Jigs and Fixtures design brief
Transcript of Jigs and Fixtures design brief
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JIGS AND FIXTURES Jigs and Fixtures are Production-work holding devices used to manufacture duplicate parts accurately
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A Jig is a special device that holds the workpiece but also guides the cutting tool as the operation is performed
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A Fixture is a production tool that locates, holds, and supports the work securely so the required machining operations can be performed
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Elements of Jigs and FixturesLocating Elements: These position the workpiece accurately with respect to the tool guiding or setting elements in the fixture.Clamping Elements: These hold the workpiece securely in the located position during operation.Tool Guiding and Setting Elements: These aid guiding of the tool in the correct position with respect to workpiece.
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Advantages of Jigs and FixturesProductivity
Interchangeability
Skill Reduction
Cost Reduction
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Jigs and Fixture Design Factor1. Study of the component.2. Study of the type of the capacity of the m/c.3. Study the locating elements.4. Study of the clamping arrangement.5. Study of clearance between jig and the component.6. Study of the indexing devices.7. Study of the fool-proofing arrangement.8. Study of the ejecting devices.9. Study of the swarf removal arrangement.10.Study of rigidity and the vibration problems.11.Study the safety devices.12.Study the methods of manufacture of jigs and fixture.
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Supporting and Locating PrinciplesPositioning the Locators: Whenever possible, locators should contact the work on a machined surface. This permits accurate placement of the part in the tool and ensures the repeatability of the jig or fixture. Basic Rules for Locating PART WRONG METHOD RIGHT METHOD
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2. Tolerance: When designing a tool, the designer must keep the part-tolerance in mind. As a general rule, the tool tolerance should be between 20 and 50 percent of the part tolerance.
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3. Fool proofing: Fooling proofing is means by which the tool designer should ensures that the part will fit into the tool only in its correct position.
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Locating Methods1. Location from Plane surface:
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2. Location from Profile:
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3. Location from CylinderPrevention of JammingRecess for burr and dirt
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Diamond Pin Locator Diamond pins are the two way locating devices, because they only locates in one axis. Diamond locating pins are used in conjunction with a round locating pin. The round pin holds the workpiece in position to the fixture, and the diamond pin holds the workpiece to keep it from rotating around the round pin.
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Restricting MovementsSix-point Location by 3-2-1 Method
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Three-pin base restricts six directions of movement
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Five-pin base restricts ten directions of movement
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six-pin base restricts twelve directions of movement
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Clamping and Positioning The function of any clamping device is that of applying and maintaining sufficient counteracting holding force to a workpiece to withstand all tooling forces
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Swinging clampTypes of clampStrap clamp
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Hinge clampSpherical washers for equalizing clamping forces.Pivoted strap clamp
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Edge strap clampQuick acting screw clamps.Edge jaw clamp
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Swinging strap clampSwinging hook clamp
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T-Slot clampEdge clamp
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Method of clamping a small crankshaft by use of a sliding clamp and equalizing pivoting clamp.
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Quick acting clamps
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Hinge clampVice
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Rack and pinion
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Universal chuck Magnetic work holding devices
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TYPES OF JIGS
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CLAMP JIGDIAMETER JIG
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CHANNEL JIGLEAF JIG
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PLATE JIGJIG FOR MULTISPINDLE MACHINE