Grinding Workpiece (Complex)

Information Sheet 2.3.1: Safety precautions in operating Grinding
Machines

 Don’t start table traverse until you are certain the table stops are set properly.
o Always wind table traverse by hand to check the trip positions.

 Ensure the work is safely held:
o Work in chucks or on face plates should be clamped firmly.
o Center holes must be large enough to support work and grinding loads.
o The tailstock should be in such a position that center position is adequate.
o For work that is heavy, lock the tailstock spindle.

 Ensure guards are fitted properly.

 Always switch coolant off before switching the grinding wheel off.
o This ensures that the coolant is not left in the wheel.

Code No. Grind Workpiec (Complex) Date Developed : Date Revised Page # 4

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

Learning Outcomes :

1 Determine job requirements

Learning Activity :

1 Identify and select grinding machine needed to produce the component

I. CYLINDRICAL GRINDING MACHINE TYPES

Cylindrical grinding machines are used extensively in engineering workshops to finish pre-
machined and heat-treated components. Grinders can rough out and finish the work to fine
tolerances. Fine surface finishes and great accuracy can be obtained more economically on
grinders than on other machines.

The four types of cylindrical grinders are:

 Plain cylindrical grinding machine
 Universal cylindrical grinding machine
 Internal grinding machine
 Centerless grinding machine

II. PLAIN CYLINDRICAL GRINDING MACHINE

This machine is used for grinding parallel, tapered, stepped or formed external cylindrical
surfaces. They were originally designed for finishing hardened work, but their operation is
so efficient that they are now used for finishing most types of metals and materials.

Figure 1: Plain Universal Grinder

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 1

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

III. THE UNIVERSAL GRINDING MACHINE

The universal grinding machine is very similar in construction to a plain grinding machine,
except for the workhead and wheelhead.

This is basically a cylindrical grinding machine but additional features give it a much wider
range of applications.

 A sliding table is fitted with a power or hand-operated movements backwards and
forwards.

 The sliding table mechanism includes two dogs whose position may be varied to limit
the movement of the sliding table in either direction.

 When the sliding table is power operated, the dogs also serve to reverse the table
drive mechanism automatically at the end of each table stroke.

Fitted to the sliding table is a swivel table.

 The swivel table may be offset to the sliding table.
 This movement is controlled by a handwheel and measured by a scale calibrated in

degrees.
o The handwheel is fitted to the right-hand end of the swivel table.

A power-driven headstock is mounted on the swivel table. The headstock mounting
includes a scale calibrated in degrees and a hand operated locking device to set the
headstock in the desired position.

 The headstock incudes a spindle with facilities for mounting machine centers,
chucks, collets or faceplates to support the workpieces.

 The spindle speeds can be selected by a hand control fitted to the machine.

A wheelhead fitted to the machine includes an external and internal grinding spindle.

 The spindles are driven by separate motors mounted on the wheelhead.
 The spindle speeds may be varied either by mechanical or electrical means, or both,

depending on the make of machine.

The wheelhead may be moved with respect to the table by:

 Rotation of the wheelhead about its vertical axis;
 Lateral movement to and fro across the sliding table;
 Vertical movement of the wheelhead
 The lateral movement of the wheelhead or “cross feed” is controlled by a calibrated

handwheel and means are usually included to provide powered feed and automatic
feed stepping at the end of each stroke of the sliding table.
 The tailstock is also mounted on the swivel table and locked in any desired position.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 2

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

Figure 2: Universal Grinding Machine

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MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

IV. INTERNAL GRINDING MACHINE

The essential elements of an internal grinding machine are:

 Work supporting chuck or faceplate
 A rotating grinding wheel

The grinding wheel is used to grind the internal surface of a hole in a workpiece supported
by the chuck or face plate.

Figure 3: Internal Grinding

The universal grinder can be adapted for internal grinding by fitting an attachment. On
modern machines, this machine is a standard fitting driven by its own motor and can be
quickly moved into position on the front of the wheelhead.

