Mechanical Engineering Section M Machine Tool Practices Kibbe Section Computer Numerical Control And Other Advanced Machining

Machine Tool Practices, 11e (Kibbe)

Section M – Computer Numerical Control and Other Advanced Machining

1) The major programmable axes on a CNC machine tool are:

A) X, Y and Z

B) A, B and C

C) I, Q and J

D) C1, I5 and B2

2) On the XY plane, all points in quadrant III are:

A) Some negative and some positive

B) Positive

C) Inversely coded

D) Negative

3) Points plotted by Cartesian coordinates are:

A) Are always positive or always negative

B) Are plotted by circular arc dimensions

C) Are plotted by their linear distance from the origin

D) Defined in angular terms

4) The Z axis on all CNC machine tools is the:

A) Longest axis

B) Shortest axis

C) Spindle axis

D) Vertical axis

5) Word address programming specifies the movement or distances from the point where the

spindle is currently located.

6) Incremental positioning is coded in a CNC program by:

A) G91

B) G90

C) G92

D) G01

7) The Z axis is ________ to the XY plane.

A) tilted 23.5 degrees clockwise

B) perpendicular

C) tilted 14.3 degrees counterclockwise

D) inverted

8) When using polar coordinates, the X value represents the radius distance and the Y value

represents the angle from 0 degrees.

9) When the programmer makes a positioning error using incremental positioning, all future

positions are affected.

10) In polar coordinate dimensioning, points are defined by their rotational angular position from

the reference axis and by the radial distance from the origin.

11) In the absolute mode, each position location move is measured from a single start point

called absolute zero.

12) On a vertical milling machine the negative Z move would move down toward the table.

13) When facing a vertical machining center left and right table movement is the x-axis.

14) On a vertical machining center the spindle moving toward the table would be a Z+ motion.

15) CNC machine axes are moved by using the:

A) Pulse generating hand wheel

B) Jog buttons

C) A and B are correct

D) Manual control

16) When facing a vertical machining center in and out movement is the X-axis.

17) The linear axes or directions of travel of the machining center are defined by the letters X, Y,

and Z.

18) Most controls are equipped with a pulse-generating hand wheel for moving thee axes.

19) The C-axis is a rotational axis about the Z-axis.

20) The part origin is the X0, Y0, Z0 location of the part in the rectangular or Cartesian

coordinate system.

21) The feed hold will stop execution of the program, stopping the spindle and any other

miscellaneous functions.

22) After and emergency stop, the program can be continued by using the cycle start button.

23) Rapid traverse is coded in a CNC program by:

A) G01

B) G00

C) G03

D) G43

24) CNC programs are written in either conversational format or in the word address format.

25) Milling at an angle on a workpiece would be done in:

A) G01 linear interpolation mode

B) G02 angle/arc mode

C) G43 linear motion mode

D) G03 circular interpolation

26) G92 sets:

A) Turning mode

B) Workpiece coordinates at program start

C) Milling mode

D) Metric dimensioning mode

27) On a CNC vertical spindle machining center, a Z axis offset is:

A) The distance of the spindle to the Y axis

B) The distance from the tool tip to the work top surface in the X axis

C) The distance from the machine to the shop wall

D) The distance from the tool tip to the work top surface in the Z axis

28) G01 is a:

A) Linear move

B) Modal instruction

C) Rapid move

D) A and B are correct

29) A G43 is used for:

A) Tool offset right

B) Tool offset left

C) Non of the above

D) Tool length offset

30) The tool length offset is the distance from the tool tip at home position to the workpiece Z

zero position.

31) Circular moves can be programmed with a radius value.

32) I and J word addresses define:

A) Circular interpolation feed rates

B) Substitute words for linear interpolation in the XY plane

C) Arc center dimensions as measured from the start of the cut

D) Interpolate and justify programming code

33) Modal commands are:

A) Used only in specialized machining tasks

B) Initiated by the M words in the program

C) Repeated in every block until turned off

D) Also called miscellaneous function commands

34) A ________ code is used to start the spindle in a clockwise direction.

A) M02

B) M03

C) M01

D) M00

35) A ________ code is used to change tools.

