Degrees of Freedom inwards space
A work-piece free inwards infinite tin deed inwards an infinite position out of direction. For analysis, this displace tin last broken downwards into 12 directional movements or "degrees of freedom". All 12 degrees of liberty must last restricted to ensure proper referencing of a work-piece.
As shown inwards Fig 1, the 12 degrees of liberty all relate to the key axis of the work-piece. Notice the 6 axial degrees in addition to 6 radial degrees of freedom. The axial degrees of liberty allow straight-line elbow grease inwards both directions along the 3 regulation axis shown equally X, Y & Z. The radial degrees of liberty allow rotational movement, inwards both clockwise & counterclockwise radial directions closed to the same iii axis.
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| Fig 1: The twelve degrees of freedom |
Degrees of Freedom of a Rigid Body
Consider the rigid body shown below which is situated in space. It tin accept 12 degrees of freedom.
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| Fig 2 : A stiff trunk on a space |
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| _Fig 3: Influenza A virus subtype H5N1 stiff trunk on a plane |
(2) X-
(3) Y+
(4) Y-
(5) ZCW
(6) ZCCW
Now endeavor to empathize 3-2-1 principle of fixturing. The role of Fixturing is
- Resting - Stability
- Locating - W.r.t datum
- Orienting - W.r.t secondary datum
- Clamping - Ensuring inwards a higher house non disturbed.
Primary Locators
First the three locators or supports are placed nether the work-piece. It volition last positioned on the primary locating surface equally good known equally datum. It volition confine 5 degrees of freedom.
- Axial Movement downward along Z- axis ( No.6 inwards Fig 2 )
- Rotation well-nigh the X & Y axis ( No. 7, 8, nine & ten inwards Fig 2 )
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| Primary Locators |
Secondary Locators
The adjacent two locators are usually placed on the secondary surface, restricting an additional 3 degrees of freedom.
- Axial elbow grease along the Y+ axis ( No.3 inwards Fig 2 )
- Rotation well-nigh the Z axis ( No. eleven & 12 inwards Fig 2 )
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| Secondary Locators |
Tertiary Locator
This locator is positioned at the destination of the part. It restricts 1 degrees of freedom
- Axial elbow grease along the X axis ( No.2 inwards Fig 2 )
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| Tertiary Locator |
All these 6 locators volition confine a full of 9 degrees of freedom. The remaining 3 degrees of liberty ( 1, four & v ) volition last restricted past times the clamps.