Internal grinding is used to grind cylindrical, tapered or formed holes in workpieces.
Our basic methods:
 The wheel rotates in a fixed position.

The work is rotated and reciprocated, that is, moved backwards and forwards to
obtain traverse.
 The wheel rotates axially and is reciprocated through the length of the hole.
The workpiece rotates
 The wheel rotates axially and also revolves around a circumference, that is, it has a
planetary motion.
- The workpiece is reciprocated but not rotated.

The method selected depends on the nature of the work and the facilities of the grinding
machine.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 4

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

V. THE CENTERLESS GRINDING MACHINE

The Centerless grinding machine produces an accurate cylindrical surface without the
use centers or a chuck to hold the workpiece.

Figure 3: Centerless Grinder

The workpiece is supported on a workrest blade between a grinding wheel and a
rotating regulating wheel. The regulating wheel turns the workpiece about its axis so that
a new portion of its surface is continuously presented to the grinding wheel.

High volume production is possible with Centerless grinding. Less handling of the work
is required than for plain cylindrical grinding as Centerless are not used.

The regulating wheel is a rubber bonded grinding wheel driven at a much slower speed
than the main grinding wheel.

 The distance between the axis of the grinding wheel and the regulating wheel
may be varied by operating a handwheel or a lever fitted to the machine

 The axis of the regulating wheel can be altered relative to the grinding wheel axis.
 The height of the workrest blade may also be varied.
 The distance between the two wheels and the height of the workpiece blade

together determine the final diameter and the roundness accuracy of the finished
workpiece

The workrest blade is set to raise the axis of the workpiece above the axes of the grinding
wheel and the regulating wheel.

 The upper surface of the workrest blade is angular

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 5

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

 The action of this surface and the manner in which the workpiece is supported

above the axes of the wheels, prevent any high spot on the workpiece from

contacting the regulating wheel and forcing the workpiece against the grinding

wheel to produce a low spot on the opposite diameter.

There are three methods of feeding of feeding the workpieces between the grinding wheel
and the regulating wheel:

 Through feed
 Infeed
 End feed

A. Cylindrical grinding machine features

The main features of a cylindrical grinding machine are as follows:

Bed

This consists of a one-piece, heavily ribbed casting designed to give maximum rigidity and
minimum vibration.

 Accurate guideways are machined into the top of the bed to support and guide
the sliding table.

 The rear top surface of the bed is machined to support the wheelhead unit.
 The guideways are protected against dust and damage by tightly fitted telescopic

steel covers.

Sliding table

The sliding table is machined and scraped to fit the ways of the bed and can be traversed
by hand or hydraulic power.

 Trip dogs can be set along the edge of the table to reverse the direction of
traverse at the required point

Swivel table

The swivel table is provided on a hardened steel plug located in the center of the sliding
table.

 The swivel table is clamped at each end of the sliding table and can be swiveled
up to about 15º to provide adjustment for parallel grinding or for offsetting the
table to permit the grinding or for offsetting the table to permit the grinding of
tapers.

 An adjusting screw and graduated scale are fitted to make adjustment easier.
 The top of the swivel table can be machined at an angle to provide accurate

location for the headstock and tailstock.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 6

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

Tailstock

The unit is mounted at the right-hand end of the swivel table and supports the other end of
the work being ground.

 The tailstock spindle is a close fit in the tailstock body and is bored to a standard
taper into which the tailstock center is fitted.

 The spindle is spring-loaded so that the work runs on a spring-loaded center
which compress for expansion of the workpiece due to the generation of heat in
the grinding process.

 The tailstock can be clamped in any position along the swivel table
 The position of the tailstock controls the tension of the spring, and the closer the

tailstock is set to the end of the work the greater will be the tension of the spring.
 The amount of tension will depend upon the weight of the workpiece but the

spring should not be fully compressed or there will be no allowance for
expansion.
 If the work is too heavy for the user of the spring-loaded arrangements, the
tailstock spindle can be locked in position by a locking screw.

