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Difference Between Lapping and Honing Process

Differentiation

What is the difference between the two cutting tool operations: Lapping and Honing?

Although the two processes are similar, each has a unique execution and result. They are employed to attain and improve some functional properties in machine components. These applications increase the smoothness of the exterior surface of the components and refine the geometry.


Lapping

Lapping is the method employed to get the smooth outer surface on metal jobs. After going through this application your part will be ready with a super-flat surface with desired close tolerances. This is regarded as one of the oldest methods to get an extreme dimensional accuracy.

In lapping, abrasives are used to do the work. Unlike grinding, where bonded abrasives are used, it uses loosely bonded abrasives. Generally, you can use this method to remove 0.0005in to 0.00002in of metal.

Lapping machine

Lapping operation with plates.

Lapping operation with plates.

Operation

Lapping machines

So, let's go to the shop-floor and start lapping operation now. What do we need for this?

The manufacturing method involves passing the metal job between one or more lap plates with a fluid consisting of abrasives. The process is mainly performed with the help of conditional rings and lapping plates. The lapping plate is made out of high-quality soft cast iron. The conditional rings are used to grip the metal component properly and rotate it in the region of lap plate.

The path of abrasive grains is prevented from repeating on the component by continuously changing the relative motion between plates and conditional rings.

The process can be performed with hand by rubbing flat-lap over the work-piece surface.

Abrasives used

The common names of abrasives used in this method are as follows,

  • Al2O3 and SiC
  • Cr2O3
  • B4C3
  • Diamond

The grain size of abrasives depend upon the work-piece material and desired results.

Master lap for hand lapping

Lap plate(master lap) for hand lapping.

Lap plate(master lap) for hand lapping.

Quiz

For each question, choose the best answer. The answer key is below.

  1. Abrasives are used as what?
    • Cutting tool
    • Catalyst

Answer Key

  1. Cutting tool

Honing

Honing is an abrasive machining process. Along with geometry control, honing is also used for getting the surface texture. In this method of super-finishing multi-edge tools are used which are coated with abrasives. This tool is often called as 'Hone'.

Again, like lapping, we can control the final results by controlling the type and size of abrasives used in the process.

Honing machine

Operation

Hone or honing stone is similar to grinding wheel. Using special adhesives the abrasives are bonded together on the hone surface. The main advantage of this process is there is no need to rotate work-piece. There are no face-plates or rings.

Most honing is performed on the inner walls of the metal body like the bore of cylinders used in automobiles.

Honing process

Honing process using machine.

Honing process using machine.

Wrap up

The summary is given below in a table format.

Difference between Lapping and Honing

LappingHoning

In this method work-piece is rotated.

In this method work-piece is not rotated.

It is not a stock removal process.

It is stock removal process.

Face-plate is used as tool.

Multi-edge tool called hone is used.

Abrasive particles are loose bounded.

Abrasive particles are bounded to honing stone as in grinding wheel.