Improving the costs and manufacturability for the hidden components of an aircraft

In industry we are all measured by how quickly and cost effectively we can manufacture a component to its desired characteristic. These two influences weigh heavily on the planning, designing and manufacturing a component. All aerospace components undergo thermal treatment processes, some at high temperatures and some at low temperatures. Aerospace transmission components are exposed to the most difficult internal conditions on an aircraft, and such require thermal heat treatment, hardening and tempering. When hardening steel components, the atomic grains of the material grow when at elevated temperatures and to achieve the desired hardness, the material must undergo a rapid quenching operation after heating to fully transform the material into its hardened condition. During this transformation, the steel component experiences great amounts of stress and when the quenching system provides non-uniform heat removal, a component will distort from its green machined condition. To offset unpredictable distortion, additional material “stock” is left on a component to absorb the distortion and then is finish machined after heat treatment. If a component distorts further than the provided stock, a decision must be made to either re-work or re-make the part. Both options are very costly and because of this, engineers and machinists are in a constant struggle with one another. The machinist does not want any more hardened material than is needed, however if there is not enough material, the part can distort and become non-conforming. Engineers are then left with the decision to add more stock to prevent non-conformance. Heat treatment has ways of controlling distortion, but it comes with various negative tradeoffs. This paper will discuss the advancements in high pressure gas quenching which allows for a drastic reduction in geometric distortion, along with each component in a lot being processed to nearly identical conditions while creating extremely consistent distortion results.