Plain Milling Machines

The base of the machine is a grey iron casting accurately planed above and below. The base serves as a foundation for the other parts of the machine and carries the column secured by bolts. The base also serves as a reservoir for the cutting fluid which flows down from the table through pipes. An electric coolant pump which feeds cutting fluid to the tool is mounted on the base.

The column is the main supporting frame. Some of the machine parts (speed gearbox, motor with the belt drive, transmission to the feed gearbox and spindle) are contained within the column and are not visible. Other parts (knee, feed gearbox, overarm, table and coolant pump) are mounted on the external surfaces of the column.

The column is box-shaped and is internally ribbed for greater rigidity; the front is a machined surface called the column face. It supports and guides the knee in its vertical travel. The top of the column has horizontal ways for the overarm.

The column is the principal component of a milling machine and is manufactured strictly to the drawing and specifications. It is cast from high-quality cast iron and is carefully machined.

The overarm is a component of both plain and universal milling machines. The overarm is mounted on horizontal ways on top of the column. It can be adjusted in and out with varying overhang.

The knee is a rigid grey iron casting which slides up and down on the vertical ways of the column face. It has horizontal ways for the saddle. It rests on a pillar containing an elevating screw which adjusts its height. The rigidity of the knee and the accuracy of its ways are of paramount importance for the operation of the machine.

The saddle is the intermediate part between the knee and the table. The saddle supports and carries the table and is adjustable transversely on the ways on top of the knee.

The table rests on ways on the saddle and travels longitudinally. It supports workpieces, fixtures and other equipment. It is provided with longitudinal T-slots for clamping work or fixtures.

The movements of the table, saddle and knee impart longitudinal, cross and vertical feed to the work relative to the cutter.

EXERCISES

1. Give different meanings of the following words:

To feed, knee, face, to travel, way, to cast, saddle, work.

2. Choose English equivalents to: