Thermal spray processes like air plasma spray and High Velocity Oxygen Fuel (HVOF) are usually thought of as being used primarily for applying protective coatings to new parts. While new part applications do indeed constitute the majority of their use, there are also a wide variety of repair techniques that employ thermal spray processes. VAC AERO has been a leader in developing repairs for aircraft structural components and gas turbine engine parts using thermal spray processes. An example of a structural component repair involves a flap track from a popular turbo-prop aircraft.  As the wing flaps of this aircraft are extended and retracted during landing and take-off, rollers run along the surfaces of a series of components known as flap tracks.

By J.E. Pritchard, S. Rush, A. Kiela

VAC AERO International Inc.

Abstract

Application of sacrificial coatings has long been used to reduce rotor-shroud clearances in gas turbine engines. Materials normally used for these coatings include sintered metal-powder segments, sintered metal-fibre segments, metallic honeycomb (filled and unfilled), elastomers and thermally sprayed abradable coatings. Thermally sprayed coatings offer advantages over the other materials, including direct application, easy removal and repair, variety of coating materials and good performance. New abradable thermal spray coating materials have been developed for performance in industrial turbine engines at operating temperatures up to 980ºC. Results are presented from laboratory evaluations of these coatings by burner rig and hot abradability testing.

by J.E. Pritchard & R. Laub

When joining aluminum for aerospace electronics, brazing often is the most practical choice for creating a continuous all-metal joint interface.

Because of its light weight and excellent thermal conductivity, aluminum often is the material of choice for assemblies that house or cool airborne electronics. Aluminum's properties are particularly important in combat aircraft. Weight minimization becomes a major design consideration for many components going into these aircraft. Thermal conductivity is especially important in the electronics packages because of the heat problems created by the dense packing of powerful systems in limited spaces. The complex aluminum enclosures, chassis and heat dissipators used in military avionics systems often are manufactured from numerous individual components, which must then be joined.

Building a Lean Supply Chain

Lean shouldn't stop with your company; to be truly lean, you must reach beyond your shop floor.

Companies of all sizes, shapes, and descriptions are attempting to implement lean manufacturing. As a company becomes lean, however, it inevitably runs into constraints imposed by its suppliers and customers, the adjacent nodes of the supply chain in which it operates. The logical next step to becoming lean internally is to try to spread the lean philosophy outward to those immediate trading partners. Sometimes doing so can bring significant improvements, especially when a large company is influencing one or more of its smaller suppliers. At other times it doesn't work so well, such as when a small machine shop attempts to influence a much larger raw-material supplier.

Metal matrix composites are becoming increasingly popular for industrial applications as diverse as  aerospace, automotive and electronics. The composites consist of an alloy matrix reinforced with ceramic particles to enhance mechanical properties. Aluminum alloys are especially popular as a matrix material. 

All aviation gas turbine engines require regular overhaul to ensure continued safe operation. During engine overhaul, decisions must be made on whether to replace deteriorated individual parts and assemblies with new components, or to repair them.