Jig versus fixture — what uniquely defines a jig? In production tooling, which statement correctly defines a jig as distinct from a fixture?

Introduction / Context:
Tooling for batch or mass production aims to reduce setup time and ensure repeatable quality. Two common devices are jigs and fixtures. Understanding the difference is crucial for correct process planning.

Given Data / Assumptions:

• Jigs and fixtures provide holding and location.
• Only jigs include tool guidance elements (e.g., drill bushes).
• Inspection gauges are a separate category.

Concept / Approach:
A jig both locates/holds the work and guides the tool (for example, drill jigs use bushes to guide drills). A fixture locates/holds the work but does not guide the tool; e.g., a milling fixture holds the part while the cutter path is controlled by the machine.

Step-by-Step Solution:
Identify the unique feature: tool guidance.Map to the options: only option (a) includes guidance.Therefore, (a) is the correct definition of a jig.

Verification / Alternative check:
Industry standards and textbooks consistently define jigs by the presence of tool-guiding elements such as bushes and templates.

Why Other Options Are Wrong:
(b) defines a fixture (holding/locating only). (c) describes gauges/inspection fixtures, not jigs. (d) cannot be correct since (a), (b), and (c) are mutually exclusive roles. (e) lacks location, which is essential for both jigs and fixtures.

Common Pitfalls:
Using “jig” and “fixture” interchangeably; forgetting that in modern CNC practice, tool guidance is less necessary for some operations, but the definitions remain.

Final Answer:
Holds and locates a workpiece and also guides/controls one or more cutting tools