Hand Hacksaw frame

Cutting tools

The tools which are used to remove or cut the material is known is cutting tools.

 Hand Hacksaw

Hand Hacksaw is used for cutting of rods, flat, etc. The Blade of the hacksaw is made up of high Carbon Steel or high-speed steel. And the frame is made from mild steel. The Blade is placed inside the frame and tightened with the help of flange nut. The teeth of the blade are generally forward cut. The hacksaw should be used in a straight direction otherwise it will result in breaking of blades. The length of blades varies from 8” to 14” but generally in 12 inches blade is used in a fixed hacksaw frame. The thickness and width of the blade are 1 mm and 1/2 inches respectively.

Classification of blades

According to the direction of cut

Forward cut                                Backward cut

Depending upon the pitch of the teeth

Coarse

Medium

Fine

Type of hacksaw frame

There are two types of hacksaw frame  

Fixed hacksaw frame

In fixed hacksaw frame only one type of blade is used.

               

Adjustable frame

In the adjustable frame, the teeth of the frame can be increased or decrease as per requirement and the blade from 8 inches to 14 long can be used in it.

Pitch  of hacksaw

It is the number of teeth on the blade in one centimeter. Hacksaw blade with small pitch is used for the thin section and the large pitch are used for the thick section.

 Use of the Hacksaw

The material to be cut with a hacksaw is clamped into vice. Marking is done with the help of a scribe. The hacksaw handle is held in right hand and the frame is kept on left hand. Start sawing at the marking, keeping the blades slightly inclined to the horizontal. The direction of hacksaw should be straight and horizontal. The speed of the hexa should be 15-25 stock per minute. Sufficient pressure should be given to the frame with the left hand while in forwarding stock. Water can be used as a coolant for sawing.

Care of hacksaw

• Always move the hexa in the perfectly straight and horizontal direction.
• Never tilt the frame while sawing.
• While cutting thin section wooden piece must be clamped along with the workpieces.
• Never use a new blade where the cut is already made by another blade.
• The blade should be tightened sufficiently.

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Gas welding

The gas flame is used to raise the temperature and produce heat with the help of gases. The metal is heated up to melting the metal and on cooling it solidify. Filler metal is used for fill the gap of welding and preparation the edges of joints. Many combinations of gases are used in gas welding but commonly used is Oxygen and acetylene.

Oxy-Acetylene welding

The process of oxy-acetylene welding can be used for all .types of metal which is used for engineering purpose. Oxy-Acetylene welding can produce 3200-degree Celsius. These are two systems of oxygen acetylene welding

High pressure system

In this process, the oxygen and acetlyene are taken for use from a high pressure cylinder.

Low pressure system

In this system, oxygen is filled in a high-pressure cylinder and the acetylene is produced by the addition of calcium carbide and water.

CaC2  + 2 H2 O = Ca (OH)2 + C2 H2

Principle of Oxy-acetlyene welding

When the gases began burning the flame is produced through the torch tip. The edge to be welded are heated upto melting. Filler metal is also added to complete the welding. This molten metal mixture when soldify on cooling forms a welding joint.

 Apparatus

Oxygen cylinder

Acetylene cylinder 

Pressure gauges 

Valve 

Hosepipe 

Torch 

Welding tips

Pressure regulators 

Lighter Goggles.

The cylinder filled with oxygen and acetylene. Both the cylinders are attached with pressure gauge, regulator and cylinder valves. The cylinder containing oxygen is painted black where the acetylene cylinder is painted Maroon. Hose pipe are provided with each cylinder. These pipes are connected to the welding torch.

Welding process

To start welding the acetylene control valve is turned first when acetylene comes out of the nozzles it should be ignited with the spark lighter. It will give a yellow coloured smoke flame after it oxygen cylinder valve is opened and supplied is increased until the best suitable flame is obtained. Then the flame is foucussed on the edges to be welded flux and filler matel are also added with the help of heat of frame, the edges and filler metal metals and a joint is performed after cooling of the molten metals. The joint may be formed with or without using filler metals.

 Applications

Same equipment may be used for cutting purpose . Oxy-acetylene welding is particular is used for sheet metal works.

 Types of gas flames

 Oxidising flame

When the volume of oxygen is more than the volume of the acetlyene mixer into the torch. This types of flame are used for cutting the metal and welding the brass metal.

