Difference Between Up Milling and Down Milling
Comparison between Up Milling and Down Milling
The Key Difference Between Up Milling and Down Milling is that In Up Milling the cutter rotates against the direction of travel of the workpiece. And, In Down Milling the cutter rotates in the same direction of travel of the workpiece.
|Up Milling||Down Milling|
|The cutter rotates against the direction of travel of the workpiece.||The cutter rotates in the same direction of travel of the workpiece.|
|The cutter rotates in the same direction of travel of the workpiece.||The chip thickness is maximum at the beginning of the cut and or reduces to a minimum when the cut terminates.|
|The cutting force is zero at the beginning of the cut and maximum at the end of the cut.||The cutting force is maximum when the cut begins and it reduces to a minimum when the tooth leaves the work.|
|The cutting force is directed upward and this tends to lift the workpiece from the fixture.||The cutting force is downwards which tends to seat the workpiece firmly in the fixture.|
|Difficulty in pouring the coolant just on the cutting edge, due to the typical nature of the cut.||The coolant can be poured directly at the cutting zone where cutting force is maximum.|
|The coolant can be poured directly at the cutting zone where cutting force is maximum.||Chips are disposed of easily and do not interfere with the cutting.|
|The actual cutting does not start at zero chip thickness as teeth slide through a minute distance which gives a slightly wavy surface.||Chips are disposed of easily and do not interfere with the cutting.|
What is the Up Milling?
- Up milling is also called as conventional milling.
- In this method, the cutter rotates in a direction opposite to that in which the workpieces.
What is the Down Milling?
- Down milling is also called as climb milling.
- In this method, the direction of rotation of the cutter and the direction of the workpiece fed is the same.
- The above relative directions of movements of the cutter and workpiece should be noted at the point of contact.
- By comparing both the figures it is found that the shape of the metal chip removed by the cutter is the same in both the cases.
- But in up milling, as the cutting proceeds, the chip thickness increases gradually whereas, in the down, milling chip thickness decreases slowly.
- In other words, chip thickness in up milling is zero at the start and maximum at the end of a cut, whereas in down milling chip thickness is maximum at the beginning and zero at the end of the cut.
- According to the nature of the workpiece, a particular method is selected.
- Up milling is generally used for machining of casting and forging, while down milling is used for finishing operations.
- Down milling is also used for small work such as slot cutting, milling grooves, slitting. etc.