PLANING MACHINE
A Planing Machine tro duction Cross-rail In
Tool head Column
This is also a recipro cating typ e of ma
chine like shap er The table with T
slots for mounting workpiece slides in
the guideways of the machine b ed past
Table
the stationary to ol head The to ol
Table
holding the to ol machines du
reciprocating head
the forward or cutting stroke of
movement ring
orktable during the cutting stroke
Roller the w
to ol remains stationary The to ol
Bed the
tal feed is given during return
Open Side Planer horizon
backward strokeof the worktable Sketch S-8.1-A or
Feed screws
Cross-rail elevating screw
Cross- Swivel heads rail
Tools
Table
Bed Cross-feed cranks
Column or housing Double Housing Planer
Sketch S-8.1-B
Planing Machine
Divided Table Planer
In this typ e of planer the table on the bed is divided into two parts it
may b e recipro cated separately or together This typ e is mostly suitable for
continuous pro duction and thus reduces the machining time by saving the
idle time One of the table is used for setting up large number of identical
workpieces while the other one recipro cates against the stationary cutting to ol
machining the workpieces Both the tables may clamp together for holding
large and heavy workpiece and can also recipro cate together under the to ol
A Table Drive Mechanism
The table recipro cates in the guideways on the machine b ed The mechanism
used to drive the table is mainly by gear drive and the reversible mechanism
is adopted byany of the following ways
a By having an op en and cross b elt drive in whichthe b elts are alter
nately used as drivers b By having a reversible typ e of D C motor drive
c By means of a crank as employed on shap ers d By reversing the ow
of oil from a hydraulic pump
A Quick Return Mechanism of a Planer to Drive the
Table by Op en and Cross Belting
Open belt (OB)
Cross belt (CB)
Pinion P1
Table S1
OF OL CF SG CL R
Free on S2 the shaft Fixed on Gear P the shaft 2 Rack and Pinion
Sketch S-8.5.1
In op en and cross b elt drive the b elts are alternatively used as drivers to
recipro cate the table The cross b elt with a greater arc of contact on the
larger pulley is used to drive the table on the cutting strokeorforward stroke
Greater power and less sp eed is essential during the cutting stroke and is
being achieved by connecting the cross b elt with larger diameter pulley CF
which is xed on the shaft S The p ower from the shaft S transmits to the
shaft S through pinion P and spur gear SG Power again from the shaft S
Planing Machine
Setting of prop er to ols as mentioned ab ove in prop er op erational sequ
ences T slot Planing to ol mayhave to b e set either to the left side or
right side according to the recess op erations to the left or to the right
side resp ectively
After arranging the ab ove the machine is started with the following
steps
a By switching on the planing machine the table holding the
job recipro cates the to ol holder holding square nose planing
to ol feeds vertically for machining key slot op eration Both
roughing and nishing op erations are done with prop er cutting
conditions
b Stopping the machine changing the to ol to T slot planing to ol
feeds crosswise directions for T slot op erations b oth left side
and right side recesses with roughing and nishing cuts are
done with prop er cutting conditions Suitable spring is provided
to raise the to ol b ox automatically after each cutting stroke
Measuring and checking the workpiece are necessary with prop er insp ec
ting to ol s
A Distinction Among Shaping Planing And Slotting
Machines
The recipro cating typ e Machine To ols like shaping planing and slotting
are primarily used to pro duce at surfaces but they di er in job to ol motion
construction work size machining time accuracy use etc
Points Shaping Planing Slotting
Machine Machine Machine
Job Tool Tool recipro cates Job recipro cates Tool recipro cates
motion in horizontal axis in horizontal axis in
and Job feeds in and Tool feeds in vertical axis and
intermittent tran intermittent tran Job feeds in inter
slatory motion slatory motion mittent transla
tory motion
Construction Lighter in con Heavier in con Lighter in
and rigidity struction and less struction and construction and
rigid more rigid less rigid but more
rigid than vertical
shap er
Motor Power Power is very less Power is very high Same as shap er
required round ab out as compared to
kW the shaping and
slotting machines
ab out to ti
mes the shap er
Contd
Machine Tools
Points Shaping Planing Slotting
Machine Machine Machine
Job size and Smaller jobs can Bigger jobs require Same as shap er
xing time b e xed quickly xtures for xing
and simply in a and hence more
vice Job size xing time and
mm cub e skillness are requi
max red Max Job
size m m
m
Number of Only one surface Three surfaces can Same as shap er
surfaces that at a time be machined at a
can be ma time
chined at a
time
Machining More time requi Less time required Same as shaping
time and red as one to ol as a number of machine
typ e of job works at a time to ols can work at a
suitability suitable for job time suitable for
bing work and few pro duction typ e of
no of pieces work
Number of Only one to ol can Three or more Same as shap er
to ols that be op erated at a to ols can be op e
can be op e time rated at a time
rated at a
time
To ol size Standard to ol size Robust to ol size is Same as shap er
is not so robust required for ma
as used in Planing chining bigger
Machine jobs with higher
depth of cut feed
and to takeupthe
impact forces
Range and Smaller range and Wide range and Same as shap er
number of smaller number of more number of
sp eeds and sp eeds and feeds sp eeds and feeds
feeds available
Amount of Heavier depth of Heavier depth of Same as shap er
feed and cut and course cut and course
depth of cut feed is not em feed can be em
ployed ployed
Cutting Fixed in a particu Ratio can b e chan Same as shap er
return ratio lar machine ged indep endently
Arrangement Generally b eing Not generally Same as shaping
of quick re adopted b eing adopted but machine
turn mecha quick return is
nism p ossible by using
variable gearing
arrangement
Contd
GRINDING MACHINES
A Intro duction
(A) Cylindrical Grinding Machine
Sketch S-9.01 (A)
Grinding is a pro cess of removing materials in the form of ground chips from
a workpiece by mechanical action of many small abrasive particles b onded
together in a grinding wheel Each abrasive particle is acting as a small cut
ting to ol It is a nishing pro cess employed for pro ducing close dimensional accuracies and smo oth surface nish
(B) External Cylindrical (C) Internal Cylindrical Surface Grinding Surface Grinding Sketch S-9.01 (B, C)
(D) Taper Grinding (E) Flat Surface Grinding
Sketch S-9.01 (D & E)
Machine Tools
the workpiece The regulating wheel is having same direction of rotation
as the grinding wheel The axial movement of the workpiece is obtained a
longitudinal feed by tilting the regulating wheel at a slight angle of to
degrees relative to grinding wheel
6
4
563 2 7 5 1
1. Grinding head 2. Regulating wheel head 3. Work rest 4. Workpiece 5. Grinding wheel 6. Regulating wheel 7. End stop
Sketch S-9.09.3
D N sin
R R
Rate of longitudinal feed of the work f V sin m min
R
where feed f in mm min
p eripheral sp eed of regulating wheel V in m min
R
diameter of regulating wheel D in mm
R
revolution of regulating wheel N in r p m
R
angle of inclination of Regulating wheel in degrees
sp eed of rotation of the workpiece V V cos m min
w R
Peripheral sp eed of the grinding wheel to m s is to times
that of the p eripheral sp eed of the regulating wheel to m min Thus
the sp eed of rotation of the work is a function of the regulating wheel
After completion of grinding the regulating wheel is backed out and the
work is replaced by a new one
A Finishing an Internal Surface by Centreless Grinder
In centreless internal surface grin
three rollers are used to + 2 ding
3
and drive the work 5 supp ort
+ 1 = Grinding wheel
They are i driving rollers
2 = Workpiece
ii work rest roller and
4 + 3 = Driving wheel
iii pressure roller Automatic
4 = Roller rest loading and unloading can b e ar
5 = Pressure roller
ranged by swinging the pressure
roller out of the way at the end of
the cycle This system can elimi
1
nate the use of work holding x
tures and can grind b oth straight
Sketch S-9.09.4
and tap ered holes
Workpiece is rotated by the driving wheel The grinding wheel
rotates at a sp eci ed sp eed and e ects the longitudinal feed and cross feed
motion The workpiece rests on work rest roller in a predetermined p osi
tion but the pressure roller is oscillated in a manner to provide a uctuating
Machine Tools
c Grinding by Vertical Spind le on Reciprocating Table
In vertical spindle surface grinding ma
chine with recipro cating table arrange
ment the workpiece mounted on magne
Grinding
huck or on xture recipro cates under
wheel tic c
the rotating grinding wheel in its vertical
Vertical and cross wise adjustment
Workpiece axis
the grinding wheel is incorp orated in
Magnetic chuck for
wheel head assembly This typ e is sp eci
Sketch S-9.09.5 (c)
ally adopted for grinding large surfaces
d Grinding by Vertical Spind le on Rotary Table
In vertical spindle surface grinding
machine with rotary table arrange
t the workpiece mounted on mag men Grinding
wheel
netic chuck or on xture rotates with
Workpieces
the rotating grinding wheel in its ver
tical axis The combination motion of
the table i e rotation as well as late
ral movement helps to grind the en
surface of the workpiece Down
tire Magnetic chuck
feed is given b y the wheel This typ e
is suitable to grind either a single large Sketch S-9.09.5 (d)
workpiece or a numb er of small pieces
in one or more circles on the table
A Disc Grinder
These grinders remove the sto ck rapidly and nish the at surfaces by the
sides of disc wheels Single horizontal or vertical spindle disc grinders are
used for rep etitivework by hand op eration or with simple xture The double
horizontal spindle is mostly used for pro duction op erations
As the name implies this typ e is mostly used to sharp en and reconditioning
various typ es of cutters like single p oint to ols milling cutters drills taps
hobs etc By using requisite attachment or xture this machine can also b e
used for grinding die jig xture light surface cylindrical internal surface
etc Abench or p edestal typ e to ol grinder is used for grinding to ols by hand
known as o hand grinding
ersal typ e grinder is equipp ed with Grinding wheels Univ
Wheel head
a universal head vice headsto ck tail sto ck
and various attachments for holding to ols
cutters This typ e is most suitable for Table and
Column the sharp ening of miscellaneous cutters
heavy box typ e base maintains the
Saddle The
machine s stability and rigidity Saddle
mounted on the base provides the arran
t for moving the work forward and
Base gemen
backward The column is mounted on
Sketch S-9.09.7
saddle The column is supp orting the
Grinding Machines
A Comparison Between Truing And Dressing Of A
Grinding Wheel
Points Truing of a Dressing of a
Grinding Wheel Grinding Wheel
De nition Truing a wheel is the op e Dressing a wheel is the op era
ration to create a true and tion to remove glazed or other
concentric surface with the adhesion particles and to ex
wheel spindle axis p ose fresh cutting particles
When Truing is necessary to Dressing is necessary to newly
necessary newly manufactured manufactured or the dulled
wheels taken from kilns for crystals clogged with some fo
truing to shap e and dimen reign materials after it is b eing
sions used for sometime on the wheel
face for the purp ose of exp o
sing new cutting particles
Tool used Commercial diamond to ol Same as Truing Tool
or conical point tungsten
carbide inserted on a shank
of cold rolled steel
Why To rotate the wheel in a Toremove the blunt surface on
necessary true and concentric path wheels necessary for e cient
cutting
Cost of More Less
machining
Grinding wheel
Guard
etch Sk ° 3 to 5 Tool rest Diamond tool Dresser Truing Dressing
Sketch S-9.11
A Cutting Sp eed Feed And Depth Of Cut
Grinding Wheel Sp eed
The cutting sp eed of a grinding wheel is the p eripheral sp eed or surface
sp eed expressed in metres min and can be calculated by the following
expression
D N
w w
Grinding Wheel Sp eed in metres min V
w
where D is the diameter of the grinding wheel in mm
w
N is the revolution p er minute of the grinding wheel
w
Work Sp eed Similarly surface sp eed or p eripheral sp eed of the work can
b e determined by the following expression
Machine Tools
Locking Bushing End
Leaf Jigs screw Leaf location
Pivot stop
It has a leaf or cover which can be
swung op en or close to load and un
the work After lo cating the
Work- piece load
workpiece inside the jig the leaf is
rmly closed and lo cked and the jig is then ready for use
Sketch S-13.7[3]
Bushing
Box Jigs
Box
is box shap ed containing box
Cam rod It
structure bush cam cam ro d etc
It contains bushings on twoormore
sides for the purp ose of drilling holes
on di erent sides of the part For lo
ading the workpiece on jig the cam
is taken out of the jig and the
Work Cam ro d
workpiece is placed in p osition in
side the jig Then the workpiece is
lo cked by rotating the cam through cam ro d
Sketch S-13.07[4]
Channel
Channel Jigs Bushing
section
It is a simple channel shap ed trough
