Engineering Metrology Question Bank on “Sources of Errors in Manufacturing Gears”.
1. Which of the following is true for generating method of gear formation?
a) No use of cutter
b) Profiles of several teeth are formed simultaneously
c) Linear motion of the tool and the blank is not constant
d) Each tool space is cut independently
Answer: b
Clarification: Gear teeth are generally made by two methods, reproducing method and generating method. Method in which the cutting tool forms the several teeth profiles simultaneously during constant relative motion of the blank and tool is known as Generating method.
2. Which of the following is true for high power gears?
a) Operated at low speed
b) Operated at high speed
c) Operated at moderate speed
d) Operated at high or moderate speed
Answer: a
Clarification: High power gears are operated at low speeds generally but it has to transmit large force. Therefore for this purpose the gear teeth should specify fullest possible contact along the tooth length.
3. Which of the following gear is used for counting and timing purposes?
a) High speed gears
b) High power gears
c) Low speed gears
d) Precision gears
Answer: d
Clarification: Constant gearing ratio is the main requirement of the precision gears. Precision gears are generally used for indexing devices and measuring instruments, or in counting and timing purposes, and usually have small face width and small module.
4. What is the kinematic error in gears?
a) Minimum error in gear rotation per gear revolution
b) Accumulated permissible error in gear rotation per gear revolution
c) Maximum error in gear rotation per gear revolution
d) Accumulated permissible error in gear rotation in two gear revolutions
Answer: b
Clarification: Kinematic error is defined as the permissible accumulated error in gear rotation per gear revolution. The kinematic accuracy index is the maximum kinematic error. It can be defined as the maximum angular error in gear rotation, when it meshes in single-profile engagement with a precise gear.
5. What is profile error?
a) The minimum distance of any point on the profile of tooth form and normal to the design profile when the two coincide at the reference circle
b) The minimum distance of any point on the profile of tooth form and parallel to the design profile when the two coincide at the reference circle
c) The maximum distance of any point on the profile of tooth form and parallel to the design profile when the two coincide at the reference circle
d) The maximum distance of any point on the profile of tooth form and normal to the design profile when the two coincide at the reference circle
Answer: d
Clarification: Profile error is a possible error on spur, helical or bevel gear etc. It is the max distance of any point on the profile of tooth and normal to the design profile when two coincide at the reference circle.
6. What is a cyclic error?
a) Mean value of the discrete values of variation in the kinematic error of the gear taken for all cycles during one revolution
b) Mean value of the range of variation in the kinematic error of the gear taken for all cycles during one revolution
c) Mean value of the range of variation in permissible deviations in basic pitch of the gear taken for all cycles during one revolution
d) Mean value of the range of variation in the angular error of the gear taken for all cycles during one revolution