Cladding (metalworking)

Cladding is the bonding together of dissimilar metals. It is distinct from welding or gluing as a method to fasten the metals together. Cladding is often achieved by extruding two metals through a die as well as pressing or rolling sheets together under high pressure.

The United States Mint uses cladding to manufacture coins from different metals. This allows a cheaper metal to be used as a filler.

Laser cladding

A schematic of the equipment

Laser cladding is a method of depositing material by which a powdered or wire feedstock material is melted and consolidated by use of a laser in order to coat part of a substrate or fabricate a near-net shape part (additive manufacturing technology) .

It is often used to improve mechanical properties or increase corrosion resistance, repair worn out parts, and fabricate metal matrix composites.

Process

The powder used in laser cladding is normally of a metallic nature, and is injected into the system by either coaxial or lateral nozzles. The interaction of the metallic powder stream and the laser causes melting to occur, and is known as the melt pool. This is deposited onto a substrate; moving the substrate allows the melt pool to solidify and thus produces a track of solid metal. This is the most common technique, however some processes involve moving the laser/nozzle assembly over a stationary substrate to produce solidified tracks. The motion of the substrate is guided by a CAD system which interpolates solid objects into a set of tracks, thus producing the desired part at the end of the trajectory.

The differents feeding systems availables

A great deal of research is now being concentrated on developing automatic laser cladding machines. Many of the process parameters must be manually set, such as laser power, laser focal point, substrate velocity, powder injection rate, etc., and thus require the attention of a specialized technician to ensure proper results. However, many groups are focusing their attention on developing sensors to measure the process online. Such sensors monitor the clad's geometry (height and width of deposited track), metallurgical properties (such as the rate of solidification, and hence the final microstructure), and temperature information of both the immediate melt pool and its surrounding areas. With such sensors, control strategies are being designed such that constant observation from a technician is no longer required to produce a final product. Further research has been directed to forward processing where system parameters are developed around specific metallurgical properties for user defined applications (such as microstructure, internal stresses, delusion zone gradients, and clad contact angle).

Advantages

• Best technique for coating any shape => increase life-time of wearing part by 6-7.
• Particular dispositions for repairing parts (ideal if the mould of the part no longer exist or too long time needed for a new fabrication).
• Most suited technique for graded material application.
• Well adapted for near-net-shape manufacturing.
• Low dilution between track and substrate (unlike other welding processes and strong metallurgical bond.
• Low deformation of the substrate and small heat affected zone (HAZ).
• High cooling rate => fine microstructure.
• A lot of material flexibility (metal, ceramic, even polymer).
• Built part is free of crack and porosity.
• Compact technology.

See also

• Copper-clad steel
• Copper-clad aluminum wire
• Laser engineered net shaping
• rapid manufacturing
• additive manufacturing
• http://www.ccl.fraunhofer.org/download/cladding_titanium.pdf

manufacturers

• Trumpf (Germany) : http://www.trumpf-laser.com
• POM (USA) : http://www.pomgroup.com/
• Optomec (USA) http://www.optomec.com/site/technology_lens
• Huffman corp (USA) : http://www.huffmancorp.com/products/laser_systems/index.html
• IREPA Laser (France) http://www.irepa-laser.com/index.php/fra/rechargement-alliage-de-surface/
• Accufusion (Canada) http://www.accufusion.com/

external links

• http://www.lasercladding.com/index.html
• http://www.designforlasermanufacture.com/
• http://www.alspi.com/lasercladding.htm
• http://www.laserweldingsolutions.com/
• http://www.fwgartner.com/fwgts_prodserv_qa_laser.htm
• http://www.laserline-inc.com/diode-laser-cladding-coating-laser-repair-welding.php
• http://www.optoiq.com/index/lasers-for-manufacturing/laser-surface-treatment/laser-cladding.html
• http://www.swansonindustries.com/lasercladding.php
• http://www.precoinc.com/capabilities/clad.html
• http://www.neotechservices.com/lens.html
• http://www.additive3d.com/lens.htm