Industrial inkjet coding and marking is the printing of the date, batch number and code on every pack as it passes the printer on the production line. It is the first step in tracing a pack later. Most of the printers are small inkjet machines that print on the pack without touching it.
A pack of medicine, a packet of biscuits and a bottle of oil all carry such a code. It usually says the manufacturing date, the expiry date and a batch number, often with a barcode or QR code. By law, many products in India must show these details, under rules such as those for packaged commodities, food and medicines.
Printers use different methods for different packs. A continuous inkjet printer fires a stream of tiny ink drops, and it suits fast lines and curved surfaces such as bottles. A laser printer burns the code into the surface, with no ink, and it suits packs that must not be touched by ink. A thermal transfer printer presses a heated ribbon on to plastic film, and it suits flexible packs such as sachets. A wrong or missing code is costly: the plant has to stop the line, and a food or medicine pack with no expiry date cannot lawfully be sold.
Imagine a plant that fills sachets of shampoo, and the line moves 300 sachets a minute. A sensor detects each sachet as it passes. The printer fires tiny drops of ink in a pattern and prints a code such as B2411, MFG 11/26, EXP 10/28. The batch number comes from the MES, so that every sachet of the batch has the same number, and the printer starts a new number when the batch changes.
Next, a camera reads the code, to check that it is complete and readable. A pack with a smudged code is thrown out. The inkjet printer is a part of an assembly line or any other special-purpose machine.
Later, if a batch has a fault, the maker can look up the batch code and find which packs to recall. That is the use of traceability. The printing is the first record, and the MES holds the rest.