Process Sensors (Europe) Limited
Process Sensors

 Applications - Paper/ Converting

 

Why Measure?

Corrugated board, paper and many converting lines are high speed thus there is the potential for significant wastage within a short timespan if the process line stops or if the product is not within specification.  Wastage can be surmised as not only lost productivity but also the cost of utilities and raw materials in generating out of spec. material.  A static or dynamic coat weight measurement will provide useful real-time data enabling the Operator to reduce start-up times and optimise the process through adjustment of line speed and the application of coating ensuring a consistent product whilst maintaining tight control on the usage of what can be costly resins.

 

 

Paper and Converting Applications

Coatings e.g. clay, PVDC, hot melt

PSA adhesives on paper and film.

Moisture in decorative laminates
Conversion coatings on rolled steel and aluminium Moisture in corrugated board
Moisture at various stages of the paper making process Moisture in sludge
Moisture in paper products – after the remoisturiser PE on foil (flexible packaging)

Sensor

Static

The cast aluminium MCT 360 is the usual choice when a fixed moisture or coat-weight measurement is required as it is robust in the event the sensor could be knocked, in addition it is fitted with an integrated cooling panel, making it easy to add a vortex cooler should this be necessary. The sensor uses smart sensor technology, all process inputs/outputs are direct to/from the sensor head making installation and networking a simple operation.  Gauge parameters can be programmed using a PC or an operator interface. The MCT 330HD sensor is a heavy duty stainless steel option well suited to high temperature and high humidity conditions, this unit requires the installation of a separate processor/display unit in a more temperate location.  An ExD explosion-proof sensor is available if the sensor is to be mounted in a potentially explosive atmosphere.

Scanning

The Guardian scanning system is designed to measure coat weight and moisture profiles across a moving web.  The Guardian system comprises a lightweight sensor in a pressed steel enclosure, a processor/display unit, an automated scanning frame and PC with SFS profile s/w.  A single system can generate up to 3 profiles simultaneously.

Accessories

High temperature locations may require a vortex cooler.

A Product loss sensor can be installed to hold the moisture or coat-weight measurement should a web break occur.

An alarm board may be fitted to enable an alarm output if the measurement exceeds a high or low limit or if the gauge malfunctions.

Photo of Guardian scanning system

Gauge outputs, Operator Interface & Display

Up to 3 x 4-20MA or 0-10V

RS232 or RS485

Optional bus

Optional Operator Interface and display unit


 

The Measurement

NIR can be used to measure moisture within, or on the surface of a web based product.  The latter measurement is useful in determining a coat weight at the wet end especially if the dry coating is organic and the substrate is also organic.  This is due to the fact it will not be influenced by variations in the substrate.  Measuring the moisture content at the exit of a coater is the only way of measuring a non-organic coating such as clay on paper.  Measurements are reliable provided the solids ratio doesn’t vary.  Measurement of wet coat weight provides the possibility of both feed forward and feedback control.  Dry end measurements are most accurate if the coating has a unique absorption or if the substrate is at a constant thickness (very flat).  Moisture levels in card and paper needs to be carefully monitored and controlled to ensure dimensional stability and that it matches up to specification for the next stage of the process  e.g. printing or lamination.

 
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