Tolerance and Surface Finish

Design engineers are always blamed of specifying closer tolerances than necessary. It  is obvious that to achieve a tolerance of ± 0.001 mm is more expensive than  to have  only ±0.01 mm tolerance because of:

1. Greater skill requirements.
2. Due to better equipment.
3. Due to increased scrap.
4. Due to costly operations such as honing lapping etc.
5. Due to severe inspection requirements.
6. Requirements of special tools jigs fixtures etc.
7. When close tolerances are required new and precision machines are used. Old machines cannot produce the component with close tolerance.