Principle Parts of Column and Knee Type Milling Machines 

 The main parts of all column and knee type milling machines are similar but, only the movements are different. All these machines consist of following main parts

 Base

Column

Knee  

Table

Saddle 

Overarm

Arbor

1. Base

 Base is a heavy casting and provided at the bottom of the machine.

On both the top and bottom surfaces, it is accurately machined.

 It acts as a load taking member for all other parts of the machine and a reservoir for the coolant.

Column of the machine is secured to the base.

Also, the base carries a screw jack which supports and moves the knee.

2. Column

Column is very important part of a milling machine and produced under careful attention because on the column many parts and controls are fitted.

Vertical parallel guide ways are provided on front face of the column in which knee slides up and down.

Also, on the top of the column overarm is supported.

3. Knee

Knee is a rigid casting which is capable of sliding up and down along the guide ways provided on front face of the column. 

With the movement of the knee, the table height or distance between the cutter and work piece can be adjusted. 

By operating the screw jack with the help of hand wheel or Powel feed, the height can be adjusted.

For cross movement of the saddle and table, horizontal guide ways are provided the top surface of the knee.

Two bolts are usually provided on front face of the knee for securing the braces it.

4. Table

Table acts as a support for the work piece.

Table is generally made of cast iron with its top surface accurately machined.

To accommodate the clamping bolts for fixing the work piece, the top surface of the table carries longitudinal T-slots.

Also, the cutting fluid after it is used drains back to the reservoir through slots these and for this purpose pipe is fitted.

Longitudinal feed is provided to the table by using hand wheel fitted on one side of the feed screw.

Vertical feed is provided by raising or lowering the knee and cross feed by the moving saddle.

Also, in case of universal milling machine, the table can be swiveled in a horizontal plane around the center of its base.

3. Saddle

Saddle is the intermediate part between the table and knee which acts as a support for the table.

To provide cross feed to the table, the saddle can be adjusted crosswise along the guide ways provided on the top of the knee.

Also, horizontal guide ways are provided at the top of the saddle along which the table can be moved in a longitudinal direction.

4. Overarm 

 It is the heavy support provided on the top of the milling machine (in plain and universal milling machines).

To support the projecting arbor, it can slide horizontally, forward and backward and adjusted at required position.

5. Arbor

Arbor is used for holding the milling cutters during the operations.

It is a common method of mounting the cutters, although they are mounted on the machine spindle directly too.

The arbors are mainly of two types i.e. standard arbor and stub arbor.

Standard arbor is provided with a set of spacing collars, which helps in adjusting the cutter position.

The slots are provided on the flange of the arbor to engage the driving dogs of the spindle.

Stub arbors are used to hold face and side milling cutters, which do not need a large overhang.

Milling Arbor

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