Headstock

The work headstock unit is located at the left-hand end of the swivel table and is equipped
with a variable speed motor to rotate the work at the desired speed.

 The headstock spindle nose is bored to a standard taper in which a center can be
mounted for supporting work held between centers.

 The center is usually of the dead center type, this is, the spindle and center
remain stationary and the driving plate revolves around the locked spindle on
anti-friction bearings.

 The use of fixed centers of this type gives greater rigidity and, provided the
centers are accurately ground, assures greater accuracy of roundness any
possible eccentricity that may result from center run out.

Driving mechanism

The driving mechanism to reciprocate the table and provide automatic infeed varies
considerably with different makes of machines but will be either mechanical or hydraulic.

 The mechanical types use an independent motor and step cone pulleys or gears
to obtain different rates of traverse.
o The equipment is situated inside the bed and reached through a door.
o The drive is carried through gears to a plain which engages a rack under
the table.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 7

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

o Reversals are affected by the trip dogs transferring the drive from one

clutch to another.

 The hydraulic type is operated by a geared oil pump inside the bed which

suppliers a special non-foam oil to a cylinder beneath the table.

o The cylinder is fixed in position, but is connected to the table by a piston

rod at each end of the piston

o Oil is admitted through valves, and pulls the table along by means of the

piston rod.

o A reversing lever operated by the reversal dog transfer the flow of oil to the

opposite end of the cylinder as required.

o The rate of traverse is infinitely variable by means of by-pass valves which

permit a greater or lesser flow of oil to the cylinder.

Wheel slide infeed

Manual adjustment of the cut is achieved by a graduated handwheel which has a fine-
setting control for applying finishing cuts.

On many machines, the wheel slide infeed occurs automatically at the reversal on the table
stroke.

Coolant system

The coolant system is designed in such a way as to prevent swarf and wheel particles
being continually pumped through the system.

 This is done to prevent unnecessary wear on the machine slides by abrasive
particles, and also to prevent the surface finish of the work being scratched by
particles caught between the wheel and the work.

 The simplest coolant system comprises three units, a tank, a filter and a pump
which may be mounted in the grinding machine.

Coolants are used to:

 keep the temperature of the workpiece uniform;
 wash away metal chips and metal particles;
 reduce friction between the wheel and the workpiece;
 prevent loading of the wheel.

Central coolant supply

A central supply system, with many machines operating from the one cutting fluid source, is
the most efficient.

 It has the advantage that careful control of cleanliness and proportion can be

maintained.

 Shown is a schematic arrangement for a central supply system.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 8

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

 Filtering, sterilizing and reclaiming of coolant fluids are now extensively used

because of the need for cleanliness and the cost of coolants.

B. UNIVERSAL GRINDING MACHINE FEATURES

The universal grinding machine is very similar in construction to a plain grinding machine,
except for the workhead and the wheelhead, both of which swivel.

 The workhead swivels on a graduated base to 100º either side of zero.
 The wheelhead platen not only swivels through 180º either side of zero, but is

also mounted on a side that swivels independently through 80º to 90º either side
of zero.
 Thus, the side can be set to the grinding angle required, and the platen swiveled
through 90º presenting the wheel face parallel to the face to be ground.

A semi-universal machine in common use is very similar, except that the wheel platen and
slide do not swivel independently of each other.

Wheelhead

This is a self-contained unit mounted on a slide base fixed to the machined surface of the
bed.

 A flat surface, machined at the rear of the wheelhead is provided for mounded
the motor for driving the wheel spindle.

