Best mass-production process for gears Considering productivity, accuracy, and economy in large batches, which manufacturing process is most suitable for mass production of gears?

Introduction / Context:
Gear manufacturing methods include forming, generating, and finishing processes. For large quantities, the chosen method must combine speed with acceptable accuracy and surface quality before finishing (if required).

Given Data / Assumptions:

• External spur/helical gears are considered.
• Mass production (high throughput) is the primary objective.
• Subsequent finishing (e.g., shaving/honing) can be added if needed.

Concept / Approach:
Hobbing is a continuous generating process, cutting multiple teeth simultaneously with a helical hob under a constant relative rolling motion. It offers excellent productivity, versatility in tooth forms, and good accuracy for most industrial needs.

Step-by-Step Solution:
Compare cycle times: hobbing < shaping for like modules and widths.Consider tooling: hobs last long, are re-sharpenable, and changeover is quick.Match quality/cost: hobbing provides consistent gear quality at high rates.

Verification / Alternative check:
Automotive and industrial gear lines overwhelmingly use hobbing as the base generating process.

Why Other Options Are Wrong:

• Shaping is slower, indexing each tooth or using a pinion cutter reciprocating.
• Casting alone lacks accuracy/surface finish; typically needs machining.
• Forming by dies applies to powder metallurgy or rolling but is less universal than hobbing.

Common Pitfalls:
Confusing hobbing (generating) with form milling; underestimating hob lead/helix setup.

Final Answer:
Hobbing with a generating hob