TYPES OF GRINDERS
GRINDING
THEORY
Grinding
Introduction
Machined surfaces are generally rough because of improper
machining. This roughness can be removed by some finishing
operations like grinding. It can be further
Abrasive belt grinders:
A strip of abrasive cloth of correct length and width is formed
into an end-less belt by connecting ends together, this is
slipped over tow drums, one of which is driven high speed.
The work is pressed against belt commonly by hand, against
open belt abrasive belt grinders are used for heavy stock
removal or for light polishing work.
Precision grinding: (cylindrical centre type grinders)
Plain centre type grinding: A plain grinding machine is
essentially a lathe or which a grinding wheel. It consists of
the following parts.
1) Base: The base is main casting that rests on the floor and on
supports the parts mounted on it. On the top of base are
precision horizontal ways at right angle for table to slide on.
2) Table: There are two tables - lower table and upper table.
The lower table slides on the ways on the bed and provide
transverse or work. Past grinding wheel can be moved by
hand or power within desired limits. (In case of big jobs
table is used). Upper table has t-slots for securing head
stock and toil stock can be positioned along table to suit
TYPES OF GRINDERS
GRINDING
THEORY
length or work. The upper table can be swiveled and
clamped in position to provide alignment for grinding
straight or tapered work.
3) Head stock It supports the work piece by means of a dead
centre and drive the work piece in a chuck.
4) Tail stock It can be adjusted and clamped in various
positions to accommodate different length of work piece.
5) Wheel head It carries grinding wheel and its driving is
mounted on the slide. The wheel head may be moved
perpendicularly to table ways by hand or power to feed
wheel to work.
Tool and cutter grinding
Tool and cutter grinders are used mainly to sharpen and
recondition multiple tooth cutters like reamers, milling cutters
drills and taps.
Internal grinders
These are used to finish straight tapered or formed holes to
correct size, shape and finish.
TYPES OF GRINDERS
GRINDING
THEORY
Types of internal grinders:
Chucking In this type the work piece is chucked and
rotated about its own axis to bring all parts of bore or other
surfaces to be ground in contact with grinding wheel.
Planetary grinders In a planetary grinders work piece is
mounted on reciprocating table. Instead the grinding wheel
is given rotary and planetary motions to grind cylindrical
holes. It is usually limited to large and awkward work
pieces.
Centre less grinders: Centre less grinding is a method of
grinding exterior cylindrical, tapered and formed on work
pieces that are not held and rotated on centers. The work
piece is supported by three rolls :1) Pressure roll: Pressure roll is to hold the work piece
firmly against support and regulating rolls.
2) Support roll
TYPES OF GRINDERS
GRINDING
THEORY
3) Regulating roll: The grinding wheel contacts inside
diameter or work piece directly opposite to the
regulating roll.
Types of centre less grinding:o Through feed: Work is passed completely through space
between wheels. It is useful for grinding long, slender
shafts or bars.
o In feed: Regulating wheel is drawn back so that work
pieces may be placed on the work rest blade. Then it is
moved in to feed the work against grinding wheel. This
method is useful to grind shoulders and formed surfaces.
o End feed: It is used to produce taper, either the grinding
wheel or regulating wheel or both are formed to taper.
The work is fed lengthwise between wheels and is
ground as it advances until it reaches end stop.
Surface grinders: They are employed to finish plane or flat
surfaces. They are also capable of grinding irregular, curved,
convex and concave surfaces. Following are types of surface
grinders:-
TYPES OF GRINDERS
GRINDING
a. Horizontal spindle reciprocating table
b. Horizontal spindle rotary table
c. Vertical spindle reciprocating table
d. Vertical spindle rotary table
THEORY
TYPES OF GRINDERS
GRINDING
THEORY
Cutter grinding and setting: When a fluted tooth is being
ground it is supported on a tooth rest whilst wheel passes
over its edge. The tooth rest can be mounted either or
machine table or on wheel head depending on cutter to
sharpened.
