A Member company recently requested a report comparing the advantages and drawbacks of the electron beam and laser beam welding processes to include an overview of the principal technical, economic and practical differences between laser and EB welding specific to their joining requirements.
The company needed to join parts of an engine crankshaft damper, a cast body with a carbon steel closure plate. A CO2 laser is now used for welding. The part comes in many different sizes dependent upon the customer, the largest being approximately 400mm diameter and 150mm deep.
With demand for the parts increasing a new production line was needed capable of processing a range of parts in a variety of materials. It also had strict requirements on joint design and weld bead geometry.
TWI delivered an overview of electron beam welding highlighting the primary differences between the processes.
Further explanation covered issues associated with electron beam, namely X-ray radiation, seam tracking, vacuum requirements, flaws and defects treatment, magnetism, weld profiles, running costs, equipment format, beam quality and use of filler wire. Also included was a checklist of points for review with prospective equipment suppliers. Finally it drew conclusions from the findings offered highlighting the relative merits of one process over the other.
To address all feasible joining options, particularly less expensive ones, the client then asked if the tungsten inert gas (TIG) process provide a viable alternative
An overview of the TIG process was provided, with an explanation of the primary differences between the three processes. Comparative notes were also supplied on TIG's characteristics and requirements, namely radiation, seam tracking, weld profiles, running costs and equipment formats.
A 12 point checklist was included in the report to guide the client in future dealings with prospective equipment suppliers. The assessment ended with an explanation of the characteristics being traded off against each other. TIG would be cheaper to implement initially, but weld penetration would be considerably less than that achieved using the power beam processes. Finally longer term costs needed to be assessed because the consumable costs would be considerably greater using the TIG process than the power beam processes.
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