Design versus manufacturing responsibilities: Are tolerance issues primarily a manufacturing concern, or should they be established during design and clearly communicated on the drawing?

Introduction / Context:
Tolerances define permissible variation in part features. They directly affect fit, function, performance, cost, and manufacturability. While manufacturing executes to tolerances, responsibility for specifying them rests with design and must be conveyed through the drafting process.

Given Data / Assumptions:

• Parts must assemble and function reliably.
• Drawings or models are the contract documents that communicate specifications.
• Tolerances influence process selection and inspection criteria.

Concept / Approach:
Designers determine functional requirements, select fits (clearance, transition, interference), and define geometric and size tolerances. Drafters document these requirements unambiguously using dimensioning and tolerancing standards. Manufacturers then plan processes capable of meeting the specified limits. Pushing tolerance decisions to the shop after design risks costly rework and functional failures.

Step-by-Step Solution:

Verification / Alternative check:
Compare assemblies dimensioned with and without explicit tolerances. Those lacking tolerances rely on assumptions, leading to inconsistent fits. Properly toleranced drawings yield predictable assembly outcomes.

Why Other Options Are Wrong:

• Leaving tolerances to the shop abdicates design responsibility and invites variation.
• Inspection does not create tolerances; it verifies compliance.
• Tolerances apply to all materials, not just plastics.
• CNC precision does not eliminate the need for defined limits; specifications must still be stated.

Common Pitfalls:
Using default block tolerances for critical features; omitting geometric controls; failing to consider stack-up across assemblies.

Final Answer:
Correct: tolerances must be set during design and communicated in drafting