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Centerless Grinding Machine

 What is centerless Grinding Machine?

Centerless Grinding is machine that is used to do grinding of outer surface of cylindrical shape, like outer diameter of bearing races, camshaft, pistons, rollers using Grinding Wheel, Regulating wheel &work rest blade.
As name suggests centerless machine not required job to hold in center to grind. Before invention of centerless grinding machine job is hold in center position and cutting/grinding is done center edge of job, like we do on Lathe machine. Centerless grinding machine give high volume of output of the grind product. This machine is also helpful to get accurate product and in large volume, that is centerless grinding machine give high output with exactly the desired size. Centerless grinding machine is used for High production volume with greater precision in less cost, as set-up of machine is simple so it can also used for small volume of production. 



Centerless machine is consist of Grinding Wheel, Regulating Wheel and Work rest blade.

  1.  Grinding Wheel: grinding wheel is known as cutting wheel, it is used to grind the job. To properly dress the grinding wheel we used the hardest material of the word that is diamond. Grinding Wheel is also called as fixed wheel, as it remains fixed in it's position. It is important to choose the right grade of grinding wheel so that cutting off the material can be done in a smooth way. Grinding wheel is generally made of aluminium oxide. RPM or surface speed of grinding wheel remain fixed.
  2. Regulating Wheel: Regulating wheel is known as control wheel as it control the speed of the output and give desired feed to the job. Regulating wheel is also known as support wheel as it gives support to the job which is pushed by the grinding wheel during grinding operation. Regulating wheel is generally made of rubber bond to observe the shock generated during the grinding operation. The RPM of regulating wheel varies with respect to the job.
  3. Work Rest Blade: Work rest blade is important part of the centerless grinding machine as the job is rest on the work rest blade, for a different operation the angle of blade can be different it generally range from 30° to 60°. Work rest blade is generally made of soft steel with carbide tip at the top where job rest/move. Work rest blade is also important to maintain the centre height of the job for different job centre height is different.

Another important part of centerless grinding machine is diamond which is used to dress both grinding wheel and regulating wheel. It is important to maintain the proper shape of both wheels, specially for grinding wheel. There are different type of diamonds available in the market like blade type, cluster type, single point or multi point diamonds one can use according to its need.

Different Types of Centerless grinding machine: 

There are three different types of centerless grinding machine.
  1. Thru Feed Centerless grinding machine
  2. In Feed Centerless grinding machine
  3. End Feed Centerless grinding machine

1. Thru Feed Centerless grinding machine:

This type of centerless grinding machine is used for cylindrical or circular shape. This is easiest form of centerless grinding machine. Distance between grinding wheel and regulating wheel is adjust according to the diameter of the job. In this continuous feeding of job is done to high production, some time Hopper is installed on centerless grinding machine for continuous feeding of material without much intervention of manpower.

Centerless Grinding Machine


The rate of longitudinal feed = Ï€ x diameter of regulating wheel x r.p.m. of regulating wheel x sin (angle of inclination of regulating wheel, usually 1° to 6°). By increasing the number of passes of job will reduce looping error from the job and job will be more circular in shape.
Thru feed centerless grinding machine is only used for circular or cylindrical shap of object but it will not use for tapper shape jobs.

2. In Feed Centerless grinding machine:

In Feed Centerless grinding machine is also know as Plunge cut grinding machine. In Feed Centerless grinding machine is used to grind tapper or stepped shape of object/job.
There is no continuous feeding of material as done thru feed centerless grinding. One job grind at a time. During the grinding operation, one job at a time placed (manually or with some automation) on work rest blade and one end stoper placed to prevent the job from vibration and after this regulation wheel slide come forward ( toward grinding wheel) as the size requirement of the job and one end stopper place. 

In Feed Centerless Grinding Machine

The regulating wheel is given a slight inclination of the order of 0.5° in order that the workpiece may remain tight against the end stop. If this inclination is not given to the controlling wheel, then there are chances that workpiece may fall down during the process. The length of object that has to grind is depend on the length of grinding and regulating wheel or vice versa. Production speed of In Feed centerless grinding machine is lower than thru feed centerless grinding machine.

3. End Feed Centerless grinding machine:

End feed centerless grinding machine is similar to In feed centerless grinding machine but there two difference between two, one is that it is used for jobs whose length is more than the length of grinding and regulating wheel. Second difference is that in this there is axial movement of job also done as length of job is more than the length of grinding and regulating wheel.
Job is feed is similar to In feed centerless grinding machine, and job move on work rest blade regulating wheel slide come forward toward grinding wheel as per the required size of the job and after this job also move axially so that complete length of the job can grind. 



End Feed Centerless Grinding Machine


Troubleshooting of Centerless grinding machines will be discussed in upcoming articles.
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