 The spindle bearings are contained in the front of the wheelhead.
 Cylindrical grinders require rigid bearing arrangements with zero clearance and

with a very accurately running wheel spindle.
 The radial bearings are usually double-row cylindrical roller bearing with one

angular contact thrust ball bearings to give axial location.
 The spindle is made from high-grade alloy steel, hardened and ground to

extremely close limits of concentricity and straightness.
 Tapers are provided at each end for mounted of the wheel and driving pulley.

Isolating switch
The isolating switch must be located close to the machine.

 When the switch is activated it cuts the power supply to the machine.

On/Off switch

This is a circuit control device which switches the supply on and off. (i.e. similar function to
a light switch)

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 9

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

Emergency stop

The emergency stop can be operated by either foot or hand and immediately isolates the
power supply.

 The machine must be restarted.
 As the name implies this switch is only used when a dangerous situation on the

machine exists.
 The emergency stop must be placed on the grinding machine where it is easily

accessible.

Table feeds (traverse)

Reversing dogs (trips)

The reversing dogs or trip do not constitute any problem in regard to the method of setting,
but careful consideration must be given to the position in which they are set, as the setting
controls the limit of traverse.

 It is usually not good practice to allow the wheel to entirely leave the work at
the end of each traversing stroke.
 The varying pressure as the wheel gradually leaves the work may
cause undersizing.
 The correct amount of run-off should be half the wheel width, as
shown.

 If grinding to a shoulder, the table traverse must be carefully set to reverse
just before the shoulder touches the wheel.

Setting the traverse rate
The traverse rate must be considered in relation to the wheel width.

Rate for roughing

The ideal traverse set for roughing is when the work moves past the wheel a distance of
two thirds the wheel width per revolution of the work.
It should not be less than half the wheel width.

Note:

If the traverse of the work per revolution is less than half the width of the wheel, the wheel
face may wear convex, as shown.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 10

MEE722308

Information Sheet 3.1.1: Types of cylindrical grinding machines

This is important when grinding work with shoulders, because the portion near the shoulder
will be of a larger diameter if the wheel wears round on its face.

The traverse must never be greater than the width of the wheel, or the work will be ground
in the form of a spiral.

Rate of finishing

The traverse rate should be up to half the roughing rate; in fact, a rate as low as 3 mm per
work revolution is desirable for obtaining extremely high finishes.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 11

MEE722308

Worksheet 3.1.2 : Grinding machine types and functions

Learning Outcomes :

1 Perform Grinding Operations

Learning Activity :

1 Identify and select grinding machine needed to produce component

Identify the types of grinding machines .Write the correct numbers in the blanks.

. 1.

2.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 1

MEE722308

Worksheet 3.1.2 : Grinding machine types and functions

3.

4.

5.

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 2

MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and
Accessories for grinding

Learning Outcomes : Select Wheels and accessories
Learning Activity : Select and mount workholding devices and accessories

I. Selecting the holding device

The correct method of holding the workpiece is determined by the type of grinding
operation, the nature of the workpiece and the machine to be used.

Check:
 The shape.
 Whether it is hollow or solid.
 Whether it includes centers.
 The position of the surface to be ground.
 The strength of the workpiece.
 The accuracy required.
 The type of material.

The results of this check will determine whether the work should be held in:
 A jaw-type chuck;
 A magnetic chuck;
 A collet;
 A vice;
 A steady rest;
 Centers;
 A mandrel.

Selection of an unsuitable method may cause damage to the work or the machine. It may
also cause injury.

II. MOUNTING IN A CHUCK

There are two types of chucks:
 The three jaw chuck.
 The four jaw chuck.

Each type is designed to screw onto the headstock of the grinding with the chuck key. The
jaws are reversible of the grinding machine or to be mounted in the tapered spindle and
held with a draw bar.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 1
MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and
Accessories for grinding

In the four jaw chuck, each jaw is moved independently with the chuck key. The jaws are
reversible and stepped to engage different sizes of work. A workpiece may be centered with
superior accuracy in a four jaw chuck but the operation is time consuming.

NOTE:
The headstock is also referred to as the workhead.

