(This article is sponsored by The Boston Group)

What is the first thing you do when you pick up that carton of milk every day? You look at the date of expiry to make sure that the milk is still good before you drink it or put it in your tea/coffee. Use By/ Use Before/ Good when used by …(date) ……… are the various codes you look at on the milk carton. Ever wonder how this code gets there on the neck of the carton.

Have you ever noticed similar markings and codlings on all the products you use in your daily life- baked goods, medicines, shampoos, drinks, food, and beverages, It is mandatory by law that all the products have to have a code giving the date of manufacturing, date of expiry, use before date etc. Since this is a legal requirement there has to be a technology that helps in printing these codes on all the products we use on a daily basis.

It is done using one of the three marking and coding technologies called - Contact coding, Inkjet coding, and now laser coding.

The longest used technology and most cost effective is Contact Coding technology. This technology uses units called 'Roll Coders" are equipped with ink rollers, inks, and different sizes of print plates and are used in a wide range of applications.

The Roll Coders are used in Industries like Food, Pharmaceuticals, Electronics, Auto Parts, Cosmetic and Toiletry products by a large number of multinationals like Proctor & Gamble, Johnson and Johnson, Unilever, Wella Corp., Oscar Mayer, General Motors for marking and coding applications of their products and labels with the date of manufacturing, date of expiry, price, company logo, use by date etc.

Technology of Roller Coders

Roller Coders include a wide range of contact Marking & Coding systems, which are characterized by cylindrical print drums, which hold rubber-printing dies. The print drums on these coders are friction driven, usually by a pair of rubber friction bearer rings, which ride on the surface of the product being marked. The inking system on a typical roller coder is usually an ink roller, which is mounted tangent to the print drum. As the printing dies are rotated past the ink roll, a thin film of ink is applied to the surface of the dies and then it is transferred to the surface of the product. In essence, this form of Marking & Coding can be defined as rotary rubber-stamping and anything from simple dates and product codes to elaborate logos can be applied by this method. Roll coders are available in a variety of styles and sizes and are typically used for marking flat surfaced, conveyed products such as corrugated cartons, lumber, paper products and both Absorbent and non-Absorbent continuous web materials

Appropriate Size of Roll Coder

Roll Coders are available in many sizes and careful consideration must be given to the specific application when making a selection. The first consideration in carton printing applications is the size of the carton being marked and the character size and length of code required. It is very important to understand that the product being marked with a friction driven coder must be capable of rotating the print drum through friction contact with the coders friction bearer rings. In most cases, this means that the carton must be of adequate weight to rotate the print drum without slipping or skidding on the conveyor belt.

Print Width

Roller coders are also available in various print width sizes, which relate to the capacity to hold larger character sizes or multiple lines of characters. For best print quality, it is generally preferable to use the smallest acceptable character size for the job (down to ¼" character height) and the least number of lines of code possible. More lines of text and larger, bolder character sizes will require greater printing pressure and a more rigid carton surface for gook quality print.

Web Printing

Applications, which require printing on any continuous roll or extruded material such as rolls of paper or plastic film, is classified as "web printing." Only Continuous coders are used for these applications since the friction bearers on the coder print drum remain in constant contact with the material. Although standard coders designed for Absorbent surface printing can be used in some of the applications, Non-Absorbent Coders are specifically designed for web printing applications and offer some distinct advantages over conventional coders.

Selection of Inks

Fast drying inks (drying in 1-2 seconds) are used for almost all materials like plastic film, corrugated boxes, tapes, labels, foils etc. There are over 100 different types of inks for different materials, with different drying times, FDA approved for food, beverage, pharmaceutical/ medical applications, printing through high humidity, low / high temp, water/ solvent resistant or water washable inks. In a typical web printing application, the material is traveling at a relatively high rate of speed and the printed codes are required to dry very rapidly to prevent smearing or transfer of ink when the web is re-rolled. Proprietary inking system design, which applies an extremely thin film of ink to the face of the printing, dies. After the code is transferred to the web material, this thin film of ink dries very rapidly.

You name it and an ink can be designed around that application.

|