EXTRUSION

In-line thickness measurement for every extrusion line

Extrusion pushes molten polymer through a die to produce film, sheet or foam with a constant cross-section. The one variable that decides quality, scrap rate and raw material cost is thickness. SCANTECH designs in-line thickness measurement systems for extrusion lines: a traversing scanner measures the product across its full width, in real time, and feeds the result back to the line to keep the profile on target.

Our measurement and control solutions cover every extrusion process:

• Blown film thickness measurement – layflat measurement with a profile every 30 seconds, mapped back to the air ring or the die.
• Cast film and sheet measurement – CPP, CPE, stretch film, barrier films and sheet, from a few microns to very thick material.
• Biax film measurement – BOPP, BOPET, BOPA, BOPE: cast and film sections, TDO stretch profile, edge profile.
• Coating film measurement – coating weight and total thickness.
• Foam measurement – basis weight, thickness and density of foam sheet.
• MDO film measurement – before and after the MDO unit, for an accurate mapping to the die.

What an extrusion measurement system measures

A SCANTECH scanner does more than a thickness gauge. Depending on the sensor, it measures:

• Thickness and basis weight (g/m²) across the whole width, including the film edges.
• Filler content: CaCO₃, TiO₂ and BaSO₄ percentage in filled or breathable films.
• Individual layers of co-extruded barrier films, such as the PA barrier layer.
• Porosity and stretch profile on biax lines.

Our X-ray sensors are non-nuclear: no radioactive source, no isotope licence, and a measurement that is not affected by pigments, colour or masterbatch. Scanners are available from 500 mm up to 13.5 m wide.

From measurement to automatic profile control

Measuring is only half of the job. The thickness profile is mapped to the die and corrected automatically:

• Automatic die bolt control: APC (Auto Profile Control) drives thermal or motorised die bolts, up to 360 bolts per die.
• Air ring control on blown film lines.
• Chill roll speed to keep the average MD thickness on target.

With automatic control, a new production run is usually stable in less than 30 minutes, with less give-away, fewer gauge bands and a flat roll.

FLEXSCAN software: one view of the whole line

All measurements are displayed in FLEXSCAN: live profile, flat and polar views, trends, alarms and a report for each roll or winder. Operators see the line in real time; quality managers get the history.

Frequently asked questions

Find the answers of our extrusion experts in our FAQ pages: blown film · cast film · cast film and calcium carbonate · biax film · sheet · foam.

Need a thickness measurement system for your extrusion line? Talk to an expert and send us your line configuration: width, speed, die type and film grades.