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Electronic fixturing: CAD-CAM expands to include fixture detail.

Electronic fixturing

CAD/CAM expands to include fixture detail

The primary use of CAD/CAM is for the design and machining of the end product. But there are great benefits in tooling design if you can expand this data base to include the design of the necessary fixturing, since a considerable portion of the fixture design depends on component geometry that is already in place.

The key is to increase the scope of this process to include the placement of clamps, supports, locating pins, and associated hardware that fixes your part in space.

This will help you avoid the delays and embarrassment of NC programs that saw clamps in half because not all the relationships between part, fixture, and tool were anticipated ahead of time.

Of course, some CAD/CAM users have already come to this conclusion and gone to "electronic fixturing.' They have developed on their own the necessary software in-house to include all their fixturing options in their CAD/CAM data base and thus gained this important new dimension in tooling productivity. But none of the major CAD/CAM suppliers have offered it yet.

Now Jergens Inc, Cleveland, OH, in cooperation with Brigham Young University, Provo, UT, has developed the first CAD/CAM tooling component data base and operating software package for fixture design. It supplements an existing CAD/CAM system by adding the Jergens catalog of standard fixturing components. The marriage of Jergens' tooling-component experience with Brigham Young's CAD/CAM talents thus yields an electronic product designed to increase the productivity of any tool-design department.

The data base consists of a series of detail drawings, Figure 1, of each of the standard tooling elements, supported by hard-copy drawings with quick reference points. When an engineer wants to generate a fixture element, he can use the data base or hard copy to identify the part he wants by the part number and orthogonal view he needs, and then identify the location on the fixture where he wants it to appear.

Once the fixturing parts are in the program, the user does not need to remember part numbers or descriptions. The user-friendly program prompts the designer as he builds the electronic fixture just as if he were pulling these components out of a tool crib. He can arrange or rearrange parts in any logical order or change a view of any drawing.

Trying out the fixture

Once the fixture design is completed, Figure 2, the designer can use any tool-and cutter-path options available on his CAD/CAM system to electronically "machine' the part. This allows him to check for clamping clearances and fit without cutting chips. Once he is satisfied with the fixture design, the Jergens /BYU data base and operating program will provide a bill of materials with complete descriptions and part numbers.

Both the data base and operating program are written in FORTRAN and are completely interactive. BUY's Professor Gregory Jensen designed the program with the busy engineer in mind, based on his experience as a tool designer at Lockheed's Advanced Systems Div.

In a published study in which 25 engineering students used this program, Professor Jensen concluded "A CAD/CAM data base of tooling components has a significant impact on the speed with which a jig or fixture can be drawn. A time/efficiency ratio as high as 8.9:1 was achieved when using a CAD tooling data base as opposed to the manual tracing-template method.'

The data base and operating program will be released this month, and for other major CAD/CAM units beginning in March. There is no need to enter hundreds of tooling component drawings; dreds of tooling component drawings; the program can be used almost immediately. It is estimated that the license fee for the data base and operating program will be $5000.

For more information, circle E3, or call Jergens at (216) 486-2100 or Professor Jensen at (801) 378-3151.

Photo: 1. Typical component drawing and subcomponent parts list as it is stored in the data base.

Photo: 2. Close-up of the completed fixture drawing (also shown above) that includes four clamps and a fixture transfer ring.
COPYRIGHT 1984 Nelson Publishing
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Copyright 1984 Gale, Cengage Learning. All rights reserved.

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Title Annotation:tooling-component software
Publication:Tooling & Production
Date:Feb 1, 1984
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