Toll Cutting???

Burnsst · Oct 2, 2019

About 10 years ago, we were making heat exchangers by sintering tiny copper rods inside a cylindrical shell. I remember asking the engineer in charge of procuring the copper rods about where they were coming from and he said that he bought them from a shop that was using a process called "toll cutting" to produce them. The copper rods were about 0.050" in diameter and maybe 0.100" long. Looking at them under magnification, the ends were very flat. The process was quite cheap and fast I think since we were buying the rods in 10 pound lots.

My question is, does anyone know what toll cutting is and/or where I can find a shop that does this type of machining? Thanks for reading.

gbent · Oct 2, 2019

Toll in this case probably means "fee", like a toll road. So much per piece for supplied material.

Milland · Oct 2, 2019

Never heard of "toll" cutting, except in a traffic situation.

If you need short pins with flat ends (and a lot of them) I'd contact the guys who do rivet-like fasteners, they should be able to set up an upsetting machine to make rod segments from wire coils. Some bucks for the dies, but after that costs should be very low.

If you don't need dead-flat ends then some slicer setup could be home brewed. Maybe a wire feeder, stop, and industrial razor blade on an eccentric.

crossthread · Oct 3, 2019

"Toll Processing, also known as toll manufacturing, is defined as a company with specialized equipment processing raw material or semi-finished goods for another company."

EPAIII · Oct 3, 2019

Copper, 0.05" diameter and 0.10" long? If you cut them from wire stock, there is going to be a lot of waste, perhaps over 50%. And copper can be expensive.

I would consider using wire stock that is just a bit under the diameter and cutting it into lengths that are a bit long with some kind of wire cutters or shear. Then using a dedicated die to press them to the final size. Zero waste and the dimensions can be tightly controlled. They are small and require only a small amount of force, so a multiple die could be made to produce a dozen or two at one pressing. With a proper ejection mechanism, it could go fast.

Robert R · Oct 3, 2019

Burnsst said:
Looking at them under magnification, the ends were very flat. The process was quite cheap and fast I think since we were buying the rods in 10 pound lots.
My question is, does anyone know what toll cutting is and/or where I can find a shop that does this type of machining? Thanks for reading.

The machine you are looking for is a impact shear. This is a machine that uses two die blocks to shear the rod. The shear will produce square cuts at several hundred parts/minute for small bar diameters.
This is the process that is used to produce the steel slugs from coiled bar stock that will be roll forged into ball bearings.

There are companies that will do this on a toll basis. You may need to pay for a custom pair of dies. Try searching the industrial directories or internet using the phrase " impact shear bar services"

For example, in Los Angeles there is:
Green's Metal Cut-Off Parts From Metal & Plastic

Burnsst · Oct 4, 2019

Thanks to everyone for the replies! This was my first post to Practical Machinist and I'm happy to receive so many helpful replies. I'll chase these down to see what will work best for this new application.

Milland · Oct 4, 2019

Let us know what you wind up with.

Burnsst · Oct 8, 2019

I think the shearing process is probably what we were using. I passed the information along to my colleague who had asked me about how to make rods like this.

Best,

Sean

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