Laser-Based Repair

Carbon Fiber Reinforced Plastics (CFRP) and Glass Fiber Reinforced Plastics (GFPR) are widely used in a large variety of industries. These composite materials are used in Sports and Aerospace industries, as well as various other industrial applications like Wind Energy and Automotive. In the past, manufacturing processes were based on lower production volumes of composite materials. A desire for energy efficient vehicles and aircraft now drive the demand for lightweight materials leading to increased production volumes of these materials. The aerospace industry as an example is increasing the share of CFRP in their aircraft to greater than 50%. The automotive industry is looking to use CFRP to reduce fuel consumption and therefore meet new directives for carbon emissions. Additional advantages of using Carbon Fiber include improved vehicle performance, larger wind mill designs due to the use of lightweight materials, and an increasing amount of offshore installation demands for new mounting and service concepts.

When processing composite material, the proper choice of the laser wavelength is critical. Most resins are transparent by commonly used 1 µm wavelength. Absorption on carbon fibers is very high. Thus this wavelength leaves a heat affected zone that is not acceptable in most applications. A CO2 laser wavelength (10.6 µm) is well absorbed by most resins and fibers. Unfortunately it inputs a lot of heat into the composite material and leaves a burnt surface or edge. The ideal wavelength for most composite processing applications is in the UV range as it is absorbed by the resin and the fiber, and offers a cold process with a low heat affected zone.