Surface flatness measurement methods

Traditionally, flatness of sheet metal was measured with wedges and straight edges, however this was time consuming and not as accurate as it could be. If not corrected, these inaccuracies lead to discrepancies in the product. Scantron’s Proscan Magnum shape measuring table offers a higher level of accuracy than ever before, ensuring precision for the end product.

Proscan Magnum flatness measurement table
Scantron Proscan Magnum Flatness Measurement Table

The Proscan Magnum uses optical measurement techniques; A laser, mounted on a gantry system, scans up to 15 profile lines on the strip with a speed of 1 m/sec taking measurements every mm. The values are presented for each profile line together with 3D displays and a plan view. This is a complete shape measurement system giving unprecedented results.

This is a complete shape measurement system giving unprecedented results.

Off-line flatness measurement is the most accurate method of measuring shape as there is no tension or stress in the material during the measuring process. A sample of sheet metal, measuring up to 3000 x 2000 mm in size, is taken from each coil and placed flat on the sturdy granite table. The granite provides a flat, solid, surface. It’s mass also helps to dampen any movement of the table caused either by machinery operating nearby, or by the laser gantry as it scans the sheet. This ensures the highest level of accuracy possible.

A laser resolving to 3 microns measures the height of the strip above the table. By means of a precision gantry system the laser is scanned over the surface and a map of flatness is generated. The scanner is set up to take height measurements (Z) at pre-determined points (X and Y) across the surface of the sheet. The resultant X, Y, Z data file is used to calculate the surface shape. The shape is quantified by calculating wave length, wave height and ‘I’ unit for each longitudinal scan.

In this way, the Proscan Magnum accurately measures and quantifies the latent shape in the sample, providing absolute values of wave heights, waves per meter and I units. Cross bow, length, width and diagonals are also available.

The Proscan Magnum shape table is particularly suited for measuring thin gauge material with very high flatness specification, such as lithographic aluminium coil, but is equally used for aluminium and steel in the automotive industry.

Accurate Measurements Backed By Powerful Software

Screenshot from the Proscan Magnum Software showing buckle height on an aluminium sheet
Screenshot from the Proscan Software showing buckle 
height on an aluminium sheet 

Taking accurate measurements is one thing, but taking that data and making it easy to interpret is another. This is where Scantron’s powerful Proscan 2200 profilometry software comes in.

This proprietary software is very powerful, having been developed and refined based on real world feedback for more than three decades. Designed to be easy to use, it offers many surface roughness parameters and filter algorithms. Step size and number of steps in X and Y are all programmable, so the smallest indent or damage can be measured to micron resolution.

The Proscan software puts sophisticated 2D & 3D mapping of sheet surface flatness at the fingertips of even non tech-savvy users.

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Why Use a Scantron Proscan Magnum Shape Table to Perform Laser Flatness Measurement?

The Proscan Magnum in action on site
The Proscan Magnum in action on site

There are many good reasons to install a Proscan Magnum as part of your quality assurance procedure. The foremost, of course, being that you can prove to ever-more demanding customers that the product you supply does indeed conform to their required levels of surface flatness.

The Proscan Magnum accurately quantifies the latent shape in rolled aluminium samples. This provides essential information to allow improvements to be made to the rolling / levelling process to improve product quality.

Many people mistakenly assume that scanning at such a level of accuracy is time consuming, making product testing a slow and laborious process. Nothing could be further from the truth: a standard table can accommodate samples up to 3200 x 2200mm in size, with a scanning area of 3000 x 2000mm. The quick and fully automatic measurement cycle can complete the measurement AND analysis the sample in less than 30 seconds. In addition to measuring the samples and displaying the results to the operator, the measured data is also archived to a database via a barcode reader, which is accessible over the company network.

The Proscan Magnum non contact shape measurement equipment is used by some of the world’s leading aluminium mills, including Hindalco India, Alcoa USA, Bridgnorth and Star Aluminium UK. It is a proven, turn-key solution, where you will see the full benefits from day 1 of installation.

It is suitable for all types of sheet material where flatness and shape have to be accurately quantified. It is also extremely safe to operate, with a fully integrated light guarding system for maximum safety.

For further information about our Proscan Magnum, or other Scantron laser flatness measurement solutions, please contact us.