When I cut steel with HSS end mill I apply some cutting oil with brush while
Oil is smoking but chips are not blue. My speed is at the top range of the right
for a given cutter diameter. Should I lower the speed or it's OK?
I think one needs to look at the whole question of cutting fluids and
their usage before giving any definitive answer.
For example on high speed auto cnc machines the cutting fluid does
1. keep the cutting tool and work piece cool. this is important so that
dimensional accuracy is maintained.
2. Swarf flushing from the work face
3. reduction of wear of the cutting tool. Especially important if your
making thousands of the same item.
there will be others who will comment with other observations.
It really depends on the job in hand and wether you dont mind cleaning
Try a soluable oil ie one that loks like milk when mixed with water.
Use plenty and you may find it wont burn up like the oil your using
Sounds to me like you have it fairly well dialed in. Colored chips are a
sign of running too fast. A slight yellowing is about as hot as you can go
without sacrificing cutter life if you're running HSS cutters. You can
expect the oil to smoke, there's a lot of heat dissipated when machining
steels. Keep using the oil, it prolongs cutter life and improves surface
I use oil..high sulphur cutting oil for several reasons:
1. Works Great!
2. Keeps my machines from rusting. Important because my shop is only
partally enclosed (converted car port) and is unheated in the winter
time. Plus fog does on occasion blows in.
3. Keeps the machines lubricated.
4. Smoke isnt an issue in a partially enclosed shop. If bad..I simply
turn on a fan
5. Mostly dirt floor..so the oil splash, if I have any..simply packs the
floor down better
6. I get it for free in large quantities.
I dont like toilet water (water based coolants) because in my job as a
paid, independant machine tool repair guy..I have to deal with machines
that have been running toilet water, and a fair amount of my business
comes from repairing the damage caused by poorly maintained water based
collants. And I want my machines to last as long as possible.
The downside..is that because its a partially enclosed shop with a
mostly dirt floor..dust is an issue. Particularly when it lands on oil
So I make it an ALWAYS point to wipe down all sliding surfaces before
operating a machine too, else the dust/oil mix makes a fair grinding
"Deep in her heart, every moslem woman yearns to show us her tits"
All depends on the material and how fast. Carbide is intended to be run
fast, but it, too, can be run too fast. If you see any signs of sparks
coming off the cut, you're running too fast. If you run carbide too
slowly, you risk breaking it. Be careful about your cutting tool choices
if you have a light duty machine. You may find you're better off with
HSS-------or not. Experience will teach you what works best for your
particular setup-----and that usually comes by making a few mistakes. Try
to remember what you do and how you do it so you don't repeat bad decisions.
Do remember that blue chips off HSS is a mistake if you want tool
life----and bright, silvery chips are probably a sign of too slow with
carbide. Depth of cut and feed rate make a huge difference in cutting
temperature, so it's not smart to lay down hard, fast rules. Too many
variables. It's never a mistake to lubricate a cut as long as you don't
experience thermal shock.