Fixtures and jigs are used to securely hold workpieces in place during manufacturing operations like machining, welding, and assembly. Fixtures are more permanently attached to machines while jigs can be removed and are more flexible. Common fixture components include a base, clamps to counteract forces, and set blocks to position cutting tools. Effective fixture design considers factors like locating parts precisely, applying proper clamping forces, and accommodating high production volumes. Welding fixtures in automotive manufacturing typically comprise various units like clamp, pin, and rest units to securely hold multiple car parts in position for welding.

2. Definitions
• 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.
Superior Jig
Flexible Fixturing Systems

3. Fixtures
• More of a permanent tool that is used for assembly purposes.
• Typically does not have as much flexibility as a jig.
• Most likely used for high volume production.
• Made of durable materials such as tool steel, iron, aluminum alloys,
etc.

4. Other Fixture Examples
• Used most commonly for welding
and metal assembly work.
• Typically used for products that
must be very precise.
• Sometimes are exposed to high
temperatures and stresses

5. Type of Fixtures
(a) Turning fixtures
(b) Milling fixtures
(c) Fixture for grinding
(d) Fixture for broaching
(e) Fixture for boring/drilling
(f) Tapping fixture
(g) Fixture for welding
(h) Assembling fixture
Standard Parts Co.

6. Fixture components
• Fixture base
• Fixture components and the workpiece are usually
located on a base, which is securely fastened to the
milling machine table.
Standard Parts Co.

7. Fixture components
• Clamps
• Clamps counteract forces from the feed of the table and
rotation of the cutter.
American Drill Bushing Co.

8. Fixture components
• Set blocks
• Cutter set blocks are mounted on the fixture to
properly position the milling cutter in relation to the
workpiece.

10. • Detailed design of locators
• Detailed design of clamps
• Detailed design of supports
• Positions of locators
• Positions of clamps
• Positions of supports, if any
• Type of locators
• Type of clamps
• Type of supports
• Clamping forces and sequence
The following outputs are included in the
fixture element design:

11. Fixture Design Criteria
• Design specifications
• Factory standards
• Ease of use and safety
• Economy

12. Body In White (BIW)
Fixtures
Example :
Fixture For Welding

13. Various Aspects Of Fixture Design

14. BIW – Weld Fixtures
 Design Process/Methodology .
 Different Types of Welding Fixture Units.
 Design Inputs.
 Design Outputs.

15. Design Input
 Functional and Performance Requirements.
 Car Product.
 System Layout.
 Tool Information Sheet.
 Weld Study Information.
 Miscellaneous Information.

16. Design Input
1. Functional and Performance Requirements
 Product Assembly Process Sheet
(Product Assembly Process Sheet is a sheet that gives
the following information about the Car Product)
 Parts Assembly Sequence.
 Sequence Of Operation.
 Cycle Time.
2. System Layout
The following Points are to be
considered while studying a
System Layout .
 Flow Of Parts.
 Station Pitch.

17. 3. Car Product
The following Points are to be considered
for the Car Product .
 GD&T Sheet.
 Part List.
 CAD Files of the car part.
Design Input
4. Tool Information Sheet
The Tool Information Sheet
consists of the following.
 Tool Summary.
 Tool Content Sheet .

18. 5. Weld Study Information
The Weld Study Information
consists of the following.
 Welding Spots.
 Welding Guns.
Design Input
6. Miscellaneous Information
 Customer preferences. Standard parts to
be used.
 Informations derived from previous
Designs and Development .
 Title Sheet Informations to be filled.

19. STAGE 1
 Study the System Layout thoroughly.
 Reviewing Customer Input Data.
 Determine the No. of Tools required.
 Study the GD &T Sheet.
 Study the PLP position.
 Rough concept of tool.
Design Methodology
STAGE 2
 Retrieve Car Part.
 Create Keysheet ( Final Tool / Station with all the Units ).
 Determine the Base Height from the Car part surface.
 Check for interference with adjacent units or Tools.
 Cut final sections and offset metal thickness .

20. STAGE 3
 Retrieve Customer approved
Standard sheets.
 Detail the unit according to the
customer specification.
 Fill out Title Block Information .
 Create BOM .
 Create LAYOUT .
 Create all necessary Views .
 Fully Dimension all the Details .
Design Methodology
STAGE 4
 Review information ,Customer
input data and Key sheet.
 Complete check.
 Updating the errors.
 Back Check.
 Plot job for Check.

21. Design Output
3D Model & 2D Drawings
 Non Unitized Tools.
 Unitized Tools require 2 types of drawing sheets.
1. Key sheets.
2. Layout Sheets.
3. Part Detailing's.
 Tool Level detailing i.e. Key Sheet Layout
 Unit Level Detailing i.e. Layout & BOM
 Part Level Detailing

22. Type of Welding Fixtures Units
1) CLAMP UNIT.
2) PIN UNIT.
3) REST UNIT.
4) COMBINATION OF CLAMP & REST UNIT.
5) DUMP UNIT.

23. Typical Clamp Unit
CYLINDICATOR
SUB-PLATE
RISER
FLOW CONTROL
CYLINDER
L-BLOCK
NC-BLOCK
CLAMP ARM
BLADE

24. A COMBINED LOCATING, CLAMPING AND RESTING UNIT
RISER BRACKET
PIN
PROXIMITY SWITCH

25. A Typical Welding fixture-after assembly

26. A Typical Welding fixture-in shop floor
Locating Pin Unit
Clamping Unit
Weld Gun
Robot
Welding
Electrodes
Car Part

28. Thanks

29. Design Example :

30. Key Sheet Layout:

31. Key Sheet Layout:

32. Key Sheet Layout:

33. Unit Level Layout:

34. Unit Level Layout:

35. Unit Level Layout:

36. Make Part Detailing:

37. Make Part Detailing:

38. Unit BOM (Commercial):

39. Unit BOM (Make Parts):

40. Thanks