The plain milling machine is rigid and sturdy machine and can accommodate heavy work plece.
It is used for producing grooves, slots on bolt head, keyways and other simple operations.
The plain milling maching its construction and working is explained below:
Construction:
Base: It is a heavy cast iron casing at the bottom of the machine. It carries a column at its one end. It also serves as reservoir for the coolant.
Column: A vertical column mounted on base carriers accurately machined guideways on its front face. A spindle is mounted on the front face of column. Guideways are machined on its front face.
Knee: A knee is mounted on the front face of column and can slide in vertical direction on the guideways. The knee can be operated by the elevating screw provided below the knee. Machined guideways are provided on the top surface of the fence.
Saddle: It is mounted on the knee and can move over it in cross-direction.. Accurately machined grideways are provided on top of saddle.
Table: The table is mounted on saddle and can be moved in longitudinal direction. The table is provided with T-slots to hold the workpiece. Also the cutting fluid can be drain back to the reservoir through these slots.
Overarm: The overarm is mounted on the top of the column. It supports the overhanging arbor through yoke.
Arbor: It is the extension of spindle over which milling cutters can be mounted. The distance between cutter can be adjusted by using spacing collars.
Working:The work plece is mounted on the table and can be moved in three directions. Vertical by moving the knee, longitudinal by moving the table and cross-wise by moving the saddle.A milling cutter is mounted on the arbor and rotates about the horizontal axis at a high speed.The work plece is first made to touch the cutter by moving the table and then machining takes place.
(Source: Nirali Prakashan Textbook Advance Manufacturing Processes)