Machining

Question 1

What is machining?

Answer 1

General term to describe material removal process

• Cutting: involves single point or multi-point cutting tools such as turning, drilling, milling, sawing, etc..
• Abrasive process: Grinding, honing, lapping etc…
• Advanced processes: non-traditional machining that use electrical, chemical, thermal and hydrodynamic sources of energy to remove material

Question 2

Advantages of Machining

Answer 2

• Closer dimensional accuracy than deformation or casting
• Can produce external or internal geometry features like sharp corners
• Parts that were heat treated may require additional finishing operations to account for distortion
• If number parts are low it may be less expensive to machine rather than cast or deform

Question 3

Disadvantages of Machining

Answer 3

• Material Waste and more energy and labor needed than other processes
• Removing volume takes more time
• Removing material can alter surface integrity and effect fatigue life

Question 4

Basic method is a cutting tool moving along workpiece at certain speed.

What are independent variables of this?

Answer 4

• Type of cutting tool and its properties
• Shape of the tool
• Workpiece material
• Temperature it is machined at
• Speed, feed, depth of cut
• Tool holder and work holder devices

Question 5

Basic method is a cutting tool moving along workpiece at certain speed.

What are dependent variables of this?

Answer 5

• Type of chip produced
• Force required in the cutting process
• Temperature rise in the workpiece
• Wear and failure of the tool
• Surface finish and integrity of workpiece

Question 6

End Milling

Answer 6

• Milling involves various shapes and contours of the material and can be straight or tilted to produce tapered surfaces giving it 3 degrees of freedom.
• Commercial tolerances range between 0.13 - 0.25mm.
• Milling operates at a low to medium production rate or in the range of 1-100 parts per hour.

Question 7

Turning

Answer 7

• Turning has different tolerances based on the application of it. Fine turning will produce a tolerance between 0.05 – 0.13mm while rough turning will produce 0.13mm.
• This machining process are performed on all types of materials and operated on only a single point cutting tool therefore only having one degree of freedom. -
• Turning operates at a very low to medium production rate ranging between 1-100 parts per hour.

Question 8

Drilling

Answer 8

• Drilling has one degree of freedom
• It will produce commercial tolerances of 0.025mm
• Operates at a low to medium production rate producing around 10 – 100 parts per hour.

Question 9

Sawing

Answer 9

• Sawing has two degrees of freedom but is not suitable for hard materials unless coated with diamond or something equally hard.
• It produces commercial tolerances of 0.8mm
• Operates at a very low to low production rate.

Question 10

Machine Turning Center

Answer 10

Is a computer controlled machine tool capable of performing a variety of machining operations on different surfaces, locations, and orientations on a workpiece.