and polishing are precision finishing processes which involve different
mechanical arrangements. Used
for many materials such as glass, ceramic, plastic, metals and their
alloys, sintered materials, stellite, ferrite, copper, iron, steel and
Lapping is a slow material removal operation.
Though lapping tends to decrease the original surface roughness, it
main purpose is to remove material and modify the shape. Lapping is used
primarily to improve form accuracy rather than to reduce surface
roughness. Polishing on the other hand deals with material surface finish
and plays little attention to form accuracy.
The relative speeds in lapping and polishing are much lower than in grinding. Consequently the concentration of energy in the contact area is much lower than in grinding.
Polishing is a surface smoothing operating. Polishing typically involves removing or smoothing out grinding or lapping lines, scratches, and other surface defects in order to decrease the surface roughness of material. Emphasis is placed in obtaining best surface finish without much regard for shame and form accuracy. As well as removing damage (such as microcarcks, voids, and inclusions) caused by previous machining operations such as cutting and grinding.
GRINDING, & POLISHING MEDIA
is a large variety of abrasives than can be used for lapping, grinding,
& polishing. Below is a description of various lapping, grinding, and
polishing media/powders that is typically used for most lapping, grinding,
and polishing operations.
– typically used for ultra hard materials and tungsten carbide. A disc
embedded with diamond will cut fast and produce fine finish. Diamond is
the hardest material known to man kind.
Boron Nitride (CBN)
– typically used for lapping ferrous metals, including 52100 bearing
steel, cast iron, tool steel, stellite, super alloys, and occasionally
Oxide – for general
lapping, grinding, & polishing with low surface roughness. Typically
used for high tensile strength materials, rough lapping operations,
hardened gears, ball bearing grooves, and lapping operations where
pressure can be exerted to break down the crystals.
Carbide – fast stock
removal for hard to soft
materials. Typically used for rough lapping and grinding operations,
forged or hardened gears, valves, tool room work and general maintenance
where polish is not essential.
Carbide – for use
with ceramic, carbide, and other hard materials
Alumina – for use
with metals, optics, silicon wafers, and other semiconductor materials
Unfused Alumina (hdrate-calcined) – Relatively soft and used for polishing. Unfused alumina abrasives are recommended for lapping and polishing of harder materials (Rockwell C 45-63). The shape, unlike the blocky crystals, is composed of flat or plated crystals with a thickness about one six the diameter. Unused aluminas allow more equal pressure to be distributed over a large surface area than the fused ones because of their plated shape. The disc shaped particles work with a shaving action rather than the rolling and gouging action of blocky abrasives and are less likely to produce deep scratches on the workpiece.
Abrasive Size & Distribution
size and size distribution of abrasive plays an important role in surface
obtained by lapping, grinding, & polishing. The size of abrasive is
directly proportional to material removal rate and surface roughness.
Larger grain sizes have a higher material removal rate. However smaller
abrasive particles will produce a lower surface roughness.
factor than may affect your lapping, grinding, & polishing operation
is the concentration of abrasive used. Number of abrasive grains in
contact with surface of material being worked on. Change in abrasive
concentration will affect distribution of load. Hence increasing the
number of grins, load per grain decreases due to larger number of contact
What you should know before you buy your next diamond tool?
UKAM Industrial Superhard Tools Division of LEL Diamond Tools International, Inc.
28231 Avenue Crocker, Unit 80 Valencia, CA 91355 Phone: (661) 257-2288 Fax: (661) 257-3833