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need ideas on turning and threading chromed rod

rosie

Hot Rolled
Joined
May 30, 2006
Location
Wisconsin
I haven't yet tried to cut chromed material. So I'm asking the brilliant world of PM.

A new customer gave a print to quote. I'm not sure if it is their typical first job for a new shop.

The material is a chromed cylinder rod. Only 2 parts are needed and it will be customer supplied material.

I need to turn a thread one end (same basic dia. as starting size), flip and cut a smaller thread on the second end. The clamping area cannot be damaged due to it being a sealing surface for a hydraulic cylinder. I have a s-26 collet head, with the proper sized smooth collet pads.

Questions
1.How difficult is it to cut thru the chrome?
2.What manufacturer/grade of insert works well?
3.Any tips?

Thanks
Rosie
 
i've cut the stuff with no problems, the chrome is probably less than .001 thk. just use the same inserts you use for cutting steel. should be no problem.
 
Okay, maybe this is a dumb question considering I'm a newb.

Why would you chrome plate it before all the machining is done?

Wouldn't you want to chrome it after the threads, etc, are all done? Is there something about chroming the threads that makes them weaker or something? Or will the chrome flake off the threads under load?

Thanks,
Michael
 
Radius,
Chromed rod is a production item just like any other bar stock. For for common sized rods, it would cost more to plate an individual rod after completion than it costs to buy the chromed rod and make the part. The chrome is there to provide a hard, smooth, rust free surface for the rod seal and wiper to slide on, and would serve no purpose on any of the machined areas on the rod.

That being said, you will find some rods from high volume cylinder manufacturers are chromed all over. Those folks would be doing their own grinding, etc in house, and producing dimensions with a plating allowance. For them, its cheaper to plate the finished product than to use plated rod.

Rosie,
The major diameter of any thread will be a few thousandths less than nominal, so all the plating on the threaded area will be removed anyway. As mentioned above, it'll cut right off without problem. The most common chromed rod material is 1045. BUT, its commonly available in both standard and induction hardened varieties. Watch the print or verify with the customer that they're not supplying induction hardened material, because cutting a nominal diameter thread on that stuff can be a real bear.
 
Metlmuchr,
thanks for the heads up on the hardened material possibility.

Old Bill,
I wouldn't have thought of the flaking.

The job has already been sent out to another shop. Which I'm a little happy about. Right now I'm swamped, so I don't want to screw something up with a potentially good customer. I told them I'd like to tour their shop, and get some sample material to practice on for future work.

Rosie
 
Metlmuchr is right on. I work for a company that grinds and chromes bar in long length so I can share a little bit of what I know.

Material grades. The typical grade for chrome rod is 1045/1050. The bar can be supplied as hot finished material with a 75k yield strength or as cold drawn with a 100k yield strength, this option is also know as fatigue proof or stress proof depending on the supplier. Another grade out there is SW85 or SW115 this are both proprietary grades supplied by my company they have better mechanical properties than 1045 but the material is a little bit gummier for machining purposes.

The typical induction hardening of chrome rod is 50HRC at a depth of 0.050" Typically the hardened layer can be peeled off with ceramics.

The chrome should not flake. If is flaking it is a sign of a bad chrome job, yes I know this from experience.

As far as not damaging the chrome try leaving the bar in the cardboard sleeve. We actually use a higher density cardboard for this reason.

Any questions let me know.
Tim
 
I machined new rods for hydraulic rams very frequently at my previous job and I honestly can't say I ever had a problem with flaking chrome. I'd agree with TimD that flaking would be indicative of poor plating. If you have to turn diameters that don't break through the chrome use ceramic, otherwise a good negative insert will work fine. Also as TimD stated the material tends to be gummier, so you need to keep your surface speeds up to get a constant finish.
In order to not damage the chrome, just wrap a few layers of paper around the bar where you're going to chuck it. You can usually hold a pretty good runout with this method.
 
I also have done my share of chromed rod. Negative insert (ceramics work well) and get under the chrome and get after it with a heavy feed. If it's flakeing, it's a crap chrome job. I "Have" had to fix flaked chrome by feathering it with a tool post grinder. What a pain in the butt.
 
the difficulty not in the chrome layer , the difficulty is that they do induction hardening for the rods before plating the rod with chrome , so under the chrome layer u will find so hard layer of steel maybe reach to 60 HRC ,
so u can try to take first depth of cut more than the hard layers thickness . maybe it will help u to cut it with the least cost and insert wear
 








 
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