Förbättringar i produktionslinjer
Förbättringar av ytvikts- och fuktsmätning
Ytvikts- och fuktsmätning kan förbättras genom att kalibrera mätarna med spårbara referenser. Åtgärden minskar osäkerheten för dessa mätningar, vanligtvis med cirka 85%. Detta resultat framgår av de två publikationerna nedan. Publikationerna baseras på förbättringar av kundernas produktionslinjer. Artiklar innehåller data som samlats in över tio år.
Förbättringar av ytviktsmätning
En artikel om förbättringar av mäta ytvikt har publicerats i ISA Transactions. Tidningen publicerar artiklar om branschens bästa praxis:
Improving integrity of on-line grammage measurement with traceable basic calibration, ISA Transactions 49 (2010) 257-263 »
Abstract. The automatic control of grammage (basis weight) in paper and board production is based upon on-line grammage measurement. Furthermore, the automatic control of other quality variables such as moisture, ash content and coat weight, may rely on the grammage measurement. The integrity of Kr-85 based on-line grammage measurement systems was studied, by performing basic calibrations with traceably calibrated plastic reference standards. The calibrations were performed according to the EN ISO/IEC 17025 standard, which is a requirement for calibration laboratories.
The observed relative measurement errors were 3.3% in the first time calibrations at the 95% confidence level. With the traceable basic calibration method, however, these errors can be reduced to under 0.5%, thus improving the integrity of on-line grammage measurements. Also a standardised algorithm, based on the experience from the performed calibrations, is proposed to ease the adjustment of the different grammage measurement systems. The calibration technique can basically be applied to all beta-radiation based grammage measurements.
Förbättringar av fuktsmätning
En artikel om förbättringar av IR-fuktdmätningar på papper och kartonglinjer har publicerats i Measurement – magasin. Magasinet har publicerad av en internationell mätorganisation IMEKO:
Improving the integrity of IR based online moisture measurement used in the paper and board industry, Measurement 44 (2011) 1937-1944 »
Abstract. The automatic control of product moisture content in the paper industry is based upon online moisture measurement. Furthermore, the automatic control of other quality variables such as coat weight may also rely on the moisture measurement. The integrity of infrared radiation (IR) based online moisture measurement systems was studied by performing basic calibrations at the mills with references sealed between two glass plates. The calibrations were performed according to the EN ISO/IEC 17025 standard which is a requirement for calibration laboratories.
The observed measurement errors were 2.9% moisture in the first time calibrations at the 95% confidence level. It is demonstrated that these errors can be reduced to under 0.5% moisture by applying traceable methods in the basic calibration, thus improving the integrity of online moisture measurements. Also a standardised algorithm, based on the experience from the performed calibrations, is proposed to ease the adjustment of different moisture measurement systems.
Förbättringar av produktspecifika mätning
Efter kalibrering / inställning med referenser måste ytvikts- och fuktsmätningar fortfarande kalibreras för varje produkttyp. Vi har utvecklat en tjänst för detta ändamål. Vi visade att det är möjligt att nå mindre än 0,5% osäkerhet i ytviktsmätning och 0,2% osäkerhet i fuktsmätning. Det är också möjligt att uppnå en osäkerhet på 0,5% vid beräkningen av torrvikt beräknad utifrån dessa. Artikeln har publicerats i Measurement – magasin:
Application of traceable sample area measurement in the calibration of online dry grammage measurement used in board production, Measurement 46 (2013) 1585-1591 »
Abstract. A method is described for the simultaneous calibration of online grammage and moisture measurement by applying machine reel sampling and traceable sample area measurement. The area measurement is based on a flatbed scanner and image analysis. It is demonstrated that a relative uncertainty of 0.5% can be achieved in dry grammage calibration at the 95% confidence level. The determination of grammage and moisture were performed by applying the EN ISO 536 and the EN ISO 287 standards, respectively. The described technique can also be applied with the calibrations performed for the paper industry.
Förbättringar av spårbarheten av torrytviktsmätning
Förbättringar av ytviks- och fuktsmätning förbättras pålitligheten av räknad torr ytvikt. Torr ytvikten berättar hur mycket råmaterial finns i produkten. Ju bättre man vet innehållet av produkten desto bättre man kan kontrollera det.
Nedan följer en länk till Aalto Universitys avhandling om förbättring av den metrologiska spårbarheten av torr ytviktsmätning på producktionslinjen:
Improving the Metrological Traceability of Online Dry Grammage Measurement Used in the Paper Industry, Aalto University Doctoral Dissertations 207/2013 »
Abstract. In the paper industry, the automatic control of raw material consumption and product quality relies upon online grammage (total mass per unit product area) and moisture measurement. The optimisation of raw material consumption is vital to the profitability of production, and the even quality is essential for satisfying customer needs.
It was shown in this work that the basic errors of radioisotope Kr-85 based grammage and IR based moisture measurements, which are commonly used in the paper industry, can be decreased on average approximately 85% with traceable calibration methods. Moreover, a novel method was created for the simultaneous grade specific calibration of these measurements by applying machine reel sampling and traceable sample area measurement. It was demonstrated that a relative uncertainty of 0.5%, at the 95% confidence level, can be achieved in dry grammage calibration. The calibrations were performed according the EN ISO 536 (grammage) and the EN ISO 287 (moisture) standards. The uncertainties of existing measurement systems can be reduced usually over 50% with the created methods.
The decrease of measurement uncertainty offers an opportunity for significant economic savings since one per cent change in the dry raw material consumption of a typical production line affects several hundreds of thousands euros in the annual raw material costs. The presented calibration methods can basically be applied to all paper and board production lines.
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