Evaluation of Expanded Gamut Printing in Flexography
Lankinen, Kai (2021)
Tampere University
2021
Teknisten tieteiden tohtoriohjelma - Doctoral Programme in Engineering Sciences
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Väitöspäivä
2021-07-01
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-03-2027-0
https://urn.fi/URN:ISBN:978-952-03-2027-0
Tiivistelmä
There is a great need in the packaging industry to produce increasingly smaller lots in a more cost-effective and sustainable way, where the spot color accuracy of the brand elements is critical. Traditional flexography is spot color printing or four-color process printing supported by spot colors that consume a lot of time, effort, and materials. This study evaluates the transition from spot color printing to Expanded Gamut Printing, EGP, i.e., a multicolor process in solvent-based wide web flexography, which reduces the complexity of the printing process and produces spot color simulations in a simpler, more effective, and more sustainable way.
The packaging printing industry has traditionally been a conservative one and new methods are usually trialled without a deep systematic and scientific approach. Therefore, there has not been a comprehensive and scientific investigation of the multicolor process in flexography and it is relatively unknown in detail; thus EGP is considered a niche process. Printers and brand owners lack concrete evidence to support its implementation. This thesis aims to fill the scientific gap and provide data and test results to facilitate the transition to EGP in flexography.
Currently, there is very little scientific peer-reviewed literature or PhD studies on multicolor printing in flexography. The materials available are mainly proprietary marketing materials, various articles, user manuals, college-level studies, and seminar presentations. The available test results typically only apply to narrow web printing, while the availability of empirical production data is almost non-existent.
This study provides examples and data to show the potential of multicolor printing. The main questions are whether and how multicolor process printing can replace conventional spot color printing. The purpose is to describe and calculate the achievable benefits of EGP in figures, since economy and ecology are also significant market drivers.
The study collects and supplements materials from various sources. A novel EGP calculator is developed to describe and evaluate the potential of the method. The study investigates and evaluates the possibilities of color gamut expansion in wide web flexography and describes and calculates the potential of the gang-run printing. Finally, a legacy job printed with spot colors is converted into EGP and the results evaluated.
Several key findings are made in the study and the calculations show great potential for efficiency and cost savings in various areas. The improvement in the press setup is clear, but one of the most interesting findings is the effect of cleaning solvent distillation. In addition, the influence of the amount of stock ink is low and the savings potential on the substrate high. It is also a novelty to link these calculations with Overall Equipment Effectiveness (OEE) and CO2 values.
The EGP calculator estimate in this study shows an improvement in the OEE of 42% to 85% and a total cost savings of around 0,6 to 1,3 million euros per printing press per year, while the CO2 equivalent is reduced by 34% to 51% compared to spot color printing, the results will be different case by case. The studied tests show the capability to expand the color gamut with additional process colors, up to 91% of the Pantone Color Matching System (PMS) colors for the studied 7-color system of less than 3,0 ΔE2000, as expected. However, against expectations, high-pigmented inks also expands the color gamut by 14% for the studied 4-color inks. The Total Area Coverage (TAC) calculations of the tests show that EGP can save ink.
The benefit of gang-run printing is generally mentioned by many sources. This study also defines the increased efficiency in numbers as the test showed the ability to eliminate 30% of the total number of inks. The calculated individual ink consumption based on TAC is reduced by 15% to 69%, while the number of printing plates is also reduced by 9%. The legacy job test proves the possibility of a real-world EGP implementation with improved efficiency, quality, and sustainability. The total number of colors is reduced by 33% and ink consumption is reduced while the quality was acceptable to the brand owner.
The results show that the use of EGP enables accurate spot color simulations in a simplified way. Therefore, the proposed method offers the basis for the industrial transition from spot colors to multicolor designs for greater flexibility, efficiency, and better sustainability.
The packaging printing industry has traditionally been a conservative one and new methods are usually trialled without a deep systematic and scientific approach. Therefore, there has not been a comprehensive and scientific investigation of the multicolor process in flexography and it is relatively unknown in detail; thus EGP is considered a niche process. Printers and brand owners lack concrete evidence to support its implementation. This thesis aims to fill the scientific gap and provide data and test results to facilitate the transition to EGP in flexography.
Currently, there is very little scientific peer-reviewed literature or PhD studies on multicolor printing in flexography. The materials available are mainly proprietary marketing materials, various articles, user manuals, college-level studies, and seminar presentations. The available test results typically only apply to narrow web printing, while the availability of empirical production data is almost non-existent.
This study provides examples and data to show the potential of multicolor printing. The main questions are whether and how multicolor process printing can replace conventional spot color printing. The purpose is to describe and calculate the achievable benefits of EGP in figures, since economy and ecology are also significant market drivers.
The study collects and supplements materials from various sources. A novel EGP calculator is developed to describe and evaluate the potential of the method. The study investigates and evaluates the possibilities of color gamut expansion in wide web flexography and describes and calculates the potential of the gang-run printing. Finally, a legacy job printed with spot colors is converted into EGP and the results evaluated.
Several key findings are made in the study and the calculations show great potential for efficiency and cost savings in various areas. The improvement in the press setup is clear, but one of the most interesting findings is the effect of cleaning solvent distillation. In addition, the influence of the amount of stock ink is low and the savings potential on the substrate high. It is also a novelty to link these calculations with Overall Equipment Effectiveness (OEE) and CO2 values.
The EGP calculator estimate in this study shows an improvement in the OEE of 42% to 85% and a total cost savings of around 0,6 to 1,3 million euros per printing press per year, while the CO2 equivalent is reduced by 34% to 51% compared to spot color printing, the results will be different case by case. The studied tests show the capability to expand the color gamut with additional process colors, up to 91% of the Pantone Color Matching System (PMS) colors for the studied 7-color system of less than 3,0 ΔE2000, as expected. However, against expectations, high-pigmented inks also expands the color gamut by 14% for the studied 4-color inks. The Total Area Coverage (TAC) calculations of the tests show that EGP can save ink.
The benefit of gang-run printing is generally mentioned by many sources. This study also defines the increased efficiency in numbers as the test showed the ability to eliminate 30% of the total number of inks. The calculated individual ink consumption based on TAC is reduced by 15% to 69%, while the number of printing plates is also reduced by 9%. The legacy job test proves the possibility of a real-world EGP implementation with improved efficiency, quality, and sustainability. The total number of colors is reduced by 33% and ink consumption is reduced while the quality was acceptable to the brand owner.
The results show that the use of EGP enables accurate spot color simulations in a simplified way. Therefore, the proposed method offers the basis for the industrial transition from spot colors to multicolor designs for greater flexibility, efficiency, and better sustainability.
Kokoelmat
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