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WORKING PRINCIPLE AND TYPES OF MILLING MACHINE

We have discussed in our previous post CNC Cylindrical Grinding machine about the fundamentals and objective of CNC cylindrical grinding machine, we have also seen various parameters which must be measure on cylindrical ground and various sensors used for smooth operation of CGM and their importance in CGM operation. 

Today we will focus on milling operation, where we will see here the basic of milling process, Principle of milling operation, up milling versus down milling and finally we will see the classification of milling machines.  

So let us start to discuss first the basic of milling operation

Milling is basically known as most common type of machining process of removing the unwanted material from workpiece. Workpiece will be machined by inserting against one rotating cutter and rotating cutter will have a number of cutting sharp edges. Unwanted material will be cut away in small-small chips to secure the desired shape. Workpiece might be curved, flat or with irregular surface. Milling process is basically prefer to use in order to produce parts those are axially unsymmetrical and with various features e.g. holes, pockets, slots or might be with 3D surface contours.

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Milling machine will have one spindle and one reciprocating adjustable working table. Spindle will be driven by electrical motor and it will mount and rotate the milling cutter. Working table will mount the workpice and insert against rotating cutter.

Working Principle of Milling machining operation

Adjustable working table of milling machine will hold the workpiece and movement of adjustable working table will govern the feeding of workpiece against rotating milling cutter. As we have discussed above, rotating cutter will be mounted with spindle which will be driven by electric motor and hence rotating cutter will rotates with high rpm. Rotating cutter will have only one motion i.e. rotating motion and apart from rotating motion, there will not be any movement in rotating cutter. When workpiece will be inserted against rotating cutter, rotating cutter teeth will remove the unwanted material from the workpiece to secure the desired shape.


Figure shows the principle of milling process. We have shown here up milling and down milling on the basis of direction of feeding of workpiece with respect to direction of rotating cutter.
Let us see the comparison between up milling and down milling

S. No.

Milling Operation : Up milling

Milling Operation : Down milling

1
Direction of feeding of workpiece and direction of rotating cutter will be opposite
Direction of feeding of workpiece and direction of rotating cutter will be same
2
Up milling process used for machining hard materials
Down milling process used for machining soft materials
3
Unwanted material will be removed in form of thicker chips  
Unwanted material will be removed in form of thinner chips  
4
Larger clamping force will be required because cutting force will be in direction of upwards and will tend to lift the workpiece
Larger clamping force will not be required because cutting force will be in direction of downwards and will tend to press the workpiece against the working table.
5
Chips will be accumulated at cutting area
Chips will be thrown away during cutting process
6
Surface finishing will be poor
Surface finishing will be good

Classification of milling machines

Milling machines are classified basically in two types as mentioned here
  1. Vertical milling machine
  2. Horizontal milling machine


Image courtesy: Google

There are few more classifications of milling machines.

  1. Knee type milling machine
  2. Ram type milling machine
  3. Bed type milling machine
  4. Planner type milling machine
  5. Special purpose milling machine

Special purpose milling machine

  1. Thread milling machine
  2. CNC milling machine
  3. Tracer controlled milling machine
Do you suggestions? Please write in comment box

Also Read

Shaft alignment techniques
Shaft alignment terminology
Basic of shaft alignment
Shaft alignment procedure

3 comments:

  1. thanks for the tips and information..i really appreciate it.. CNC machining service

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  2. Much thanks for composing such an intriguing article on this point. This has truly made me think and I plan to peruse more stainless steel turning parts factory

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  3. PTJ is a globally recognized and renowned manufacturing solutions provider.We developed this reputation by dutifully maintaining an unwavering commitment to providing unparalleled levels of quality and precision in all that we do. This commitment was a pillar of PTJ when we were founded in 2007 and it still remains an important pillar today.One of the ways PTJ ensures quality and precision parts for our clients is with our Swiss turning capabilities.Swiss Turning vs CNC TurningThe turning process, sometimes referred to as lathing, is a machining process that dates back to ancient Egyptian time.Though ptj uses state of the art, automated computer numerical control (CNC) turning machines as compared to ancient Egyptians’ hand-turned lathes, the underlying mechanics of the process are virtually unchanged. Material, generally bar stock, is spun at a high rate of speed around its longitudinal center. Cutting tools, various rotary and non-rotary tool bits alike, are used to remove material from the spinning workpiece.Swiss turning — which is also referred to as Swiss machining or Swiss screw machining — is a virtually identical process to CNC machine with one small, but important, difference.When bar stock is spun on a one sided lathe, as with all CNC turning and Swiss turning machines, the centrifugal force can sometimes cause wobbling in the bar. This wobbling in the bar, though often imperceptible to the naked eye, can cause loss of tolerance in parts. Both longer and narrower parts are susceptible to this wobbling.Swiss style machines are designed to reduce this wobbling and neutralize its effects, thus resulting in perfect precision in even very long and very small diameter parts. It does this in two ways.First, Swiss turning machines incorporate a guide bushing near the collet chuck, which is the opening that the bar stock is fed through. The guide bushing helps to stabilize the rotating bar stock, minimizing wobble. Second, all of the cutting cools on a Swiss machine perform their duties next to the guide bushing, reducing the deflection from the force of the tool as well as wobble from the rotation of the bar.Let’s get started! Request a quote today! >>>Swiss Machining at PTJPTJ’s two modernized facilities — DONGGUAN and Suzhou, China — are equipped with a number of cutting edge Swiss turning machines from Star, Traub, and Tsugami. With this high quality equipment, we can guarantee high quality and precision in all parts, including small diameter and long parts which are traditionally difficult to keep in tolerance.To learn more about our Swiss machining capabilities, contact PTJ today

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