QMT Features: March 2008
How do you measure the shape of steel or aluminium strip sheet?
Manufacturers that have invested in modern production equipment with the capability of higher yields and higher quality often have to retain their traditional methods of measurement


Manufacturers that have invested in modern production equipment with the capability of higher yields and higher quality often have to retain their traditional methods of measurement because the alternatives are either not accurate enough or there are too many compromises to make an investment in measurement worthwhile.

Traditional methods for measuring wave heights are manual; utilising a flatness step block gauge, flatness tapered gauge, 6” rule or tape measure. The step block or tapered gauge is inserted in the gap under a wave under the sheet and a figure for wave height is recorded.

Of course, only waves at the edges of the sheet can be measured using this manual method. To measure wave heights or buckle heights in the middle of the sheet, a straight beam is ‘bridged’ across the sheet, supported at each end by pillars of the same height; the inspector must then reach across the sheet and measure the gap from the beam to the wave height peak. Once a calculation is made, the wave height can be calculated. Clearly this is very time consuming and still wave-lengths have to be considered to establish an ‘I’ value.

With Scantron’s latest Proscan Magnum shape table, you can measure ‘I’ values, wave or buckle height, waves per metre, sheet width, edge waviness, edge camber, cross-bow, hook and coil set.
The Proscan Magnum uses a laser triangulation sensor which is accurate to within 5 microns. The system provides a very accurate measurement of the surface characteristics of sheet metal and does it at high speed, typically 20 seconds for a 2m x 1.5m sheet. It provides an absolute measurement figure regardless of who is using the machine.

Typically sheet metal manufacturers like to see five lines of data along the sheet. Proscan can display from two to fifteen lines on the screen.
The results from the scan can be saved to a database and there are user-defined fields for recording, for example; the operator name, the name of the line, the lot number, customer name etc.

If required, the results can be imported by the customers’ production control system and then a detailed trend of performance can be recorded.
The screen can be easily configured to show the form of the sheet in 3D view; this view can be swivelled using the mouse; cross-section views are also selected with the mouse and displayed in the bottom left hand view.

E-mail: pa@scantron-net.co.uk
www.scantronltd.co.uk

  
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