What is Difference Between Lapping and Honing?

Hello Friends, In this topic we are going to discuss about Lapping and Honing in briefly.

At the end of this topic, we will also learn what is the difference between lapping and honing.

Lapping and Honing both are the machining process which is used to improve surface finish of any type of metal but there is some common difference between lapping and honing which we will know completely in detail.

So let's get started to know what is lapping and honing and their differences?

What is Lapping?

Lapping is a machining process that is used to improve surface finish by reducing roughness, waviness and other types of irregularities on the surface. A very thin layer of metal is removed in the lapping process.  

The process of making the metal surface more perfect is called lapping and with the help of Lapping Compound (Lap) is done to get a good finish on the metal surface.  

Lap is flat or cheek, a metallic piece of any shape, which is soft with a finished workpiece. The lap is charged with the abrasive material and brought into contact with the task.  

Lapping dimensional accuracy is of very high degree and can be done by hand or machine.

The metal can be cut from 0. 003 mm to 0.03 mm by lapping.

Difference between lapping and honing
Lapping

Lap

A lap is a cutting tool that cuts the metal under the movement process and is often softer than the cutting metal.

For making a lap generally using the cutting tool materials are copper, bronze and forge steel.

Types of Lap

  • Flat Lap 
  • Cylindrical lap
  • Ring lap 
  • Floated or Spring Loaded Lap 

Flat Lap  

Flat lap made of soft gray cast iron and it has rectangular contoured shape.

It is used for lapping flat surfaces.


Cylindrical Lap

It is made of round shape with hollow inside and its another name is expansion lap. 

It is used for lapping inner holes and ring gauges, etc.


Ring lap 

Ring lap is used for lapping outer cylindrical surface. This type of lap, slight adjustment in size is possible.

Floated or Spring Loaded Lap 

It is used to lap large diameter cylinders or gauges. This type of lap is set according to the diameter of the job by applying spring behind the lap.

Charging Lap

Charging metals for laps like Emery, Corundum, Aluminum Oxide, Silicon Carbide, Diamond, etc. are widely used. 

During charging, firstly use lapping oil on the lap like machine oil, grease, kerosene oil, etc.

Then put abrasive material on the lap like aluminum oxide, silicon carbide, etc.

Then after, Lap moves back and forth giving light pressure to the job.

There are following abrasive materials used during charging the lap

Diamond  

Diamond is the most rigid abrasive, mostly used in rotary lapping.

Silicon Carbide 

It is used for removing excess material like hard steel and cast iron. 

Aluminum Oxide 

It is used for high finishing and metal cutting slowly. 

Boron Carbide 

It has a high cutting capacity.  

Lapping Allowance 

The allowance for the finishing process depends on the size and condition of the surface. For flat surfaces the allowance should be about 1/10 μm/cm of the surface and for cylindrical surfaces it should be around 2/10 μm/cm.


What is Honing?

It is an abrasive machining process used to finish the cylindrical surface of a metal workpiece by rubbing an abrasive grinding stone or grinding wheel with a controlled path.

Honing is mainly used for engine cylinders, boring, pin holes, etc.

Honing operation is performed on a machine called honing machine. 

Honing operation is often preferred for internal cylindrical surfaces, but honing can also be done on external surfaces.
  
difference between lapping and honing
Honing


This process is done for the following reasons

(i) To bring a good finish and to make the bore of high grade. 

(ii) To increase the size of the bore.  

(iii) To fix the tolerance of the deformed bore during heat treatment.  

Hone  

The tool used for honing is called Hone.
 

Hone is an abrasive stick made of materials used to make grinding wheels.  

Bonding materials such as vitrified and resinoid bonds are used for sticks with aluminum oxide, silicon carbide and diamond grit.

As a rule, hard sticks are used for soft materials and soft grade sticks are used for hard materials.

Types of Hone

According to their work and shape hone can be classified into following types

  • Rectangles Hone
  • Triangles Hone 
  • Spheres Hone 
  • Semicircles Hone 

Honing Machine 

Honing machines can be divided into two classes.

  1. Vertical Machine
  2. Horizontal Machine

Vertical Machine

Vertical machines that prevent the tilt of the workpiece and tool.

Horizontal Machine

Horizontal machines that can be worked on quickly and are more suitable for manual operations and long pieces. 

Honing operation 

In a manual honing operation, it is common practice to hold the workpiece and move it back and forth over the tool, moving around the end of the spindle. Manual honing, especially the head stock, has a spindle under which a pan is attached to collect the cutting fluid. The tool at the end of the spindle can be stretched by a linkage with the foot pedal. 

Honing tool speed 

Surface cutting speed is lower for hard metals and higher for soft metals as per a general rule. This rule is also used for honing operations. Honing operations are usually performed at 10–30 m/min. 

Honing Allowance 

Two types of surfacing are often honed: 

  1. Fine-Turned
  2. Grinded

Grinded surfaces require less honing allowance, and turned surfacing requires more honing allowance. 

Coolant for Honing

Turpentine, kerosene and thin soluble oil solutions are good coolant for honing.

Difference Between Lapping and Honing

There are following difference between lapping and honing

Lapping

(i) In lapping process flats and outer cylindrical surfaces are preferred for a smooth finish. 

(ii) Usually hard and grinded. 

(iii) Give fine finish like glass and It is more fine than honing. 

(iv) IT 01 tolerance grade can be obtained in this process.

(v) Sliding is not suitable for the surface because it has more adhesive.

(vi) In lapping process metal can be cut from 0.003 mm to 0.03 mm.

(vii) The lapping speed is slightly less than honing.

Honing

(i) In honing process internal cylindrical surfaces are preferred for a smooth finish.

(ii) Grind or fine machine is done. 

(iii) It is less fine than lapping.

(iv) Up to IT 4 tolerance grade can be obtained in this process.

(v) Sliding is suitable for surfaces.

(vi) In honing process metal can be cut from 0.010 mm to 0.15 mm.

(vii) The honing speed is slightly higher than lapping.


So, Friends I hope you all find this topic lapping and honing interesting and also will be know very well What is difference between lapping and honing.


Thank You

Post a Comment

0 Comments