Almost everything we consume today is marked or coded in one way or another, from best-before to lot dates to batch dates, etc. These unique markings tell us, or the supplier, information relating to product safety, consumer protection, traceability or to avoid counterfeiting. Manufacturers try to meet the various regulations which they are required to operate within by using marking and coding equipment in their factories and where needed within their supply chains.
Many different printing techniques are used from laser coding, thermal transfer or continuous inkjet technology. Each of these has its own unique advantages and sometimes challenges.
Continuous Inkjet (CIJ) technology
One of the oldest inkjet technologies used today is CIJ. Its major advantage is the capability to print at high speeds without the ink nozzles clogging because the jet is continually being used. This allows volatile solvents to be added, like alcohols and ketones, to give the ink the capability of “biting” into the substrate and drying quickly.
Thermal Inkjet (TIJ) technology
In TIJ, the printing cartridges contain small chambers that contain a heating element that is activated by a pulse of current. When the current passes through it, a rapid vaporization of the ink causes bubble to form which propels a droplet of ink onto the substrate. Because no special equipment is required, TIJ print heads are generally cheaper to produce than more specialized print heads used in other inkjet technologies.
Piezo Drop on Demand (DOD)
In piezo DOD printing, a permanent print head is used. A piezoelectric material is placed inside a chamber containing ink located behind each nozzle. When voltage is applied, the piezoelectric material changes shape to force an ink droplet from the nozzle. Piezoelectric inkjets allow a wider variety of inks to be used because no volatile component is needed and there’s no ink residue buildup. However, the print heads are more expensive to manufacture.
Laser Marking and coding
Laser technology uses a laser to etch or vaporize the top layer of the substrate to leave permanent text or graphics or other data directly onto many different substrates including paper, cartons, glass or plastic. No inks or fluids are involved, so laser etching systems are cost-effective and environmental friendly. Lasers remove material or coating from the product or packaging by permanently scribing the substrate without weakening the material.
Thermal Transfer (TTO)
TTO is a digital printing process which applies a melted wax-based coating in a ribbon onto paper or another substrate. The substrate then passes under a thermal print head and the coating melts and adheres permanently after it cools. TTO printouts are not as sharp as those from inkjet or color laser printers. However, this type of printer is often used because of its speed, water-fastness and high reliability because of the small number of moving parts.
Each of these different types of printing techniques has its own advantages and disadvantages. The overall purpose is to help manufacturers track and date their products and to adhere to the various product safety regulations that apply. Consumers today are rarely aware of these numerous manufacturers’ efforts but in reality they are generally much better off today because of the latest advances in marking and coding technology.