and clamp ed by rotating a knurled
knob of a screw There is a drill bush ber
Work to guide the to ol on the top mem
the channel This jig is suitable
Screw knob of
for the workpieces of simple symme
Sketch S-13.7[5]
trical shap e
Diameter Jigs
These typ es of jigs are used to drill or ream radial holes on cylindrical or
spherical workpieces The cylindrical workpieces maybe placed on xed V
blo ck and clamp ed by clamping plate and clamping b olt There is drill bush
on clamping plate for guiding the to ol Refer to sketch S B
A Typ es Of Fixtures
Fixture
A Fixture is a device for holding a workpiece to a machine b enchina xed
p osition during machining op erations It do es not have sp ecial arrangement
for guiding the cutting to ol A xture is used for holding and lo cating the
workpiece only when a large numb er of identical parts are to b e machined to justify its cost
Jigs and Fixtures
Typ es of Fixtures
Common typ es of xtures are vice lathe b oring broaching milling
grinding etc
Vice Fixtures
A Workpiece
machine vice with the ar Standard Special Regular
jaw jaw
rangement of sp ecial jaws is provided
for an easy way of holding the parts
for machining Sp ecial jaws are desig
ned according to the requirementofin
dividual workpieces Small castings or
forgings with irregular contours can b e
Sketch S-13.8.1
held in standard machine vices
A Lathe Fixtures
Most of the lathe op erations can be done by using standard chucks and
holding metho ds But many castings and for
parts cannot easily be mounted by the Counter ging
weight
standard metho ds and require sp ecial work holding xtures
Workpiece
Face Plate Fixture
Face Plate Fixture is mounted to a stan
dard lathe face plate The at base of xture
Angle
is b olted to the face plate The workpiece is
Section
dynamically balanced as accurately as p ossi
by using a suitable sliding counterweight
Face plate ble
turning high sp eed op erations Accurate
Lathe Fixture for w
Sketch S-13.8.2 static balancing is satisfactory for turning lo
and medium sp eed op erations
A Boring Fixtures
Machine
xtures may be of a drill
Boring spindle
on the
dig or a mill xture dep ending Master hole
yp e of op eration Boring xtures have
t for fixture Boring bar
adjustment on the machine table
the Fixture
may require additional b oring bar
or Boring tool
or indicating surfaces for initial
holes Workpiece
alignment Single piloted bar is guided
on its leading end to prevent springing
under cutting thrust and an end sup
vided for alignmentby
p ort is also pro End support
adjustment of the b earing blo ck Pur ork
p ose of this xture is to hold the w Machine table
piece in the correct relation to the b o ring bar
Sketch S-13.8.3
A Broaching Fixtures
Simple plate plug or horn xtures lo cate the correct p osition of the work
piece in relation to the broach and machine face plate The gure ab ove
Machine Tools
shows a simple xture used for broaching a keyway Wire strip of desired
thickness made of to ol steel and heat treated wear resistance is used when
to cut a keyway deep er than that can b e achieved in one pass of the broach
Machine face plate Adopter
Broach
Wear strip
Workpiece Work horn
Sketch S-13.8.4
A Milling Fixtures
Strap clamp
A milling xture holds the work
in the correct relation to the
piece s Fixture
cutter as the table movement
milling Job base
carries the workpiece through the cut
ters The xture consists of xture
base strap clamp nuts and b olts lo
points Strap clamp should be cating Machine table
extremely rigid to exert the cutting for Feed movement
ces byinterrupted cutting of the milling
Sketch S-13.8.5
cutter
A Grinding Fixtures
Lathe xtures may b e used for cylindrical grinding Grinding is a nishing
op eration requires great accuracy and close tolerance is to b e considered in
designing of grinding xtures ork
Workpiece The standard metho d of holding the w
pieces for surface grinding op erations is mag
netic chucking Quick loading mounting and
unloading the workpieces and also no distor
is caused by mechanical clamping The
Magnetic chuck tion
basic xture is made of a numb er of mild steel
plates separated from each other by a non
ferrous spacer The magnetic ux passes from
the magnetic chuck through the steel plates
to the workpiece Plates round bars even
odd shap ed workpieces can be mounted on
hucks parallels V blo cks and mag Ferrous and non-ferrrous magnetic c
plates alternately
netic chucks with ap oxy to oling materials
Sketch S-13.8.6
resp ectively