Shaft Material 1

[Dymalica]

We have a large hanging hanger door with a large shaft that runs the length of the door. The motors are attached at the top and pull of the 3 pieces of the hanger door together using the pulley and wire system. What material do you think the shaft should be considering the site is about 1 mile from the ocean? The contractor is thinking of using a primer on it to prevent rust, but in my experience I usually don't see any paint or primer on shafts. The shafts I see are normally indoor motors and really aren't exposed to the elements. What material and finish on the shaft would you use?

Thank you for the help

 

[CoryPad]

Just a single shaft? I would investigate a stainless steel shaft so that it could be maintenance free. It could be a simple Type 304 if you don't need high strength, or you could select 17-4 PH for a heat treatable, high strength shaft. If you can't find these alloys in the size/shape/configuration you need, you may need to use a low alloy steel. If so, then see if you can use a zinc-containing coating (e.g. Zn-rich epoxy or Zn-rich inorganic) to prevent corrosion.

 

[Dymalica]

I was told that it is C1045 turned, ground and polished. Does that mean that the shaft is corrosion resistant?

 

[TVP]

No, 1045 steel is not corrosion resistant. It will need some type of corrosion protection.

 

[Dymalica]

Do you now any coatings that could help?

 

[CoryPad]

Yes, the Zn-rich ones I mentioned in my previous post.

 

[bithkits]

Primer or paint is not a good idea - it will rub off or flake in places making it useless.

I'm with CoryPad on this one. A coated/plated shaft is the way to go, or even better, use stainless.

Adriaan.
I am an Engineer/part time student (Mechatronics) from South Africa.
Advice from lecturer: "Be warned - when you go into industry your boss will give you a thousand things to do and he wants them done yesterday!" So far he is right...

 

[diskullman]

A mile from the ocean?
I think you are over-thinking. Use a cold rolled shaft and let it rust. If you're that concerned about corrosion, I would coat it with a tacky rust-preventative spray.

Russell Giuliano

 

[plasgears]

Weatherable steels such as Cor-ten have been in use in highway structures for years. Look into it.

I once recommended it for automotive use, and the powers that be quashed it. Was this part of their plan to support planned self destruction?

 

[Tmoose]

I recall reading that Corten needs well defined wetting and drying cycles to form its protective coating. I think Some areas under bridges were failing because they were too well protected to weather properly.

Dan T

 

[tbuelna]

Dymalica,

1045 with thin dense chrome would give excellent corrosion resistance, excellent wear, accurate dimensional control, and could be periodically re-plated if necessary. Thin dense chrome on 1045 steel may be a less expensive option than using a stainless steel alloy.

http://www.hitecplating.com/tdc.php

Hope that helps.
Terry

 

[dgallup]

What is the length of this shaft? I'm thinking it will be much too long for most platers to handle. I've been to Hi-Tec's facility, they are a first rate shop but I doubt they can plate anything longer than about 10 feet.

 

[SKinzel]

Going with a stainless steel may be very expensive. Especially the 17-4PH. That can also be somewhat difficult to machine also. In my experience 304 stainless may be too soft, I don't know what typical hardness is but I believe it is somewhere in the "butter" range, and not be able to support its own weight if it is an overly long shaft.

Using regular cold rolled steel and coating the exposed parts with something like Cosmoline or painting the shaft with Carbomastic might be the way to go. Carbomastic paint is often used on the steel parts of moveable bridges. You could also coat the coupling journals with NeverSeize if you don't need the friction of the fit to help transmit torque.

 

[unclesyd]

As you mention that you are near the ocean I would go with the aforementioned 17/4 PH SS, like Aqualoy 17. You buy this material treated for use as boat shafting. It will be straight, ground, polished and it is not hard to machine in boat shaft condition.

There are several suppliers of the 17/4 PH SS shafting material like Western Branch Metal's Aqualoy 17

http://www.wbmetals.com/

 

[carburized]

Stainless steel is good for these application specially for close to ocean. But, you should realize, stainless steel is not as strong. You could use galvanized coating to prevent it from rust. But the coating shoud adhere to shaft good. Any time it peels off you will have problems. I work for gear industry and have to deal with materials. You can visit my site

http://www.gearsandbearings.com