Technology Transfer>'O' Frame corner For Flat film

Infra-Gauge System with 'O' Frame corner For Flat film Extrusion Line

DESCRIPTION

Co-extruded plastic films are widely used for packaging a variety of both industrial & consumer products including food items like dairy products, edible oil etc.,.

Thickness or weight measurement during extrusion is important to maintain consistent quality along with raw material , energy savings and less recycling.

On-line plastic packaging film gage monitoring during manufacture is emerging as a necessary element to meet quality demands of end-users including single roll certification. Plastic film manufacturing processes are of two major categories: blown film and flat film extrusion lines. Cost effective and efficient operation both types of processes demands reliable on-line measurement of film caliper or thickness as the basis of its control strategy, whether manual or automatic.

Two prototypes of infragauge systems i.e., one for blown film co-extrusion plant and another for flat film co-extrusion film line have been indigenously developed for the first time in India at CEERI Center located in Chennai . Infragauge sensor technology was developed with funding support from Department of Science & Technology, Govt. of India.

The sensing principle is based on the fact that almost every one of all the common plastic packaging materials have a characteristic Infrared absorption spectrum. The amount of absorption(i.e the depth of the absorption bands) is a function of the grammage(grams/sq.meter) of the plastic web-in other words, a function of the length of the path that the I-r radiation takes in passing through the web. A simple two wavelength gauge employs a “reference” wavelength which is not absorbed by the polymer and another which is. Ratio of the absorbed and unabsorbed infrared light is proportional to the polymer thickness or weight and is calibrated against standard laboratory type gauges.

The technology of on-line non contact film thickness measurement systems will meet the long felt need of indian plastic industry.

These systems are being demonstrated live to all interested user industries and equipment manufacturing companies who wish to commercialise the technology.

In case of extruded sheet or cast film plant, the molten material will be coming from a flat rectangular disc in single layer form. Infragauge system for cast film line consists of Infragauge sensor mounted on O-frame scanner, control panel and 19” rack with industrial computer and associated interface cards. The sensor carriage is fitted with linear bearings which moves on grounded steel rods mounted on rails. A FHP AC motor is driven by a thristor frequency converter to precisely control the position of the sensor on the film. Computer control of the sensor head enables to position the sensor at any specified point or scan the web from end to end or take the carriage to parking positions. A digital shaft encoder coupled to the drive transmits position data to the computer at any instant. In scan mode the process computer acquires sensor data as the film web gets scanned and computes and displays thickness/grammage profile variations.

O’ Frame Scanner with Infragauge sensor for flat film extrusion line

The following types of profiles are available and can be selected for operaton and display:

Last scan profile (previous scan profile)
Composite scan profile (Last scan average profile)
Machine direction profile
Reel average trend profile
Process data display

The cross direction thickness profile is plotted in such a way that precise registrations to that die bolt position is displayed. This will enable operator to identify and adjust the die bolts to reduce cross film thickness variations to a minimum. Advanced windows application software developed in visual C++ enables multitasking functions like dynamically changing graphic pot scales, colors, set values etc. and background printing of screen displayed data. User friendly icon based commands eases the training and operation of the system. Built in diagnostics help the engineer easily check all the subsystems functionally to trouble shoot.

An Off-line calibration utility would help the user calibrate any new product with a specified minimum number of standard samples. Statistical measurement data like standard deviations, mean, SSE etc. are also computed and displayed on relevant display screens. 

FEATURES: Non -contact ,non-destructive measurement
Fast measurements for mean thickness and profile control
Provision for stored calibrations of many different products
 Savings in raw materials, energy and less recycling
Consistent product quality and rapid return on Investment
Lower wastage & Better yield for end-user
Profile variations mapped with reference to die zones
Graphic plots to show long term trend, MD profile
calibration facility for user with password protection
Benefits of on-line gauging systems: Reduction in process vaiability
Better material yield
Less wastage & faster startups
Better and consistent quality
Can be tailor-made and retrofitted to any Industry with little downtime SPECIFICATIONS

Sensor	Infrared absorption based Transmission type suitable for monitoring total thickness of a single layer or multi layer Co-extrusion films.
Range	20 to 200 microns (Depends on the type & blend of film)
Accuracy	±1 micron or within 2 % whichever is higher
Sampling Area	10mm Dia. typical
Calibrations	Built in calibration & validation facility for user with password protection
Display	Composite Profile product setup Reel Profile Machine direction Profile Process Data
Reports	printing facility for all display screens Shift report, Reel Report
Sensor Enclosures	Built to meet IP 55 Industry Standard
19" system computer	Intel Pentium based industrial Computer 14" SVGA Colour monitor *Add on multifunction I/O card with 12 bit   ADC & digital I/O *Signal interface cards *± 15 V Power Supply Modul *Optional air cooling unit for the 19" rack keep the electronic assemblies cool.
Software	Windows application software developed in VC++