Manufacturing Process Lab Manual

EXPERIMENT 01

Objective:

To Prepare a Plastic product using Injection Molding machine.

Equipment:

Injection molding machine Setup.

Material Required:

High grade poly ethylene

Injection Molding

An important industrial method of producing articles of thermoplastics is Injection Molding. The process is essentially as follows:

 The moulding material is loaded into a hopper from which it is transferred to a heating section by a feeding device, where the temperature is raised to 1500C – 370 0C and pressure is built up. The material melts and is forced by an injection ram at high pressure through a nozzle and sprue into a closed mould which forms the part. The mould is in at least two sections, so that it may be split in order to eject the finished component. For the process to be competitive the mould must be fairly cool (between ambient temperature and the softening point of the plastic) and consequently the mould must be cooled by circulating water.

 The single – screw pre-plasticizer is probably the most successful design for injection moulding machines.The rotation of the screw provides the plasticizing action by shearing and frictional effects and the axial motion of the screw provides the filling action. Injection moulding machines range in size from an injection capacity of 12,000 mm3 to 2.2 x 106 mm3 . The injection pressure may range from 100-150 MPa.

Procedure:

·        Pour the raw material in the hopper.

·         Place the die in such a way that its hole coin sides with the central axis of the cylinder.

·         Heat the cylinder by pouring plastic pallets in it.

·         When the metal is heated at 800C to 1000C it is converted into molten metal.

·         Press the lever so that the softened plastic will enter into the die and gets the desired shape of the mould.

·         Allow it to cool for some time.

·         Open the die and eject the article.

Precautions:

1. Align the opening of the die and an orifice of the cylinder carefully.

2. Use gloves while holding die.

EXPERIMENT 02

Objective:

To generate an arc & create a weld bed.

Equipment:

Gloves, Safety Helmet, 250 amp welding machine, hammer, cleaner,etc

Material Required:

work piece, electrodes etc

INTRODUCTION:

Welding is more than dragging a welding rod across a piece of steel &gluing it to  another one. The process begins with properly fitting and securing the work piece., or metal to be welded together. For thicker pieces you may want to grind a bevel so subsequent beads can be placed in the groove to fill it completely with a solid weld. Here are the basic steps for completing a simple weld.

Procedure:

·        Strike the arc.

 (This is the process of creating an electric acr between the electrodes and the work piece. If the electrode simply allows the current to pass directly into the grounded work piece, there will not be enough heat produced to melt & fuse metal to-gather).

·        Move the arc to create a bed.

(The bed is the metal from melting electrodes flowing together with the molten metal from the base metal to fill the space between the pieces being joined by welding).

·        Shape the weld bed.

(This is done by waving the arcback and forth across the weld path either in a zig zag or in motion so the metal spreads to the width that you want your finished weld bead to be).

·        Chip and brush the weld in between process.

(Each time we compete the process ,or trip from one end to another of your weld we need to remove the slag , or the melted electrode flux material from the

surface of the weld bead so only clean molten metal will be filling the weld on the subsequent process.

COMMENT:

            During welding process the electrode should not touch the surface of work piece . There sould be distance in between the metal and the electrodes otherwise the metal will stick to the electrode and cause sparking ,that can cause harmful for the person who is welding or can damage the work piece.

Safety Recommendations for ARC Welding:

The beginner in the field of arc welding must go through and become familiar with these general safety recommendations which are given as under.

1.      The body or the frame of the welding machine shall be efficiently earthed. Pipe lines containing gases or inflammable liquids or conduits carrying electrical conductors shall not be used for a ground return circuit All earth connections shall be mechanically strong and electrically adequate for the required current.

2.     Welding arc in addition to being very is a source of infra-red and ultra-violet light also; consequently the operator must use either helmet or a hand-shield fitted with a special filter glass to protect eyes.

3.     Excess ultra-violet light can cause an effect similar to sunburn on the skin of the welder .

4.     The welder’s body and clothing are protected from radiation and burns caused by sparks and flying globules of molten metal with the help of the following.

5.      Gloves protect the hands of a welder.

6.     Leather or asbestos apron is very useful to protect welder’s clothes and his trunk and thighs while seated he is doing welding.

7.      For overhead welding, some form of protection for the head is required.

8.      Leather skull cap or peaked cap will do the needful.

9.     Leather jackets and 1ather leggings are also available as clothes for body protection.

10.          Welding equipment shall be inspected periodically and maintained in safe working order at all times.

11.          Arc welding machines should be of suitable quality.

12.          All parts of welding set shall be suitably enclosed and protected to meet the usual service conditions.

EXPERIMENT 03

Objective:

To create different types of  welds.

