Unit - 3
Fitting Operations & Power Tools
Fitting work is a very important work in engineering point in fitting shop unwanted material is removed with help of hand tools. It is done for manufacturing and repair purposes. Commonly used tools are hacksaw, files chiesel etc.
Vices:
Vices are the most suitable and widely used tools for gripping different jobs in position during the various operations carried out in a fitting shop.
Common types of Vices
Bench Vice: It is a common tool used for holding jobs. It consists of cast iron body and cast-iron jaws. 10 is fixed to the body and second slides on a square thread screw with the help of a handle. The jaws are opened up to required length job is placed in the two jaws and fully tightened with handle.
Hand Vice: Hand vice is used to grip very small objects. These are made in different shapes and sizes. It consists of two Steel legs hinged together at the bottom and carrying the hardened Steel jaws at the other end point a spring attachment is is provided between the two legs, which always tend to keep the jaws separate. A screw is fast and to one leg and passes through the other point at the free end of screw, a wing nut is provided. The peace to be held is gripped between the serrated jaws by tightening the wing nut.
Pin Vice: A pin vice is used for holding very small pieces like wire nails and pins etc. It is nothing but a small form of collect chuck. It consists of a handle and a tapered nose carrying a small collect chuck at its end.
Pipe Vice: It is used to hold pipes. It consists of a vertical screw with square threads. Handle is attached on the top of the screw. Immovable Jo is fixed on the lower end of the screw. It grips the pipe at four points.
Fitting Tools
Fitting shop tools are classified as under:
(a) Clamping tools
(b) Measuring and marking tools
(c) Cutting tools
(d) Striking tools
(e) Drilling tools
(f) Threading tools
Cutting tools
The tools which are used to remove the material are known as cutting tools. These tools are:
a) Hacksaw: Hacksaw is used for cutting of rods, flats etc. The Blade of hacksaw is made up of high carbon steel. Frame is made from mild steel. The length of blades varies from 8 inches to 14 inches but generally 12-inch blade is used in fixed frame hacksaw. The thickness and width of blade are 1 mm and half inch respectively. Blades are classified as under:
(i)Depending upon the direction of cut
(a) Forward cut
(b) Backward cut
(ii) Depending on the picture of the teeth
(a) Coarse (8-14 teeth per inch)
(b) Medium (16-20 teeth per inch)
© Fine (24-32 teeth per inch)
Types of hacksaw frames
In fixed frame only one type of blade is used whereas in adjusted frame the length of the frame can be increased or decreased as per requirement.
Pitch of hacksaw
It is the number of teeth on blade in one centimeter. Hacksaw blade with small page is used for thin sections and large Pizza used for thick sections.
File
File is also a mouth tooth tool. it is used to remove the material by rubbing it on the metal. Classification of files on the basis of grade
Rough (20 teeth per inch)
Second cut (40 teeth per inch)
Smooth file (50-60 teeth per inch)
Dead smooth (hundred teeth per inch)
Classification on the basis of shape and size
1. The length of files vary from 4 inch to 14 inch.
2. The shapes available are flat, square, round, triangular, half round etc.
Classification on the basis of number of cuts
i)Single cut
The teeth are cut in parallel rows at an angle 60 degree to the face.
ii)Double cut
In addition, two single cut, and other row of teeth is added in opposite direction.
Chisels: These are used for keeping away the material from the workplace. These are made up of high carbon steel generally 5 inch to 8 inch long. The top is flattened and a shop cutting edge is made on the bottom side.
Chisels are classified on their shape and weight of the cutting edge. Commonly used forms of chisels are flat, crosscut, half round and diamond point chisel. Cutting angle of chisels is kept as under
(a) For hard material (70 degree – 75 degree)
(b) For medium hard material (60 degree)
(c) Four soft material (90 degree)
Striking tool:
Farmers are the only tools generally used for striking in fitting shop. These are used for sleeping, fitting, punching etc. Hammer consists of a heavy iron body with wooden handle. The weight ranges from 0.25 kg to 2kg.
Types of hammers: Ball Peen. Straight, Peen and cross peen hammer.
Fitting process
a) Marking
b) Scrapping
c) Chipping
d) Grinding
e) Drilling
f) Measuring
g) Reaming
Power tools
A large number of power tools are used to carry out these operations. The use of power tool results in
Power tools can be group as
Stationary Power tools is called machine tool. The source of energy is electric power. Example bench drilling machine, bench grinder, power hacksaw etc.
Portable Power tools
The source of energy is battery, electricity or compressed air. Example, portable drill machine, portable grinder, portable metal cutting machines.
References:
1. Hajra Choudhury S.K., Hajra Choudhury A.K. And Nirjhar Roy S.K., “Elements of Workshop Technology”, Vol. I 2008 And Vol. Ii 2010, Media Promoters and Publishers Private Limited, Mumbai.
2. Kalpakjian S. And Steven S. Schmid, “Manufacturing Engineering and Technology”, 4th Edition, Pearson Education India Edition, 2002.
3. Gowri P. Hariharan and A. Suresh Babu,” Manufacturing Technology – I” Pearson Education, 2008.
4. Roy A. Lindberg, “Processes and Materials Of Manufacture”, 4th Edition, Prentice Hall India, 1998.
5. Rao P.N., “Manufacturing Technology”, Vol. I And Vol. Ii, Tata Mcgrawhill House, 2017.