Carburising flames

When the volume of acetylene mixed in more than oxygen carburizing frame is formed. This flame is used to welding nickel, monel

 Neutral flame

It is known as balancing flame oxygen and acetylene gases are mixed in equal volume. This types of flame used for welding steel and cast iron.

 Flux

The chemical which deoxidise the metal surface and provide an inert atmosphere around the molten metal is known as flux. The function of flux

• To prevent oxide from the hot surfaces
• To reduce the viscosity of molten metals
•  It contains a study Arc in the case of arc welding.

Flux is available in liquid, powder, paste, and gas. Powder flux is sprinkling on the surface to be welded or the filler rod is dipped into the Powder liquid and paste flux are sprayed on the surface to be welded. Gas fluxes are used to form in the inert atmosphere around the joint to be welded.

Filler metal

The rod which provide additional metal in completing the welding is known as filler metal. The composition of filler metal should be same as metals to be welded

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Fitting Shop Tools

Fitting Shop Tools

Clamping tools

 The clamping tools that are used in the fitting shop are called vices and this is used for holding the jobs firmly during various is fitting operations.

Bench vice

For holding the jobs bench vice is used. It has a cast iron body. Two jaws plates are fitted on both the Jaws. Jaws plates are made up of high carbon steel and are wear-resistant. One jaw is fixed to the body and the second slide on the square threaded screw with the help of the handle. The jaws are open up to the required length, the job is placed in the two jaws and is fully tightened with handle. It is fixed at the four corners of the fitter ’s working Bench and it is up to the waist height.

 Leg Vice

It is made of mild steel and the jaws are of cast Steel. It is stronger than parallel jaws bench vice and used for heavy works. It is used when the operation such as chipping or hammering is to be performed. It is fixed on the bench grouted in the foundation.

Hand vice

The small objects are held in the hand vice. These are made of different shapes and sizes. It has two steel legs which joined at the bottom. A Spring is provided between two legs. The jaws are holding with nuts.

Pin vice

For holding small diameter rods and wire are used to pin vice. It is also used for grinding small drills. It consists of small chucks made up of tools steel and mild steel handle.

Pipe vice

It is used to hold pipes. A movable joint fixed on the lower end of the screw. It grips the pipe at four points. The Jaws of this pipe vice are  V-shaped. This vice can be fixed on the bench or it can be grauted.

 Measuring and marking tools

 Try Square

It is used for checking the squareness of two surfaces. It consists of a blade made up of Steel which is attached to a base at 90 degrees. Try square is also used for marking the right angle and measuring the straightness of the surface. It is an instrument used to draw a straight line at a right angle to a true surface.

 Bevel protector

It consists of a steel dial divides into the 360-degree division. The dial can be rotated around the center the lines at any angle can be marked on or measured by the straight edge. The straight edge can be slide along the length. 

Combination set

It is a multipurpose instrument that can be used as a protector, a level, a miter, a center square, and a try square.

Centre Square

Center square is used to find the center of the round jobs. It consists of a straight edge and two arms for finding out the center around the job is placed between two arms.

Scriber and Surface Gauge

It is used for marking lines. A scriber mount on a vertical bar is called surface gauge. A heavy base is provided at the bottom. There is not fixed on the bar and this nut the scriber can be loosened and fixed anywhere in the bar in this way the inclination can be varied. It is kept on the surface plate during any measurement Primarily it is used along with V block to draw a line parallel to the surface.

Universal marking surface gauge

It consists of a heavy base is scriber and a bar. It is used for marking purposes. It is used to draw a parallel line at any desired height with respect to the surface plate.

Dot punch

It is used for marking dotted lines. Its material is high carbon or high-speed steel. One end is sharpened and the second end is flat and hammering is done on this end while working. The angle of the punch end is 60 degrees.

Center punch

It is like a dot punch expect the angle of punching end is 90°.

Surface Plate

The surface plate is used for testing the flatness, trueness of the surfaces. Surface plate made of cast iron or graphite. Its upper face is plane to form a very smooth surface. It is used to test try square and this plate is used as a base for V block, sine bar, and another measuring instrument during measurement.

 Angle plate

It consists of cast iron in which two ribs of metals are standing at a right angle to each other. Holes are providing for clamping purposes. It is used for holding and Sporting the jobs.

 

V block

It is also used for Sporting as well as marking purposes. Round jobs are placed on the V block to mark the centerline. It holds the jobs in the V portion.

Steel rule

These are made up of stainless steel and are available in many sizes ranging from ½ ft to 2ft. These are marked in inches and millimeters. The edges of the steel rule should be protected from rough handling.

