Laser technology is often used to mark products. Conventional laser marking offers persuasive advantages though it is not suitable for all applications.

The Laser Color Transfer (LCT®) process, developed by MERCK in conjunction

with KURZ, integrates the advantages of laser marking while taking it a step further.

Laser marking has established itself as a fl exible and cost-effective labeling process in many areas. It is utilized in the automotive and automotive supplier industries, in machine and plant construction as well as in the packaging, cosmetics and pharmaceutical industries. Laser marking is being used on

investment and consumer goods, blanks, semi-fi nished and fi nished products like electrical and electronic components, labels, packaging, and credit and customer cards.

Laser marking is being used on investment and consumer goods, blanks, semi-fi nished and finished products like electrical and electronic components, labels, packaging, and credit and customer cards. Laser markings are used for product

identifi cation, traceability and copy protection. They present device controls and scales, provide manufacturer addresses, device types, test marks, safety instructions, barcodes and data matrix codes.

There are a number of reasons for the growing popularity of this labeling process.

• It is compact and inexpensive; it requires neither printing nor stamping machines, and no plates or artwork.

• It is uncomplicated, fast and flexible. There is little to no setup, preparation or retooling work required. The laser enables highspeed marking and fast design changeovers, is simple to program, and can be integrated into industrial production lines without difficulty. Individual parts can be marked just as economically as small and large runs.

• Laser markings are characterized by their high resistance to abrasion, heat, chemicals and UV light.

• In contrast to thermal-transfer printing, this process can also be employed on surfaces that are not completely flat.

• The laser also allows pressure-sensitive components to be marked, a significant advantage over hot stamping which can only be used for pressure-resistant surfaces.

Laser marking is performed without the use of printing inks; the substrate reacts to the laser energy by changing color. The coloration is determined by the material being marked and its reaction, so color variations cannot be achieved. If the marking includes design, the limitation of printing inks is a detractor.

• Depending on the base color of the plastic and its color reaction to the laser energy, the contrast between the product color and the marking may be small. Forexample, application of the laser to white plastic can only produce gray, not black, lettering.
  
  Additionally, it is not possible to achieve white labeling on black plastic. The result in such cases is often visually unsatisfactory, and the insufficient contrast also adversely affects the readability of the barcodes.

• There are plastics that are fundamentally diffi cult to mark by laser because the application of temperature does not invoke the desired reaction.
  
  It is for these reasons that MERCK, in conjunction with KURZ, developed the patent-pending LCT® process, a marking technology for thermoplastic polymers that incorporates the advantages of laser marking but none of its disadvantages. This innovative marking process is equally suited for C02 and NYAG laser technology.

A transfer color ribbon is passed across the plastic part to be marked by means of a supply and take-up unit. Since air gaps would render a laser unusable (air acts as an insulator), the foil is sucked onto the substrate by means of a vacuum.

The laser heats the foil and plastic, releasing the color from the carrier foil forming a permanent bond with the molten plastic. A print image with sharp contours and vibrant, deep colors is produced.