The document discusses jigs and fixtures, their purposes, types, and design considerations. It explains that jigs automatically position workpieces for machining or assembly and can guide and clamp work. Fixtures only clamp work during machining. Locating methods include the 3-2-1 principle to cancel freedoms of movement. Support should be rigid to prevent deflection and locating can use vices, blocks, pins, or vee blocks. Clamping must be strong, rigid, and able to withstand vibration during machining.

1. Hasitha Wipulaguna

2.  What is Jig/ Fixture ?
 Types of Jigs / Fixtures
 The Purpose of use of a Jig or a Fixture
 Design considerations of a Jig/Fixture
 Illustrate the method of
 Locating
 Supporting
 Clamping
 Guiding

3.  JIG-a device that automatically determines location
dimensions for machining or assembly. A jig can
assist in guiding tools and will clamp the workpiece.
 Fixture- A device which clamps work during
machining.

4.  Plate Jig

5.  Channel Jig

6.  Pot Jig

7.  Milling Fixtures

8.  To eliminate marking, punching, positioning,
alignments.
 Easy, quick and accurate locating,
supporting and clamping blank in alignment
of the cutting tool.
 Guidance to the cutting tool like drill, reamer
etc

9.  Easy, quick and consistently accurate locating
of the blank in the jig or fixture in reference to
the cutting tool.
 Providing strong, rigid and stable support to
the blank.
 Tool guidance for slender cutting tools like
drills and reamers etc.
 Easy and quick loading and unloading the job
to and from the jig or fixture.
 Use of standard parts as much as possible

10.  Locate
 3-2-1 Principle
 One of the basic fixturing methods is the 3-2-1 system. This
method cancels the twelve degrees of freedom of a part and
positions it in three perpendicular planes.

11.  3-2-1 Principle
(3) Three points establish base plane
(2)Two points establish vertical plane for reference
(1) One point in third plane positively locates part

12.  Support
Deflection due to Supportive forces
Recess in long span supporting

13.  Support
 Methods of Supporting Workpieces
 supporting on vices
 supporting on flat surfaces / blocks
 supporting by fixed pins
 supporting (and locating) on vee blocks and
mandrels

15.  Clamping
 clamping need to be strong, rigid enough to hold the
blank firmly.
 should be easy, quick and adequate.
 clamping should be such that it is not affected
by vibration, chatter or heavy pressure.

16.  What is Jig/ Fixture ?
 Types of Jigs / Fixtures
 The Purpose of use of a Jig or a Fixture
 Design considerations of a Jig/Fixture
 Illustrate the method of
 Locating
 Supporting
 Clamping
 Guiding