On-line extrusion measuring gauge avoids sampling

A NDC Infrared Engineering product story

Edited by the Engineeringtalk editorial team Mar 6, 2001

Scott and Fyfe of Tayport has cut costs by fitting an on-line measuring gauge for measurement and closed-loop control of film thickness to the extrusion line

Scott and Fyfe of Tayport has significantly enhanced its industrial textile business by fitting an on-line measuring gauge for measurement and closed-loop control of film thickness to the extrusion line.

The 6100TC from NDC Infrared Engineering's range of on-line analysers, has cut costs dramatically by eliminating time consuming and costly sampling, and reducing scrap at the plant by half.

The family owned business employs 280 people in two plants in Tayport, Scotland.

Market leader Scott and Fyfe is one of the largest providers of polypropylene woven fabrics into the packaging industry for the manufacture of Flexible Intermediate Bulk Containers (Big Bags).

The 6100TC thickness-measuring gauge was installed to maximise efficiency of a new Polyproylene (PP) film extrusion line.

Tom Maloney, Plant Supervisor, explains how the system has improved production: "The gauge allows us to control the profile of the extrusion much more closely - to within a tolerance of (1.2% - and considerably reduces the amount of scrap we produce.

The extrusion profile is continuously displayed on the profile display system, allowing us to see at a glance what happening." At Scott and Fyfe, Polypropylene film is extruded from Polymer granules and cooled using a water bath.

The film is then scanned by the 6100TC gauge to determine the thickness or tex (weight / unit length), before being cut into tapes for weaving into industrial textiles.

Before the 6100TC gauge was installed an operator would take samples of tapes in order to test the tex by weighing in the lab.

The die head or extruder speed would then be manually adjusted accordingly.

This process could take up to an hour to test the full width of tapes.

If the tex profile was found to be out of tolerance, up to 380kgs of film could be lost.

The 6100TC beta gauge is now installed above the Polypropylene film extrusion line on a scanning frame, which allows the instrument to scan across the width of the web, taking a continuous measurement of the thickness of the film as it passes below.

Tom Maloney explains the importance of the system to Scott and Fyfe's production process: "Previously we worked to a tolerance of ( 5%; if heavy tex got through our system it could stop the looms.

The precision measurement of the NDC gauge now allows us to work to a tolerance of (1.2% which means less stoppages and smoother running of the plant." Edge trim material is auto-fed into the main extruder via a regrind system.

The density of the regrind typically alters the tex rating by a drop of six, which requires a big adjustment to the extruder to compensate.

These adjustments were made based on samples and operator experience.

Now the 6100TC system adjusts the extruder speed automatically.

Tom Maloney said: "Since installing the NDC system, we have seen a significant reduction in costs due to the reduction in scrap." The 6100TC system from NDC Infrared Engineering is a robust and reliable system for continuous on-line measurement and / or control of cross-web product profile.

It is available with a range of measurement technologies including beta transmission and gamma backscatter gauges to suit a wide range of thickness measurement applications.

The operator interface provides a clear display of the film profile in real time, and touch-screen control of all gauge settings and measurement and control functions, including data acquisition and reporting.