Wednesday, January 9, 2008

Types of Lathe:

Lathes of various designs and constructions have been developed to suit the various conditions of metal machining. But all of them employ the same fundamental principle of operation and perform the same function.

Generally used Lathes are:

  • Speed Lathe
  • Engine Lathe
  • Bench Lathe
  • Tool Room Lathe
  • Capstan and Turret Lathe
  • Special Purpose Lathe
  • Automatic Lathe

The Speed Lathe:

The speed lathe, in construction and operation, is the simplest of all kinds of Lathe. It consists of a bed, a headstock, a tail stock and a tool post mounted on an adjustable slide. There is no feed box, lead screw or conventional type of carriage. The tool is mounted on the adjustable slide and is fed into work purely by hand control. This characteristic of lathe enables the designer to give high spindle speeds which usually range from 1200 to 3600 rpm. As tool is controlled by hand, the depth of cut and thickness of chip is very small.

The headstock construction is very simple and only two or three spindle speeds are available. Light cuts and high speeds necessitate the use of this type of machine where cutting force is minimum such as in wood-working, spinning, centering, polishing. Etc. The “Speed Lathe” has been so named because of the very high speed of the Head stock spindle.

The Engine Lathe or Centre Lathe:

This Lathe is most important member of the lathe family and is the most widely used. The term “Engine” is associated with the lathe owing to the fact that early lathes were driven by steam engines. Similar to the speed lathe, the engine lathe has got all the basic parts for example bed, head stock and tail stock. But the head stock of engine lathe is much more robust in construction and it contains additional mechanism for driving the lathe spindles at different speeds. Unlike speed lathe, engine lathe can feed the cutting tool both in cross and longitudinal direction with reference to the lathe axis with help of carriage, feed rod and lead screw. With these additional features an Engine lathe has proved to be a versatile machine adapted for every type of lathe work.

Engine lathes are classified according to the various deigns of the head stock and methods of transmitting power to the machine. A lathe that receives its power from an overhead line shaft is a belt driven lathe and is equipped with a speed cone and one or more back gears to get a wide range of spindle speeds. A lathe that receives its power from an individual motor integral with machine is called a motor driven lathe. A geared head lathe gets its power from a constant speed motor and all speed changes are obtained by shifting various gears located in headstock. It has no cone pulley.

The Bench Lathe:

This is a small lathe usually mounted on a bench. It has practically all the parts of an engine lathe and it performs almost all the operations, its only difference being in the size. This is used for small precision work.

The Tool Room Lathe:

The Tool room Lathe having features similar to Engine lathe is much more accurately built and has a wide range of spindle speeds ranging from a very low to a quite high speed up to 2500rpm. This is equipped besides other things, with a chuck, taper turning attachment, draw in collet arrangement, thread chasing dial, relieving attachment, steady and follower rest, pump for coolant etc. This lathe is mainly used for precision work on tools, dies, gauges and in machining work where accuracy is needed. The machine is costlier than an Engine lathe of same size.

The Capstan and Turret Lathe:

These Lathes are development of the Engine lathe and are used for Production work. The distinguishing feature of this lathe is that the tail stock of Engine lathe is replaced with a hexagonal turret, on the face of which multiple tools can be fitted and fed into the work in proper sequence. The advantage is that several different types of operations can be done on a work piece without re-setting of work or tools, and a number of identical parts can be produced in minimum time.

Special Purpose Lathe:

As the name implies, they are used for special purposes and for jobs which cannot be accommodated and conveniently machined on a standard lathe. The wheel lathe is made finishing the journals and turning the tread on railroad car and locomotive wheels. The gap bed lathe, in which a section of the bed adjacent to head stock is recoverable, is used to swing extra large diameter pieces. The T-Lathe, a new member of the lathe family is intended for machining of rotors for jet engines. The axis of the lathe bed is at right angles to the axis of head stock spindle in the form of T. The duplicating lathe is one for duplicating the shape of a flat or round template on to the work piece. Mechanical, air and hydraulic devices are all used to co-ordinate the movements of the tool to reproduce accurately the shape of the template. The Missile Lathe, which has a very large swing for accommodating long missile component of very large diameter, is the most modern and latest in Lathe design.

Automatic Lathe:

These are high speed, heavy duty, mass production lathes with complete automatic control. Once the tools are set and the machine is started it performs automatically all the operations to finish the job. The changing of tools speeds and feeds are also done automatically. After the job is complete, the machine will continue to repeat the cycles producing the identical parts even without attention of the operator. An operator will simply look after general maintenance of the machine and cutting tool, load up a bar stock and remove finished products from time to time.

1 comment:

Mikes said...

Lathe consists of a bed, a headstock, a tail stock and a tool post mounted on an adjustable slide. There is no feed box, lead screw or conventional type of carriage.

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