Today, there are many ways to increase the productivity of the printing process. No one is surprised that equipment manufacturers in the flexible packaging sector must constantly improve their procedures to reduce manufacturing time, costs and, at the same time, maintain great quality standards.
In this respect, the latest market studies reveal some of the main trends that are marking out the future of this industry. One of them is the growing reduction of job length, due to the fast, constant changes required by end clients, which is altering paradigms and systems, and making the reduction of downtime during job changeovers increasingly more important than the actual printing speed. At present, clients ask that machines satisfy the demands of short runs in terms of profitability, and high and consistent quality, above all.
Today there are presses that excel in ergonomics and accessibility, and are also small, which facilitates all the operational tasks. With drums that are just 4.9-ft. in size, operators and technicians can access all the printer units without having to use ladders or platforms. At the same time, by applying SMED (single-minute exchange of die) concepts in each changeover operation, switching from one job to the next can be done in less than 20 minutes. These are key factors in the current market.
In our company, the minimum printing repeat and the width of our flexo presses allow clients to benefit from low production costs associated with the smaller dimensions of the photopolymer plates. The link is clear in machines with these characteristics: the shorter the job run, the greater the profit. As we can see in Figure 1, production costs vary according to the length of the job to print, depending on whether a compact or standard machine is used.
Also, apart from their size, these compact presses maintain the same design features as their larger counterparts: robustness, accuracy and efficiency to guarantee optimum quality, job speed, and a wide range of optional and peripheral equipment to satisfy any needs in the most demanding markets.
In this respect, and with the intention to reduce changeover times, engineers are reconsidering machine structure, and analyzing and encouraging potential developments regarding peripherals—elements that often remain in the background. Their objective: provide significant advantages in terms of reducing time and maintaining optimum, consistent print quality.
So, if we analyze the time used in a job changeover in Figure 2, we can see that approximately 50 percent is used in establishing the color set point.
An Automated Approach to the Color Set Point Process
There are various ways of optimizing the time used during the color set point process; one of them is automating the procedure. At present, we have equipment that integrates with the press and determines the precise amount of ink to add to a direct color to obtain a Delta E less than 2. This equipment works by using:
- A spectrophotometer for measuring the reference color and the color of a printed sample. Specific, online color measuring systems that do not require taking a sample and which are equal to the table spectrophotometers in terms of precision already exist on the market
- A specific software for calculating the amounts and types of ink to add to the direct color
- A system for measuring the ink present in each tank
- A system for weighing the amount of ink to add
All these systems guarantee the color set point in a maximum of two iterations and provide many of the advantages of automation—accuracy and consistency irrespective of the operator’s skill. Additionally, they are not affected by the turnover of personnel that may occur in the production plants—advantages that have a clear link with the current trends and requirements in the flexible packaging sector.
Training for the Printing Process
A second way of optimizing the time used during the color set point process is associated with training those responsible for the color standardizing and management process. At present, there are programs and courses aimed specifically at increasing the productivity of the printing process through color management. These have had very good results, enabling the printers to save time and material during the changeovers, and consequently increase the OEE (overall equipment effectiveness) of the whole plant.
The advantage of this type of training is that it is independent of the machine; therefore, once the personnel are trained, the process can be extended to one or several machines at no additional cost.
A Crucial Component
Pressure and register set point times are a critical part of the printing process. Left unaddressed, they can generate uncertainties in the overall changeover time and quality defects in the printing. These parameters affect the resulting losses of material and the machine availability time.
To overcome these variable aspects, automatic printing and register set point systems have been designed. The premise is to fully inspect the printed sample, compare it with the PDF file used to create the plates and automatically find the exact point for optimum printing quality. They minimize application of overpressure and waste generated, independent of the operator’s skill.
To reduce downtime, we can go one step further by perfecting all the elements that are linked to the printing process, such as the ink changeover and cleaning times.
Fixed Palette Printing
Recently, a specific printing process has been gaining substantial ground—a system which, precisely, minimizes said tasks, and possibly deletes them: fixed palette printing (CMYK), with or without using expanded gamut or EG (OGV). The constant improvements to plates, inks and programs facilitate implementing this type of procedure. It achieves very high levels of quality, while also considerably reducing production costs. By maintaining the colors in the press, without any changes, cleaning is not necessary, thereby saving time and, above all, money in solvents. Just by maintaining stationary colors, the ink changeover task is deleted. Also, the color set point is done in the prepress stage, which means the press just has to do one thing: print.
In recent years, centers and companies have invested in developing their in-depth knowledge of color management. Therefore, they are now able to offer consulting services to those who think it is a good idea to implement a fixed palette printing system, and they can help them improve their efficiency and general productivity.
About the Author: Raúl El-Fakdi is currently flexo brand manager for Comexi, and has more than 10 years of experience in multinational companies, with experience in leadership, business process design and managing successful project teams.Raúl has a Bachelor of Applied Science in chemical engineering. In five years, he obtained three different master’s degrees in operations management and supervision, project management and engineering, and industrial management by Universitat de Girona, Universidad Camilo José Cela and Universitat Politècnica de Catalunya (UPC). Raúl completed the postgraduate course in Project Management by IESE Business School – University of Navarra and received an MBA at UPC.