speed -- part off tools

[apprentice]

Hello,

 

What is the best speed for part off tools (carbide -- Material: 01)? I found when i have 370 rpm the workpiece is hot and when I further reduecd it and the cutter borke (disregard I have constant coolant on). Please help.

[crazy^millman]

Sounds to me like you are too slow to be honest. I would think between 115 to 165 sfm would work quite well may even be low. That is surface speed not rpm. The reason the tool broke is what so many do not realize when cutting any metal if you are to slow of the rpm to the feed you being to rub more than you cut. The idea shows itself very well in postive type cutters. In postive type cutter the cutter is just like a shovel removing metal. The idea is that you remove all the heat in the chip as well as the stress thus you do not effect the part or the cutting tool becuase all the stres ans heat is in the chip. Now with parting this is very hard beaucse most time the chip has no where to go. I have done what I call peck parting real easy on most cnc and their automated cycels but if doing ti conventional you have to just think about going say .05 deep then let off the pressure then go .05 and so forth paying close attention as you get clode to the center. Now here in this become part of your problem the smaller the area you are cutting gets the more you are rubbing verse cutting becuase you do not maintian the rpms unless yo are using constant surface speed and anyone who has run a CNC lathe knows this when it ramps up the spinlde as you closer to the center. This is the problem the faster it is parting off the more likely it is to bing bang boom around inside the machine. No good for many reasons and yes I have broke more than one piece of glass. O1 is tough but look at doubling your rpms and try doing it with steps if by hand but ot be honest I always feed the transverse cross slide when parting off elimates any backlash and will 99% time not break the tip unless it is a bad set-up or not enough rpms or is way to much rpms. Oh yeah always like oil better for parting off O1 if done conventional.

 

HTH

[Mike Whitten CAD/CAM Contractors]

apprentice,

 

If you give us a little more Info, we can give a better answer.

 

-Material size (type is -01 tool steel correct?)

-machine type

-Exactly what type of tool

-proto or production

 

There are many variables. There are very good turning people here and they could pin it down for you with the proper data.

 

HTH

Thanks,

Mike

[Mike Whitten CAD/CAM Contractors]

Oops Ron, I posted before yours came up.

 

Mike

[crazy^millman]

No problem all trying to help.

 

[apprentice]

Hello, Michael,

 

Sorry for not being specific.

 

Cutter: Saw Man .125" wide

Dia. of Material: 1.25"

Material: Tool steel 01

Machine: Hass

Type of work: prototype

 

Thank you for your help.

[apprentice]

Hello, everybody,

 

More questions: (1) what is the speed recommanded for part-off? 1/3 of turning ?? Please advice. It is very embarrasing to have two tools broke to make two pieces. Absolutely don't look good!

 

(2) how do I avoide the rough machining mark on the surface where got part-off (this is Mass Production job)? Do I need to touch up the part-off tool before I use it??

[crazy^millman]

Again sound way to slow. I would think you would need closer to 1200 rpm for this Material. The roughness comes from the tearing and not cutting no the material. Should be able ot get away with .0025 to .003 per rev if you do not have the blade sticking out way to far. I would only hang the blade out about .05 longer than you need to hit the holder and that is it. The long it sticks out the more problems you are going to have. Might also make sure you got the spindle going the correct direction. I have seen it where if the the is upside down people get consfused as to the correct spindle direction so look in there being very careful of course that you have it spinning the correct way. Speed kills and not enough speed kills soemtimes worse than to much.

 

HTH

[mrainey]

Make sure your tool is perfectly on center. If not, can rub and break.

[dan m]

I normally run about 200 sfm and .002 ipr in M2. I don’t know if that helps or not. I also would peck the tool like Ron suggested. I usually give it a peck distance = to the width of the tool.

[jeff]

Also make sure that your coolant is flooding the heck out of the GROOVE.

Not familiar with saw man cutters,but we use Iscar and probably would run it around 400 sfpm.

start at 1220 rpm and go faster when you get closer to center.

[apprentice]

Thank you so much, guys. I played around today and the speed I used was too slow. Feel like sending you guys cakes for helping me out!

[DavidB]

If you use a nuetral part off tip correct you will get a nipple on your part.But you can get left and right hand part off inserts so there is no nipple left on either part or stock.

 

CCS is a must for parting