28 Jun 2022

Bashing Heads – the complex ways of head technology

Bashing Heads – the complex ways of head technology.

A recent industry trade show offered me the chance to view lots of new stuff and meet with industry leaders and fellow industry members. At night while sitting at the hotel bar, I overheard an in-depth conversation about inkjet head technology. Yes, inkjet head technology is still a big discussion at trade shows, especially in the hotel bar for some reason.

The first guy was arguing that his company XYZ was making the fastest head and largest output on the market. The one sitting next to him was agreeing; it was fast, but his company ABC had a print head that was wider and therefore could print more in the same time, making it much better.

Last of the three guys was from FGH and his company was proud to be the one with a replaceable head, so no service issues and fast changing. He also mentioned that with his technology he could keep on adding heads if needed. ABC asked why add heads if you have a big one that you could stitch together in one long seamless printhead.

This would be compact and fast. Well, FGH mentioned, you don’t need to have a complicated large long head, especially if you needed to replace it. He continues explaining about the headache you would have replacing one head. With his technology you would just replace what was broken and you’re up and running in no time.

XYZ continued that with the technology from his company, you would only need to replace heads after two to three years, so where is the problem?

Finally, they all agreed to disagree on this topic and ordered more beer. As the beer arrived they continued with printhead drop size: where one head was able to print with 2 picolitre the next one was proud to say that 11 to 12 picolitre was a lot better as density and coverage was so important. One commented that if you want ink on the substrate then the valve jet was your solution, with up to 260 picolitres and a resolution of 35 dpi it could print on anything as long as you looked at it from a kilometre away. They all burst into laughter.

With flat beer in their glasses, the discussion continued, but now about the differences between piezo, thermal and valve jet technologies. As all of these are inkjet printheads and the discussion became less friendly. The XYZ company man told everybody that it did not matter as piezo is the most common technology and that most of the heads are piezo heads. FGH started to laugh, his company has made more thermal inkjet heads than anybody in the world, so no, piezo is not the only technology. They rambled on about the technologies and what was better and why…

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I decided to leave the gents to their discussion and consider their statements. Was size, speed, technology and drop size worth the discussion? No, the core is what are you going to use the technology for. The key word here is “application”.

Let me go deeper into this. Let’s take a UV ink-based flatbed printer. Here the size of the droplet is important if you want to have sharp small text (say 2 points) at the same time you would like to have the possibility of a variable drop size. This gives us a better coverage and a more uniform image build-up, especially if you have large one-colour high-density blocks on the print (such as for logos and other vector data).

Thermal technology is not recognised as multidrop technology. It can still produce decent output with water-based or resin-based inks but it would not be the best solution for UV inks and UV curing lamps.

So how about the size of the heads for this flatbed table? Big heads like from ABC could make the carriage weight very high and would make the printer slow and bulky. Not only that, the print would also be very heavy to carry all this weight. In my opinion the best solution would be a printhead that is fast, relatively small (I can use multiple heads so more colours or more speed) and piezo-based if you are designing a flatbed UV printer.

So how about if we would like to print carpets, especially the long pile ones? A fast print head would be great but we need penetration of the inks, so we also need lots of ink. The wide head could be a solution if it can give lots of ink and speed. And the high-resolution head would give us good quality, right?

Unfortunately for high pile carpets all of these heads would not survive because of the long pile, so here is where the valve jet would be the better solution. Lots of ink, reasonable speed but low resolution. Finding the right head for such an application is not easy. That’s why there are only a few companies making these printers.

Again the key is application. This is why manufacturers make printers for specific markets and trends. Textile printers are mostly piezo-based because of the accuracy, speed and drop size. CAD printers are mostly thermal (bubblejet) inkjet-based because of the relative low cost, easy installation and water-based dye or pigment inks. And, yes, flatbed UV inkjet printers are mostly equipped with a piezo head technology.

So if you are looking for a new printer don’t jump on the technology train. Think: what will I be producing? What is my need? And how much do I need to print? Putting all these things in order, you might opt for the most expensive device because the ROI would be better than the cheap one. Take your application to the next level by comparing the quality of the output on your application, not the head type. The right printer is certainly out there to meet your needs.

Just a word of caution: technology is changing so fast that this blog could be obsolete before you even read it. I just wanted to give you a heads-up on what the market has to offer to your business and how you can benefit from one evening of discussions at a trade show.

Mike Horsten
ZEMT Consultancy and freelance writer
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All brands names are fictitious and no reference is made to any specific brand