Types of Spindles
An important category of machine tool spindles are grinding machine spindles. As the name suggests these spindles are specially designed to grind. They are of various types and available in various configurations. For any kind of grinding whether on a large scale or a small scale, the grinding spindles play a vital role. Grinding spindles are used in any machine tools with grinding wheels for precision, size and surface finishing. Most of these spindles are designed in such a way so as to be fully interchangeable with each other and with existing systems. They are made of hard, durable steel alloys which helps to prevent premature damage on the surface as well seizing during machine assembly. The grinding spindles' housing diameters are available in various lengths depending on the size of the machine tool in which it will be fitted while some are available in standard, industry dimensions. Coolant and oil connections meet the most common worldwide standards.
Grinding : Meaning
The process of removing metal by using abrasives bonded to form a rotating wheel is known as grinding. When the moving abrasive particles come in contact with the workpiece, they act as tiny cutting tools, thereby cutting a tiny chip from the workpiece. Though many people believe that grinding abrasive wheels remove material by the method of a rubbing action, the process is the same as a cutting action as drilling, milling, and lathe turning.
Grinding spindles: Characteristics
Some important characteristics common to many grinding spindles are as follows:
- In most grinding spindles, there is an oil/air mist lubrication
system with an effective heat dissipation method which helps in
simplifying the spindle configuration.
- There is the standard spindle range for vertical grinding and
horizontal grinding which is developed to enable vertical applications
and horizontal applications.
- There is also spindle range for internal grinding and motorized main
spindle ranges.
- Grinding spindles include special solutions to prevent or avoid dirt
collection inside.
- The spindle design also considers the different vibration behavior of a rotating shaft from vertical and horizontal positions etc.
Grinding spindles: Uses
The grinding efficiency is measured in terms of material removal rate which is attained by employing ultra high wheel speeds. For any ultra high speed grinding machine tool, the spindle is a key component. The various uses of grinding spindles are given below:
- The grinding spindle is used for roughing and finishing flat,
cylindrical and conical surfaces.
- The grinding spindle is used for finishing internal cylinders or
bores.
- It helps in forming and sharpening cutting tools.
- It also helps in snagging or removing rough projections from castings
and stampings.
- Another important task of grinding spindles is to cleaning, polishing and buffing surfaces.
New innovations
Many grinding spindles are now combining cutting and grinding into a single platform. The benefits of performing multi tasks lead to improved work flow, fewer machines and operators, reduced setups, and higher and better parts resulting from performing all operations in one setup.
Types of grinding machine spindles
All spindles are usually classified into three main categories-high frequency, belt driven or motorized. Other popular types of grinding spindles are:
- Internal grinding spindles: Internal grinding is considered
to be the most challenging of all grinding applications. Internal
grinding means the precision grinding of the inside surface of the hole
in a work piece, enlarging or finishing of the cylindrical opening or
inside diameter in a workpiece.
- External grinding spindles: External grinding, which is also
important to many manufacturing organizations, refers to grinding of the
outer surface of a workpiece.
- Horizontal grinding spindles: Horizontal grinding spindles
are designed to grind advanced materials, including wafer backside
grinding operations, achieving a high degree of flatness while at the
same time optimizing surface finishes. They are so called because the
grinding process takes place in a horizontal way. On machines with
horizontal spindle the motor-driven spindles are horizontal. In such
machines the parts are guided through the grinding wheels vertically.
- Vertical grinding spindles: Vertical grinding , as the name suggests, fixes the workpiece on a rotary chuck in the machine base , similar to the orientation of the workpiece on a vertical lathe. The vertical grinding spindle travels up and down and side to side and at times may also swivel from above the workpiece. On machines with vertical spindle, the motor-driven spindles are vertical and the parts are guided through the grinding wheels horizontally.
All these spindles can either be belt driven or motorized or high frequency spindles. Let us now explain in details the various types of grinding spindles on the basis of the above classifications:
