Transmission Components

Features

• Very high welding speeds and outputs can be achieved
• Complex components can be simply fabricated
• Minimised distortion and low heat input allowed welding to be a final assembly operation
• Versatile weld parameters and precision control employed to achieve the desired end product
• Repeatable weld configurations
• Near parent metal strength on the weld
• Precision control and accurate jigging enables low incidence of defects

Problem

The manufacturers of gearbox and transmission components operate in an increasingly competitive marketplace. Any savings that can be made on materials and machining time can significantly improve the position of the manufacturer within the industry.

Solution

Electron beam welding, performed in a vacuum and using a stream of finely focussed electrons to melt and fuse joint surfaces, was recognised by a leading international company as a production technique that could make substantial savings in both the material and the machining of its gearbox and transmission components for off-road vehicles, including earthmovers, cranes, fork trucks and four wheel drive units.

Components, which had traditionally been machined from solid bar-stock, were broken down into discrete sub-sections and electron beam welded together. These smaller, simpler parts are much easier and quicker to produce on repetitive machining centres.

Considerable savings in the space and weight of the finished transmission assembly were feasible. Wherever possible, the use of standard stock size material for the manufacture of sub-section parts also offers cost reductions.

When producing a new gearbox or transmission train, engineers are able to benefit from the precision of electron beam welding and design components which are either impractical, uneconomical or impossible to fabricate by other means.

Process

Welding parameters were developed for a whole family of different components. As predicted, the work was rewarded with minimal distortion, so that further machining operations after the welding process could be reduced. The component shown above had run out improved from 0.152mm to less than 0.076mm at the periphery when compared with earlier fabrication techniques. Problems experienced both with swash and concentricity were cured by a carefully developed tacking routine and accurate slope in and slope out control of the beam.

A problem often associated with welding of heavy carbon steel sections is hairline circumferential cracking around the joint. The cure in this application is to ensure adequate penetration whilst accurately controlling the under-bead. The customer could accept no ‘debris’ below the weld because of adjacent bearing faces. The high stability of the electron beam welding process is vital to give consistent penetration. Furthermore, accurate slope out control is again important to avoid the formation of a small crater from which a crack can propagate.