A) M05

B) M07

C) M06

D) M08

36) Canned cycles (fixed cycles) simplify the programming of repetitive machining operations

such as drilling, tapping, and boring.

37) The Z position is very important when you call a canned cycle. The present Z position

becomes the Z initial plane. The machine will normally rapid back to the Z initial position before

a rapid to the next hole.

38) The R-plane is a rapid point to start feeding.

39) Tapping is done with a G81 drilling canned cycle, by adding the T parameter.

40) Subprograms can be used to reduce redundant programming and shorten programs.

41) On a CNC turning center, two types of tailstocks are available: manual and programmable.

42) On a turning center, the Z axis is in the same plane as the spindle, just as on machining

centers.

43) There are two kinds of offsets used on CNC turning machines: tool offsets and geometry

offsets.

44) The typical CNC turning center has two major axes, the X and y axes.

45) Parting is a machine operation that cuts the finished part off from the rough stock.

46) Geometry offsets, or workpiece coordinates, are used to tell the control where the workpiece

is located.

47) The feed hold will stop execution of the program without stopping the spindle or any other

miscellaneous functions.

48) Tool offsets, or workpiece coordinates, are used to tell the control where the workpiece is

located.

49) On a turning center the diameter of the work is controlled by the Z axis of motion.

50) Tool offsets, or workpiece coordinates, are used to tell the control where the workpiece is

located.

51) On a turning center the length of the workpiece is controlled by the X axis of motion.

52) To find the centerline of the workpiece, the operator takes a skim cut off of the outside of the

workpiece. The operator then measures the turned diameter and adds that dimension to the X-

axis machine position.

53) A standard startup procedure usually involves cancelling tool compensation, absolute or

incremental programming, standard or metric, and the setting of the work-plane axis.

54) An M06 tool change code is not used on the turning center for changing or selecting tools.

55) A turning center tool change of T0808 would load tool number 8 with offset number 8.

56) A G28 enables the programmer to determine how a turning center should move to home.

57) Circular interpolation is not used on turning centers.

58) A G41 code is used to offset the tool to the right.

59) Tool-nose radius compensation is a type of offset used to control the shape of machined

features.

60) ________ and ________ are used to represent the center of an arc in the X and Y axis on a

turning center.

A) I; J

B) I; K

C) X; Y

D) U; W

61) Constant surface speed can be used on a turning center to change the spindle speed based on

the diameter of the work.

62) A tool change call of T0604 would:

A) Return tool 6 to the zero position

B) Change the tool to 6 with an offset 4

C) Do nothing until an M06 is used

D) Not work as the tool number and offset number have to be the same

63) The spindle centerline on a turning center is the Z0 position.

64) In workpiece coordinate setting on a turning center, the spindle or workpiece center is the

location of the X0 position, and the Z0 position is typically the right end of the workpiece or the

chuck face.

65) Canned cycles are sets of preprogrammed instructions that can dramatically shorten the

number of lines in a program.

66) A G71 roughing cycle reads a specified number of program blocks to determine the part

profile, depth of cut, and feed rate. From the parameters in the program the control then

calculates all of the moves to rough the part out from the rough stock.

67) The G76 thread-cutting cycle can cut multi-pass threads with one block of information.

68) When using a G71 roughing cycle the programmer programs the point that specify the rough

shape of the part.

69) When programming a G70 finish cyle, the programmer can use the points that define the

shape used in the roughing cycle.

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70) On a wire EDM the wire never touches the material.

71) Brass is the most commonly used wire type on a wire EDM.

72) Water jet cutting is well suited to quickly cutting complex geometry that is difficult or

impossible by regular machining methods.

73) Abrasive waterjet systems inject an abrasive, usually diamond, into the jet of water as it

leaves the nozzle.

74) Abrasive waterjet cutting is very economical for low volume production.

75) Abrasive water jet cutting is limited to steels with a hardness of less than Rockwell Rc 60

and 1 inch of thickness.

76) A starting hole is not required for water jet cutting.

77) Layering is the term used to maximize the number of parts that can be made from a piece of

metal.

78) Laser machining can be used to cut extremely hard materials, such as titanium, hastelloy, and

inconel.

79) Gasses are used to assist in laser cutting.