The jaws of three jaw chuck are moved in unison with the chuck key. Centering may be
carried out quickly, but is not always as accurate as with the four jaw chuck. The centering
accuracy of the three jaw chuck is dependent on the wear of its jaw surfaces, but should be
within 0.05 mm to 0.80 mm.

Some three jaw chucks are able to be moved on their backing plate. This enables a
workpieces to be held in the chuck and adjusted to run true using a dial indicator.

The three jaw chuck is used to support.
 Short cylindrical workpieces for internal or external cylindrical grinding operations;
 One end of a long cylindrical workpiece not provided with centers.
o In case the other end of the workpiece must also be supported in a rest or a
center.

CAUTION:
 Use soft metal packing pieces to prevent scoring of the workpiece
surface.
 Do not tighten the jaws excessively on the workpiece as the jaws
may mark or deform the surface.

The three jaw chuck may also be used to hold hollow workpieces for external or internal
grinding operations:

In this case, select the appropriate jaw set and adjust the jaws to bear against the interior
surface of the workpiece.

NOTE:
It is essential that the end face of the workpiece bearing against the chuck is true and fitted
carefully to prevent eccentric movement of the workpiece during rotation of the chuck.

8.1.1 Use of the four jaw independent chuck

A four jaw chuck will hold work more accurately that the three jaw chuck. As the jaws move
independently, it may also be used for holding workpieces that are not perfectly round.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 2
MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and
Accessories for grinding

To use the chuck
 Open each jaw with the key.
 Place the work between the open jaws and locate as centrally as possible against
the chuck.
 Use the guide rings to held center the workpiece.
 Tighten the jaws against the workpiece.
 Rotate the chuck and mount a dial indicator to rest against the workpiece so that it
touches only the high spots during rotation. The dial indicator will show any
eccentricity of the workpiece.
 Position the workpiece so that the dial indicator is in contract with the high point on
the workpiece circumference.

NOTE:
If the high point is at near one of the chuck jaw it is advisable to loosen one of the jaws 90º
away from the high spot before adjusting the jaws aligned with the high and low spot. If this
is not done, the workpiece surface may be scored. This jaw must be re-tightened after the
correction is made.

 Carefully retract the jaw or jaws of the chuck opposite the high point by an amount
approximately equal to half the run-out of the high spot.

 Tighten the opposite jaw or jaws as necessary to move the workpiece into contact
with the retracted jaw or jaws.

 Rotate the chuck again and note the dial indicator reading.
 If eccentricity is still present read just the jaws until true running of the workpiece is

obtained.

NOTE:
The precautions taken with three jaw chucks to prevent workpiece damage should also be
taken with four jaw chucks.

III. Holding in a magnetic chuck

A magnetic chuck may be used to hold ferrous workpieces during cylindrical grinding
operations. Some magnetic chucks are designed to screw onto the headstock spindle and
some to be clamped to a face plate or held with a draw bar.

The field generated by permanent magnets in the body of the chuck holds the work firmly
on the chuck face.

This force is sufficient to make centering of the work difficult. A soft faced hammer may be
used to carefully tap the workpiece and adjust its position as the chuck is rotated.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 3
MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and

Accessories for grinding

Holding the workpiece in a magnetic chuck is also useful where the workpiece has an

unusual shape not suited to other mounting methods.

NOTE:
The face of the chuck will attract metal particles. These must be cleaned off to prevent
damage to the face of the chuck and faulty centering of the workpiece.

CAUTION:
Turn the field off before locating the workpiece. The magnetic field action is quite
strong and may snatch the workpiece from your hand as you approach the chuck. Do
not forget the field on again before releasing the workpiece.

IV. Mounting in a collet

Collets are designed to hold work which is close to its required final diameter. A collet
should only be used for holding work which is within about 0.13 mm of size.

