Slitting & Rewinding
Resealable packaging using a laser in one single slitting process
For over 60 years, Comexi has been developing technologies for printing, laminating and slitting solutions. Recently the company met with brand owners and converter companies in the sector to learn about the needs and problems regarding their products
T
he need to provide a solution for single dose and/or fast consumer
products, such as snacks or chocolates in removable labels, was agreed upon at Comexi’s meeting. All brand owners and converters are aware that wherever there is a zipper there should also be an easy open with a laser. If this is not included, consumers run the risk of injuring themselves when opening the packaging with scissors or other tools and/or breaking the actual zipper, rendering it useless. In short, this means making an
opening in the packaging and placing a self-adhesive lid to it that allows opening and closing.
FROM THE CURRENT SYSTEM TO THE LASER SYSTEM At present, we can find products that make the opening with a die at the bottom and then place a label over the top part. Many of these packs are for snacks, which highlights the current problem. The whole barrier has to be provided by the label itself and, also, this implies completing the packaging on two different machines, by adding an extra process. After going through the slitting machine, the reel must
be sent to another wide band machine where the label will be added to the top surface and the rotary die-cutting will be done on the bottom part. This process is normally done in a narrow band machine to avoid the die cutting bending. Therefore, the internal product’s whole barrier against humidity and oxygen is damaged. With this system, there are three
problems: 1 -With a mechanical system, it is very dificult to remain within tolerances. Therefore, when the thickness is very fine, the mechanical system could also damage the label, and it is dificult to go down to certain material thicknesses because we would not be able to control it. On the other hand, when the material is very thick it can also be dificult to produce a good finish. 2 - Creating dies for each design
or promotion means there is little flexibility in marketing and promotions, making it impossible to obtain a good time to market. 3 -We add an extra process after
going through the slitting machine, also increasing costs and time. However, the laser system has a
series of advantages over the mechanical system; mainly, its simple design, faster action (because it uses software and not
By Jordi Prat, technical director slitter and rewinder at Comexi
die systems), and less wear. As well as all these advantages of reducing stock and preparation times, it is also possible to improve the die-cutting speed. Do not forget that both repeatability and quality are better when using a laser. This will mean fewer claims and product faults. The solution with laser and in-line
labelling improves three problems with the current system: 1 - We can penetrate to the desired substrate layer precisely, without damaging the internal product barrier. 2 - In a single machine, it is
possible to cut the reel, make the perforation with the laser and add the label all in one single process. 3 - Depending on the number of
lasers and labelling machines set up, we are going to double, triple or quadruple productivity by 400 per cent or more.
PROBLEMS IN REWINDING WITH EXTRA APPLICATIONS The CingularLaser system by Comexi is being provided in high range machines, like the S1 DT, because in such a process for in- line labelling, a laser is required as well as very good tension control. Comexi has developed a patent for this form of control. It is important to control the rewinder and horizontal nip with independent control for each S1 DT axis. The difference in gauge that is going to
34 March 2017
be generated by the BOPP or PET label must be absorbed, and it may reach 80 to 120 microns. This gauge difference could cause excess tension or telescoping problems if this tension control did not exist. Comexi provides the S1 DT solution without lowering the quality of the rewinding and good performance in the subsequent packaging process.
100 PER CENT QUALITY SYSTEM Using its knowledge of the market, Comexi has anticipated and carried out labelling control with a Keyence machine vision camera to make sure that it is arranging the label in the right place. Just as with the Comexi CingularLaser, creating this product ofline (making the process with the easy open form and labelling, slitting the corresponding tracks and rewinding in one single stroke), allows the machine to gain in versatility because it has many more functions. On the horizon, the Comexi
CingularLaser system is still at an early stage because of its potential for developing new applications in the flexible packaging conversion industry. Therefore, the company is continuing to explore in this area to provide added value to its clients in each of the printing and flexible packaging conversion processes.
uwww.comexi.com www.convertermag.co.uk
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