Objectives Identify the classes of jigs and fixtures

Objectives • Identify the classes of jigs and fixtures • Identify the types of jigs and fixtures • Choose a class and type of jig and fixture for selected operations on sample parts

Jigs and Fixtures The difference between jig and fixture • Both jigs and fixtures hold, support, and locate the workpiece • The difference is in the way the tool is guided to the workpiece. • A jig guides the cutting tool • A fixture references the cutting tool

Jig and Fixture Design • Jig: A device that holds the work and locates the path of the tool. • Fixture: A device fixed to the worktable of a machine and locates the work in an exact position relative to the cutting tool.

Jigs and Fixtures The difference between jig and fixture

Jigs Classes of Jigs may divided into two general classes – Boring jigs: used to bore holes or drill in odd size – Drilling jigs: used to drill, ream, tap, chamfer, counterbore, countersink, reverse spotface, or reverse countersink The difference is in size of bushing used

Drill Jig

Drill Jig

Jigs Types of Jigs divided into two general types – Open jigs: for the parts machined only in one side – Closed jigs: used for parts machined on more than one side

Channel Jig • Channel jigs • Simplest form of box jigs • Work is held between two sides and machined from the third side

Jigs: Types of Jigs Template jigs • Normally used for accuracy rather than speed • Fits over the work, not usually clamped • Least expensive and simplest

Template Jig

Plate Jig Similar to template jigs Built-in clamps

Table Jig • Plate jigs • Sometime made with legs called table jigs

Sandwich Jig • Sandwich jigs • Form of plate jig with a back plate • To prevent bending or warping for thin or soft parts

Angle Jig Modified Angle Jig • Angle-plate jigs • To hold pars that are machined at precise angle to their mounting locators

Box Jig • Box jigs • Usually totally surround the part completely machined on every surface

Box Jig

Box Jig

Leaf Gig Leaf jigs • Small box jigs with a hinged leaf to allow for easier loading and unloading

Leaf Gig

Indexing Jig Indexing jigs • Used to accurately space holes around a part • Reference itself • Larger indexing jigs are called rotary jigs

Diameter Jig

Jigs: Types of Jigs Trunnion jigs • Form of rotary jig for very large or oddshaped parts

Jigs: Types of Jigs Pump jigs • Commercially made jigs that must be adapted by user • Very fast load and unload

Jigs: Types of Jigs Multi-station jigs • Made in any of the forms of jigs • Commonly used on multiple-spindle machines

Drill Jig Components • Drill bushings Precision tools that guide cutting tools such as drill and reamers into precise locations in a workpiece.

Drill Jig Components • Jig body – Holds the various parts of a jig assembly. • Cap screws and dowel pins – Hold fabricated parts together

Drill Jig Components Screws and Bolt

Drill Jig Components • Locating devices – Pins, pads, and recesses used to locate the workpiece on the jig.

Drill Jig Components • Clamping devices

Drill Jig Components • Locking pins – Inserted after the first hole is drilled to lock or hold the workpiece securely to the jig plate while subsequent holes are being drilled.

Dimensioning Jig Drawings

เอกสารอางอง Jigs and Fixtures Design Second Edition, EDWARD G. HOFFMAN