The type of collet selected will depend on the shape and size of the workpiece. The
following example is one of a spring collet to hold a solid cylindrical workpiece of small
diameter for an external cylindrical operation.

To mount the workpiece
 Select a round collet with an internal diameter suitable for holding the workpiece.
 Fit the collet to the headstock spindle and secure it in position with the collet hood.
o Use the hood tool provided to screw the hood to the spindle and lock it in
position.
 Insert the collet by passing it into the hood and along the interior of the spindle
towards the end of the pull rod.
 When the collet meets the pull rod, rotate the hand wheel carefully to engage the
collet loosely with the pull rod thread.
o Do not tighten by turning the wheel further.
 Pass the end of the workpiece into the collet and towards the pull rod. If necessary,
the extremity of the workpiece may pass into the bore of the pull rod.
 Rotate the hand wheel to clamp the collet firmly against the workpiece.

CAUTION:
Do not tighten the hand wheel excessively as this may damage the collet
threads.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 4
MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and
Accessories for grinding

V. Mounting with a vice

When the shape of a workpiece is irregular it may be necessary to use a machine vice to
hold it during grinding.

The steps to follow are
 Mount a face plate of suitable size on the machine headstock.
 Loosely bolt the vice to the faceplate.
 Secure the workpiece in the vice, taking any precautions necessary to protect the
workpiece and vice jaws from damage.
 Center the workpiece as accurately as possible by sight, moving the vice and
workpiece as required.
 Firmly fix the vice to the face plate and mount the workpiece in the vice.
 Remove the handle from the vice.
 Disengage the headstock drive to allow the face plate to rotate freely.
 When the faceplate comes to rest, mark the uppermost parts of its edge with chalk.
This point is diametrically opposite the heavy point.
 Balance the face plate by bolting or clamping counterweight on or near an imaginary
radius from the faceplate center to the chalk mark. Position the weights as close as
possible to the vice.
 Adjust the size and, if absolutely necessary, the position of counterweights until the
faceplate is statically balanced
 Re-engage the headstock drive.

WARNING:

Make sure the clamps are correctly fitted and firmly secure the
counterweights.

 Rotate the face plate at a slow speed and check centering of the workpiece. Adjust
position of work and vice until the grind centering accuracy is obtained.

 Check that the work is still balanced.
 When grinding, use a suitable slow speed to eliminate chatter and vibration.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 5
MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and
Accessories for grinding

VI. Using a steady rest

To main accuracy during internal grinding it may be necessary to use a steady rest to
support the end of the work remote from the chuck.

The steps to follow are
 Mount the workpiece in a four jaw chuck.
 Center the workpiece accurately in the chuck and if possible, in the tailstock.
o Fitting the workpiece in the tailstock is not possible for internal grinding as
illustrated.
 Retract the adjustable fingers of the rest, open the rest and pass it over the
workpiece to be supported.

 Fix the rest to the worktable, making sure that it is correctly aligned with the axis of
the workpiece.

 Advance each finger until it just touches the surface of the workpiece.

 Check that centering of the workpiece is still correct.

 Run a dial indicator along the top and the side of the workpiece (while it is stationary)
to ensure that the steady is not bending the component.

The outer surface of the workpiece may be scored by:
 The jaw of the chuck;
 The fingers of the rest.

To prevent, fit soft metal spacers between the surface and the chuck jaws and between the
surface and the rest fingers.

Bend the spacers around the rest fingers to prevent them from slipping out of position.

Position the rest accurately in alignment with the headstock center to prevent tapering of
the workpiece.

NOTE:
The fingers of rests are often provided with fiber pads, making the use of soft metal spacers
unnecessary.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 6
MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and
Accessories for grinding

VII. Mounting between centers

Centers are normally used when grinding cylindrical workpieces.

The steps to follow are

 Set the headstock and tailstock of the machine in correct alignment
 Fit a center to the headstock and the tailstock.
 Check that the centers are clean.