Cutting Tools

The tools which are used to remove or cut the material are known is cutting tools.
Learn also: Fitting Shop Tools in Hindi

 Hand Hacksaw

Hand Hacksaw is used for cutting rods, flat, etc. The Blade of the hacksaw is made up of high Carbon Steel or high-speed steel. And the frame is made from mild steel.

 Files

A file is a tool which has multi-tooth. It is used to remove the unwanted material by means the rubbing on the metal. The files are available in many shapes and sizes.

Striking Tools

Hammers

The striking tools are used in different shops for different operations. The striking tool is identified by a hammer. These hammers are used for chipping, fitting and punching processes. A hammer has a heavy iron body with a wooden handle. The weight range from 0.25 kg to 2 kg.

Fitting Shop Practical File

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Forging Tools Name

Forging tools name with the images

Anvil

Anvil is the sporting device that is a sport the material when hammering is performed on it. A block on which forging work is done is called Anvil. It is made up of steel, cast iron or wrought iron. It acts as a Sporting device for all forging operation. The weight of the anvil varies from 100 kg to 150 kg. It is available in many size and shape

Hammer

Hammer is used as a striking tool. It is divided into three types.

Hand hammer

Sledgehammer

Power hammer

Hand hammer is a light in weight used by Smith himself. Sledgehammer is heavier in weight and is used by the Smiths helper. All the hammers are divided into 4 parts namely.

 

1. Pean             2. Eye                3. Cheeks              4. Face.

Hand hammer of four types based on the shape of pean if the pean is along the axis of the handle then it is straight peen hammer. When the pean is across the axis of the handle then it is called cross pean hammer. In case the shape of the pean in the same as the shape of the face then it is double-ended. If the shape of the pean is spherical then it is a ball-peen hammer. The weight of the hand hammer varies from 1 kg to 2 kg and that of the sledgehammer is 3 kg to 8 kg. When the quantity of jobs is to be produced is more the power hammer is used. Commonly used Hammer:-

Spring hammer

Pneumatic hammer

Steam hammer

Drop hammer

The power hammer is generally driven by electrical power. The job to be produced is placed on the anvil of the hammer with the help of the liver the weight is allowed to fall on the job. The factor which influences the working of the hammer.Size and shape of jobs

The falling weight of the hammer

The height of the falling weight

Tongs

Tongs are used for holding and turning hot metal pieces depending upon their uses, tongs are classified into many types. All types of tongs have a similar construction to accept the mouth. Tongs have two legs shifted from a suitable place these are made up of mild steel. Various types of tong used in forging shop it is made in two pieces and both of the pieces are joined by hinges. The length of the tong varies from 12" to 18".It is classified based on the shape of the mouth of the tongs.

Chisel

Chisel is used for cutting a metal piece in hot and cold states. Chisel is divided following categories.

Hot chisel

Cold chisel

Hard die set

Hot chisel is used to cut the metal in a hot state and cold chisel to used cut the metal in cold state, the main difference between these chisels is the cutting angle. In hot chisel, the cutting angle is 30 degree but in the case of a cold chisel, it is valued is 60 degrees. Hard die set. A hard die set consists of three parts:-

 1.Shank                     2. Body                   3.Cutting Edges

The shank is fitted into the hard die hole in the anvil. Chisels and hard resets are made from carbon steel. It is hardened up to the desired label with proper tampering.

Punches and drifts

Punches are made up of high carbon steel and are used for making a rough hole in hot metal pieces. Punches are available in a different sizes but have a common shape. A drift is a largely sized punch used to enlarge a whole.

 Flatter

Flatter, as indicated by the name flatter, is used to flattening the workpiece. It is held in a thin wire. The material of the flatter is high Carbon Steel. The body of the flatter is squared in cross-section.

Fuller 

Fuller is used for grooving and drawing. These are made in two-piece lower and upper parts. The lower part is mounted on the Anvil and the upper part is held in hand from a wire handle. These are made up of high carbon steel and medium carbon steel. These are used for hot work only.

Swages

Swages are used for giving various shapes to the workpieces. These are made up of high carbon steel and used in two pieces as in case of the fuller.

Swage Block

Swage block is a cast iron or cast steel rectangular block having a number of holes on it. Holes are made in different sizes and shapes. Its outer sides are also made sectional forms to receive various types of jobs. It is always planning on the cast-iron frame.

Set Hammer

Set hammer has a similar shape to the flatters. It is made to tool steel.

