Honing process
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.
Machine honing
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.
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