromet 100 is a good material for very highly stressed, critical joints.
The thing that you need to remeber about most of this thread is that all involved are coming at it from different backgrounds and as a result our POV tends to be different. The thing that I always remind myself when dealing with aircraft fasteners (vs. ones for Corey in Detroit) is that an airplane doesn't coast to the side of the road when one breaks. The Supertainium bolts will likely work, but true aircraft spec parts have more precise chemistry, geometry heat treat and plating controls. It's not just the amount of documentation (which is considerable), but the actual requirements are more stringent (off hand, my rule of thumb is that most aerospace specs use 1/2 the tolerance of an equivalent commercial or automotive spec). It's because of criticallity that they have adopted this approach over the years.
Either way; have fun with the rotor craft. Always remember: a helicopter is a group of loosely attached parts attempting to find a way to separate themselves from one another.

 

[CoryPad]

a aircraft quality fastener, depending on the material, is subject to the same problems as the Supertanium

This is true assuming a carbon steel fastener is used. My recommendation, supported by your U.S. Army Corps of Engineers report, was to use other alloys that are less susceptible to chloride corrosion and subsequent hydrogen embrittlement.

[blue]klyde[/blue],

Hydrogen embrittlement is not entirely understood today, and certainly wasn't in the 1950's when your helicopter was designed. The coatings you quote are good for corrosion resistance. However, hydrogen embrittlement is still a concern, and I would never use a Supertanium fastener for your application. Good luck with your project.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Timurlane]

I know this is a little old, but I just stumbled across this thread.

I used to sell Supertanium products (in a past life). Just a few notes on what has been said.

1. It is a very well made maintenance fastener and was sold by the Premier company for years (also owned Newark Electronics). It is manufactured in the US (I believe Lake Erie Bolt) and private labeled 'Supertanium'.

2. The Premier MRO line was purchased by Lawson Products in 2001 (Farnell, the owner of Premier, kept Newark). Lawson is another solid and reliable distributor of MRO products (by 'solid' I mean I would be greatly surprised if these guys ever sold you a 'counterfit' fastener).

http://www.lawsonproducts.com

3. Supertanium capscrews are a heat-treated, 3x tempered (austempered), cold formed, high-strength alloy steel screw.

4. The coating is a mechanically applied, multi-layered zinc with a polymer wax finish (trade named Corro-Shield). This method is not only superior to both traditional zinc or cadmium electroplating in terms of corrosion resistance, it avoids the whole problem of hydrogen embrittlement because nothing is electroplated.

5. That all said, I do not believe Supertanium bolts are certified for aircraft applications. It is a production capscrew intended for maintenance applications where a balance of high strength and corrosion resistance are required. Though they are very popular with the military. When I was selling them some of our biggest sales were to military maintenance departments.