1.1 Machining Process
Machinability is described as the case with which metal can be removed. The various machining processes
are briefly described below:
• Blanking: In this process also “punch and die” is used for making domestic utensils or machine
components. It produces necessary depressions and cut-outs.
• Boring: In this case, the work piece is held by a fixture and a rotary cutter is used for boring a hole in
a cylindrical shape. The existing hole may be enlarged. The boring may be straight or tapered.
• Broaching: The broach is made up of a bar of suitable length with a series of cutting edges on its
surface. These cutting edges are arranged progressively higher from the starting to the end and hence
each successive tooth removes an additional amount of material. This is done with the help of a cutter
known as “broacher”. This process also produces slots and gear teeth.
• Die Cutting: It is of two types ‘punching’ and ‘Blanking’ type. In the punching die, the metal removed
by the die is a scrap, leaving a hole in the work piece. The blanking die shears through the work piece
and the metal removed by the die is the finished work piece.
Overview of Production Process
6
• Drilling: The work piece is clamped on the work table and drill is fed into for generating a hole and
enlarging an existing hole. It is the operation of making a uniform hole through the work piece with
the help of a cutter known as ‘drill bit’. The hole can be made by rotating the job also.
• Facing: Facing is an operation of producing a smooth flat surface on the face of the job.
• Flame cutting or gas cutting: It employs an oxyacetylene torch, which may be directed either by hand
or pantograph and cuts up to 40inch.thickness. Flame cutting is an inexpensive method. Gas cutting
is the process of heating the metal to red hot temperature and then oxidising it by an oxygen jet. The
metal oxide is removed by the pressure of the oxygen jet. Oxyacetylene flame is used for heating. A jet
of high pressure oxygen is used to effect the cutting.
• Grinding: It is a process of removing the metal form and finishing the surface of a metal object by a
grinder with the help of abrasive wheel rotating at high speed. It produces smooth and accurate
surface finely finished at a quicker rate. It is suitable for repetitive jobs and for mass production.
Grinding may be done on the job of any size or shape and on internal as well as external surfaces. It
ensures high dimensional accuracy and surface finish. Normally the grinding follows some other
machining like turning and milling etc.
• Milling: Milling is a method of removing metal with a milling cutter in order to produce specific
shape. The function of milling is to dress a flat or other surface to a fine finish, surface forming of gear
teeth, keyways etc.
• Parting: In this process, a parting tool or hack-saw is used for cutting off a part from the job.
• Plaining and Shaping: In shaping, the tool is reciprocated while the work piece moves straight forward
at each stroke. In Plaining, the work piece reciprocates while the tool is moved for each new stroke.
The shaper takes small work pieces and the planer takes larger work pieces.
• Punching: It produces cut-outs or perforations on plate surface e.g. holes in washer and slots in channels
with the help of combination tool known as “punch and die”.
• Reaming: The main purpose of reaming is to smooth the hole. In this process, a multiple point cutting
tool called ‘Reamer’ is used.
• Sawing: Sawing is a cutting operation done by saw. Common types are Hacksaw, Circular saw and
Band saw.
• Screw cutting: It is a process of cutting screw threads on the outside surface of a job with the help of
a multiple point cutting tool known as ‘Die’.
• Slotting: This process is used to produce the slots on the job.
• Taper Turning: After turning, it produces conical shape instead of cylindrical shape.
• Tapping: In this process, a multiple cutting tool called “Tap” is used for making threads on the inside
surface of a hole.
• Turning: The work piece mounted on the lathe rotates at high speed above its axis. The path of the
tool is parallel to the axis and the cutter is applied to the work piece as it turns thus chipping away the
metal. Then a cylindrical external surface is formed. It is the operation of cutting and removing material
from the surface of the job.
No comments:
Post a Comment