It is an abrasive process used for finishing previously machined surface. It is generally used for finishing drilled or bored holes. The tool used in this process is called as hone. Hone is a bonded abrasive stone made in the form of a stick.
The honing tool works the same way as that of the expanding reamer. These honing stones are forced away by mechanical or hydraulic pressure against the surface of the bore. Aluminium oxide, silicon carbide or diamond grains of suitable grit are bonded in resinoid or vitrified bond to form the honing stones. Both internal cylindrical and flat surfaces can be easily finished using the honing process.
There are two types of honing process
Manual honing process
On this process a suitable quantity of coolant is used along with the honing stone hence this process is called as wet process. In this process the hone is continuously rotated and the work piece is moved front and back with the help of hand.
The process of honing can be done on any type of machines such as lathes and drilling machines. Fixed type of machines does not suite the honing process. A portable small drilling machine can also be used for the process of honing by fixing a honing tool head at the place of a drill bit. These small machines will fail to yield accurate results in mass production. So a regular honing machine is to be used in order to obtain a good result. Many types of honing machines are available the most common types are explained below.
Horizontal honing machines
Longer jobs are machined with the help of these machines. These machines carry a horizontal spindle on which honing tool is mounted. On some machines the work piece is mounted on the table and it reciprocates to and fro. The hone rotates about its own axis and also slightly oscillates. This oscillation is controlled mechanically or hydraulically. In some cases the honing tool is mounted on a travelling head is rotated as well as reciprocated.
The work piece is held in a horizontal position and rotated about its own axis. This type of machine is meant for very longer jobs. Correct machining sizes are checked with the help of gauges. Two spindles are present in some machines.
Vertical honing machines
In this type of machining process the tool as well as the work piece is held vertically. These machines are available in more spindle types. The work piece is stable and the tool reciprocates. Fixtures are present to hold the work piece in correct position. Hydraulic drives are present in modern machineries to control the tool and the work piece.
Vertical types of honing machines are generally suitable for shorter jobs. These machines are widely used when compared to that of horizontal honing machines.