CAPSTAN AND TURRET

Comparison among Centre , Capstan Lathe and Turret Lathe :

Feature Centre Lathe Turret Lathe Capstan Lathe Headstock Cons pulley or all gear Heavy construction, Same as Turret Lathe driven. Can Provide wider range of spindle lesser speed than the speeds from more other two powerful motor than centre lathes Toolpost Usually a single Toolpost Its cross slide carries a Same as Turret Lathe (with a single ). square turret type Sometimes, a square Toolpost carrying 4 . turret type Toolpost is Additionally, it has a provided which can hold Toolpost at its rear to 4 tools. hold 1 or 2 tools. Tailstock Usually used for Carries a hexagonal turret Carries a square, round supporting the WP. head instead of tailstock, or hexagonal turret Sometimes, some cutting which may hold a tool or called Capstan head in tools (, reamers etc) tool head on each of its place of tailstock. This installed to perform face. They are provides the same operations at the end face automatically indexed in facility of mounting and of WP. sequence to bring each 4-6 tools as in tool in proper position for case of turret lathe. performing operations sequentially. Leadscrew Always provided on Thread cutting generally Same as Turret Lathe centre lathe to enable performed by taps and die thread cutting by a single heads fitted to the turret point tool. head. Method of Not applicable Turret head directly Capstan head is mounting the mounted on a saddle and mounted on a ram or Turret or for feeding the tool on the slide , which travels on Capstan Head WP the entire saddle has the fixed saddle. The to be moved. tools are fed on the WP by moving the slide . No. of tools Usually 1 for single tool 4 tools on the front tool Same as Turret Lathe mounted post. If a square turret post, 1 or 2 on the rear type Toolpost is provided tool post and 4-6 tools on then 4 tools can be the square or hexagonal mounted. turret head. No. of tools can be increased by using multiple tool holders on the turret . Skill required Very high Very nominal after setting Same as Turret Lathe for operator of tools Tool setting High. Tool has to be Initial tool setting time Same as Turret Lathe time changed every time a required. During new operation is to be operation all the tool are done. available in the turret. Degree of Very nominal (manual) Semi automatic Semi automatic automation Application More versatile. Made in Used in mass production Used for relatively various sizes and of identical components. lighter and smaller jobs capabilities to handle Can handle heavier jobs than turret lathes, but jobs of various sizes and than capstan lathes. with more precision. level of machining. Rate of Lower Higher Higher production Overhead Less than the other two Higher than centre lathes Same as Turret Lathe charges because of higher initial investments, more power consumption and higher maintenance. Labour cost Higher (require skill Lower, because after Same as Turret Lathe labour) initial tool setting unskilled/semi-skilled labour is required.

Difference between a Turret and Capstan Lathe:

S. No Turret Lathe Capstan Lathe 1. Its turret head is directly mounted on the Its turret head is mounted on an auxiliary saddle slide which moves on the guideways of the saddle . 2. For feeding the tool on the WP, the entire For feeding the tool on the WP, the slide saddle is moved moves over the guideways of fixed saddle 3. The above arrangement enables better As the ram or slide is overhung, hence less rigidity as all the cutting forces are rigidity due to vibration, bending and transferred to the lathe bed deflection. 4. Due to the above, this lathe can Due to the above, its use is confined to accommodate heavier WP, involve heavier relatively lighter and smaller jobs. cutting forces and severe cutting conditions. 5. Operations my be performed on bars size Up to 60 mm diameter only. up to 200 mm in diameter 6. Since the turret saddle (along with all the Tool feeding done by movement of slide tools) moves over the guideways of the over the saddle. Hence, movement is limited lathe bed, hence it can move almost the entire length of the bed. 7. Heavier designs of turret lathes are No such arrangements provided provided with pneumatic or hydraulic chucks to hold the heavier jobs firmly. 8. Some versions of this lathe may provide for No such arrangements provided cross feeding of the hexagonal turret.