Investigating the potential of friction stir welding at South Yorkshire's TWI Technology Centre entered a new dimension recently. In fact it entered three dimensions. A cavern of opportunity has opened because the business hasinvested in the robotic RoboStirTM system.
An articulated robot has been introduced to investigate FSW's effectiveness in welding complex structures from a three dimensional platform.
Already TWI has been able to assess the technology regarding programming and operation as well as understanding and overcoming the practical limitations of robotic friction stir welding.
Since delivery and installation the robot has demonstrated success in welding a variety of joint configurations including linear lap and butt friction stir welds, circular and circumferential friction stir welds, and friction stirspot welding.
Typical industrial applications investigated include welding aerospace stringers to skins, joining aluminium extrusions for an automotive application and sealing a demonstration box for the electronics industry.
A high quality friction stir welded aerospace component The aerospace prototype component consisted of Z-shape extrusions, with one and half millimetre wall thicknesses, that were welded to an aluminium panel two millimetres thick. Two dissimilar aluminium alloys were used. They werewelded at a traverse rate of half a metre per minute. The result was a flaw-free weld with an excellent surface finish. Another common application of friction stir welding is sealing a lid into a box. This is useful for packagingelectronics that are exposed to harsh environments such as those encountered in automotive applications, and sealing of heat exchangers.
To investigate the feasibility of using a robot for such applications, a demonstration part was designed consisting of a box with a square cut out and radii in each corner, into which a six millimetre thick mating lid was placed.The robot was programmed to weld around all four sides of the lid whilst maintaining a fixed tool tilt, before moving off the joint line and parking at a non critical area of the part.
A fully consolidated weld with an excellent surface finish was produced proving that robotic friction stir welding is capable of producing high quality friction stir welded parts. This, coupled with the tradition that robots ideallyfunction in high volume mass production, indicates that robotic friction stir welding is now ready for industrial integration.
For further information please contact Jonathan Perrett at TWI, or email friction@twi.co.uk
