Gravimat DFI

Measurement of basis weight (mass per unit area) / thickness

Transmission of beta rays

The weight monitoring and control system measures the weight continuously, without contact, destruction-free and on moving product. The measurement is based on the attenuation of rays from a radioactive isotope through the substrate located in the measuring gap. This attenuation in intensity is an indication of the weight of the product.

The Gravimat uses a target weight to reduce the range of different m2 weights and thereby ensure a more consistent product.


The Mahlo® Gravimat DFI (Dynamic Flutter Independent) beta sensor uses a revolutionary new sensing technique that allows:

  • Complete insensitivity to web flutter throughout the entire measurement gap
  • The smallest beta sources and the highest measurement performance
  • Very fast scanning speeds with ultra-narrow web defect detection
  • Long-term trouble free, cost effective operation in the harshest environments.

Virtually all web processes have problems with maintaining consistent flatness. Cast, extruded and calendered film and sheet exhibit ripples and flutter due to line tension changes, static electricity or in-line vibration. Paper and coating converters must deal with baggy substrates, edge curl and distances of unsupported web.

Nonwovens and textile manufacturers see variations in the loft, density and thickness of their webs which result in center of mass changes.

Correct basis weight measurement - unconditionally

All of these conditions result in measurement errors with traditional transmission sensors like X-ray or beta gauges. Backscatter sensors like gamma or X-ray are even more sensitive to web movement and some are even required to contact the web!

The new Mahlo® patented DFI Beta Sensor is not affected by web flutter, passline change, ripples, sag or edge curl. The DFI measures accurately throughout changes in loft, density or thickness.

Product highlights

  • Intelligent sensor with ultrafast microprocessor for preprocessing measurements
  • Precise measurements as a result of using extremely efficient beta radiation detectors
  • Four temperature-compensation sensors along with air pressure compensation



Customer benefits

  • Non-destructive, continuous determination of the weight per unit area of product webs
  • Highly stable and accurate measurement along with a minimum need to calibrate
  • The DFI allows wider measurement gaps and avoids damage to soft webs or wet coatings
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Extrusion 2019

Conference for all extrusion processing
17 - 19 Sept 2019
Chicago, USA



International Trade Fair for Plastic and Rubbery Machines
16 - 23 Oct 2019
Düsseldorf, Germany
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Hofer Vliesstofftage

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Conference for fleece
06 - 07 Nov 2019
Hof, Germany
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Exhibition for Textile Machines
25 - 28 Nov 2019
Shanghai, China
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Exhibition for Nonwovens
11 - 13 Dec 2019
Shanghai, China
Visit us at booth 1A26!


Mahlo GmbH + Co. KG • Donaustraße 12 • 93342 Saal /Donau
Tel.: +49-9441-601-0 •