Lapping Machine Process and Application

An ISO 9001:2008 & EMS 14001 Company

10/20111

What is Lapping?

Lapping is a mechanical precision finishing operation done to achieve high dimensional accuracy

Diagram of the lapping process in action

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What is Lapping?

It helps achieve positive sealing by obtaining high degree of flatness and surface finish

A typical example would be lapping automotive pump

seals


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The Lapping ProcessLapping improves surface finish by

reducing peaks & valleys on a surface

Surface finish of 0.2 µ Ra achievable with GMT Lapping machines

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Advantages of Lapping

Accessible flat surfaces of parts of any shape & size and any type of material can be lapped

Improves service life of the moving parts which are subject to wear

Improves geometrical & dimensional accuracies

Absolutely no distortion in the component after

lapping since no clamping devices are used

The lapping process generates minimal heat so hardened

parts will not have to be hardened again

Reduction of peaks and valleys results in maximum bearing area between mating surfaces - This ensures tight seating of seals

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Typical Applications & Industries that Make Use of Lapping

Valve Manufacturers

Air Compressor Industries

Automotive industries

Pump Manufacturers

Electronic Industries

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Carbon

What Can be Lapped?A wide variety materials, hard or soft can be lapped.

A partial list includes:

Cast Iron

Tungsten Plastics

Ceramics

Stainless SteelBronze

Silicon (Eg.wafer)

Rubber

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GMT manufactures flat lapping machines both

single side & double side

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Single Side Lapping Machine

Consists of a rigid rotating spindle with a lapping plate, and three or four conditioning rings

GMT’s single side lapping machines provide flatness to a precision of one light band (0.0003mm) on 75mm diameter with a surface finish of 0.2 µRA

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GMT has supplied lapping machines to

over 300 customers all over India

Sizes range from 300mm to 3000mm diameter

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Our Customers Include:11


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Range of Lapping Machines Manufactured by GMT

Single side lapping machines300mm - 400mm

diameter

Model 06-01, 06-02

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Single side lapping machines610mm diameter

Model 06-13

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Model 06-03

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Model 06-05

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Model 06-06

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Model 06-07

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Double side lapping machines/Planetary lapping machines

Model 24-01

To maintain:•Flatness•Surface finish•Parallelism

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Model 24-02 with pneumatic

lifting arrangement

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Model 24-11

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Model 24-11 with 4 way lapping

(rotating top & bottom lap plates)

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Accessories

Hand lap plate

To correct minor imperfections and for

small batches

Cupboard

To store polishing paper, pad, hand tools etc,

(can be used as a machine stand for 300 and 400mm

diameter bench model lapping machines)

Straight Edge

To check the flatness of lap plate

Monochromatic Light & Optical Flat

Used for measuring the flatness.

Sodium Vapour Lamp used with a wavelength

of 0.00058 mm

Polishing Stand

Fitted with 4/0 emery paper to achieve reflective surface after lapping for light band

interpretation(for flatness checking)

4/0 Emery Paper

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Measuring Flatness

Unit for flatness measurement is half the wavelength i.e. λ / 2 = 0.000589 / 2 = 0. 0002945mm(rounded off to 0.0003mm i.e. 0.3 micrometer)

Monochromatic Lamp

Optical Flat

Flatness is measured using GMT make Monochromatic lamp & Optical flat

The GMT Monochromatic lamp unit provides light source with sodium vapour lamp.The wave length of Sodium light in air (λ air):0. 000589mm i.e. 0. 589 micrometer)


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Measuring Flatness

An imaginary tangent intersects one interference band immediately above it

Imaginary tangent line

This shows the flatness to be below one band or 0.0003mm

Point of contact


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Measuring Flatness

Optical flat is in contact with the surface being tested, usually where pressure is applied causing the air film to be squeezed thin at that place

When light is reflected from the surface under test, interference occurs and is visible as a pattern of light & dark bandsThe width of each band = λ / 2 ( (i.e.) 0.0003 micrometer)

Point of contact or line of contact

Point of contact

Straight, parallel and equally spaced bands show that surface is

perfectly flat within 0.0003mm


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GMT also offers optional features like: • Water cooling for lap plate,• Variable speed drive,• Pneumatic lift arrangement,• Lapping fluid recycling

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Accessories for Lapping

Guindy Machine Tools Limitedwww.gmt.co.in

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Lapping Machine Process and Application

Engineering