There seem to be a fair few engineers on here and google hasn't helped. Got a short test coming up and there's a bit of disagreement on this question.
When using a lathe around 80% of the heat produced by cutting is dissipated into:
a) the swarf
b) the cutting tool
c) the material being worked on
My hunch is that it's the swarf...
As usual, uninformed opinions and flaming are more than welcome.
The air
Coolant (emulsified oil)
my hunch is the cutting tool - no practical experiance to back that up though just a imo educated guess 
the cutting tool. Although if you look at my user name it might contain a clue as to my competence .....
the cutting tool, the material being cut is moving across the tip of the tool, therefore the only single point to be heated constantly is the tip of the tool.
i could be wrong like.
Cutting tool, but will vary on material (being cut and tool), depth of cut, speed, angle of tool, profile of tool, type of cutting fluid being used and so on.
I think you'll find that the correct engineering response is
d) it depends.
My argument would be initially the cutting tool. All frictional heat will be generated at the tool tip as the material being worked on is constantly moving away from the cut face. Then, the coolant must remove the heat from the cutting tool or it would heat up and begin to deform.
Been a few years since I used a lathe mind....
80 % does seem quite a large proportion of the heat
kevj - isnt that why you use cutting fluid/coolant ?
trail_rat - Memberkevj - isnt that why you use cutting fluid/coolant ?
Yes, my error, post edited 
typically the swarf.
'Depends' is the correct answer, far too many variables: material, speed, tool sharpness, size of cut. Also in engineering it doesn't really matter, what is important is what you do about it. Bad question IMHO
I think from memory it is the swarf.
My logic is the cutting tool increases in temp, harder to put more energy into it when it is already at a higher temperature. Swarf gets hot and is removed, reducing the temp of the material, and due to the high surface area of swarf it cools rapidly, so not as noticable (although is does smart!). This removal of the hot swarf reduces the temp of the material, allowing more heat to build up and then be removed by further cutting.
In reality, it will depend on lubrication, cutting speed, materials, cooling of parts, etc etc (usual engineers' response, it depends
General consensus is swarf.
Hang on, I'll go and check...
**** it all get ***** hot.
But I think it may depend on the material be cut.
Thanks for all replies. Managed to find the answer in a handbook in the end. It seems the energy going into deforming the swarf is the most important factor.
So ahwiles and motivforz have got it (in theory at least) - a) the swarf.
The swarf, Ive seen it come off white hot.
I was gonna say the swarf too. Honest.
Motivforz has it. The TEMPERATURE of the tool will be higher probably, but that doesn't mean the most heat has gone into it. The swarf will be taking the heat away all the time where it'll then dissipate pretty quickly. You could do an experiement - cut just a tiny short bit and feel the swarf quick before it cooled down, then feel the tool.
THE CHIP...(or other wise known as swarf),
I can dry cut stainless steel 316 at 6000 rpm taking a 16mm wide cut 8mm deep with just an air blast, all the heat goes into the chip away from the cutting edge and mat'l
Woo! And i don't even have my degree yet. £3000 x 3 years so far, I make that £9000, I'll let you give me half because ahwiles got it too. email in profile
You could do an experiement - cut just a tiny short bit and feel the swarf quick before it cooled down, then feel the tool
Wouldn't really test it, the tool has much larger mass and better conduction to absorb the same heat, so it will always feel cooler. Teh swarf deforms massively so I'd have guessed teh swarf over anything else but it would have been an educated guess rather than knowing.
If I get mine (2 years left) you'll get your share of what my degree costs.
I'm doing it in Sweden so expect a Paypal gift of (2 years x £0)/2 in 2013 
Why isn't there a smiley for the finger?
Some materials are free cutting without the need for any cutting fluid, so that's that option gone!
Ceramic tools won't conduct much heat away at all.
Swarf?
I was trained as a mechanical engineer both an college and EITB and worked as one for many years. I don't recall learning this though.
bit of a badly worded question - the heat will go into the swarf, piece and tool first, and through themn into the coolant.
Makes sense that it's the swarf though, which cools down very quickly IME.
The heat's scoming from friction but also the deformation, and the swarf's the bit tht's being deformed the most.
In my experience the swarf takes ages to cool down when it's flicked down the neck of your polo-shirt......
In my experience the swarf takes ages to cool down when it's flicked down the neck of your polo-shirt......
Or inhaled nasally. When dressing the bottom of some cast iron packers a piece the same size and shape as a fly maggot caster and a deep cherry red with heat flicked up my left nostril. Sadly I'd just exhaled so had to inhale before I could snort it out. This dragged it further up my nose, with a terrifying sizzling sound. Then the pain kicked in. It was days before I could smell anything other than fried hair, snot and flesh.
NOt using enough coolant stumpy?
cynic-al - Member
NOt using enough coolant stumpy?
Coolant's for wimps (and people who know what they're doing!)
This topic has been closed to new replies.
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