Thread: Milling feed rates

How many teeth in the slitting saw.
Your feed for the End mill depending on teeth would be from 3"/min to 6"/min at 120RPM,based on 4 to 6 teeth.
At 160 RPM 4"/min to 8"/min based on 4 to 6 teeth.

Slitting saw has 34 teeth and is 4 inch diameter.

My 2inch end mill is a 6 flute and I was feeding it at 6 inch per minute.

I however came up with a speed of 90rpm using the spindle speed calculator I found online, and a figure of 90 surface feet per minute for mild steel.

Brendan

With your slitting saw it should be around 6" to 8"/min at between 60/80 RPM.

I came up with 18 by using the following formulae

Spindle Speed
4 (constant) x 90 feet per min / 4 (cutter diameter)
= 90rpm

(formula from wikipedia feeds and speeds page)

Then feed
RPM x Teeth X Feed Per Tooth
90 x 34 x .006
= 18.36 inches per minute

Brendan,

Coolant is your friend. The aim of course is to dissipate heat from the tool by getting the chips to remove properly without clogging and bluing. I bought some soluble oil and mixed it with water, applying it to the cutter regularly with a small brush. If the chips coming off are blue, you can slow your cutter down to give the teeth time to remove the steel instead of reducing feed (Unless the speed is excessive too). Slowing the cutter is also recommended when you get chatter on a bit your turning.

That chart I gave you will save you a lot of tools, especially in breakages.
If you were in Melbourne I would have recommended to have you come over and try some stuff at my place. Maybe someone in Canberra could give you a few minutes as you seem to want to get this stuff all right in your head. It's hard to do it well on forums.

/Michael

Is the .006" a reccomended feed/tooth for your slitting saw or is it a feed rate for another type of cutter.

You could buy some soluble oil and put a bit in one of them spray bottle and mix it until you get your coolant set up. You will probably find the chips you are getting that are tan would be steel colour when you are flooding it with coolant. Wd40 works alright but it doesnt work as well as soluble oil.

.006" seems a bit heavy to me I would be using around .002 to .004 chip thickness for steel with hss

.006 was the figure I dug up off the net somewhere, in some ambiguous site. It wasnt explained well at all on said site, and was what precipitated me putting this post up in the first place. The chart that was posted earlier on has heaps more info in it (which is fabulous) but there doesnt seem to be a column for slitting saws. Why would .006 be too agressive for a slitting saw yet fine for a 2 inch end mill with 6 teeth?

Re coolant, my mill (the old horizontal thing) has a massive resevoir in the base for oil. It seems the same oil is used to lubricate the machine. It still has all the plumbing for pumping this oil out of the resevoir and up to the table, but the pump has been knocked off at some point. The switch gear is still there though.

One of the jobs I will do soon is to change this oil, as its very rusty in colour. Then i'll replace the pump. The resevoir is huge, I imagine there would be a couple of hundred litres in there for sure. What sort of oil do you reckon goes in there? Would it be one of those shell lubricool oils or equivalent?

Brendan,

Sounds strange to me (Not knowing your machine type) that they would use the coolant oil system to lubricate the machine too. Swarf would be a huge problem.

Tell me about it...there is a shyteload of swarf in the resevoir.

Its kind of hard to tell whats going on, but I did capture some falling lubrication oil and its the same stuff as whats in the bottom, same rusty colour. From the shape of the machine I assumed they were both coming from the same source but I may be wrong. I'll investigate and let you know.

Originally Posted by 19brendan81

.006 was the figure I dug up off the net somewhere, in some ambiguous site. It wasnt explained well at all on said site, and was what precipitated me putting this post up in the first place. The chart that was posted earlier on has heaps more info in it (which is fabulous) but there doesnt seem to be a column for slitting saws. Why would .006 be too agressive for a slitting saw yet fine for a 2 inch end mill with 6 teeth?

Depth of cut has alot to do with chip color. I'd guess .006 was a little heavy also, but if you are taking a shallow cut it would be fine. My ref says doubling the F number is fine for shallow cuts "as long as the surface finish is acceptable".

Originally Posted by 19brendan81

Re coolant, my mill (the old horizontal thing) has a massive resevoir in the base for oil. It seems the same oil is used to lubricate the machine. It still has all the plumbing for pumping this oil out of the resevoir and up to the table, but the pump has been knocked off at some point. The switch gear is still there though.

Its common to have the coolant reservoir in the base of the machine but like seafurymike I doubt its for lubricate. All the mills I have seen are total waste lubricated, the lubricate will end up in the coolant reservoir but it isn't reused.

Stuart

"the lubricate will end up in the coolant reservoir but it isn't reused."

F*ck a duck. I really need to find out whats going on there before I use the mill more....it would be a disaster if I ran the lubricant resevoir dry whilst using the machine!

I have old TAFE texts here for milling. It's got some ballpark chip per tooth numbers on a chart here:
On Steel (in mm)

End Mill HSS 0.03 - 0.15
Slitting Saw HSS 0.012 - 0.042

Brendan what makes you think the Sump at the base of the Mill is for Lubrication.

This switch gear you reffer to is it an ON/OFF.

Also if that Sump is for Lubrication there would be,if it was original more than likely Copper tubing running from a metering block either next to or in close proximity of the Pump.

These lines would run to various parts of the Mill distributing oil at different rates.

Have you checked the substance in the sump of the Mill to determine if it maybe Solubile Oil.

In regards to the Question re Feed Rate Slitting Saw/End Mill,it has to do with the Ridgidity of the Cutter.

Slitting is generally done at a Slower feed rate than other Milling opperations and quite often done Climb Milling.