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snowman
12-07-2009, 01:38 PM
I need to make a couple of wear surfaces that a piece of steel will be riding against. Basically a small slotting attachment for my mill.

I am considering using either steel on steel or cutting up a cast iron belt cover that I have and flycutting it flat and using that. Just curious if the cast iron thing is a bad idea, and if the grade of cast iron in the belt cover would be considerably lower than that used for wear surfaces (it's a 60 year old belt cover off an old leblond lathe)

A brass wear plate is just too soft for what I want to do.

wierdscience
12-07-2009, 01:48 PM
The cast will work so long as the loads aren't to heavy and lubrication is provided.

A better material would be some 932 bronze flat stock though.

davidfe
12-07-2009, 02:04 PM
I read post like this and wonder why some of the
new hi-tech coatins would not help.

I know of one because I receive their newsletters. I am
sure there are many otheres.

Look at www.techlinecoatings.com/ (http://www.techlinecoatings.com/)

The auto industry and others use these products
to coat piston skirts. So why not a wear surface
in the shop?

snowman
12-07-2009, 04:35 PM
I'm sure a lot of the new high tech coatings would work, but I'm not goin to send something made out of mystery metal in my garage out to get coated by a job shop to the tune of $100....that's a lot of tools!

davidfe
12-07-2009, 05:10 PM
I'm sure a lot of the new high tech coatings would work, but I'm not goin to send something made out of mystery metal in my garage out to get coated by a job shop to the tune of $100....that's a lot of tools!

1. Did you look at the site?

2. Did you see the DIY coatings?

3. Who quoted the $ 100.00 price to you?

I get the idea you are over-generalizing here.

Just trying to let you see another avenue that might improve the
performance. I think this is something that could be performed
by a HSMer.

Of course, I am like wrong too. Let's see if anyone else
replies.

Regards.

darryl
12-07-2009, 06:59 PM
Haven't had my afternoon coffee yet, so bear with me- how about a coating which is applied electrically- like leads for a pencil, these would be fed through an insulated 'pen'. These would be rods sintered using hardening powders, and you would 'color' with it, adjusting the current flow to get the material wiping off onto the conductive substrate (your unhardened lathe ways, etc) A colorant would show coverage, and the feed current could be enhanced with voltage spikes if that would help the materials infuse into the surface.

Something a little more rigorous than electroplating, which should be possible considering the point-source size of the tip- that's what I'm envisioning anyway.

I've had some pretty good luck with some coatings- my fave at this point is the saw table lube by Bostick, Top Cote. Not totally high tech, but it works nicely.

snowman
12-07-2009, 09:47 PM
The coatings I have experience with have a high startup cost, a small maintenance cost, and are cheaply applied to parts in bulk. When you try to get one part coated however, you start to look at minimum handling costs for the coating companies. These larger companies don't want anything to do with the hsm market, and the amount of time making friends with a guy in back with a six pack can get the job done.

So it's impossible to answer the question of quality of cast iron as a wear surface?

TGTool
12-07-2009, 10:16 PM
You can get materials like Turcite that are used for way linings. There are places that use it you can buy from. McMaster Carr also has an equivalent in their plastic materials. I've used it for a slide like a hand shaper that shows no signs of wear yet.

snowman
12-08-2009, 12:01 AM
With the use of polymers, do you just have the sliding joint highly polished with a couple of oil grooves? I've got a good amount of acetal on hand, but always considered it a little too soft for an application like this. Hadn't really considered it.

JRouche
12-08-2009, 02:02 AM
Im not sure what exactly the part looks like or what kind of loads its going to see. But I accidentally found a decent wear plate. On the cheap.

I was making some wear blocks for something like a bandsaw. To guide the blade. I made the wear blocks from some 4140 steel that was brought to cherry red throughout and quenched quickly in water.

I polished up the sliding surface to a mirror finish with progressive grits of abrasive, ending with a micro abrasive film to get a nice finish. The edges were all beveled over so there wasnt any sharp edges.

I had to make a simple holder for the blocks because they couldnt be supported on their own. They were glass hard, or as hard as 4140 can get, not like some other alloys.

Anyway.. They worked!! No wear on the blocks after a few years and no apparent wear on the steel band that was riding over the blocks.

Dunno what your need is. But the blocks I made up can handle some pressure, a lot of wear. Problem? They cant take any force. Meaning they can not be used to support any force. They are only good for wear blocks. And they need a holder... JR

TGTool
12-08-2009, 11:03 AM
With the use of polymers, do you just have the sliding joint highly polished with a couple of oil grooves? I've got a good amount of acetal on hand, but always considered it a little too soft for an application like this. Hadn't really considered it.

There may be some plain polymers that can stand up, but the ones designed for this service have characteristics for both withstanding pressure, wear and providing lubricity. Stuff I saw used at a previous employer looked like it had tiny bronze beads embedded in the matrix. I haven't looked at the Turcite under magnification, but there's no apparent metalic glisten to it but it must have something as a strong filler. One side is etched so it can be adhered with epoxy. The supplier I talked to said way wipers were important when installed on lathe carriages for instance, since if chips got dragged in they deteriorated much faster.

Plain teflon I don't think has good wear characteristic for this sort of application, and I've seen it creep and leak when used as a gasket for an auto engine wet sleeve.

If you look at McMaster Carr's pages on plain bearings you can pick up info on what is used and various characteristics that might be important. I'm guessing that a wide temperature range isn't critical for you, nor is very high speed movement, but withstanding high loads probably is. Rulon shows up in plain bearings and can be purchases as sheet or film in various thicknesses. I bought a sheet of 1/32" for slides I've made and used unhardened ground stock against it.