Milling Machines, Milling Operations, and Work-Holding Devices (Week 9)

Question 1

Milling Machine Safety Guidelines?

Answer 1

1. Be sure the work and cutter are mounted securely before taking a cut,
2. Always wear safety glasses,
3. When mounting or removing milling cutters, always hold them with a cloth to avoid being cut,
4. When setting up work, move a table as far as possible from the cutter to avoid cutting your hands,
5. Never attempt to mount, measure, or adjust work until the cutter completely stopped,
6. Keep hands, brushes, and rags away from revolving milling cutter always,
7. Do not use an excessively heavy cut or feed - Cause cutter to break and fly apart,
8. Always use brush, not rag, to remove cuttings after cutter has stopped revolving,
9. Never reach over or near revolving cutter - Keep hands at least 12-in from revolving cutter,
10. Keep floor around machine free from chips, oil, and cutting fluid

Question 2

What is a Milling Cutting Tool?

Answer 2

A milling cutting tool is like the single point tool used in turning operation tool, but many cutters called “multi cutting teeth” integrate it.

Question 3

What is a Milling Machine?

Answer 3

Milling machine which is used to remove metals from the workpiece with the help of a revolving cutter called milling cutter.

It is used to machine the flat, rough and irregular surfaces and this is done by feeding the workpiece against a rotating milling cutter

Question 4

What are 3 types of Milling Machines?

Answer 4

1. Vertical Milling Machine
2. Horizontal Milling Machine
3. Universal Milling Machine

Question 5

Properties of a Vertical Milling Machine?

Answer 5

In the vertical milling machine, the spindle axis is vertically oriented.

Milling cutters are held in the spindle and rotate on its axis.

The spindle can generally be lowered (or the table can be raised), allowing plunge cuts and drilling.

Question 6

What are he Main Components of a Vertical Milling Machine?

Answer 6

Column and base:- provide support for the other parts of a milling machine. There is an oil reservoir and pump in the column to lubricate the spindle

Spindle: The spindle is used to hold and drive the cutting tools of a milling machine.

Knee:- supports the worktable. It has all the linear movements: X, Y & Z.

Ram:- the overhanging arm in the vertical machine is called a ram. One end of the ram is mounted on the top of the column and on the other end milling head is attached.

Question 7

How is a Bed-Type Vertical Milling Machine different from a standard Vertical Milling Machine?

Answer 7

The sliding table is mounted directly onto the massive bed of the machine and cannot be raised or moved transversely; table movement is longitudinal only.

Question 8

Properties of a Horizontal Milling Machine?

Answer 8

A horizontal mill has the same sort, but the cutters are mounted on a horizontal spindle across the table.

o It is a very robust and powerful machine.

o It is used when a vertical miller is less suitable. (if a lot of material must be removed by the cutters)

Question 9

What is the Arbor Support in a Horizontal Milling Machine?

Answer 9

It is a casting with a bearing that supports the outer end of the arbor. It also helps in aligning the outer end of the arbor with the spindle.

Question 10

Differences between Vertical Milling Machines and Horizontal Milling Machines?

Answer 10

Vertical Milling Machines :
1. In a vertical milling machine, a spindle axis is aligned vertically.
2. It is cheaper in price.
3. This machine requires a smaller area.
4. Its working capacity is low and tool life to low.
5. This type of machine is less powerful and are lighter in weight.
6. Operations : Angular milling, slot milling, T- slot milling, flat milling

Horizontal Milling Machines :
1. Here, a spindle axis is placed in a horizontal direction.
2. A horizontal milling machine is a little bit costly.
3. A horizontal milling machine requires a bit larger area.
4. It can do the work of 3 or 4 vertical milling machines easily and tool life is longer
5. It is heavier in weight and more powerful than vertical milling machines.
6. Operations : Plain milling, gear cutting, form milling, gang milling

Question 11

What are the main differences between Lathe and milling machines?

Answer 11

1. Machine axes:
   o Lathe machine has two main axes X and Z
   o Milling machine has three main axes X, Y and Z
2. Features:
   o Lathes spin the material,
   o Whereas a milling machine uses a spinning tool for various cutting operations.
3. Cutting Tools shape:
   o The main tool used on a lathe is a single-point cutting tool.
   o The most used tool on milling machines is the end mill, which is a multipoint cutting tool

Question 12

What is the main mechanical property should these cutting tools have?

Answer 12

The tool should be harder than the material of the workpiece.

Question 13

What is a drill vise?

Answer 13

A drill vise is used to hold round, rectangular, square work

Question 14

What is an Angle Vise?

Answer 14

An angle vise has an angular adjustment on its base to allow the operator to drill holes at an angle without tilting the drill press table

Question 15

What are V-blocks?

Answer 15

V-blocks, made out of cast iron or hardened steel, are generally used in pairs to support round work for drilling.

V-blocks are Used in pairs to support round work

Question 16

What are Step Blocks?

Answer 16

Used to provide support for the outer end of strap clamps

Question 17

What are Clamps for?

Answer 17

Used for big size or irregular parts.

Part is hold using clamps, t-slot bolts, screws, washers, nuts, parallels, step blocks,…

It is important to keep in mind the efforts/deformations produced on the part.

Question 18

What are 4 Milling Operations?

Answer 18

1. Plain milling operation
2. Face milling operation
3. Side milling operation
4. End milling operation

Question 19

What is Side or Peripheral Milling?

Answer 19

• Cutting depth in radial direction
• It uses mainly the cutting edges on the periphery of the tool.
• Surface roughness created by side teeth.

Question 20

What is Shoulder Milling (Face and Side Milling)?

Answer 20

• Cutting depth in axial and radial direction.
• It uses the cutting edges on the face and periphery of the tool.
• Surface roughness created by face and side teeth.

Question 21

What are some End Mill Forms?

Answer 21

Ground into required shapes :
o Flat bottom-end mill (most common)
* Used for all operations requiring flat bottom and sharp corner between the wall and bottom

o End mill with a full radius (ball nose end mill)
* Used for 3-D machining various surfaces

o End mill with corner radius (bull nose end mill)
* Used for either 3-D work or for flat surfaces that require a corner radius between the wall and bottom

Question 22

What is Down/Climb Milling?

Answer 22

o Cutting edge takes full thickness of cut at entry and exits at zero thickness

o Here the cutter and the workpiece move in same feed direction

o Increasing the tool life up to 50%

Climb milling—cutter rotation and table feed in same direction.

Question 23

What is Up/Conventional Milling?

Answer 23

o Most common method is to feed work against rotation direction of cutter

o Thin cut at entry with abrupt exit

Conventional milling—cutter rotation and table feed opposite directions.

Question 24

What is the difference between spot-facing and counterboring?

Answer 24

The difference between counterboring and spotfacing is that a counterbored surface usually has a shoulder at the bottom of the enlarged hole, while a spotfaced surface is flat, shallow, and always at right angles with the axis of the hole.