Measurement of basis weight (mass per unit area) / thickness /density
The beta sensor measures grammage and material thickness by means of isotope rays
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.
- 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
- 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
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.
Problems with product flatness exist with almost all treatment methods for product webs. Cast and rolled film as well as rolled sheet metal exhibit ripples and flutter, triggered by tension changes, electrostatic charges or band vibration. Paper and coating converters must deal with faulty substrates, edge curl and unsupported product web areas. Manufacturers of nonwovens and fabric are facing fluctuations of degree of drying, density and thickness of their product webs, caused by changes in centre of gravity.
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 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.
(Pm - 147)
|Measuring range 1||10 - 1400||100 - 6000||2,5 - 160||g/m²|
1) Referring to PET