Equipment:

 Mild steel electrode and electrode holder, Ground clamp, Face  shield , Apron, Chipping hammer, 250 amp welding machine

INTRODUCTION:

Lap weld joint:

 Single-Lap Joint

 This joint, made by overlapping the edges of the plate, is not recommended for most work. The single lap has very little resistance to bending. It can be used satisfactorily for joining two cylinders that fit inside one another.

Double-Lap Joint

 This is stronger than the single-lap joint but has the disadvantage that it requires twice as much welding.

Butt weld joint:

Single-Vee Butt Weld

 It is used for plates up to 15.8 mm thick. The angle of the vee depends upon the technique being used, the plates being spaced approximately 3.2 mm.

Double-Vee Butt Weld

It is used for plates over 13 mm thick when the welding can be performed on both sides of the plate. The top v-angle is either 60° or 80°, while the bottom angle is 80°, depending on the technique being used.

Etc

LAP JOINT

Procedure:

·        The given M.S pieces are thoroughly cleaned of rust and scale.

·        The two pieces are positioned on the welding table such that, the two pieces overlapped one over the other as shown in drawing.

·        The electrode is fitted in the electrode holder and the welding current is ser to be a proper value.

·        The ground clamp is fastened to the welding table.

·        Wearing the apron and using the face shield, the arc is struck and the work pieces are tackwelded at both the ends and at the centre of the joint.

·        The alignment of the lap joint is checked and the tack-welded pieces are required.

·        The scale formation on the welds is removed by using the chipping hammer.

·        Filling is done to remove any spanner around the weld.

BUTT JOINT

Procedure:

·        The given M.S pieces are thoroughly cleaned of rust and scale.

·        One edge of each piece is believed, to an angle of 300 , leaving nearly ¼ th of the flat thickness, at one end.

·        The two pieces are positioned on the welding table such that, they are separated slightly for better penetration of the weld.

·        The electrode is fitted in the electrode holder and the welding current is ser to be a proper value.

·        The ground clamp is fastened to the welding table.

·        Wearing the apron and using the face shield, the arc is struck and holding the two pieces together; first run of the weld is done to fill the root gap.

·        Second run of the weld is done with proper weaving and with uniform movement. During the process of welding, the electrode is kept at 150 to 250 from vertical and in the direction of welding.

·        The scale formation on the welds is removed by using the chipping hammer.

·        Filling is done to remove any spanner around the weld.

EXPERIMENT  04

OBJECTIVE:

To perform the fine surface Grinding operation on a given work piece.

TOOLS AND EQUIPMENT:

Surface grinding machine, steel rule.

MATERIAL REQUIRED:

M.S Flat ( 60x45x5)mm3

SEQUENCE OF OPERATION:

·         Mark the require dimensions on the work piece.

·         Hold the work piece in the magnetic chuck.

·         Adjust the grinding wheel on to the work piece.

·         Start the machine and perform grinding operation.

·         Reduce the required thickness on the work piece by grinding operation. Perform fine

finishing operation on the work piece.

PRECAUTIONS:

1. Do not wear loose clothes.

2. While measuring the work piece dimensions, stop the grinding machine.

3. Ensure the optimum feed and depth of cut and must be maintained during the

operation accident may occur.

4. Do not start a machine of which operation is not known. Damage to the machine as

well as accident may occur.

5. Before starting the work chuck whether all levers are in proper position.

RESULT:

Work piece has been machined according to given measurement.

EXPERIMENT  05

OBJECTIVE:

To perform the Step cutting operation on shaper

TOOLS AND EQUIPMENT:

 Shaper machine tool, Planing tool, Key way cutting tool, Vernier caliper.

PROCEDURE:

1. Hold the work piece in a vice or holding device.

2. Set the planing tool in the tool head with minimum overhang. Raise the table up to

required position.

3. Adjust the length and position of the stroke.

4. Adjust the cutting speed and feed.

5. Perform planning operation on the work piece.

6. Mark the dimensions on the work piece.

PRECAUTIONS:

1. Do not wear loose clothes

2. While measuring the work piece dimensions, stop the machine

3. Ensure the optimum speed, feed and depth of cut during the machine operation.

4. Do not start the machine, of which operation is not known damage to the machine as

well as accident may occur.

