Honing Principle of Operation

Honing Principle of Operation

Honing Principle of Operation - Honing is a wet cutting process which removes metal from the workpiece by means of revolving honing tool that also reciprocates up and down, usually inside the workpiece. Honing is usually applied to internal cylindrical surfaces but special machines have been developed for honing external surfaces.

A - Universal Joints	A - Stick Expansion
B - Micrometer Adjustments	B - Enlarged View of Honing Tool
C - Honing Sticks

A - Stones	A - Honing Stones
B - Guides	B - Work piece

Honing is a lowvelocity abrading process. Since material removal is accomplished at lower cutting speeds than in grinding, heat and pressure are minimized, resulting in excellent size and metallurgical control.

For honing operation, the spindle of the honing machine rotates the hone (at a surface speed of 20 to 50 meters per minute for steel and 65 to 80 mpm for cast iron workpieces) and simultaneously reciprocates it (at a speed of 10 to 20 mpm) in the hole of the workpiece, Contact with the surface being finished is maintained through a positive but variablepressure mechanism.

As the bottom of the hone clears the hole in the workpiece, the reciprocating movement of the hone is reversed so that now it moves :up. The length of the reciprocating motions should be such that the hone extends beyond the work surface at the end of each stroke, and at this stage the abrasive sticks of the hone are expanded to apply the feed.

The reciprocating movement of the hone distributes the wear over the whole length of the sticks and keeps the bore cylindrical. The chance in direction of reciprocation of hone helps to clear the sticks of swarf which may tend to load them, and makes free cutting continuous. The cutting fluid used for the honing operation is usually paraffin.

The success of the process is based upon the large number of cutting points in simultaneous abrading contact. For example, in a bore 75 mm diameter X 200 mm long, j 50 grit stones have an area of 4687 sq. cm., or estimated 96,000 cutting points.

Although the amount of stock removed by each cutting edge is small, the combined action of the numerous cutting edges work­ing, simultaneously provides a relatively fast and accurate means of stock removal. The material thus removed from the hole surface helps smoothing down irregularities, to obtain the required size and finish.