What is a jig, and how does it differ from a fixture?

Short Answer:

A jig is a device used in manufacturing to hold the workpiece and guide the cutting tool during operations like drilling or tapping. It ensures that holes are placed accurately and at the correct angle or position. Jigs are mostly used in manual or semi-automatic operations.

A fixture, on the other hand, only holds and supports the workpiece but does not guide the tool. Fixtures are used in processes like milling, grinding, or turning, where the tool is guided by the machine. The main difference is that a jig guides the tool, while a fixture only holds the job.

Detailed Explanation:

Jig and how it differs from a fixture

In mechanical workshops and manufacturing units, accuracy, repeatability, and efficiency are very important. When the same part is made repeatedly, using hand measurement each time is time-consuming and can lead to mistakes. That’s why special holding and guiding devices are used — known as jigs and fixtures.

Both jigs and fixtures are used to hold the workpiece firmly, but their roles are slightly different. They are designed to reduce human error, save time, and improve quality in processes like drilling, machining, or welding.

What is a jig

A jig is a type of tool used in manufacturing to both hold the workpiece and guide the cutting tool into the correct position. It ensures that the tool follows a fixed path or direction.

For example, in drilling, a jig is used to make sure that the drill bit goes into the exact position and angle every time. The jig usually has bushings or guide holes that control the path of the drill.

Key features of a jig:

  • Holds the workpiece firmly
  • Guides the tool during operation
  • Mostly used for drilling, reaming, and tapping
  • Can be used manually or on machines
  • Improves accuracy and speed

Types of jigs:

  • Drill jig
  • Template jig
  • Plate jig
  • Angle jig
  • Channel jig

What is a fixture

A fixture is a tool that only holds and supports the workpiece during machining. It does not guide the tool. The fixture is fixed on the machine table, and the cutting tool is guided by the machine.

Fixtures are used in operations where the tool’s movement is already controlled by the machine, such as milling, turning, grinding, etc.

Key features of a fixture:

  • Holds the job in correct position
  • Does not guide the cutting tool
  • Often used in high-speed and CNC machines
  • Increases safety and productivity
  • Custom-built for specific shapes or processes

Types of fixtures:

  • Milling fixture
  • Lathe fixture
  • Grinding fixture
  • Welding fixture

Main differences between jig and fixture

  • Tool guidance:
    • Jig guides the tool
    • Fixture does not guide the tool
  • Use in operation:
    • Jig is mostly used for drilling
    • Fixture is used in milling, turning, grinding
  • Position:
    • Jig is often placed on the workpiece or tool
    • Fixture is fixed on the machine table
  • Complexity and weight:
    • Jig is generally lighter and simpler
    • Fixture is heavier and more rigid

Why understanding the difference is important

  • Helps in selecting the right tool for a machining operation
  • Improves work accuracy and production speed
  • Reduces tool wear and machining time
  • Important for mass production and CNC programming
Conclusion

A jig is a device that holds the workpiece and also guides the tool, making it perfect for accurate drilling or tapping. A fixture only holds the workpiece but does not guide the tool. Understanding the difference between jigs and fixtures helps in selecting the right tool setup for each machining process. Both devices are essential in mechanical workshops for improving speed, accuracy, and efficiency in mass production.