Laser Cleaning Today

Laser cleaning has advanced far beyond its experimental stages. In recent years, Nd: YAG lasers emerged as a viable, reliable and often cost beneficial cleaning option for surface preparation and coatings removal. It is a versatile method that works on various substrates, including but not limited to metals, plastics, composites and even stone. Laser technology can be adapted to numerous contaminants and applications, cleaning safely and effectively (see Figure 1). Cleaning lasers are used with great success in many areas such as the automotive and aerospace industries. Marked growth is being experienced as lasers constructed continue to increase in size and capability.

Cleaning lasers remove contaminants through a process termed ablation. Ablation occurs as a highly focused laser beam is directed onto a contaminant or coating, causing the layer or coating to absorb the light emitted from the beam and vaporizes the contaminant. The greater the capacity of the contaminant to absorb the light, the more easily and quickly it is removed. Cleaning halts when the light reaches the substrate where it is reflected. Given the reflective nature of metal surfaces, they are particularly well suited for laser cleaning.

Tools, Parts and Plant

Machines and parts manufacturing stand to benefit from laser cleaning technology. Tools such as rubber and plastic injection molds are cleaned of production residue effectively and safely. They can often be cleaned at high temperatures and sometimes even in the press. Both manually controlled and automated optics are capable of cleaning complexly profiled mold cavities. With lasers, the precise geometry of expensive molds can be maintained indefinitely and the surface can be cleaned safely without degradation (see Figures 2 and 3).

Lasers afford the opportunity to prepare surfaces of substrates prior to coating in several different manners. The surface can be cleaned of contaminants such as oxides, oil and grease, scale or other production residues. Automated and integrated cleaning systems were developed to remove contaminants from the back plates of brake pads prior to coating, replacing sand blasting as the cleaning method. Companies such as Audi can be emulated; Audi operates automated cleaning lasers continually on their production lines to pre-treat metal surfaces on body panels prior to welding.

Adjustment of the parameters gives the ability to roughen or profile the surface of metal, plastic or composite parts as a pretreatment. This assists in bonding when adhesive or protective coatings are subsequently applied, as many of these coatings require an abraded surface free of oxides. Conversely, thermal staining can be removed from materials such as stainless steel without roughening the surface (see Figure 4). Through the use of a two-dimensional scanning optic, precise shapes may be removed from coatings and contaminants, thus eliminating the need for time-consuming and costly masking processes. One such example is the removal of varnish from electrical components. Further, with painted objects, coatings can be selectively removed making partial stripping possible.

Compared to some existing cleaning technologies where dangerous chemicals are used or released, laser technology is very safe and clean. With mold cleaning, the unpredictability of salt baths can be removed. With aircraft depainting, harmful chemicals in the coatings can be contained as they are removed. Effluent is quickly evacuated and contained, leaving no mess like that associated with abrasive methods.

Laser Cleaning in the Aerospace Industry

In recent years, laser cleaning technology has become a preferred means used by the aerospace industry to handle aircraft coatings removal. Traditionally, aircrafts are de-painted using abrasive and/or chemical methods. However, these means have come under increased scrutiny due to the environmental and health hazards they pose and their inability to remove coatings selectively from components with expensive and very sensitive substrates.

Laser technology and application became even more attractive with the Occupational Safety and Health Administration’s (OSHA) recent lowering of the Permissible Exposure Levels (PEL) of Hexavalent Chromium (Cr[VI]), a metal often found in aircraft primers and conversion coatings. Hexavalent Chromium is also present in processes such as electro plating and stainless steel welding, to name just two. Research conducted by the U.S. Air Force concluded that de-painting performed with a cleaning laser paired with a high performance HEPA fume extraction system creates Cr(VI) levels far below the new threshold.

Through the employment of 2D scanning optics, high powered cleaning lasers are capable of very precise and selective coatings removal. This means that portions of a coating can be removed with each pass while allowing for the maintenance of specific layers. For example, an anodized coat on aluminum can be preserved even if the primer coat atop it is stripped.

Together, the compact size, maneuverability and effectiveness of cleaning lasers create a means of removing coatings and contaminants from a variety of materials in numerous situations. Substrates are cleaned gently without generating dangerous waste that is difficult to dispose. Surfaces can be cleaned selectively and precisely, which means that portions of layers or specific shapes can be cleaned while simultaneously allowing certain adjacent coatings to be preserved. All of these factors are clear indicators that laser cleaning is widely versatile.


Nathan Jonjevic is manager of operations for adapt laser systems, llc. (Kansas City, MO). He graduated with a M.A. from Cornell University in 2001, and has extensive experience managing projects where laser cleaning technology is employed. He can be reached at (816) 531-7402 .