First, what's the functional diff between coolant and cutting oil? Does "coolant" just usually denote water soluble oils?
Next, suppose I'm turning a 2" solid round, mild steel, down to, say, 1.5", in multiple passes. I can smear oil on the total surface area, cut, and get a good plume of smoke, presumably indicating that the oil is doing whatever it's sposed to do.
However, the surface is not what's really being cut. It's the face that the lathe tool hits as it travels toward the chuck, the "cutting plane". So smearing oil on the surface, altho it is doing something, is probably not doing all it can do.
Unless somehow the oil is being wick-ed off the surface, onto the cutting plane of the lathe tool.
I can't quite tell if a flux brush brushing oil directly on the cutting plane results in more smoke, which would indicate more effect. For, say, .025-.050 cuts.
Any thoughts on this?
If oil brushed directly on the cutting plane is much much superior to oil initially brushed on the surface area, then that would be more incentive to put recirculating coolant/cutting oil on these manual babies.
If you're running a reasonably sized lathe, the cut you're attempting could be accomplished in one pass, two, tops. That's assuming you're not sticking out more than 3 diameters unsupported. Use negative rake and coarse feed---at least. .010". You'd run this cut dry, or flood coolant. Brush would be impossible, plus you risk thermal fracturing of the cutting edge.
Brush application of oil is very acceptable, assuming you're not running carbide. What's important is to lubricate the point of contact, and the chip flow area, which will minimize chip welding and lower friction, each of which help keep overall temps down.
If you're running HSS and understand chip breaker technology, you can still take that amount of material off in a single pass, but lubrication would be critically important. As you alluded, smearing oil on the surface isn't doing all it can-----and smoke coming from the cut isn't necessarily an indication that the oil is reaching the place it's needed most. You're most likely just over heating the oil that's coming off with the chips.
If you can't run coolant, whether it's water based or oil, keep your brush on the cut, where it will distribute the maximum amount of oil possible. It's actually not a bad way to go, for it minimizes the amount you end up wearing. The one negative is it tends to shorten brush life considerably.
A lot of my turning is on alum (6061), with brazed carbide. Is coolant/cutting fluid still important enough to go through the trouble? I occasionally get welded alum on the tool tip, but it chips off most often, as the cut proceeds. Once in a blue moon I'll have to dig it off. And, what is the diff. between coolant/cutting oil?
HD: shoplifting is so pennyante. However, I have contemplated renting the biggest truck U-haul carries, and backing it up to a HD loading dock. :) Sadly, 1. Gonads are too small, and 2. Ahm deathly afraid of the wife. :) :)
The name. Both features are desirable in what ever is being used. It's a matter of terminology, used interchangeably in most instances, although cutting oil is always a coolant, but a coolant isn't always a cutting oil. There are times when you must use a proper coolant for the task at hand. You're not always free to pick and choose. An example might be where no chlorides are permitted.
In your circumstance, lubrication is critical to avoid chip welding, and is more than adequately provided even by brush. If you allow the chip that welds to chip off, it's only a matter of time until the tip goes with it. Carbide has poor tensile strength, although it's very high in compressive strength. Problem is, the chip will often dislodge itself by sliding, taking the keen edge with it. Chipping it off by hand is an open invitation to taking the tip with the chip. You don't have much worry about thermal shock with what you described. Machining steel is a whole different kettle of fish.
Doesn't stop some folks.
Who, rightfully, would stomp a huge turd out of you! Good for her! :-) You're a lucky man to have a moral wife.
I was in a Dollar Tree store today and while at the checkout stand noticed a blister pack of little batteries. They looked like the size I'd been meaning to buy for my HF calipers and sure 'nuff were the right ones. Eight alkaline batteries for $1. Not bad.
Are you saying that coolant with carbide on alum is as important as coolant while turning steel? But for different reasons? The reasons being that w/ aluminum, the welding will break the tool tip, while for steel, lack of coolant will just prematurely dull it? Other diffs?
And super-religious--go figger. Ahm hangin on to her coat-tails/apron strings, come Judgment Day. Mebbe I'll be able to slip on by.... :)
Depends on the material in question. You can turn Stressproof or 12L14 dry with very good results. By sharp contrast, C1018 machines far better if you can keep it lubricated. 7075-T6 or 2024-T351 aluminum would machine dry far better than would 6061-T6. Almost without exception, you're always better off to provide some lubrication. The problem is intermittent lubrication, whereby you experience thermal shock. I mentioned machining aluminum only because it's virtually impossible to raise the tip temperature to a critical point, unlike machining steel. You can turn the tip red machining steel, hot enough to melt the silver solder that bonds the insert to the shank. Needless to say, you must either have flood cooling, or no cooling when you're dealing with temperatures in that range.
