Traceability and the need for product marking are well understood across a wide range of industries today.

No longer is the subject restricted to aerospace, food and pharmaceuticals, for example, but it now extends across almost all manufacturing industries due to issues surrounding efficiency and liability.

Applying marks

An appreciation of the need for product marking is one thing, but designers of products and automated assembly, processing, testing and packaging equipment are faced with numerous different technologies for applying marks.
With products and packaging that need variable data to be marked, whether for serial numbers, date codes or test results, for instance, it is important that the marking technology has mark-on-demand capability.

Popular options

No single technology will be suitable for all applications, but inkjet, laser marking and rapid indent marking have generally established themselves as three of the most popular options for the food, medical device and general engineering sectors respectively - but not exclusively.
Now a new alternative, based on low-cost CO2 laser marking, is available for direct marking of products, as well as for labels and packaging (Fig.1).
The potential applications are certainly very wide-ranging, from casings for electrical/electronic equipment to marking directly onto foodstuffs, pharmaceutical tablets and tobacco products.

Combining chemistry, substrate conversion and laser energy, the Datalase process has now been developed by Sherwood Technology to use a very low power laser light for the high-speed printing of images, barcodes, two-dimensional dot matrix codes or alphanumeric characters (Fig.2).
Various substrates can be marked, including metals, plastics, flexible packaging, paper, and board.
Imaging can also be formed through polypropylene and polyethylene films, allowing the image to be permanently embedded or 'sandwiched' within laminates.
It is even possible to mark pharmaceutical tablets, confectionery or other foodstuffs directly, and research is underway for marking glass.

Non-toxic ink

The Datalase process uses a non-toxic and environmentally friendly ink, coating or substrate additive that changes colour to produce a stable, high-contrast image when marked by a low-power CO2 laser. Compared with more traditional imaging processes, it is also claimed to have a higher fidelity.
Materials to be marked can be treated either by direct doping of the additive into the substrate or its existing surface coating, or by a separate coating or printing operation.
As the subsequent laser imaging process does not require any ink or ribbons, it is virtually maintenance-free.

In addition to inks and coatings, Sherwood Technology has recently launched Datalase Masterbatch, which uses an additive that enables polymer components to be extruded or moulded with an inherent ability to be marked by a low-powered CO2 laser.
Prior to this, manufacturers had abandoned the use of these CO2 lasers in preference for higher powered versions and YAG lasers, particularly for polyolefins such as polypropylene and polyethylene.
Other additives have also been used in the past, but these tend to require higher activation energy and cause a localised change and charring to the surrounding plastic.
The Datalase Masterbatch is thermally resistant at normal injection/blow moulding and extrusion temperatures up to around 250ûC.

Developments

Other ongoing development projects include: transparent coatings for plastic films and glass; a range of different colours produced following laser activation; brand protection materials; materials for multicolour imaging; and laser markable foodstuffs.
Clearly the full potential for the Datalase process has not yet been explored, but this is a technology that will certainly be of interest to designers of products and automated assembly and test machinery.