 Use a center gauge to check that the centers are ground at the correct angle of 60º

 Fit a face plate to the headstock.

 Check that the workpiece centers are clean.

 Use the center gauge to check that the workpiece centers are of the correct size.

 Oil both workpiece centers.

 Fit a carrier to one end of the workpiece.

 Fir the workpiece between the machine centers by moving the tailstock towards the
headstock as required.

 Check that the carrier engages the face plate.

 Adjust the pressure of the tailstock center on the workpiece so that it will move freely
between the centers but without axial movement.

 Clamp the tailstock in position.

To avoid irregular wear of the worktable it is good practice always to center the workpiece
to the grinding wheel center.

 This means setting the position of both the headstock and the tailstock for a
particular workpiece when using centers.

 In this way, the wear caused by movement of the headstock and tailstock will be
distributed over the length of the worktable during the life of the machine.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 7
MEE722308

Operation Sheet 3.2.1. : Select and mount workholding devices and
Accessories for grinding

VIII. Mounting on a Mandrel

To grind the exterior surface of a cylindrical workpiece with accurate central bore, a
mandrel to mount the workpiece between the centers of the grinding machine may have to
be used.

Procedure
 Select a mandrel with a diameter appropriate for the bore in the workpiece.
 Clean the surface and centers of the surface,
o Distribute the oil evenly.
 Check that the mandrel runs true between the machine centers.
 Remove the mandrel from the machine and slide the workpiece onto the narrow end
of the mandrel.
 Tap the thick end of the mandrel gently with a soft faced hammer to firmly locate the
workpiece on the mandrel.
 Fir a carrier to the larger end of the mandrel and a face plate to the headstock of the
grinding machine.
o The headstock must be fitted with a dead center.

 Mount the mandrel between the machine centers.

Failure to clean and oil the mandrel before fitting the workpiece may result in the
workpiece binding to the mandrel. This will make it difficult to remove the workpiece
without damage to the mandrel and the workpiece.

To remove the workpiece from the mandrel, clean the mandrel surface and then tap the
narrow end of the mandrel with a soft faced hammer.

When using the soft faced hammer to tap the workpiece onto or off the workpiece onto
or off the mandrel, support the workpiece to prevent it from falling to the floor.

NOTE:
A good for fitting the workpiece to a mandrel is by using an arbor press to press the
mandrel in, where the illustration shows the use of a soft faced hammer.

Code No. Grind workpiece (Complex) Date Developed : Date Revised Page # 8
MEE722308

Job Sheet 3.4.1 : Grind a workpiece to dimension

Learning Outcomes :

1 Perform grinding operations

Learning Activity :

1 Grinding a workpiece to dimension

I. Equipment and materials

A. Cylindrical grinder with coolant, centers, and general-purpose grinding
wheel mounted

B. Diamond in table-mount holder
C. Shop towel
D. Work-driving dogs
E. Micrometer, 1- to 2-inch
F. Micrometer, 0- to 1- inch
G. SAE 4140 steel bar, 1 ¼- by – 6 ½ inch, premachined and heat-treated

to 58 C (Figure 1)

FIGURE 1

6.375”

(NOTE: All diameters on workpiece to be ground are 0.020 inch larger
than finished dimensions.)

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 1

MEE722308

Job Sheet 3.4.1 : Grind a workpiece to dimension

II. Procedure
A. Set the headstock to zero
B. Set swivel table to zero
C. Put work-driving dog on small diameter of workpiece
D. Adjust and set footstock to proper tension so that workpiece can be
removed without moving footstock
E. Set wheel speed at about 5, 600 sfpm
F. Set work speed at 175 rpm
G. Dress wheel
(NOTE : It may be necessary to remove workpiece before dressing
wheel.)
H. Clean table
I. Set table feed for 25 ipm
J. Set headstock for dead-center grinding
K. Lubricate both ends of workpiece
L. Place workpiece between centers
M. Adjust table dogs so that edges of surface to be ground are in center of
wheel at limits of table travel (Figure 2)