Yeah, I know, my comments border on the extreme, and are not likely, although I have experienced exactly what I described. I've had inserts come unsoldered.
Each suffer the same fate, so I'm not suggesting that one benefits more or less by lubrication----it's a matter of thermal shock. Lack of coolant won't necessarily prematurely dull your tool when machining steel, but if you're running dry and raise the tip temperature excessively, then apply coolant, you risk thermal fracturing. By keeping the cut wet, you lower the cratering on the tool, lowering the chance of chip welding. Friction in the cut is a serious problem---so you almost always benefit by lubrication. You may find there are times when you can slow down surface speed enough to permit using a brush with oil and benefit by a better outcome (steel)------whereas when machining aluminum, I can't think of any reason to slow down. If you can keep the point of contact wet with kerosene (WD-40 works fine, too, as does dirty solvent) speed is a non-issue, at least in my considerable experience.
How much experience do you have on machines? Any formal training, or working under a tutor? It might help to understand where you fit in the scheme of things-----some folks are beginners and are totally lost----others have more experience than I do (although they must be old bastards-----)
Surely, Sir, you jest! The lady is religious and she chose you? My lady is one of the finest people I've ever known. Kind, gentle, almost never utters profanity---yet she chose me-----a guy that has a mouth as vial as yours. Big difference is she's not religious-----so it half makes sense. Does your lady read your comments on RCM? Do you often stand in the corner at her command? :-)
Yeah, in the corner, with her "yer gonna burn in hell f'dat", and occasional mutterings of "666.... 666".
And yeah, we can proly trade wife barbs for quite some time. I proly already observed, in the infamous HD thread, that yours is likely on the list for sainthood.... Etc.... :)
Funny, tho, as a pretty devout Pagan, I *only* get along with religious people! Go figger. And if god forbid I gotta do the marriage thing again, my very first stop will be a pentecostal church. Ahm figgerin, women who can have orgasms rolling around in the aisle are sure to make my life a lot easier.... Next would be the Baptists, cuz they sing real good. Or the 7th Day Adventists, cuz their diet/food is legendary--well-studied in peer-reviewed journals on the health benefits, etc. As a last resort, I might go to Jehovah's Witness Kingdom hall--but these people are a bit of a pita.
Me on a lathe: Been in a machine job shop, can do some shit but it always takes me goddamm forever. No formal training... besides rcm. :) Understand speeds/feeds, but pretty much turn everygoddamm thing at 700 rpm. :)
The point of my previous Qs will be in a new thread, on recirc. coolant on a manual lathe.
Bullshit! I'm anything but religious (agnostic leaning *very* heavily atheistic) and you can get along with me. It's all up to the other guy. I'm willing to get along with anyone-----but they have to share the same feeling. Some folks have an attitude and refuse to get along with anyone----and think it's the other guy's fault.
Ok, you bastard-----in the corner!! :-)
You need experience, and a little tutoring, so you'll understand the benefit of running at the appropriate speed. Most metals have a "sweet spot" where they machine better than above or below that speed. As your confidence increases, you may find yourself using a greater range of speeds------probably feeds, too----especially if you get involved with negative rake and chip breakers. You need good speed and heavy feed for the chip to break, so it often forces your hand. It also helps if you're running an industrially rated machine. Light duty machines are usually incapable of performing.
The idea of taking forever. It's very important to understand the concept of moving metal, Roughing parts is very much a part of proper machining. You crash through the part, staying safely away from finish sizes by somewhere between .040"/.060". That allows you to work quickly, taking heavy cuts, with little regard for size and finish. You can't be stupid--you can still scrap parts if you don't pay attention. The parts can come off hot, because size isn't a factor-----and the roughing operation allows the balance of the material to move about, relaxing internal stresses.. The finish machining normally doesn't further release stresses enough to be a problem, your tools are now not being heavily abused, and are usually different in configuration, going from negative to positive rake, speeds can be increased, feeds decreased--------and the end product turns out a lot nicer than it otherwise may have.
Don't expect to be a machinist without paying the dues. There's a lot to learn, and running the machine properly is a prerequisite to getting it down. You can't learn it from books, or from talking, or from RCM-----but you can get some damned good guidance by all of the above. It's up to you to develop the skills.
