One of the most common problems I notice on production lines is that the date coder on the line is not the correct type for the application. So, which printer should you be using? There are many different types of printers out there: CIJ, TIJ, Laser… the list goes on. So, which printer should you be using? And how can I inform myself before the salesman overloads me with info? Well, I am going to try and help educate you a little and narrow your options down in the following article.
The common term for these printers is “Date Coders” and the type of DC that will best serve your needs is dependant on a couple of factors, these are not all the variables but the most common. Namely:
- The type of material/ink required
- The shape of the material
- The speed of the line
- The physical location and amount of space where the printer needs to be installed
So firstly, lets look at the type of material/ ink required. If you are printing on a non-porous surface such as glass, plastic or even gloss cardboard, then you will most likely need to use a solvent based ink. This is because the solvent evaporates quickly and allows the ink to dry on the surface. There are also food grade inks, Thermochromic inks, pigmented and many others. Another option is Laser printing, these are by far the most expensive to buy. You will not be using ink and solvent in a Laser printer so your running costs are alomost zero. If you are printing on plain or matt cardboard or if your product has a designated area where ink can be absorbed, then you can go with a water bsed or ethanol ink. There are exceptions, as always, I have a customer who uses ethanol based ink on their ceiling boards and another customer who uses water based ink on the boxes of soft cheese. The brown paper which covers the ceiling board absorbs the ethanol ink easily and the cheese boxes, although they are glossy, have a small rectangle which is not glossy, designated for the best before date, the water based ink adheres to it quite nicely. If you gave it a rub straight after it was printed on, sure it would smudge, but once it reaches the end of their short conveyor it has dried sufficiently to be handled and packed into larger boxes without smudging. So, there are always exceptions but the general rule is, if a pencil can mark it without pressing down hard, water based ink should work for you.
Secondly we come to the shape of the product. In the case of a flat box or any straight edged object, you can usually use a “box printer” or Thermal Ink Jet here. These printers usually have rows of piezo nozzles, electro-mechanical nozzles or a Thermal Ink Jet system, they are generally known as dot-on-demand printers and are mostly used to print a large, bold print. If you are printing on the underside of cans or anything with an irregular surface where you have more than 5mm distance from product to printhead, then CIJ (continuous ink jet) printers are normally the go-to for these applications. There are rare occasions where the two types over lap. For instance, since the new regulation for the packaging of potatoes states that the date has to be on every single sack, I have installed four printers which print on the sacks while they travel along a carousel. Now the experience I have had down in Cape Town has been completely different to my colleagues up in Johannesburg. Here in Cape Town the bags are extremely irregular and lumpy due to the way the carousels are designed, so we have no choice but to go with CIJ because the ink is sprayed out the printhead and can manage the product distance changing in relation to the printhead. In Johannesburg they are using TIJ (thermal ink jet) printers with no trouble at all. This is because of the type of carousels they use for their potatoes. They have a roller system which pulls the top of the bag straight up and guides the bags uniformly and within close proximity to the TIJ printhead.
Next we come to the speed of the line.TIJ printers are able to print at very high speeds. If you need to use CIJ printers and you have multiple lines of print running at high speed, you will most likely need to opt for a high speed model. This is because a message with multiple lines needs to be processed by the CIJ Printer at a faster rate in order to control the millions of droplets in the ink stream. These high speed units are generally a little more expensive and the inks and solvents they use also cost a little more. So, once again, depending on the application you will need to decide which is better suited for your production line. You can normally get around the need for a high speed units by rearranging your message from say, 3 lines to 2 lines of text.
And now we get to the physical location and space you have for the printer to fit in on your line. This is where the physical size of the printhead and printer body come into play. I recently completed an installation at a wine bottling plant where a CIJ would be perfect for them but, due to the space constraints inside their new labelling machine, we could not get the print head to fit. There just wasn’t enough space. Luckily the TIJ printheads we have are nice and compact so, it fitted inside their label applicator quite easily. It has enough room to be accessed to change the ink cartridge and also to be adjusted for height. So consider where on your production line the printer will or can be installed before purchasing. A demo is always the best option.
Lastly, and not included in my list, is an obvious one: price. Prices are all over the place, the best advice I can give is: Figure out what will work, demo all types of printers first, make sure you or you’re operators can manage with the user interface first, then look at budget and price.
So, in conclusion, every installation is dependent on multiple factors and this article only covers some of the more common ones. It is always best to consult a printer technician on which printer will best serve your needs. I just hope this article will help you to be a little bit more informed and point you in the right direction.