Lathe Accessories Use in Lathe Machine - ITI ONLINE NOTE

 Why Lathe Accessories Use in Lathe Machine? 

1- The lathe accessories are independent units supplied along with the lathe. 

2- The lathe accessories are essential for the full utilization of the lathe. 

3-  Lathe accessories can be grouped into two types

i- work-holding Lathe accessories 

ii- work-supporting Lathe accessories. 

Work-holding Lathe accessories 

1- The work can be directly mounted and held on these accessories. 

2- The following are work-holding accessories. 

i- Four jaw independent chuck.

ii- Three Jaw Chuck

iii- Face Plate

iv- Lathe Mandrels.

work-supporting Lathe accessories

1- These accessories do not hold the work themselves.

2- These accessories only for Supporting the work.

3- The following are the work-supporting accessories.

i- Catch Plate.

ii- Driving Plate.

iii- Lathe Centers.

iv- Lathe Carriers.

v- Steady Rest.

Chucks 

1- Chucks are used to hold workpieces of short length and large diameters or irregular shapes . 

2- This is attached to the lathe spindle and the work is held between the jaws of the chuck.

3- Some of the commonly used chucks are 

1- Three jaw universal chuck for circular objects . 

2- Four jaw independent chuck.

3- Magnetic chuck . 

4- Collet chuck . 

1- Three jaw universal chuck(Lathe Accessories) 

1- This chuck has three jaws . 

2- Three jaws chucks are used to hold round and hexagonal work .

3- When the chuck key is turned , all the jaws will move equal distance in radial direction and work is centered automatically.

4- The depth of cut is comparatively less . 

5- Work pieces cannot be set for eccentric turning . 

6- 3 - jaw chuck centering accuracy is lower . 

7- It has less gripping power . 

8- Setting up of work is simple .

9- Heavier jobs cannot be turned . 

10- Good all - round chuck for common round work need precision and excellent for repair work.

2- Four jaw independent chuck(Lathe Accessories)

1- This chuck has four jaws and each jaw can be moved independently .

2- These jaws have rotating screw which meshes with the teeth cut on the underside of the jaw .

3- Concentric circles are inscribed on the face of the chuck for quick centering of work pieces .

4- It can be used for non - circular object like turning of shank on a hexagonal headed bolt.

5- Non injector type blowpipe . 

6- Work pieces can be set for eccentric turning . 

7- 4-jaw chuck centering accuracy better than a 3-jaw chuck . 

8- It has more gripping power . 

9- Setting up of work is not easy .

10- Heavier jobs can be turned . 

11- Slower and more difficult to use for repeat work but more versatile.

3- Magnetic Chuck

1- Thin jobs can be held by means of magnetic chuck .

2- Work piece is held in position due to the magnetic power.

3- The main disadvantage is that only magnetic material can be held in this chuck .

4- Collet chuck(Lathe Accessories)

1- Collet chucks are used for holding bar stock in production work where quick setting and accurate centering is needed . 

2- The chuck consists of a thin cylindrical bushing known as a collet having a slot cut lengthwise on its periphery . 

3- Different sizes of collets are used for holding different sizes of the bar stock .

Face plate(Lathe Accessories) 

1- It is open slotted circular plate with large diameter . 

2- Work piece is clamped using T - bolts . 

3- Mounting work on face plate provides an ideal way of supporting works which cannot conveniently held by chucks .

Drive plate(Lathe Accessories) 

1- Drive plate is a slotted circular plate attached to lathe spindle . 

2- The drive plate is used to drive a work piece with the help of carriers ( dog ) . 

3- A lathe dog or carrier is securely clamped to the work piece and its bent tail fits into one of the slots in the face of the plate . 

4- Rotation of drive plate is transferred to work piece through dog .

Lathe centers(Lathe Accessories) 

1- Lathe centers are hardened devices used for holding and locating the work to be turned between centers . 

2- They are provided with a standard taper on one end and a 600 point at the other end . 

3- The center that is fitted in the headstock spindle is called live center . 

4- The center that is used in tailstock spindle is called dead center .

 Various forms of lathe center are 

Ordinary center 

Dead center 

Live center 

Half center 

Ball center

Antifriction ball bearing Center

Dead Center

1- Dead center is a non - rotating center . 

2- Tail stock center mostly act as a dead center . 

3- Dead center : used for general purposes .

Live center 

1- Live center is a rotating center . 

2- Head stock centers are live center . 

3- Used while machining the entire length of the job in one setting .

Half center 

1- Though it is termed as half center , little less than half is relieved at the tip portion . 

2- Used while facing the job without disturbing the setting . 

3- Used for taper turning and offers minimum wear and strain.

Ball center 

1- The ball center is used to minimize wear wear and strain . 

2- Particularly suitable for taper turning . 

3- Used while facing the job without disturbing the setting .

Antifriction ball bearing center

1- It eliminates the friction and permits work to be turned at high speed . 

2- It revolves with the work .

Carrier(Lathe Accessories)

1- A lathe dog or carrier is securely clamped to the face of the plate . 

2- The rotation of the drive plate is transferred to work piece through dog . 

3- Used to drive the work piece when it is held between two centers .

Rests

1- Provide additional support for long work pieces . 

2- It helps to prevent deflection of work piece under the action of cutting force of tool . 

3- The use of rest is recommended where the length of work piece is 10 to 12 times the diameter . 

Types of rests 

Steady Rest 

Follower Rest 

Steady rest 

1-Steady rest is clamped on the bed ways in the required position between head stock and tail stock . 

2- Work piece is supported by three jaws and hinged on the top . 

3- Used when a long piece is machined or drilled at its end by holding the job in a chuck . 

4- It avoids the chances of deflection of job at the other end.

Follower rest

1- It is mounted on lathe saddle and moves together with the carriage .

2- It performs the same function as the steady rest but it has two jaws which support the work opposite to the tool . 

3- It is used when the work piece is too flexible and needs continuous support.