Draw Thickness
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Got problems with wrinkles, tears or improper work hardening
in draw and form operations?

The application below can monitor key characteristics of these processes during the hit and provide process verification on every part.  These are very advanced systems using much of the SAMview software family for accomplishing the task.  In-die force sensors are a must for meeting todays quality standards.  However, the illustrations below use press connection mounted strainlinks and work well for process analysis.

Using the Signature Technologies SA-2000 Statistical Analysis Module (SAM), SAMview software with the SPCview/FeatureView and the exclusive Patented Ford Features.

Signature Technologies has cooperatively developed with Ford Motor Company a means of determining percentage variation of material thickness away from nominal IN CASES where a free stretch draw is made by measuring the force during the draw and post-processing the data with algorithms developed and patented by Ford Motor Company.

In practice, one ST feature called "Ratio" is taken at the beginning of the draw process, and another "Ratio" feature is obtained later in the draw, well up the force slope.  ST processes are used to eliminate the draw ring backpressure so that only the draw forces are considered.

The system works by post processing the returns from the "Ratio" features with the patented Ford algorithm to discern changes in the amplitude, and the slope of the signature.  

The feature screens are shown in the screen shots to the right.  These illustrate how the features are extracted from the signatures which later are used in the calculations performed.

Note the placement of the Ratio Features, red vertical lines, on the forming slope.



The screen capture to the right shows variations of stock thickness in fractions of a percent from nominal on every panel.  Selection of N Factor would provide another critical material property.  Display shows the quality and control limits of the process and displays the measured values.


The SAM™ module can handle measurement inputs in groups of 8 up to 56 total points 

Signature Technologies can supply a wide variety of  solutions to various manufacturing process problems dealing with measurement, verification of properties, tool condition, and machine health.  We can also “close the loop” by performing process adjustments in response to specific variations in force, location, or shape of the work piece, as well as more simple controls which can track and reject specific parts which don’t meet specific quality criteria.

For a .pdf file copy of this bulletin please click here.





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