The electric spindle is the heart of your machine tool. Correct selection is imperative for optimum machine performance. This guide is to help you to select the most suitable electric spindle for your application.Your choice of electric spindles comes from considering interrelated variables: type of material, cuts, tools, feed rates and spindle speeds. Detailed information is available to calculate these factors, but our guide below may help.

Cooling is an essential part of the designing process of the electrical part (stator). It strongly affects on the spindle performances and duration.

Thanks to the long experience and the tests done on the field, GC spindles are offered in the widest cooling range types available on the market.

RA – Liquid cooling The spindle is connected with a chiller that maintains the correct constant coolant temperature. The flow and the pressure of the coolant (water + glicole) change dependently by the spindle housing cooling circuit dimensions and spindle power.

RC – Compressed air cooling The spindle is connected with a compressor that provides the sufficient air flow to hold the motor at the right temperature. The air flow and pressure (dry compressed air) change dependently by the spindle housing cooling circuit dimensions and spindle power.

RS- Cooling by powered fan The spindle is equipped with a powered fan (V230 or V24) that provides the required air volume to hold the motor at the correct temperature.

RV – Fan cooling The spindle is equipped with a fan directly mounted on the shaft. When the spindle runs the fan, thanks to an apposite room on the back of the housing, provide the correct air amount for the cooling.

Notes: 1. Maintain normal operating TEMPERATURE between 100 and 140 degrees Fahrenheit, measured on the front bearing support. Maintaining this temperature range will help maximize spindle bearing life and avoid premature bearing failure.2. Spindle bearing will sound noisy during warm-up to 100 degrees Fahrenheit until thermal expansion reaches required preload.

GC Electric Spindles are available in either Constant Power or Constant Torque. Both types offer advantages depending upon the operating speed for the cutter(s) used in your application.

- CONSTANT TORQUE electric spindles suit application where maximum cutting power is required near maximum spindle speed. Their torque is constant, so power increases steadily from zero at zero speed to full power at full speed.

- CONSTANT POWER electric spindles provide flexibility for a wider variety of cutting tasks. They deliver more power at mid-range speeds but less power at maximum speed than constant torque spindles. Typical constant power ranges are 9000 – 18000 rpm, 12000 – 18000 rpm or 18000 – 24000 rpm. The selection depends upon the operating speed for the cutter range & material type.

Incorrect spindle speed is a common error in CNC machining. Generally, each material and cuts has an ideal tool profile and cutting speed. Larger diameter tools require slower speeds.

Spindle speed and feed rate for a given cut must be balanced for best work quality, tool life and spindle life.

Speed is controlled by a FREQUENCY INVERTER connected to the electric spindle. All spindles are 3-phase, cycle with infinitely variable speed from 0 to maximum rpm by correctly programming your frequency inverter drive for each spindle.

CLEANING

Keep spindle body, fans and airways clean to allow the cooling system to function correctly.

Keep tool tapers, shafts and collets scrupulously clean.

Collet life is

COOL DOWN

Allow cooling system (fan, compressed air or liquid) and bearing pressurization (if fitted) to run for 10 minutes after stopping work.

This minimizes condensation as well as contaminants being drawn into the bearing supports.

WARM UP

Do not apply load to a cold electric spindle. Run the spindle at 9,000 rpm for 10 minutes or until the spindle bearing supports reach 98 degrees F (human body temperature).

This allows bearings, supports and shaft to reach their designed dimensions. Applying load to a cold spindle will cause premature failure of bearings.

TOOLING

Use only balanced tools and tool holders. Rebalance all tools after each sharpening. Vibration from unbalanced tools can rapidly destroy bearings. The balance standard is 1.0 g (ANSI 1940/1).

Replace any worn, scratched or deformed tool holders and collets with new items to prevent tool slip (heat) and imbalance from run-out.

Keep tools sharp to reduce forces, heat and to maintain cut quality.

Monitor increases in electric current to the spindle to detect loss of tool sharpness.

