Types of Grinding Methods

There are many different types of grinding methods some of which are Cylindrical grinding, Centerless grinding, Internal Grinding, Surface Grinding.

Cylindrical grinding : As the name suggests, this method is used when grinding the outside diameter of a cylindrical part. Different profiles can be created using cylindrical grinding, some of them can be done using straight grinding, taper grinding, profile grinding or angular grinding.
Centerless grinding : This is one of the most common grinding process for all cylindrical parts. In this process, a workpiece is sandwiched between grinding wheel and regulating wheel where the grinding wheel provides the abrasive material and grinds the workpiece until achieving the desired size surface finish.
Internal grinding : This is done by making the work piece either rotational or stationary and where an abrasive wheel then grinds the inner diameter of the workpiece to achieve the desired size and surface finish.
Surface grinding : This is done on flat workpieces using either a horizontal axis surface grinder or vertical axis surface grinder on a table or a rotary table. Material removal is done only on one side. If needed to be done both sides, workpieces can be flipped and must be performed as a separate machining operation. Surface grinding is different from lapping. In lapping material removal is done on both surfaces simultaneously.

Grinding Wheels / Abrasive Wheels

There are various types of grinding wheels available. Depending on the application the proper grinding wheel needs to be chosen. Grinding wheels vary according to the abrasive type, grit size, bonding degree, concentration, type of bond, bond name, thickness of abrasive layer, etc. - in short... there are plenty of different ones that are applicable to many different parts as different materials / alloys and processes often times require different abrasive wheels, and the usage of an incorrect grinding wheel might not yield the desired results on a workpiece.

The Different Types of Grinding Machines

Some of the Precision grinding machine types are :

Cylindrical Grinder - This is mainly used to grind the outer diameter of a cylindrical part. A Grinding wheel is fitted on the shaft of an electric motor and part is spun between centers, the workpiece is fed into to the grinding wheel until the desired size and surface finish is achieved.
Centerless Grinder - This is also very commonly used to hold surface finish and tolerances for all cylindrical parts. Here workpieces are placed between a grinding wheel and regulatory wheel and the centerless grinding process can be either a thru-feed grinder or a in-feed grinder.
Internal Grinder - This is mainly used to grind the inner diameter of a cylindrical part. Here the part is held on a chuck and a grinding wheel smaller than the size of the bored ID is fed into the part until the desired size and surface finish is achieved.
Surface Grinder - This is used on flat surfaces, where the thickness of workpiece has close tolerances in size, flatness are/or parallelism. Grinding wheels are mounted on to the spindle of the machine and parts are either placed on a rotary table, fixture or using a magnetic fixture depending on workpiece material. Coolant is fed while grinding and the grinding wheel is fed into the workpiece until desired size / surface finish is achieved.
Profile / Form Grinder - This is used when multiple ground surfaces have to be held at close tolerances and each ground surface is dependent on another surface. Abrasive wheels are created custom to the exact geometry of the part and slowly fed on to the part until desired size / surface finish are achieved on multiple surfaces simultaneously.
Universal Grinder - This is another form of cylindrical grinder where its worktable, headstock and grinding head are on a swivel.
Tool and Cutter Grinder - This is a specialized grinding process used to create endmills from carbide’ ‘blanks’ and also can be used to re-grind / grind carbide cutting tools. Its wheel head can be turned at any angle to grind flutes and/or any other complex geometry.

Some of the other general grinding machine include :

Bench Grinding Machine - Bench grinders are generally fixed on the workbench for the operator. They can use to either re-sharpen tools, break edges or remove burrs at the cnc machine.
Hand Grinding Machine - Similar to a bench grinding machine, this grinding machine has the provision of moving the grinding wheels.
Pedestal Grinding Machine - Also similar to bench grinding machine, except it is setup on a separate pedestal frame mounted to the ground.
Portable Grinding Machine - This is a small grinder which can be held in one’s hand. Smaller abrasive wheels are fitted on the shaft and most of these portable grinding machines have high-speed motors.