The Screen Print Column
How to remove the bottle neck T
here is a general perception that comes from the marketing in magazines and social media, that digital printing is growing in strength and has more to offer than screen printing. Of course, itʼs well accepted that digital printing is quicker in taking an image and getting it on to the garment for short run lengths and some printers have moved away from screen printing for this exact reason. However, screen printing can stay ahead of digital printing for long run lengths. It provides a wider colour portfolio, has an excellent wash resistance and allows for special effects such as glitter, high build, flocculation etc. to be possible on our garments. If we look at the garment printing industry today, the majority of the screen cleaning and making processes are predominately labour intensive and are prone to creating bottle necks and technical difficulties that causes problems during the printing process. For screen printing to stay ahead of digital printing there is a need to close the gaps in the pre- and post-press functionality and time commitment. If you look at the bigger picture of screen printing and its growth, there is a clear market sector leader in the form of industrial printing i.e. printing processes that are involved in the manufacture of solar cells, flexible circuits, membrane touch switches etc. As this market grows and develops technology that is pushing the boundaries of our printing process. You can clearly see that the process moves away from just being printing to it actually becoming part of the manufacturing process and automation becomes key to its success.
In garment and bag printing, automation typically stops at the printing press by investing in a fully automated carousel and drier. In industrial screen printing set ups, the automation goes beyond the printing press and can include full automation of the pre- and post-press and at some printers this even includes full in-line screen making (made up of a cleaning machine, multiple drying cabinets, coating machine, computer to screen and washout) and screen cleaning process, where you start with a dirty screen and end up with a fully processed and ready to print screen at the end.
There is a lot to learn from this approach for todayʼs screen printers and I am not saying that every screen printer should go out and purchase a full in-line
| 72 | June 2019
system for screen making and screen cleaning as this is an expensive investment. However, investing in key processing kit to start bringing in automation into your facility can make the difference and will help you keep ahead of the digital printing market for the future.
What equipment could you invest in to bring better control, decrease processing time and achieve a better printing result.
Coating machine
This is equipment that brings automation to the coating process and controls factors such as pressure, speed and angle and all of these contribute to reducing thick edges, minimising the amount of emulsion used and brings a consistent profile of the emulsion on the mesh. It will also save you time in the screen making process as they can coat both sides of the screen at the same time.
Direct to screen (DTS)
This is one of the growing markets of automation in the screen making process and eliminates the need to use film and ink jet printers to create positives, especially as the image is directly placed on to the dried screen before exposure. Personally, I would recommend going with a wax system vs. an inkjet system as you will achieve a better quality stencil and higher resolution images. However, donʼt forget this process will still require you to conduct the exposure process using either a conventional or LED exposure source.
Laser to screen (LTS)
Laser or computer to screen (CTS) making dominated the graphics printing sector until digital printing established it self as the leading printing process of this market. It is now becoming well established in the workwear transfer
printers and industrial printers and offers the opportunity to eliminate positives by imaging and exposing the screens in one process. With todayʼs modern LTS systems it is even possible to image and expose high build stencils that was not previously possible with the original CTS equipment. It also gives the best resolution and definition that is possible in automated screen making and offers the screen printer a dpi range from 854 to 2540dpi.
Cleaning machine
This is the ultimate automation of the screen cleaning process. It is the screen reclaimer and makersʼ dream, as they no longer have to manually clean the stencil and reduces exposure to the chemicals that can be used in this process. When it comes to taking this step into the investment of screen cleaning machine I highly recommend doing your homework and seeing how the equipment could work for you and if possible, invest in equipment that is ATEX compliant and multi chamber (ink removal, stencil removal and if possible in-line degreasing). The multi chamber equipment will allow you to clean more than one screen at a time and will utilise high pressure spraying systems that will give you the cleanest of screens at the end of the process. Equipment that utilises brushes and lower pressure cleaning will typically result in poor cleaning results.
Summary
Screen printing has a bright future and investing in technology in the pre- and post-press will improve profits and keep screen printers ahead of the digital printing world. It could even help you develop into the industrial printers of the future, as printed garments move into adding technology that monitors heart rates, blood sugar levels etc. and creates wearable technology of the future.
www.printwearandpromotion.co.uk
William Shorter, of SPT Sales + Marketing, explores the automation of the screen printing process and how removing bottle necks will keep screen printing ahead of digital printing.
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