Heat generated from tools can overheat bearing grease, evaporate its essential components and lessen bearing life. Maximum bearing temperature of bearing supports is 150 degrees F. Excess heat will cause tool holders to jam in automatic tool change spindles. Be sure all spindle sensors operate to avoid damage.

CAUTION: All GC spindles are designed to accept only ISO or HSK tool holders. BT tool holders are not interchangeable.

1. What to do if the electric spindle doesn’t work? First of all, check the following conditions:

Is the inverter protection present? Check the manual or ask to the inverter manufacturer.

Are S1 sensor or SP sensor damaged or disconnected? - Check the connectors; - Check the continuity and the integrity of the electrical connections; - Contact the GC Service.

Is the rotation acting denied? Check the manuals or contact the machine, CNC and inverter suppliers, which the electric spindle is connected to.

Are there foreign bodies between the tool shaft and the electric spindle? Remove the macroscopic impurities and carry out the maintenance as shown on the manual.

The tool-holder taper doesn’t fit to the required one? Choose a tool-holder according to the manual instructions.

Doesn’t the clamping unit open due to lack of pressure? Check the integrity and the efficiency of the pneumatic circuit.

2. Doesn’t the tool-holder hook up? First of all, check the following conditions:

Is the S2 sensor connected, damaged? - Check the connectors; - Check the continuity and the integrity of the electrical connections; - Contact the GC Service.

Is there a check error? - Check the pressure values required; - Check the integrity and the efficiency of the pneumatic circuit.

3. Isn’t the tool-holder ejected? First of all, check the following conditions:

Is the pressure enough? - Check the pressure values required; - Check the integrity and the efficiency of the pneumatic circuit.

Is the tool ejection acting possible? Check the manual or contact the machine supplier which the electric spindle is connected to.

4. Is there pressurization lack? First of all, check the following conditions:

Is the pressure enough and the pneumatic circuit efficient?

- Check the pressure values required;

- Check the integrity and the efficiency of the pneumatic circuit;

- Contact the GC Service.

5. Doesn’t one of the sensors provide the the output required? First of all, check the following conditions:

Is the sensor disconnected or damaged?

- Check the connectors;

- Check the continuity and the integrity of the electrical connections;

- Contact the GC Service

6. What to do if the elctic spindle gets overheated? First of all, check the following conditions:

Are there cooling problem?

- Check the specifications of the cooling circuit within the manual;

- Check the integrity and the efficiency of the cooling hydraulic circuit;

- If the problem persists, contact tha GC Service.

Is the working too heavy?

Reduce the heaviness of the working.

Is the inverter parameters adjustment correct?

Check on the electric spindle nameplate or within the use manual that the parameters are the correct ones.

Is the voltage correct?

Check on the electric spindle nameplate or within the use manual that the voltage parameters are the correct ones.

7. Are the performances of the electric spindle inferior to the specifications? First of all, check the following conditions:

Is the inverter parameters adjustment correct?

Check on the electric spindle nameplate or within the use manual that the parameters are the correct ones.

Is the voltage correct?

Check on the electric spindle nameplate or within the use manual that the voltage parameters are the correct ones.

8. Does the electic spindle vibrate? First of all, check the following conditions:

Is the tool-holder balanced?

Choose the correct tool-holder according to the use manual instructions.

Is the tool balanced?

Choose the correct tool according to the use manual instructions.

Are there foreign bodies between the tool-holder taper and the spindle shaft?

Remove the macroscopic impurities and carry out the cleaning as shown on the manual.

Is the working too heavy?

Reduce the heaviness of the working.

Are the fastening screws well locked?

Check that the fastening screws are not loose.

Are the bearings damaged?

Contact the GC Service.

9. Are the bearings noisy? First of all, check the following conditions:

Are the bearings damaged?

Contact the GC Service

10. Doesn’t a sensor read properly? First of all, check the following conditions:

Is the sensor broken or damaged?

Replace this sensor.

Has the sensor lost the original position?

Adjust the sensor swinging it as long as it shows the correct signal.