TECHNOLOGY | LASER MARKING AND WELDING
Right: The sustainability benefits of laser marking are emphasised in Gabriel- Chemie’s Think Green line
Digitally-driven The two key drivers behind interest in laser marking — aesthetics and traceability — both exploit, to some extent, its flexibility. Laser marking is digitally driven so every part marking can be unique. Personali- sation of consumer products such as cosmetics is becoming increas- ingly popular — smaller customised batches are more “exclusive” so drive higher margins. Hannah says Gabriel Chemie and its laser marketing partners are working to develop solutions that incorporate multiple lasers to make complex decorative marking possible within an economically accept- able cycle time. The traceability trend is driven by the need to permanently mark objects so they can be identified throughout the product life cycle. “The Unique Device Identification (UDI) system in place in the medical industry is a good example,” Hannah says. “One of the main areas for laser marking remains the automotive industry, where both of these trends can be observed. Firstly, more individual interior designs are required, where laser marking has a lot of value. Secondly, more product trace- ability under-the-hood is leading to laser marking of individual components.” Germany-based additive maker Chemische
Fabrik Budenheim highlights several issues currently impacting the market for laser marking and welding materials. “For laser marking, these include regulatory issues and the requirement for traceability. There is also a need for clean and contactless marking, as well as further moves towards high speed and cost saving in-line production. Laser marking must also be perma- nent, indelible, and resistant to solvents, humidity and abrasion. In addition, the marking process must be highly flexible,” says Dr Heiko Rochholz, Head of Marketing, Business Unit Material Ingredi- ents. “In laser welding, there is a need for extra tight and strong welding seams, without the use of glue, as well as gapless laser contour welding.”
Eco developments Rocholz identifies a number of current areas of development in laser marking and welding. These include the need for marking additives to be eco-friendly, antimony-free and safe for food and medical applications, and for welding the need for transparent additives that do not compromise colour. Budenheim’s latest product introduction — Budit
42 COMPOUNDING WORLD | July 2021
L21 — is targeted at injection moulded applications. “Budit L21 is used in applications where light active features are introduced,” says Rochholz. “The additive has high selective absorption in the spectral range of near infra-red (NIR). In typical applications of laser marking, welding and cutting, a matrix polymer will absorb the NIR-laser light much more efficient- ly when doped with even small concentrations. The let-down rate depends on the final application but is typically 2-5%.”
The company says Budit L21, which is antimony-
free, is convenient to handle in further master- batching and compounding processes where further additives are added. The universal carrier is said to be designed to function well in engineering plastics such as polyamides but it will also function with polyolefins. An additional grade — Budit L23 —has been developed for compounding master- batches with a higher pigment concentration. Budenheim says the Budit L Series additives
offer good laser marking with selective absorption in the NIR range and high transparency in the visible range. They are designed for use with Nd:YAG lasers at a wavelength of 1064nm and, depending on the energy level, can produce visual marks ranging from bright to dark on the polymer surface. The company says that, due to the low dosages required, they can be used to mark transparent polymers. The Budit additives create a mark around 10
microns beneath the surface of the plastic. De- pending on the laser parameters selected, the absorbed NIR energy causes one of two processes to occur: either the additive is degraded to create a dark marking colour or the energy is converted to heat, which releases gas and creates microbub- bles. In this way, the visual appearance can be tuned from black to very light black. The company says metallised markings are also possible. Budenheim says major application areas for laser marking at present include best-before dates and codes on food packaging or bottle caps, numbers on technical parts or electronical compo- nents, resistant bar codes, and ear tags for cattle.
Marking polyolefins Plastics applications are a target for Eckart’s Lasersafe laser marking additives. The company says that the heavy metal-free Lasersafe additive provides strong contrast, high writing speeds and
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IMAGE: GABRIEL-CHEMIE
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