Friction-weldingLow cost, High yield:SOLUTIONS with Effective, Powerful Advice
Friction-welding process, inertia welding, friction-stir welding, suitable joints, different materials, rotary Friction welding, solid state welding, mass production, exceptional properties, excellent quality, welding links, welding tips: these are some of the items developed in this Site for the benefit of interested readers. What is in here for me? Will you ever need information on Friction Welding? Even if you may doubt it now, having a good idea of the process may help you, should the case present itself, to remember it and to search deeper when you need it. Friction Welding, a specialized process having valuable advantages and some limitations, is presented here. In a separate page we are providing some more details on Friction Welding Equipment.
Some more details... In a previous page on WELDING PROCESSES, a short review was offered grouping processes according to some general characteristic. Here we are going to enter into some more detail for the class of Pressure Welding processes known and described as Friction-welding processes. Friction-welding is a sub-class that includes variations of a process that uses the heat obtained by the transformation of mechanical energy into heat, through the attrition of two elements, to bring about a solid state joining under pressure without resorting to melting. Briefly the Friction Welding process consists in bringing into contact two elements to be welded while one of the two is static and the other is rotated rapidly on its axis. As soon as the heat generated by attrition at the interface is sufficient for solid state welding without melting, the rotation is stopped and the elements are forced together under pressure producing local forging, which concludes the intimate joining and also expels at the joint all surface contamination and some of the upset material called flash.
Tip!: The interested reader wishing to study the applicability of a Friction-welding solution, should be alerted that the joint (not the elements), in general, must present rotational symmetry (must look like a round button or a ring). An economical process... Friction-welding is economical in that it permits joining together different materials, one of which may be inexpensive, and its quality control cost is minimal with a guarantee of high quality welds. Moreover the weld cycle is extremely short, so that productivity is very attractive. Once set up the Friction-welding process is carried out by unskilled workers and could be automated. The Friction Welding process is suitable for mass production. As such it is not an option for a general welding job shop. However even a small shop can specialize in Friction-welding provided large orders can be secured for relatively small items to be manufactured in very large quantities. Friction-welding has been used with success, however, for repairing expensive rejected shafts of turbine engines, by discarding the damaged end and welding in place a new section, with the result of salvaging a most expensive item with a high quality weld. This is sufficient justification for an expensive machine and for a short run job. Disadvantages... The disadvantages of Friction Welding are that not every configuration is feasible, that a machine of sufficient power is needed, and that for short runs the process may not be economical. Apart from the cost of equipment, which must be suitable for the intended joints, the Friction-welding process has some costs in tooling and setup that must be taken into account when calculating the cost per weld. Tight concentricity requirements, when needed, may be difficult to meet. Also finishing operations may be requested which sum up to the total cost. Best quality... The quality of the welds is very high and repeatable, as long as all the functions of the machine can be properly monitored and maintained, so that it is perfectly obvious that Friction Welding can be the process of choice for certain classes of automotive parts that lend themselves to be friction welded. The Friction-welding process is suitable for non homogeneous joints involving materials having quite different chemical, mechanical and thermal properties, producing welds of the most favorable metallurgical characteristics. Therefore it has been used to weld a bit of expensive materials (to be exploited where needed) to a stem of a simple and inexpensive one. Exhaust valves of internal combustion engines are an example. Other applications involve the Friction-welding of a forged part to a simple bar, a practice that has the potential of providing substantial savings. An Article on Weld Crack Repair in a Transition Part was published (3) in Issue 50 of Practical Welding Letter for October 2007. Easy preparation... Preparation of the elements is simple and easy, provided that the design of the joint lends itself to Friction-welding, and the process is friendly to the environment. As there is always an axial shortening of both elements, their exact length before welding must be established experimentally prior to production. The Friction-welding process is performed with different machines, in which the details of the mechanical movements may vary, but with no substantial change in the realization of the joint. An emerging technology development, first demonstrated as a laboratory curiosity, has been recently adopted for actual production of aerospace, automotive and ship hardware. It is called Friction Stir Welding and it consists in the use of a moving element whose function is to heat two static faces of a butt joint by mechanical friction and then to move on along the joint, leaving the weld completed in its wake. Such a weld, being in a fine grained hot worked condition, has considerable metallurgical advantages especially for aluminum alloys, like absence of porosity or oxides and very good mechanical properties. Some more details on this development and a few links can be found in a page on Friction Welding Equipment. An Article on Friction Stir Welding, one of the most important innovations of recent times, was published (2) in Issue 47 of our Practical Welding Letter for July 2007. Click on PWL#047 to read the article. An Article on Friction Stir Surfacing was published (2) in Issue 49 of Practical Welding Letter for September 2007. To see the article click on PWL#049. To receive every issue of Practical Welding Letter as it is published, please subscribe.
Any questions or comments or feedback? Write them down and send them to us by e-mail. Click on the Contact Us button in the NavBar at top left of every page.
Friction Welding Processes
To reach a Page, listing the most important Articles from Past Issues of Practical Welding Letter, click on Topics. For your FREE subscription to our periodic Practical Welding Letter and for downloading your FREE copy of our book right to your computer (in pdf format) PRACTICAL HARDNESS TESTING MADE SIMPLE, click here. It is usually necessary to know the hardness of the items to weld, beforehand...
Important Announcementa rich collection of valuable information on Materials, Volume 1, and Metals Welding, Volume 2, from expert Internet Sources, see our New Page on Metals Knowledge
POWERED BY:
Click on this Logo NOW! Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009 by Elia E. Levi and www.welding-advisers.comAll Rights Reserved
Friction-welding processes are highly rewarding for specialized niches of applications. See here when and why they are successfully used... |
