Types of Spindles

Spindles are a very important and integrated component of different machine tools. Though the spindles are used in different fields and for different purposes, those which are used in machine tools are called machine tool spindles. They are rotating devices used to hold and act as axes for cutting tools or workpieces on lathes, milling machine and different other machine tools. To drive these spindles, the machine use motors, belts, gears, hydraulic or pneumatic and other ways. They are found in different configurations suiting variety of machines and applications. Some machine tool spindles are encased in solid boxes or box like cases. Some others are bolted at the bottom of housing. Sometimes multiple spindle heads are used to speed up the processing and machining operations. To drive these spindles different types of bearings are used with the machines such as hydrostatic, roller, air, angular contact etc.


Types of Machine Tool Spindles
The criterion, for defining types of machine tool spindles, covers a wide range. We can define the types on the basis of applications, performance specifications, medium of drive, configuration etc.

Machine tool spindle based on applications
Machine tool spindle has found variety of applications in a number of fields such as drilling, boring, milling, turning, grinding etc.

• Drilling Spindles: They are designed for drilling operations and have good thrust capacity in addition to radial load rating.
  
  
• Boring Spindles: They are designed for boring operations, used in the machining of internal diameters of workpieces.
  
  
• Milling Spindles: They are designed for various milling operations and are used with a wide range of machine tools.
  
  
• Turning Spindles: They are designed for working in vertical or horizontal lathes or other machinery tools.
  
  
• Grinding Spindles: They are designed for working in grinding wheels for precision, size, and surface finishing.

Machine tool spindle based on drive
Machine tool spindles are basically rotating devices so some type of medium is required to drive these spindles. These drives may be belt, motor, gear, shaft or any other medium.

• Belt Driven Spindles: These spindles have a pulley at the end to drive via a belt.
  
  
• Motorized Spindles: These spindles are provided with a drive motor integrally built into the spindle.
  
  
• Gear Driven Spindles: These spindles are provided with gear coupling to allow for high or low-speed spindle rotation.
  
  
• High Frequency Spindles: These spindles are equipped with separate external frequency converter used to drive them at very high speed.

Machine Tool Spindle Based on Performance Specifications
A well recognized criterion used for specifying spindles is their performance. It includes spindle power, operating speed, input voltage, maximum torque etc..

Selection criteria of machine tool spindles
For any type of spindles , the selection criteria depends on whether the use of that particular spindle is Not Recommended, Acceptable, Better and Best in relation to certain important features. The important features to take in to consideration is given in the following box:

Features

Performance features

• High Speed Capability
• High Rigidity
• Smooth Running - Low Vibration
• High Accuracy - Runout Tolerances
• Low Speed - High Torque Operation
  
  

Application

• Machining
  • Grinding
  • Drilling
  • Turning
  • Boring
  • Reaming
  • Milling
  
  
• Balancing
• Winding
• Processing
• Non-Machining
  
  

Environment

• Heavy Chip or Dust (build-up around spindle)
• Medium Chip or Dust (regularly removed)
• Light Chip or Dust (frequently removed)
• Tunnel Guarding
• Dry Floor Guarding
• Enclosed, creating trapped coolant and chips
• Open, allowing coolant and chips to flow away
• Chip wash
• Spindle wash
  
  

Accessories supplies

• Bearing type
• Lubrication type
• Collets
• Frequency Drives
• Chilling Units
• Motor
  
  

Industry

General

• Cost
• Quick and easy Delivery
• Compact Design
• Extensive Choice of Accessories
• Availability of Customization etc.
  
  

Types of spindles
Let us now discuss in details the various types of machine tool spindles:

Gear Driven Spindle Motorized Spindle Grinding spindle Milling spindle Turning spindle Boring spindles Drilling spindles Engraving spindle Lathe spindle High speed spindles

Multi spindle Air Bearing spindle Hydrostatic spindle Hydrodynamic spindle Air Driven spindle CNC spindle Cartridge spindles Routing spindle Dicing spindle