Clamping vice

Clamping vice is only a clamping device used in the Smithy shop. It is mounted with a table or wooden base. It consists of two jaws a spring and a leg. The hot workpiece is clamp in it while working.

Note:- Forging Operations

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Pattern Allowance in Casting

Pattern shrinkage allowance

After pouring the molten metal into the mold, the metal has a tendency to contract during solidification. The total casting product has shrunk and become small than the pattern. The difference occurs between the pattern and casting is known as shrinkage allowance. The factor that affects the shrinkage is temperature while pouring the metal, the material of the mold and the method of molding.

Machining allowance for sand casting

Matching allowance may be required by casting may partially or fully. In drawing the portion to be machined to be identified and in those portion machine allowance is provided apart from shrinkage allowance. Machining allowance also depends upon casting metal, machining methods, the specification of casting and the finish required.

    Draft allowance in casting

In the draft allowance, the pattern remains taper from all vertical surfaces. It provides the internal and external surfaces. It is required for easy removal of the pattern. It depends upon the vertical height and molding method.

Shake allowance in a pattern

Before the withdrawal of the pattern fist of all, it is shaken so that it is free from the adjoining wall, due to this size of mold cavity increase so a negative allowance is given to the pattern.

Distortion allowance in casting

There are certain casting in which the cooling of the metal is not uniform throughout the casting due to very complicated shape. Due to this distortion in the casting.

Movement of the mold wall

Due to excessive heat, the wall of the mold has a tendency to move, this movement of the wall affects the final size in the casting.

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Question for Mechanical Engineering

What is the mold?

The mold is a cavity which is prepared in sand or any metallic part that can be used to make casting by molten metal into the mold.

What is clay?

Clay fine soft soil which is used for the strong bond in the molding sand.

What is cope?

The top part of the flask is called Cope.

What is Drag?

The bottom part of the flask is called Drag.

What is flask?

The rectangular box which is used for making a mold to place the sand in it. This is made of wood or any other metal.

What is the wooden board?

The wooden board is placed on the floor for the flask. The drag part is placed on the wooden board for producing a smooth surface.

What is a pattern?

The pattern is a modal of anything which is used to prepared mold by placing the pattern in the sand.

What is a runner?

The runner is a vent or hole for pouring the material into the mold. The runner is prepared by sprue pin or sprue cutter.

What is a riser?

The riser is a hole or vent for escaping the gases which are produced during casting.

What is casting?

The casting is a process to producing new shape to molten metal poured into the mold, on cooling is known as casting.

What is Molasses?

It a black syrup which gained by the refining the sugarcane juice. This molasses increase the strength of the sand.

What is the core?

The core is an internal cavity of a mold which remains in solid condition. In the area of the core, the molten metal has not entered.

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Pattern Making and Pattern Materials

Pattern 

The pattern is a mirror image of casting. The mold is created by the pattern in the form of a cavity. When this cavity filled by casting and after solidification get desire product or job that is called casting. Some allowances are provided during pattern making.

1.   Allowance for shrinkage
2.   Allowance for machining    
3.   Draft allowance for easy removal from sand
4.   Core prints in the form of extra projections to produce a sheet for cores.

Tools used for making Pattern

•   Planer
•   Saw
•   Measuring
•   Marking
•   Miscellaneous tools

Pattern Materials

1.    Wood

The most common material for the pattern is wood has the following material.

1.    Economically and easily available

2.    Easy to convert in required shape and size

3.    Light in weight and a good finish is obtained only by planning.

4.    Can be preserved for a long time

2.    Plaster

Plaster of pair can be cast easily to any shape due to high compressive strength make small size of pattern with closer dimension. It has the property that can expand on solidification.

3.    Metal

When the large quantity of pattern is fabricated and with more accuracy, the metal piece is used. There are some limitations.

• It is costlier than wood
• In the case of machining is required it can increase the cost of the pattern.
• It is heavier than wood
• It is affected by corrosion due to treatment.

4.    Plastic

Plastic can be used due to light in weight and more strength with lesser wear. It gives a better finish and low shrinkage during melting and not much, not costlier.

5.    Wax

In this case, the mold is made of two halves and wax is poured in this. The cooling of the die takes place by circulating water.

Factor Affecting the Selection of Pattern Material

These are the point that must be considered while selecting material for the pattern

•    The rate of production of casting
•    Molding is done manually or by machine.
•    What are the casting methods?
•    Accuracy and surface finishing required in finishing. 

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