Laser bonding

Laser bonding is a marking technique that uses lasers and other forms of radiant energy to bond an additive marking substance to a wide range of substrates.

Invented in 1997, this patent protected technology^[1] delivers permanent marks on metals, glass and ceramic parts for a diverse range of industrial and manual applications, ranging from aerospace to the awards & engraving industries. It differs from the more widely known techniques of laser engraving and laser ablation in that it is an additive process, adding material to the substrate to form the marking instead of removing it as in those techniques.

For metals, parts can be permanently marked with high contrast, high resolution marks for logos, bar-coding, identification and serialization purposes, without damage to the substrate. With glass and ceramics, complex surfaces can be decorated or marked and the traditional firing process replaced by a laser, with its permanent bond fired on in seconds.

Laser bonding has been achieved by Nd:YAG, CO₂ laser, Fiber laser and Diode-pumped solid-state laser and can be made by other forms of radiant energy.

Laser bonding is often referred to as "CerMark', "CerMarked", or "CerMarking". "CerMark" is a registered trademark of the Ferro Corporation, Cleveland Ohio, USA. This trademark, like Xerox, has become synonymous with the laser bonding process.

The laser bonding process

Mark quality depends on a variety of factors, including the substrate used, marking speed, laser spot size, beam overlap, materials thickness, and laser parameters. Materials may be applied by various methods, including a brush on technique, spraying, pad printing, screen printing, roll coating, tape, and others.

The marking process generally comprises three steps:

1. Application of the marking material

2. Bonding of the marking material with a laser.

3. Removal of excess, unbonded material.

The resulting marking is fused to the substrate, and in most cases it is as durable as the subsrate itself.

The durability of laser bonded markings

Markings placed on stainless steel are extremely durable and have survived such testing as abrasion resistance, chemical resistance, outdoor exposure, extreme heat, extreme cold, acids, bases and various organic solvents.

Marks on glass have been tested for resistance to acids, bases and scratching.

NASA's International Space Station, or ISS, was home to aluminum squares laser marked with CerMark marking material for almost four years. These squares were part of the Material International Space Station Experiment, or MISSE.

In this experiment test markings were applied to coupons made of materials commonly used in the construction of the external components used on space transportation vehicles, satellites and space stations. Markings applied using a wide range of different methods and techniques, including laser bonding. The material test coupons were then affixed to spaces provided on test panels, which were then installed onto trays which were attached to the ISS during a space walk conducted during the STS-105 Mission flown on August 10, 2001. The trays were positioned on the ISS so that they to could expect to receive the maximum amount of impact damage and exposure to a high degree of atomic oxygen and UV radiation.

The experiment was recovered on July 30, 2005 during STS-114 and returned to earth on August 9, 2005. The markings, DataMatrix two dimensional bar codes, were evaluated and found to be readable and visually looked as good as the day they were placed in orbit ^[2].

The laser bonding process is outlined and specified in both military^[3] and NASA^[4] marking specifications and standards. Laser bonding is also a preferred technique for use in the United States Department of Defense "Item Unique Identification" system (IUID).

See also

• Laser engraving
• Laser ablation
• Laser applications

References

1. ^ USPTO #6,238,847
2. ^ Report: "Marking Tests to Certify Part Identification Marking Processes for use in Low Earth Orbit (LEO)", Roxby, D., Siemens Symbology Research Center, 5000 Bradford Drive NW, Suite A, Huntsville, Alabama 35805, Oct. 11, 2005.
3. ^ MIL-STD 130M DOD Marking Standard, p.24, Table II
4. ^ NASA HDBK-6003 NASA Marking Handbook, Laser Bonding Section 5.1.5, p.15