Everything You’ve Ever Wanted to Know About Milling Process.


Define milling process?

Milling could be a machining operation that’s performed with a rotary cutter with several cutting edges arranged on the circumference of the cutter.

This process creates flat surfaces or curved profiles and lots of other complex shapes with great accuracy and also contains a superb surface finish.

What is a milling machine?

A milling machine is the one which removes metal because the workpiece is fed against a rotating multipoint cutter.

The arbor can accommodate one or more cutters simultaneously within the miller.
In many applications, because of its higher production rate and accuracy, the milling machine has even replaced shapers and slotters.

Fig. 1 Multi-Point Cutter
What is the principle of milling process?

In this machine, the metal is cut employing a rotating cutter having multiple cutting edges.

For cutting operations, the workpiece is fed against the rotary cutter.
As the workpiece moves against the cutting edges of the milling cutter, metal is removed in the form of chips.
The machined surface is created in one or more passes of the work.
The work to be machined is held in a vice, a rotary table, a three- jaw chuck, an index head, between centers, in an exceedingly special fixture, or bolted to a machine table.

What are the basic types of a milling process?

There are 2 basic types of the milling process.

  • Up / Conventional milling process.

  • Down / Climb milling process.

Fig.2 Up & Down Milling Process

  • Up / Conventional milling process. 
In this style of process, the metal is removed in the form of small chips by a cutter rotating against the direction of the travel of the workpiece.
The chip thickness is minimum at the beginning of the cut and maximum at the top of the cut.

  • Down / Climb milling process.
Cutter moves in same direction as that of the workpiece and removes the material. 

In this style of process, it is claimed that there’s less friction involved and consequently less heat is generated on the contact surface of the cutter and workpiece.

Power consumption is reduced by this process.

What are the types of milling process?

This process is broadly classified as:

  • Peripheral milling
  • Face milling
  • End milling

Fig.3 Peripheral & Face Milling Process

  • Peripheral milling:

In this process, the cutting edges are on the circumference of the milling cutter and also the milled surface is mostly parallel to the cutter axis.

The peripheral milling cutters are supported on an extended arbor.
The deflections of arbor cause changes in dimensional and form accuracy of this process.
Horizontal milling machine normally uses peripheral milling cutters. 
  1. Peripheral milling is adopted for the following machining operations:

        a. Slab milling to provide flat surfaces. 

        b. Slot milling to supply precision slots.

        c. Slide and face milling to machine adjacent horizontal and vertical surfaces.

        d. Form milling to supply the prismatic shape of any form.

        e. Straddle milling to machine 2 parallel vertical surfaces.

        f. Gang milling to machine a variety of surfaces simultaneously with a collection of cutters.

Fig. 4 Different Peripheral Milling Process

  • Face milling:

In this process, the cutting edges are provided on the face likewise as on the periphery of the cutter, the surfaces generated is parallel to the face of the cutter and is perpendicular to the cutter axis.

This process is widely used for milling operations involving a high metal removal rate.
The operation of face milling is typically through with a face milling cutter having coated tungsten carbide inserts.
Face milling cutters are employed in conjunction with vertical shaper.

Fig. 5 Face Milling Process

  • End milling:

 End mills are capable of performing peripheral further as face milling operations simultaneously.

It has got cutting edges on the underside face additionally as on its periphery.
They are used for machining edges, shoulders, grooves, slots, and keyway pockets.
End mills have a tapered shank that matches into a tapered sleeve provided within the spindle of a vertical shaper.

Today, end mills are available in many tool materials.

  1. Cobalt High-Speed Steel (Super H.S.S).
  2. Coated High-Speed Steel.
  3. Solid Carbides.
  4. Micrograin solid carbides.
  5. Indexable inserts of cemented carbide or coated carbide.

What are the types of milling machines?

The classification of 5 types of milling machines are as follows:

1. Column and knee type milling machines.

a. Hand milling machines.

b. Horizontal milling machines.

c. Universal milling machines.

d. Vertical milling machines.

2. Planer milling machines.

3. Fixed bed type milling machines.

a. Simplex milling machines.

b. Duplex milling machines.

c. Triplex milling machines.

4. Machining center machines.

5. Special type of milling machines.

a. Rotary table milling machines.

b. Planetary milling machines.

c. Profiling machines.

d. Duplicating machines.

e. Pantograph milling machines.

f. Continuous milling machines.

g. Drum milling machines.

h. Profiling and tracer controlled milling machines.

Milling Machine pdf:
Frequently Asked Questions:
What is the process of milling?

Milling could be a machining operation that’s performed with a rotary cutter with several cutting edges arranged on the circumference of the cutter.

What is milling used for?

This process creates flat surfaces or curved profiles and lots of other complex shapes with great accuracy and also contains a superb surface finish.

What are the types of milling?

The types of milling are as follows:

  • Peripheral milling
  • Face milling
  • End milling

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