Cutting steel

[rtunison]

A slo-mo video of steel being cut on a lathe.

http://www.wimp.com/cuttingsteel/

 

[digger]

Richard T.
I think he's showing the tool more than anything else.
I'm no metallurgist by any means, but he ain't cutting steel from this planet. It's to fuzzy on top.LOL

 

[thoffman]

That's almost like porn!

 

[aschumacher]

Tom, I was wondering why I kinda liked it !

 

[dfrisk]

THAT is pretty darned interesting. Did everyone notice the build-up of metal at the cutting edge of the insert? And what happened when the build-up started getting bigger? The build-up made the cut deeper, then when it slipped away you imbedded a bit into the surface of the cut.

When you perform cutting operations that have to be "Smooth" you have to add secondary finishing operations to really get the surface smooth, as well as a couple passes with slower feeds & speeds, starting with a rough cut, semi-finish cut, then finish cut, and then probably grinding & polishing to get a smooth surface. And the type and style of cutting insert all effect the finish of the cut too. The Titanium Nitride coated inserts made a lot nicer cut, smoother surface on the piece.

I was actually surprised the SS material had as nice of cut as it did. Normally it machines up fairly rough.

 

[jchamberlin]

The metal seemed more like cheese in the photographs.

Denny, I did notice the buildup on the cutting edge.

I'm not sure that "cutting" adequately describes what I was seeing in the video; "whacking, hacking, and making a mess of the piece of stock" would seem more accurate.

I would be curious to see if changing speeds affected some of the cuts.

 

[aschumacher]

If one considers the position of a cutting bit on a metal lathe and the actual cutting angle, I supposed they could have been making plywood laminates, or if in Wisconsin, different way of slicing cheese! <font size="-2">As J.C. suggested.</font>

 

[dfrisk]

Jeremiah - A VERY Smart Quality Manager at one company I worked for told me one day, "All metal is RUBBER, You put enough force on it and it ALL moves!". We were talking about HUGE cast iron castings for machine tools, machine tables, beds, head stocks, etc. They had a Coordinate measuring machine right outside our door that was large enough to park my F250 pickup on and measure every dimension with to +/- .00002" accuracy.

When you get into the finer points of machining, there's pretty well established tables for proper speeds & feeds for turning, drilling, milling, etc. You can run slower with just extended times for the task at hand, but running faster normally burns up the tool. On today's cutting inserts used for turning metal the edges are not sharp. So I expect speeds & feeds wouldn't effect the chip much. The idea is that most of the heat is supposed to be removed with the chip, the work piece is supposed to stay cool, or at least cooler. Lubricant helps a LOT to keep things cool.

Takes a LOT of horse-power to take big cuts. Company I used to send a LOT of work to had a big lathe, could turn 30 feet between centers up to 5-6 FEET in diameter, and there was a Bigger lathe in town too, but I didn't send as much work there. The company bought a piece of old propeller shafting salvaged from a scrapped ocean going freight ship. They turned the diameter down about a foot one Saturday. They had LOTS of HP in that lathe, they were taking a cut with a 3/4" or 1" square insert, cut was about 1/2" deep at a 45 degree angle, and the feed was pretty good too, probably about .050" per revolution. The chips were close to 1/8th inch thick, almost an inch long and an inch wide. The lathe operator was pushing a wheel barrow along the bed of the lathe to catch the chips as they came off the cutting tool. It saved them time from just letting them fall into the bed of the lathe. I've since bought finished parts that were much smaller than those chips were!

Most companies want the chips to break up into small pieces. Some materials, like normalized alloy steel sometimes produce long stringy chips, which form rats nests around the cutting tool. If that happens on a CNC turning center with a tool changer it fouls the tool holder and the machine will probably drop the tool. I had a manufacturing engineer, a VERY GOOD one, bring me a little "Project". "This suppliers 304 SS castings are, "Good", (he dropped a handful of small broken-up chips on my desk), This suppliers castings are BAD..(places a rat's nest of ONE stringy chip dozens of feet long on my desk), Now get So-in-So to make their castings like the OTHER Guy!" Turned out the last operation on 304 SS castings is "Solution Annealing", similar to a quench & temper on a steel casting, the heat-treater for the supplier of the rat's nest casting wasn't holding the parts at the temp necessary to convert all the carbides in the metal long enough.

When I was at FARMALL, they machined tons of gray iron castings every day. It's real easy to machine, the chips are always small and break up really fine. Cuts like butter. But it's filthy because of all the carbon in the metal. Even though steel is much tougher I like machining it much better because it's clean.

 

[jchamberlin]

Dennis: Metal does have special properties. I remember coming away from a chemistry class I took at the local community college with the conclusion that as hard as metals appear, they really are more comfortable as liquids. (Think "Terminator") It all has to do with their molecular structure and the nature of their chemical bonds. I remember being quite impressed by the unique properties of those group of elements we call "metals."

Thank you too, for the wonderful descriptions of the huge metal lathe and working "dirty" cast iron. You rival "Hydro Harry" Bursell with the way you can communicate images with words. It is no mean feat, I can tell you!