Feedrate trouble

[cleverson]

Is possible change spindle speed without feed rate get down on EMC2 ?

[Zig]

Spindle speed and feed rate are linked to the kind of material you are machining and the amount of material the cutting tool can remove per spindle revolution.

It is possible to increase feed rate only if you increase the spindle speed ( assuming material and tool remain the same).

The penalty for this is that tool life will be reduced quicker at higher spindle speed ( quicker = shorter overalltotal cutting length ).

[TDA]

Originally Posted by cleverson Is possible change spindle speed without feed rate get down on EMC2 ?

I'm not sure what you mean by "without feed rate get down". However, depending on your cnc you should have control of spindle RPM through one of the following, VFD, the router/spindle, EMC2, or gcode. Without knowing your setup it is impossible to tell you how to change your spindle speed.

Originally Posted by Zig Spindle speed and feed rate are linked to the kind of material you are machining and the amount of material the cutting tool can remove per spindle revolution.

True, RPM and feed rate need to be matched to the material being cut.

Originally Posted by Zig It is possible to increase feed rate only if you increase the spindle speed ( assuming material and tool remain the same).

I assume you mean if you are already cutting at a good feed and speed. For example if you were feeding too fast then you would want to either slow your feed rate or increase you RPMs separately.

Originally Posted by Zig The penalty for this is that tool life will be reduced quicker at higher spindle speed ( quicker = shorter overalltotal cutting length ).

I either don't understand what you mean or completely disagree with this statement. We have multiple customers that use the same tooling at 60k RPM that get just as much life out of their tooling as people running 20k RPM. Assuming of course that both are using the proper feeds for their RPM.

[kudos]

im not sure what you mean by your question,
can u over ride spindle speed with out feed rate going up or down also

yes, just like any other control

can you alter feed rate override with out spindle speed changed
yes, just like the above.

the only time the above is not true is when in a spindle synced mode, EG Constant surface speed.
or feed per rev mode. as then the axis have to obay set rules to the spindle etc.

rob

[Zig]

Hello John,

Let me just reaffirm my belief that excessive speed will diminish life of the tool.

Do you have any reports of comparative analysis of RPM versus total usable cut legth against some parameter ( a quality of finished edges of the cut or surface finish of the cut).

[acondit]

Originally Posted by Zig Hello John, Let me just reaffirm my belief that excessive speed will diminish life of the tool. Do you have any reports of comparative analysis of RPM versus total usable cut legth against some parameter ( a quality of finished edges of the cut or surface finish of the cut).

Zig,

I think that you are right with regard to excessive speed.

However, what constitutes excessive speed is where the rub comes in. If I am using plain HSS excessive speed is much lower than if I am using using carbide tooling and some coatings allow a tool to cut much faster than an uncoated tool (depending on the material being cut). So what excessive speed is, seems to me to be relative to the rigidity and power of the machine, the material of the tooling, the material being cut and whether it is being cut wet or dry (maybe even some other things that I haven't mentioned).

Alan

[Zig]

Alan,

Yes that is indded the point.

My experience is limited to working with PCB laminates.

The laminates come in a variety of toughness grades. The common garden variety FR4 is rated to be cut at 150 m/min. This is not the linear infeed rate this is the equivalent, if I can put it that way, rate at which the material can be removed by the cutting edge.
Various other materials are ment to be removed at other rates.

For example non ferrous metals, prepreg,Teflon, Aramid, Polyimide,high glass transition temperature FR4 are best cut at 100m/min whereas other materials will go up to 250m/min.

Excessive speed for the same bit will vary across this range of materials.

[cleverson]

Originally Posted by kudos im not sure what you mean by your question, can u over ride spindle speed with out feed rate going up or down also yes, just like any other control can you alter feed rate override with out spindle speed changed yes, just like the above. the only time the above is not true is when in a spindle synced mode, EG Constant surface speed. or feed per rev mode. as then the axis have to obay set rules to the spindle etc. rob

First, tank you for help me and forgive if my english is not very good.

what i want is to change spindle speed without the motion axes decelerate and accelerate every time i make it.