Tool stops cnc lathe

[Skuteris]

Hi everybody, i know i will get some negativity about this but here we go, i have a cnc lathe (well its china made lathe to be honest) it is ck6136 lathe. Guys i am from europe so i will write in milimeters so dont get angry the problem is not i am working on kinda big thing in diameter (162mm) basicly i am making dies for tube bender, and the problem i have i cannot cut into material i am using S100m/min speed and the F0.1mm/rev thats for feed rate and the tool is OD grooving tool with straight nose the width is 3mm and when the tool touches the material it basicly stops the lathe i can see the chip forming nicely but it stops, the rpm on lathe is around 200rpm, what could be the fault of this, or it is because it is china lathe? The lathe does not a gearbox it is just straight belt from spindle to motor. When the lathe stops and i break a chip with hand or pliers i can spin chuck anti clock wise and then with some force i can move it over that place where the chip ended.
I can reduce feed rate but then lathe starts to chatter, i can see chatter on the thing i am spinning. Almost forgot the material i am working with is C45 steel.
The second question is: is there any way to check power on motor if it is making good power ? How do you check motors ? The motor is kinda very large.

 

[David Ferguson]

So you are feeding in, and the depth of cut should be 0.1mm. Has the stock been rough turned so that it is round? Do you start your feed in free air, so that the depth of cut is no more than 0.1 if the stock isn't round?

How much horsepower does your lathe have?

 

[Overland]

Maybe your lathe has a VFD drive (inverter), so at just 200 rpm, you may have very low torque available.
Maybe you can see the frequency your drive is delivering to the motor. If this is low, like 10 to 15 Hz, you'll have very low torque. I believe "normal" frequency in Europe is 50 Hz.
Bob

 

[Skuteris]

So you are feeding in, and the depth of cut should be 0.1mm. Has the stock been rough turned so that it is round? Do you start your feed in free air, so that the depth of cut is no more than 0.1 if the stock isn't round?

How much horsepower does your lathe have?

Yeah i machined outside diameter no problem it is round, yes i do start in free air and it slowly comes in contact and then when it touches it just stops the spindle.The depth of cut is 0.1mm/per the piece is round and it wont even make it around one turn.

 

[Skuteris]

Maybe your lathe has a VFD drive (inverter), so at just 200 rpm, you may have very low torque available.
Maybe you can see the frequency your drive is delivering to the motor. If this is low, like 10 to 15 Hz, you'll have very low torque. I believe "normal" frequency in Europe is 50 Hz.
Bob

It might be a case, it does have a inverter for the motor. How do i check what Hz it is running ? Or it just says on the inverter? And if that is the case what are my options to have more torque on low rpms ?

 

[memphisjed]

If you can change up belt pulleys (bigger on spindle, smaller on motor). Or gear head the motor. Or add step pulleys, same idea as first concept.

The inverter will have on its display options hz.

 

[sinha]

What is depth of cut?
Why not use a diamond or a triangular tool?

 

[Mtndew]

The lathe does not a gearbox it is just straight belt from spindle to motor.

Is the belt tight?

 

[rick-b]

Check the inverter, I had trouble with mine when I got it.

 

[Overland]

If its a direct drive from motor to spindle, with just an inverter, then get the speed range of the lathe, and the speed range of the motor and compare them.
That way you can estimate the speed of the motor at 200 lathe rpm, therefore the Hz, and then have an idea if your problem is low motor speed, and therefore low torque.
If this is the case you can change out some pulleys to get more torque at lower speeds, or maybe change your tooling to run a higher cutting speeds and therefore higher rpm.
Bob