Gear Cutting – Gear Manufacturing | Interview Question and Answers

Gear Cutting – Gear Manufacturing | Interview , viva , oral Question and Answers

1. Write any four advantages of milting gears?

The advantages of milling gears are:
1. All types of gears i.e. spur, helical, worm, bevel are possible and easy to cut.
2. Both roughening and finishing operations can be easily done and fine surface finish can be obtained.
3. It is useful for any tooth form
4. Initial cost is low

2. Where is the form of relieved convex involute gear used?

Involute gear cutter is used in forming of gear in milling machine.

3. State the principle involved in gear shaping?

The principle involved in gear shaping is that an involute gear will roll with any other involute gear of the same base pitch

4. What are the various methods of shaping the gear blank?

There are two methods involved in shaping the gear blank. They are:
1) Shaping with single point tool formed to the tooth space of the gear.
2) Generating with pinion type cutter.

5. What do you understand by gear generating?

Gear generating process is based on the fact that any two motives gear of the some module will mesh exactly. In this process one of the gears act as cutter. Due to relative rolling motion of the cutter and blank, gear teeth are generated.

6. Distinguish between the forming and generating methods?

Single point Tool (Forming): Here the tool is a single point tool. The job should be indexed for every tooth; The tool is fixed. Pinion type cutter (Generating): Here the tool is also a gear made of hard steels, (Used as cutter). The job is not indexed for every tooth. The cutter as well as the blank rotates simultaneously meshing with each other.

7. What are the factors affecting geometrical accuracy of the circular component . in shape?

Geometrical accuracy of the circular component depends upon:

a) The trueness of the work piece rotation,
b) Parallelism of the tool movement with the work spindle axis,
c) The effect of the tool wear.

8. Write the advantages of gear shaping (Generating)?

The advantages of Gear shaping are:

a) with a particular module of DP cutter, gears having the same module of DP but different number of teeth can be cut accurately,
b) Quicker and economical,
c) Only one cutter is used for cutting all spur gears of same pitch,
d) Both internal and external gears can be cut.

9. What is the main disadvantage of gear shaping?

The main disadvantage of gear shaping is that Worm and worm wheels cannot be generated on a gear shaper.

10. When do you prefer shaping process for generating a gear?

Gear shaping is preferred for operations like cutting gear segments, cutting, spur gear, herringbone gears, splines and sprockets etc., of gear shaping over other diameter.

11. What are the advantages of gear shaping over the other methods?

The advantages are:
a) The finished gear has a generated profile
b) It is suitable for cutting internal gears
c) Only one cutter is used for cutting all spur gears of the same pitch.

12. What are the specific types of gears that could be formed specifically by gear shaping process?

Shaping process can operate on classes of gearing outside the capacity of other methods. Example are: a) Internal gears with or without back shroud, b) Cluster gears.

13. Distinguish between gear shaping and gear planning?

Gear shaping:
a) The job is indexed and tool reciprocates
b) Gear can be generated by using form tool as well as pinion cutter.

Gear planning:
a) Job is indexed and reciprocated but the tool is fixed.
b) Gear can be produced by means of form tool and Rack cutters.

14. What is the basic condition to use ‘Bobbing’ in geers?

Hobbing can be done only if the gear blank to be generated are of the same modules

15. Write the formula for calculating index change gears in gear bobbing?

For Index change gear: Driving Teeth – Indexing constant x Number of teeth of hob Driven Teeth Number of teeth to be cut.

16. Name the different types of bobbing?

Different types of bobbing arc classified under the direction of feed of hob are:
a) Axial hobbing b) Radial hobbing c) Tangential nobbing.

17. Explain axial hobbing process?

a) Gear blank is brought towards the hob for required depth.
b) Table slide is then clamped.

18. What are the advantages of gear hobbing?

The advantages of gear hobbing are:
a) The method is versatile and can generate spur, helical, worm and worm wheels.
b) It is rapid, economical and highly productive.

19. Give any three differences between gear bobbing and gear milling?

Gear Hobbing:
a) Hob operates on several teeth at a time.
b) It is not necessary to disengage cutter and work before indexing.
c) Gear hobbing is faster process than gear milling.

Gear Milling:
a) Milling machine can cut only one tooth at a time.
b) It requires cutter and work to get disengaged before indexing can occur.
c) It is slower process compared to gear hobbing process.