Up Milling and Down Milling-Definition, Differences, Working, Advantages, Application, PDF

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Up Milling and Down Milling:

Let’s first understand the Milling Machine which I also written separate articles just check out. I will drop the link below.

Definition:

  • This machine perhaps most widely used in manufacturing industries after the lathe machine
  • However, In the case of lathe machine, the tools used there single point cutting tool but In the case of the milling machine, the tools used are multi-point cutting tools.
  • The milling is a process of metal-removing by feeding the work past a rotating multipoint cutter. The diagram is shown below:

MILLING MACHINE

  •  This machine can hold one or more, number of cutters at a time and rotates at high speed to remove the metal at a faster rate.
  • The metal removal rate is faster as compared to a lathe machine.
  • This machine is used to make gears like Spur gears, and also drill the workpiece bore, and produce slots.

Parts and its brief details:

Base:

  • It is the foundation part of a milling machine and all other parts are joined on it.
  • It carries the entire load so it should have high compressive strength and it is made up of cast iron.

Column:

  • It is mounted vertically on the base.
  • It supports the knee, table, etc. Work as housing for all the other driving member.
  • it is a hollow member which contains driving gears and sometimes motor for the spindle and the table.

MILLING MACHINE PARTS

Knee:

  • It is a casting that supports the saddle and table.
  • All gearing mechanism is enclosed within the knee.
  • It is fastened to the column by dovetail ways.
  • The knee is supported and adjusted by a vertical positioning screw (elevating screw).
  • The elevating screw is used to adjust the knee up and down by raising or lowering the lever either with the help of hand or power feed.

Saddle:

  • It is placed between the table and the knee, and work as an intermediate part between them.
  • It can moves transversally to the column face.
  • It slides over the guideways provided situated on the knee which is perpendicular to the column face.
  • The main function is to provide motion in a horizontal direction to the workpiece.
  • It is also made by cast iron.

Table:

  • It is a rectangular casting which is present on the top of the saddle.
  • The table is situated over the knee.
  • It is the part of a machine which holds the workpiece while machining.
  • It is made by cast iron and has T slot cut over it. 
  • It provides vertical motion by moving the knee up and down.
  • It provides horizontal motion by the feed screw.
  • It provides a horizontal (transverse) motion by moving the saddle.

Overhanging arm:

  • The overarm is used to fastened arbor support.
  • It may consist of one or two cylindrical bars which slide through the holes in the column.
  • It is made by cast iron.

Spindle:

  • The spindle is the main part of the machine which holds the tool in the right place.
  • The spindle provides the drive for arbors, cutters, and attachments used on a milling machine.

Arbor:

  • It is a mechanical part, on which is used as an extension part of the spindle in a horizontal milling machine.
  • It is fitted on the spindle whenever it’s required.
  • It holds the tool and moves it in the correct direction.

Arbor Supports:

  • There are generally two types of arbor supports used in the milling machine. The first one has a small diameter bearing hole, 1-inch in maximum diameter.
  • And the other one has a large diameter bearing hole, usually up to 23/4 inches.
  • The arbor support has an oil reservoir that lubricates the bearing surfaces.
  • It can be clamped anywhere on the overarm.
  • The arbor support is used only in the horizontal types of milling machine

Milling head:

  • It is the upper section of a vertical milling machine.
  • It consists of a spindle, driving motor and other controlling mechanisms.

Ram:

  • One end of the arm is attached to the column and other ends to the milling head.
  • The ram can be a moved transversally ( in and out) on the column by a hand lever.

Types/Classification:

Column and knee type machine:

COLUMN AND KNEE TYPE MILLING MACHINE

  • It is the very common milling machine types.
  • In this machine, a vertical column is attached to the bed which consists of all gear drives which rotate the knee and saddle.
  • A knee is situated on the base which provides vertical motion to the workpiece or which moves up and down.
  • A saddle is attached to the upper section of the knee which can move in the transverse direction.
  • The table is placed over the which can hold the workpiece by use of climbing bolts.

In this there are several machines like:

Vertical milling machine:

  • The spindle if this machine is in the vertical position.
  • No arbor is required in this machine.
  • The cutter tool has the cylindrical shape and the cutting edges are situated at the circumference of the cylindrical face.

Continue readings on Milling Machine

Up Milling:

  • The up milling is also called as conventional milling or Climb up milling.
  • In which the cutter and feed moves in the opposite direction i.e the rotary cutter moves against the feed.

up milling and down milling

  • With reference to the adjacent figure, the cutter rotates in the anti-clockwise direction, while the direction of feed is from right to left.
  • So, due to this opposite motion, the width of the cutting chips gradually increases from minimum to maximum.
  • There is massive friction between the cutter and workpiece which results in generating a large amount of heat.

Advantages:

  • This is a safe operation because It has no tendency to drag the workpiece into the cutter.

Application: 

  • The up milling is generally used for milling of casting and forging.

Down Milling:

  • The down milling is also called a Climb down milling.
  • In case of down milling, the cutter rotates in the same direction as that of the feed.
  • In down milling, there is less friction involved between the cutter and the workpiece as both.

up milling and down milling

  • Therefore, the cutter and feed are moving in the same direction. This small amount of friction results in the generation of minimum heat.
  • Here, the thickness of the chip varies from a maximum to minimum during the process.

Advantages:

  • This machine poses a longer tool life.
  • This machine produces a good surface finish.

Application: 

  • This type of machine generally used for finishing the operation like sawing, grooving, keyway cutting, etc.

Difference between Up and Down Milling Machine:

Sl.No Up Milling Down Milling
1. This machine is also called as conventional milling or climb up milling. Down milling is also called a climb down milling.
2. The cutting forces act upward. The cutting forces act downward.
3. Up milling is mostly used for rough cutting operations. Down milling is used for finishing operations.
4. Due to more tool wear rate, the durability of the tool is less. Due to less tool wear rate, the durability of the tool is more.
5. Tool wear rate is more, as the direction of the rotary cutter is against the feed. Tool wear rate is less, as the direction of a cutter is the same direction as the feed.
6. This process is mostly used in the conventional way of cutting the surface. Nowadays, down milling is a better operation choice then up milling machine.
7. Effective cooling is not required during cutting action. Effective cooling is possible during cutting action.
8. Cutter rotates against the direction of travel of the workpiece during metal cutting. Cutter rotates in the same direction of travel of the workpiece during metal cutting.
9. Poor surface finish. Good surface finish.
10. It requires a large amount of force compared to down milling. For down milling, there is a requirement of less force.
11. This machine is mostly used cutting of brass, bronze, and ferrous materials. And whereas this is applicable to aluminum and aluminum alloys.
12. Chip thickness starts at zero and increases towards the end of the cut. Chip thickness is maximum initially and reduces to zero at the end of the cut.

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3 thoughts on “Up Milling and Down Milling-Definition, Differences, Working, Advantages, Application, PDF

  1. Thanks for helping me understand that this machine is to remove the metal at a fast rate. I just got curious about how this works since my brother will be buying one. It appears that he will be using it for personal projects that he plans to sell online in the future. He has always been a tinker ever since we were kids. He even made his own kite back then without any help.

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