Chapter 9

Question 1

Numerical control

Answer 1

• auxiliary machine controlled equipment that may be applied to any kind of mechanical device that can function by repaying a certain cycle of operation
• most economical to use on relatively small quantity lots 1-2 hundred pieces
• closed loop design
• controlled motions called axes

Question 2

High energy beam machining

Answer 2

The laser
- plasma arcs and elections beams are heating sources for welding

• plasma arcs: localized energy inputs to that surface mat may be vaporized with small heating of adjacent material

Question 3

Ultrasonic machining

Answer 3

• abrasive machining process used for cutting hard materials by projecting tiny abrasive particles at the work surface at high velocities
• the heat is the transducer made with nickel laminations that are placed in a oscillating magnetic field amplified by a horn, most common boron carbide
• works best with material that is hard and brittle

Question 4

Electrochemical machining

Answer 4

Both the tool and the workpiece must be conductive
- different electrolytes are used so that the material revived from the anode forms insoluble oxides or hydroxides

-tolerances must be greater compared to eel to obtain proper flow the the electrolytes between the tool and the work

Question 5

Electrical discharge machining

Answer 5

-Oldest most successful, versatile and widely used
- electrons are separated by a dielectric hydro carbon oil, capacitors across the electrons is charged by a direct current power supply
- Advantages some shapes easy to produce, workpiece hardness is not a problem.

Question 6

Chemical milling

Answer 6

-shaping metals by chemical dissolution without electrical action
- areas of the part where material is not to be removed are first masked off with an oxidation resistant coating
- deep straight cuts impossible,used in the manufacture of electronic boards

Question 7

Electropolishing

Answer 7

-electrochemical only for improving a surface that is already good or complex and irregular shapes which are not accessible to mechanical or buffing equipment

• will remove material faster from high spots of the surface than from depressions

Question 8

buffing

Answer 8

• A fine abrasive carried in a wax or a similar substance is charged on the surface of a flexible wheel.

Question 9

polishing

Answer 9

• Any non-precision procedure providing a glossy surface but most commonly used to refer to a surface finishing process using a flexible abrasive wheel

Question 10

barrel finishing/ rotating barrel

Answer 10

-when large numbers of small parts that do not need to have sharp details or accurate dimensions require cleaning

Question 11

abrasives

Answer 11

• Are used as wheels, sticks or stones or in free form cuts by exactly the same mechanisms as waved single point cutting tool
• Aluminum oxide- cutting tools
• silicon oxide- tool grinding, low strength material
• diamond- for finish grading some of the harder cutting tools
  Boron- almost same hardness as diamond

Question 12

Friction sawing

Answer 12

Localized heat is created in the workpiece by contact with the edge of a disc or blade
- speed of 3000 to 7000 m/min

• KERF- slit or notch made by a saw or cutting tool

Question 13

Torch cutting

Answer 13

Keeping material being cut above its bending temp 800C for pure iron
- limited to mostly steels
- easily mechanized, scarfing (removal of discontinuities in large castings and forgings done commonly by flame cutting)

Question 14

Grinding

Answer 14

• Finishing Operation, rotates an abrasive wheel at high cutting speed for the cutting motion

Question 15

Straight line machine

Answer 15

Provides straight line motion for cutting motion

-Shaper: Straight line motion of the cutter
- Planer: Straight Line Motion of the Workpiece
Broach- Straight line Motion of special multitooth cutter

Question 16

Milling

Answer 16

• Employ multi edge cutters, multidirectional feeding and cutting
• principle cutting on their periphery Edges

Question 17

Drilling

Answer 17

-Special Fluted Tool with two or more cutting lips on its exposed end called a drill
- Drill press rotated and advanced axially into the workpiece

Question 18

Turning and boring

Answer 18

• Normally rotate the workpiece to produce the cutting motion and feed a single point parallel to the work axis
• Cylindrical machining called turning
  Internal cylindrical called boring
• making a flat face surface by feeding the tool perpendicular to the axis = facing

Question 19

Machining tools

Answer 19

• Group of equipment that hold a cutting tool and a workpiece and establish a suitable set of motions between the to remove material
• two motions necessary cutting motion and feeding motion
• 5 machine phases: turning and boring, drilling, milling, Straight line machines, grinding

Question 20

Rake Angle

Answer 20

-Angle of the cutting face relative to the work

Question 21

Lay

Answer 21

Lay of a surface is the direction of the predominant surface pattern

• Determined by the cutting motion

Question 22

Roughness

Answer 22

• relatively finely spaced surface irregularities, the height, width and direction which established the surface pattern

Question 23

Waviness

Answer 23

• Describes the variations of conformance that are relatively widely spaced or large in size

Question 24

Diamonds

Answer 24

• hardest material known to man, brittle and subject to failure from thermal shock
• used for machining low-tensile strength materials

Question 25

Ceramics/ cermets

Answer 25

-Powder metallurgy, most successful aluminum oxide - Economical to use for large amounts of material with uninterrupted cuts

Question 26

Cemented carbides

Answer 26

- Powdered metallurgical product of tungsten, titanium and or tantalum carbides - most important industrial cutting tool group - withstands temps over 1100 C or 2000F

Question 27

Cast Nonferrous Alloys

Answer 27

-Not normally machinable except by grinding - used for machining cast iron and malleable iron because of non abrasion resistance More commonly used as a structural material or coating

Question 28

High Speed steel (HSS)

Answer 28

- maintains cutting hardness and strength to about 550 Celsius or 1000 degrees Fahrenheit - Used where cutting speed has relatively small effect on overall manufacturing cost

Question 29

Carbon tool steel

Answer 29

- Plain high carbon steel containing .9 to 1.2 percent carbon machinable in its annealed condition - little use as a cutting tool material except for some special low use tools

Question 30

Chatter

Answer 30

Most chips from ductile material tends to form somewhat intermittently with some material adhering to the tip temporarily

Question 31

Chip Form

Answer 31

if material brittle will only stand a small amount of plastic deformation without fracture failure - If ductile, chip may hold together in a long strip

Question 32

Stresses

Answer 32

- external force applied in a single direction, may set up stresses in other directions within the material - Max shear stresses induced at 45 degrees to the direction of the resultant - plastic flow occurs when shear stresses reach critical value

Question 33

Tool motion

Answer 33

- face perpendicular to the tool face called normal face - face along the tool face, friction force - Come Together to give you resultant force

Question 34

Cutting Tool

Answer 34

- Merely a device for applying external loads to the work material

Question 35

Deformation process ( Mainly Force energy over large area)

Answer 35

- All operations are basically three same that a given quantity of metal is placed in a new shape without any change in volume

Question 36

Welding ( Heat and force energy)

Answer 36

placing the metal in a molten or near molten condition by the addition of heat, effecting a union by fusion may include pressure.

Question 37

Casting ( Heat Energy)

Answer 37

heat energy when casting a material - Internal structure is changed and it becomes liquid

Question 38

machining

Answer 38

Most universally used and most important of the manufacturing processes - material removed called chips - preferred method for producing one or a few parts - high accuracies and surface finishes possible