Motorized Grinding Spindles

Motorized grinding spindles are a popular category of spindles used in various grinding applications covering a wide range of horse power and speed combinations. Such types of grinding spindles as the name suggest are operated with the use of a motor either installed inside the spindle housing or outside and recommended for high speeds, increased power and extended service life. Such type of spindles allow extremely good cutting capacities and surface finishes of the workpiece. Designed for internal grinding applications, the motorized spindles are engineered for optimal reliability and long-life.

Features of motorized grinding spindles
Some common features of motorized grinding spindles are as follows:

• All motorized grinding spindles come with a high horse power integral motor.
  
  
• "Rigidity at speed" is a common feature available in all these spindles.
  
  
• Motor of these grinding spindles is designed looking to job specifications.
  
  
• These motorized grinding spindles are usually fitted with angular contact bearings.
  
  
• They have spring pre-load and synthetic grease lubrication.
  
  
• Motor is air or water cooled.
  
  
• These motorized grinding spindles are vibration and noise free.
  
  
• These spindles are integrated motor spindles built with usually 3 phase induction A/C or air cooled motor in different sized poles & power rating .
  
  
• AC Induction motors fitted to the spindle shaft.
  
  
• Available in various sizes.
  
  
• Depending on the suitability on machine & on the job requirement these motorized spindles are supplied with interchangeable bracket holders for its mounting or installation on the machine.
  
  
• Precision balancing of the motorized grinding spindles provides high accuracy and high-speed capability.
  
  
• In most motorized spindles, there is a temperature controlled assembly.
  
  
• Motor horsepower (HP) is a function of the RPM and the size of the motor. The larger the motor, the greater the horsepower at a given RPM and hence greater the speed of the spindle.
  
  
• Most of these motors when generating greater heat loss can be cooled with a fan that blows air over the motor.

Additional feature: Variable Frequency Drives
Motorized grinding spindles are capable of operating in any speed. A variable frequency drive is required if it operate at speeds other than 900, 1200, 1800 or 3600 RPM. These drives must be carefully matched to the motors they drive. Motors and variable frequency drives have pre-defined volts-to-hertz ratios, and they must match for a successful application. Speed control can be adjusted into the machine control for ramp-up, ramp-down and adjustment.

Applications of motorized grinding spindles
Motorized grinding spindles are easily mounted on vertical, horizontal boring and grinding machines, vertical turret lathe, ordinary lathe, surface grinders etc. They are made to grind special jobs. They are used in applications like

• Internal grinding of bearing races
• Internal thread grinding
• Deep hole grinding
• Grinding long bores or deep faces
• Other precision bore grinding applications.
• Tool machine manufacturing
• Automotive
• Aerospace
• Woodworking

Buying tips Certain parameters to consider are as follows: Spindle speed: Maximum RPM Spindle power: Maximum horsepower Spindle Lubrication: Special bearing lubrication Axial load Radial load Body styles: These include Flange Cartridge, Cartridge,Block Style, Base Mounted. They can also be manufactured to replace OEM spindles in certain applications. Motor type: Integral motor or external motor If integral motor: Power connection type whether fixed, quick disconnect, closed loop or open loop plus motor model If external motor: Motor speed, motor HP, motor mounting whether behind, front Application environment: Wet or dry Spindle rotation: Clockwise or anticlockwise Special spindle feature: Special runout or tolerances, special material property requirements, thermal expansion requirement etc.