Thread: Annular cutters - better coolant delivery setup needed

I do a few small runs of parts for a mate’s fabrication business, and they involve lots of hole drilling with annular cutters on the mill.

I’m running straight mineral oil as a flood delivery cutting fluid as it gives awesome tool life with HSS cutters, but the issue I have is the long swarf from the annular cutters keeps grabbing the nozzle/hose and throwing it out of the way. I end up holding it in place

With the oil being more viscous I can’t move the nozzle back and just hose it on from a distance like you could with normal water based coolant, so thinking some sort of a solid delivery nozzle or going to a through-coolant style holder.

I don’t want to go to a water based coolant as the knee lube oil tends to get into the coolant sump and grow snot, plus the mill can sit unused for a few weeks at times - with the usual rust issues from water based ones.

Any suggestions?

Steve

Lift the cutter to break the chip.

Use something like WD-40 in a spray bottle (with the nozzle set to a stream) so you can apply from a distance. Breaking the chips as Peter said would probably help too.
A straight mineral oil would not really be acting as a coolant, more as a lubricant. Lubricant is still good, but if you are after a cooling action you need something that will either evaporate or take heat away as it passes by the parts and I doubt you are getting (much) of that happening.

Michael

You’re correct Michael - it’s more the lube that I’m after rather than just cooling.
There’s definitely still a decent amount of cooling from the oil though - as soon as the cutter isn’t flooded it starts to smoke.

Ive tried a few different fluids but come to the conclusion that it needs to be flooded to get the best cutter life. The $20 18mm cutter from M&G that I’m using now would have done at least 400 holes - and still cutting well. Prior to the flood oil, by about 200 holes they were definitely starting to dull and went blunt very quickly from there.
I’m happy with the flood oil - really just need a more solid delivery method.

I’m already breaking the chip regularly but due to its geometry - until the cutter is engaged to full diameter it tends to send the swarf out almost horizontally.
That’s when I’m having the most problem with the nozzle getting grabbed. The material is mostly 4mm SHS, ie lots of shallow holes so theres a lot of time spent hole starting at less than full diameter.

If anyone has experience with the through-coolant arbors I’d be interested to know what size orifice they have in them.
I’d be keen to try one, but no point wasting money on one if the holes are too small to pump the oil through.
Another option I’ve been thinking about is something like a copper tube flattened at the end for a nozzle and mounted solidly to a base of some form. The swarf isn’t particularly thick, so as long as the nozzle is solid enough to cope with light whipping it might work. The flattened end should help to get a bit more reach.

Steve

Oil lines in lub systems are around 1/8" diameter, so I don't think pumping will be a problem unless you are chasing high flow; then it's just a bigger pump.

Michael