FIGURE 2

N. Set automatic feed for 0.005 inch
O. Set right and left dwells for two seconds

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 2

MEE722308

Job Sheet 3.4.1 : Grind a workpiece to dimension

P. Set feed right
Q. Start grinding wheel and workpiece
R. Bring wheel to workpiece until it just sparks
S. Turn on coolant and adjust flow
T. Start table traversing, and engage power feed
U. Grind surface from edge to edge
V. Move wheel back one revolution of cross feed; measure workpiece

near each end of ground surface; align table if required
W. Note diameter of workpiece, and set index dial
X. Start wheel, workpiece, and table
Y. Bring wheel to workpiece until it starts to spark
Z. Engage automatic feed; allow wheel to grind to the stop and spark out
AA. Move wheel back one revolution of cross-feed handwheel
BB. Measure workpiece, and repeat grinding as necessary
CC. Remove workpiece from centers
DD. Stop machine
EE. Remove work-driving dog from small diameter, and place driving dog

on large diameter (surface just ground)
FF. Place workpiece between centers with driving arm in “V” of work-

driving dog (Figure 3)
FIGURE 3

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 3

MEE722308

Job Sheet 3.4.1 : Grind a workpiece to dimension

GG. Adjust left table dog so that left side of wheel is near shoulder; adjust
right dog so that edge of surface to be ground is under center of
wheel at limits of table travel (Figure 4)

FIGURE 4

HH. Start wheel, workpiece, and table
II. Use fine adjustment knob to adjust left table dog until left side of

wheel sparks shoulder
JJ. Bring wheel to workpiece until it sparks; grind diameter the entire

length of workpiece
KK. Move wheel back one revolution of cross-feed hand wheel
LL. Stop workpiece and measure diameter
MM.Set indexing dial; grind surface to dimension
NN. Repeat procedure for remaining surfaces
OO. After last surface is ground to size, move wheel away from workpiece
PP. Stop workpiece, coolant, and table
QQ. Allow wheel to rotate for one minute to remove coolant; stop wheel
RR. Remove workpiece
SS. Clean machine, and put away all tools
TT. Turn in workpiece to instructor for evaluation

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 4

MEE722308

Information Sheet 4.1.1. : Select appropriate measuring device

Learning Outcomes :

1 Check/measure component

Learning Activity :

1 Identify and select appropriate tools to measure component quality

I. Micrometers come in many forms, the most commonly used in surface grinding for
measuring thicknesses though are;

A standard micrometer measures up to An indicating micrometer may be used
0.01mm as a comparator to check arts to ten-
thousandths of an inch

A Digimatic micrometer provides a Depth Gage Micrometer used to
digital display of readings to 50 millionth measure depths of shoulders and
of an inch steps

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 1

MEE722308

Information Sheet 4.1.1. : Select appropriate measuring device

II. Vernier height gage

A height gage fitted with an A height gage used to measure
indicator to measure height of height of workpieces
workpieces

III. Gage Blocks

Used in Surface grinding for:

1. Checking the dimensional
accuracy of fixed gages to
determine wear , growth or
shrinkage

2. Setting comparators; dial
gages, height gage to exact
dimension

3. Setting sine bars and sine
plates when extreme
accuracy is required in
angular set-ups

4. Measure accuracy of finished
parts

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 2

MEE722308

Information Sheet 4.1.1. : Select appropriate measuring device

IV. Universal Bevel Protractor for measuring angles of finished workpieces
V. Roughness Comparator Gage – used for comparing the finish surfaces on the

workpiece with calibrated finish on a test block using the fingernails.

Measuring an obtuse angle Measuring an acute angle

Roughness of workpieces can be compared (visually) with the standard
specimens in a roughness comparator

Code No. Grind Workpiece (Complex) Date Developed : Date Revised Page # 3

MEE722308