5. Before starting the work, check whether all levers are in proper position.

RESULT

Stepped block has been produces on Shaping machine.

EXPERIMENT  06

OBJECTIVE:

To perform drilling, reaming and tapping operations on the given M.S Flat work-piece.

Apparatus:

1. Drilling Machine with standard accessories

2. Work piece

Material:

 Mild Steel round rod of diameter 20 mm.

INTRODUCTION:

The drilling machine is one of the most important machine tools in a workshop. As regards its importance it is second only to the lathe. The hole is generated by the rotating edge of a cutting tool known as the drill, which exerts large force on the work clamped on the table. As the machine tool exerts vertical pressure to originate a hole it is loosely called a “drill press”.

Procedure:

1. The given work piece is first fitted to get required length, breadth and thickness wet chalk

is applied on four sides and with the scriber lines are drawn to get centre hole at required

location.

2. The centres are punched with a Punch and hammer.

3. The work piece is fixed firmly in the vice of the Drilling Machine

4. 3/8” drill bit is fixed firmly in the chuck and drilling is performed giving uniform depths.

5. The drill bit is removed from the drill chuck and is replaced by a reamer.

6. The reaming operation is performed on the hole which has been previously drilled.

7. The work is removed from the vice for performing tapping operation.

8. The job is fixed firmly in a bench vice.

9. Tap is fixed in the tap handle and pressure applied on the taps to obtain internal thread.

Precautions:

While performing reaming and tapping operations lubricant should be used to

minimize friction.

Result:

 Drilling and Tapping operations are performed on the given work piece as per given

dimensions.

EXPERIMENT  07

OBJECTIVE:

To perform a sheet metal cutting operation using Power Press.

APPARATUS:

Power Press, Sheet Metal.

THEORY:

A power press is a very useful machine used in mass production mainly from cold working of ductile materials such as mild steel. Normally a power press has a rotating flywheel which acts like a storehouse of energy and is used to operate the ram which provides the necessary impact to the work-piece.

Power press is a machine that houses the stamping tool (tooling) and carrying them around to the kinematics indicated by the user (process set-up). The knowledge of press used for the stamping operation .

PROCEDURE:

A sheet formed part is usually obtained through a number of operations:

·         Gravity fall

·         Holding

·         Forming

·         Trimming

·         Spring back

GRAVITY FALL

The blank adapt to the blank holder shape.

HOLDING

The die pushes the blank holder & squeezes the blank.

Holding controls the shape of the blank & the contact between the blank & punch.

FORMING

The die goes down until it squeezes blank onto the punch.

The forming operation can be divided into 2 parts:

·         First the volume of the part is created

·         The geometry details are formed.

SPRING BACK

Plastics deformation leaves some stresses locked through metal thickness. After the extraction from the tool these stress are released originating a different shape than that of the tool. Spring back before trimming is something important for the design of tool and robots of the press. Spring after trimming may change the shape of the part to the point that is impossible to assemble.

EXPERIMENT  08

OBJECTIVE:

To do Facing, Straight Turning, & Taper Turning on job using Lathe Machine.

APPARATUS:

Single point cutting tool, Mild Steel Rod, Steel Rule, Vernier Caliper, Lathe Machine.

INTRODUCTION:

The lathe is an ancient tool. The earliest evidence of a lathe dates back to Ancient Egypt around 1300 BC. There is also tenuous evidence for its existence at a Mycenaean Greek site, dating back as far as the 13th or 14th century BC.

A lathe is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece to create an object with symmetry about that axis.

PROCEDURE:

FACING OPERATION

1.      It is done for getting fine finish (good surface finish) on the face of the job.

2.      Facing tool is set at an angle to the work piece.

3.      The tool is fed from the center of work piece towards the outer surface against the rotating work piece.

4.      Depth of cut is low for the facing operation.

FACING OPERATION

TURNING OPERATION

·         It is done for reducing the diameter of the work piece.

·         A cutting tool with 70° setting angle is used for roughing operation.

·         More feed is given for rough turning while less feed is given for finishing.

·         Work piece is held in chuck and tool is set to center height of the work piece.

TURNING OPERATION

TAPER TURNING

·         It is different from the turning operation.

·         • Taper is defined as uniform change in the diameter of a work piece measured

·         along its length.

TAPER TURNING

Where,

·         D – large Diameter

·          d – Small diameter

·          l – Length of taper

·