TWI Industrial Member Report Summary 266/1985
By A Sanderson
The complexity and cost of components presented for electron beam welding (EBW) continue to grow, and this increases the need for EBW equipment of greater reliability. One potential source of equipment malfunction is electron gun discharges caused by metal vapour generated at the weld pool entering the electron gun. The development of the magnetic trap device offers a solution to this problem. This report summarises recent work carried out on the re-design of the magnetic trap and control unit. The effect of pole-piece shape on magnetic field strength distribution was studied using an electrostatic computer model. From the results, an improved pole-piece shape was devised and manufactured. This has led to a reduction in beam aberration, allowing the device to be fitted as a standard unit in both 75kW EB sets at The Welding Institute. The performance of the trap device is demonstrated by recent welding applications involving high value components and reference is made to wider industrial use.