7 Internal Grinding Machine

Report No : 07 Shop : MT (Light)

Title : Study & Observation the MT (Light) Shop. Lathe Section Lathe is one of the most important machines in any workshop. The initial objective of using a lathe was to remove material from the outside of logs of wood while they were revolving, thus producing a cylindrical shape that is uniform in diameter. Removal of material from a piece of revolving work is still the main purpose of a lathe and it can also be used to perform many other jobs as well. Principal parts of a lathe machine :(1) Bed (2) Headstock (3) Tailstock (4) Carriage (5) Feed mechanism (6) Thread-cutting mechanism (7) Tool post (8) Live centre (9) Dead centre (10) Spindle The machinery operations that may be performed on a lathe: straight turning, taper turning, facing, straight boring, taper boring, knurling, external threading, internal threading, drilling, reaming, and undercutting.

Types of lathe machine and their advantages & disadvantages:-

Types of machine

lathe

1) Center lathe

Advantages

Disadvantages

•All types of lathe operation can be • It requires more time to attach performed.

different cutting tools • Not more than one cutting tool can be attached at a time.

2) Vertical lathe

•All types of lathe operation can be performed.

• Not more that one cutting tool can be attached at a time.

•Lathe operations can be performed in a comparatively large work piece. 3) Capstain lathe

•Drilling in several steps (maximum

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6 steps) can be performed by attaching different sizes of drill bit in a tool-post at a time. •Less time is required in making a desired shape of job. 4) Semi-Capstain lathe

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• Comparatively less no. of cutting tools can be attached in a tool-post at a time.

Milling Machines A milling machine is one that is designed to remove metal and other materials from a piece of work with a revolving cutter as the work is fed against it. Principal parts of a milling machine:(1) Column, (2) Knee, (3) Table, (4) Spindle, (5) Over-arm Types of milling machine and their advantages & disadvantages:-

Types of machine

milling Advantages

Disadvantages

1) Vertical milling machine It is used for face milling, profiling, diesinking and various odd- shaped jobs.

• Vertical milling attachment is used for vertical milling operations with large end mills and face mills. The spindle head can be swiveled accurately to any degree required from angular milling.

•More time is consumed ad different attachments are required for face milling, profiling, die sinking and various odd shaped jobs.

2) Horizontal milling machine

• Vertical machine attachment is used for horizontal milling operations with large end mills and face mills. The spindle head can be swiveled accurately to any degree required from angular milling.

•More time is consumed ad different attachments are required for face milling, profiling, die sinking and various odd shaped jobs. •Spiral –bevel gear can not be cut by horizontal milling machine •Only gear can be cut by hob milling machine.

It is used for face milling, profiling, diesinking and various odd- shaped jobs.

3) Hob milling machine It is specially used for cutting gears. Different types of cutter are end mill cutter, side milling cutter, angular cutter, double angle cutter, convex cutter, concave cutter and corner rounding cutter.

•All types of gear can be cut by hob milling machine. •In case of cutting gears no attachment is required.

Grinding Machine A grinding machine is a machine which employs a grinding wheel for producing cylindrical, conical, or plane surface accurately and economically, and to the proper shape, size and finish. Types of Grinding Machine:1) Cutter Grinding Machine:- A cutter grinding machine is a machine that holds the cutter while a rotating abrasive wheel is applied to the edges for the purpose of sharpening it. Main parts of this machine are work head, work head spindle, longitudinal slide, wheel head, wheel head spindle and vertical slide. 2) Cylindrical Grinding Machine (External):- External grinding, as commonly thought of, is the act of grinding the outside diameter of a piece of work while it is revolving on its axis for the purpose of reducing it to size, and leaving a fine finish. However, external grinders are also used to produce external cams, eccentrics and special forms on the outside diameter of work. Capacity: Bed size – 42 inches, Max. diameter – 10 inches, Max. length – 6 ft. Operation: Grinding the outside diameter of a piece of work, producing external cams, eccentrics, and special forms on the outside diameter of work. Advantages •After a job has been heat-treated (hardened), a good surface finish and extreme accuracy as to size can be obtained. •If parts can be designed so that the amount of stock to be removed is within grinding limits, the grinding is much less costly than lathe turning. Speed: Max. Speed -2000 r.p.m. 3) Surface Grinding Machine:- Surface grinding is the act of producing and finishing flat surfaces by means of a grinding machine employing a revolving abrasive head. Capacity: Max. length - 3 ft., max. width -12 inches, max. weight - 60 kg. Specification: Magnetic table Speed – Max. speed – 2800 r.p.m. Limitation: Only flat jobs can be machined, the cylindrical shaped job can not be machined by this grinding machine

4) Internal Grinding Machine:Internal grinding is the operation of grinding straight-cylindrical, tapered or formed holes to accurate size. Capacity: Max. length – 2.5 ft., max. diameter -5 inches 5) Center Grinding Machine:In center grinding machine headstock and tailstock are not included. Capacity: Max. diameter - 8 inches. Advantages: It can be used for large production. Limitation: The job must not involve more than step. 6) Jig Boring Machine:Hard metal can not be cut by this machine as there is no grinding wheel in this machine. Capacity: Max. diameter - 4 inches, max. length – 5 ft. Specification: Boring spindle Main partsEnd mill cutter – for cutting slot, face is flat (2, 3 & 4 slot) Drill cutter - Face is an angle- 2, drill angle – 116 Boring output – Center punch – Central drill – boring. Advantage: Max. accuracy can be maintained (0.0001 inch or 0.002 mm). Limitation: Atmospheric temperature must not exceed 400C. If the temperature is exceeded, the spindle will jump. Speed: Max. speed 2500 r.p.m. 7) Jig Grinding Machine:-

It can be operated for hard and soft metals. Main parts: Grinding wheel, grinding head and air compressor Capacity: Max. diameter - 8 inches, max. length – 5 ft Speed- 1,60,000 r.p.m Advantage: Both hard and soft metal can be operated here as grinding wheel is provided. Disadvantage: This machine should be kept under 400C, otherwise grinding can not be performed.