In many cases, "good enough is indeed good enough."
If you are getting satisfactory [to you] tool life and surface finish, and are doing prototype work where an extra few minutes per part is meaningless, a cat food can and a solder brush may well be optimal. Although I suggest that a large 2-inch pipe cap with a flat end may be better as it is heavier and less likely to be spilled. FWIW - I have also seen people glue a section of flexible magnet on the bottom of the cat food tin so it would "stick" to the lathe.
In many cases the evaporation [smoke] is cooling the tool. For light cuts and low power, the typical black sulfur oil may be too thick, and you can thin it with varsol/paint [not lacquer] thinner which will also provide additional cooling as it evaporates.
For a very fine finish on aluminum, I have seen some of the magic machinists use a solution of 2 to 4 parts trichloroethylene to 1 part olive oil, which I understand is the old Tap-Magic formula.
You will need a covered container as both varsol and trichloro evaporate easily. Avoid breathing the fumes, but with a little air flow and home shop / hobby use levels you should be fine.
Unka' George ================ When we are planning for posterity, we ought to remember that virtue is not hereditary. Thomas Paine (1737-1809), Anglo-American political theorist, writer. Common Sense, ch. 4 (1776).
Yep! What Unka' George said. If you're not involved in production, a few seconds one way or the other makes little difference. If you're facing a thousand parts, every second trimmed from an operation amounts to some serious time. You have to keep things in perspective. You also use these reasons as a basis for improving your capabilities, even when they're not necessary. It's best to learn to play a piano before scheduling your first concert, eh?
Agreed. I've done that on occasion, but my favorite trick was adding 1,1,1, trichloroethane to the oil. It not only cools better, it improves surface finish in ways that are hard to understand.
Whoa! Careful, Unk. You just posted some deadly advice. Not trichloroethylene, just 1,1,1 trichloroethane. The one you recommended, if memory serves, is used in vapor degreasers. Bad stuff. I could be wrong, at which time I'd stand corrected.
Anyway, you don't use trichloroethane on aluminum----but I agree----the Tap Magic formula, what ever it is---would be great for aluminum-----but remember, they market a special formulation for aluminum, because of what I said, above.
Mr.' I have not scrolled down to read any of the responses yet, because I wanted to write you while the feeling was still strong and say that you just asked a question that has been on my mind since I first came into this trade. Although it's only been a few years. It always seemed to me that the oil smoking was simply some form of evaporation from the heat being generated by the chip. If you look at any close-up shot of a cutting tool in action, the tool is sheering off the chip at a thickness near equal to your depth of cut. I just can't see ant lubricating qualities being put to use hear. Except at the beginning of the cut when the tool is exposed and not in metal to metal contact with the work. As far as coolent goes, I use it every possible time. If you have to take a lot off a piece of steel, using coolant will help tremendously, both in finish and tool life. "Keep The Tool Cool". And now I shall venture below to learn the real answer to this conundrum of ours. Later.
How cutting fluids work was a mystery from day one, as it was not obvious how the cutting fluid got into the zone around the cutting tool tip. But that it did work was obvious, even if nobody knew why.
But research continued.
The effect of the trichloroethane is chemical. The chlorine in the solvent is getting into microcracks (caused by the tool-induced strain) in the metal and chemically reacting with the newly-generated metal surfaces, thus preventing them from welding back together.
This is beaten to death in "Metal Cutting Principles" (by Milton C. Shaw).
chemical compound 1,1,1-trichloroethane is a chlorinated hydrocarbon that was until recently widely used as an industrial solvent. Other names for it include methyl chloroform, chlorothene, and the trade names Solvent 111 and Genklene (used by ICI).
1,1,1-trichloroethane was first produced by the French chemist Henri Victor Regnault in 1840. It was produced in large quantities by the chemical industry beginning in the mid-1950s and continuing through 1995. ==>Today, it is banned by the Montreal Protocol.
========= I have never tried this but a solution of one part caster oil to
3 or 4 parts trichloro would be worth trying on steel or iron. Caster oil is an exceptional high pressure / high temperature lubricant, which is why it was used for many years in racing and aero engines. It also adheres very well to steel/iron.
Anyone tried this? How did it work out? Unka' George ================ When we are planning for posterity, we ought to remember that virtue is not hereditary. Thomas Paine (1737-1809), Anglo-American political theorist, writer. Common Sense, ch. 4 (1776).