Spindle Draw Bar force gauge & testing equipment Dynamometer
Draw bar force gauge or Dynamometer is used to measure tool clamp force of spindles. Including 30,40,50 taper machines and many other types of spindles.
Indications of low spindle drawbar clamp force include
Machine problems that can cause low spindle tool clamp force
- Broken belleville washers or springs on the drawbar
- Coolant or debris contamination causing excessive friction
- Tool retention fingers worn
- Spindle taper has been reground causing tool to sit deeper in spindle
- Draw bar shaft worn from belleville rubbing on the main shaft
- Retention knobs of tools worn
What kind of damage can low spindle clamp force cause?
Damage to spindle-must be replaced
Damage to machine and waycovers when the tool lets loose or the retention knob fatigues and breaks.
Injury to an operator!! That tool holder can many times find a hole around a pallet changer and go through to the setup station or go through a window.
Damage just about anything when that tool is spinning at 10,000 plus RPM.
Types of Spindle clamp force gauges
There are basically two types. One has a digital display and the other uses a pressure gauge. The digital clamp force gage is more accurate but generally costs anywhere from $3000-4000 for a CAT 40/50 setup. The clamp force gauge using a pressure gage is generally within 30-50psi of the true reading and costs much less typically around $1000. The accuracy of a digital gauge is not really needed as a typical 40 taper spindle is usually around 1800-2300psi. A 40 taper machine will start to show symptoms of low drawbar force generally around 1200-1300 depending on types of jobs run. Also when maintenance guys work on a machine sometimes the gage fall out of the spindke either by manually unclamping the spindle, accidentally activating a switch or for some other reason. The digital gauge seems like it will not hold up as well to this abuse. Typically this is an accident but it happens to the best of us.