13.Practical introduction to toots and accessories of engineering section

Pillar Drill

Introduction_

There are two types of machine drill, the bench drill and the pillar drill. The bench drill is used for drilling holes through materials including a range of woods, plastics and metals. It is normally bolted to a bench so that it cannot be pushed over and that larger pieces of material can be drilled safely.

The larger version of the machine drill is called the pillar drill. This has a long column which stands on the floor. This can do exactly the same work as the bench drill but because of its larger size it is capable of being used to drill larger pieces of materials and produce larger holes.

Safety_

1. Always use the guard.

2. Wear goggles when drilling materials.

3. Clamp the materials down or use a machine vice.

4. Never hold materials by hand while drilling.

5. Always allow the ‘chippings’ to clear the drill by drilling a small amount at a time.

6. Follow all teacher instructions carefully.

Cost_

15000rs

Bending Machine

Bending Machine

Introduction_

A bending machine is a forming machine tool. Its purpose is to assemble a bend on a work piece. A bends is manufactured by using a bending tool during a linear or rotating move. The detailed classification can be done with the help of the kinematics.

Cost_

45000rs

Spot Wielding Machine

Introduction_

Resistance spot welding [RSW] is a process in which contacting metal surface points are joined by the heat obtained from resistance to electric current. It is a subset of electric resistance welding. Work-pieces are held together under pressure exerted by electrodes. Typically the sheets are in the 0.5 to 3 mm [0.020 to 0.118 in]thickness range. The process uses two shaped copper alloy electrodes to concentrate welding current into a small "spot" and to simultaneously clamp the sheets together. Forcing a large current through the spot will melt the metal and form the weld. The attractive feature of spot welding is that a lot of energy can be delivered to the spot in a very short time [approx 10 – 100 ms]. That permits the welding to occur without excessive heating of the remainder of the sheet. The amount of heat [energy] delivered to the spot is determined by the resistance between the electrodes and the magnitude and duration of the current. The amount of energy is chosen to match the sheet's material properties, its thickness, and type of electrodes. Applying too little energy will not melt the metal or will make a poor weld. Applying too much energy will melt too much metal, eject molten material, and make a hole rather than a weld. Another feature of spot welding is that the energy delivered to the spot can be controlled to produce reliable welds.

Cost_

25000rs

Shearing Machine

Shearing Machine

Introduction_

Shearing, also known as die cutting, is a process which cuts stock without the formation of chips or the use of burning or melting. Strictly speaking, if the cutting blades are straight the process is called shearing; if the cutting blades are curved then they are shearing-type operations. The most commonly sheared materials are in the form of sheet metal or plates, however rods can also be sheared. Shearing-type operations include: blanking, piercing, roll slitting, and trimming. It is used in metalworking and also with paper and plastics. A punch [or moving blade] is used to push a workpiece against the die [or fixed blade], which is fixed. Usually the clearance between the two is 5 to 40% of the thickness of the material, but dependent on the material. Clearance is defined as the separation between the blades, measured at the point where the cutting action takes place and perpendicular to the direction of blade movement. It affects the finish of the cut and the machine's power consumption. This causes the material to experience highly localized shear stresses between the punch and die. The material will then fail when the punch has moved 15 to 60% the thickness of the material, because the shear stresses are greater than the shear strength of the material and the remainder of the material is torn. Two distinct sections can be seen on a sheared work piece, the first part being plastic deformation and the second being fractured. Because of normal homogeneity in materials and inconsistencies in clearance between the punch and die, the shearing action does not occur in a uniform manner. The fracture will begin at the weakest point and progress to the next weakest point until the entire work piece has been sheared; this is what causes the rough edge. The rough edge can be reduced if the work piece is clamped from the top with a die cushion. Above a certain pressure the fracture zone can be completely eliminated. However, the sheared edge of the work piece will usually experience work hardening and cracking. If the work piece has too much clearance, then it may experience roll-over or heavy burring.

Cost_

6500rs

Co2 Welding Machine

Introduction_

Gas Metal Arc Welding [GMAW], sometimes referred to by its sub types Metal Inert Gas [MIG] Welding or Metal Active Gas[MAG] Welding, is a Welding process in which an electric arc is formed between a consumable wire electrode and the work piece metal, which heats the work piece metal, causing them to melt and join. Along with the wire electrode, a shielding gas is fed through the welding gun, which shields the process from the contaminants in the air. The process can be semi-automatic or automatic. A constant voltage, direct current, power source is most commonly used with GMAW, but constant current systems as well as alternating current can be used. There are four primary methods of metal transfer in GMAW, called globular, short circuiting, spray and pulsed spray each of which has distinct properties and corresponding advantages and limitations. It is a faster and economical welding process. Almost all metals can be welded with this process Argon, Argon+CO2 or only CO2 is used as shielding gas depending upon the metals to be welded. Inert gas[Argon] is used for Aluminium, SS etc. Active Gas CO2 or mixture of Argon+ CO2 is used for mild steel welding. Sometimes flexed cored wires are used.

Cost_

45590rs

Arc Welding Machine

Introduction_

Arc welding is a process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals when cool result in a binding of the metals. It is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct [DC] or alternating [AC] current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, or slag. Arc welding processes may be manual, semi-automatic, or fully automated. First developed in the late part of the 19th century, arc welding became commercially important in shipbuilding during the Second World War. Today it remains an important process for the fabrication of steel structures and vehicles.

Cost_

8000rs