Precision Model Manufacture – Instrumented

CNC Machining

During the first stage of machining operations 3-axis CNC machines are used. These machines are robust and high powered, allowing for the rapid removal of material.
For high speed and high accuracy final machining 4- and 5-axis machines (with advanced functions) are used. These machines allow for a high degree of process control and the possibility of automation, for example automatic tool changing and measurement. On-machine inspection of the 4- and 5-axis machines is performed using touch-probes.

Spark erosion (die sink).
EDM is used to produce tunnels for pressure plotting in model wings, which has the dual benefit of reducing the number of coverplates in the airswept surfaces and increasing model strength. It produces features which would be impossible with conventional machining processes (eg. undercuts, non-geometric shapes, fragile features, etc). It can plunge slots in strain gauge balances to produce flexure cages. EDM drilling permits machining of holes as small as 0.2mm diameter using the EDM process which would otherwise be very difficult to produce.

Wire erosion.
Here, EDM is used to manufacture one piece missile models and small control surface balances. It is a non-contact process, and is therefore suitable for fragile parts.

There is a high degree of finesse required for the manufacture of small scale models (accuracy of ±0.025 mm).
This includes the model assembly in preparation for wind tunnel testing and the final polishing of airswept surfaces to provide the high quality surface finish demanded by customers. Cryogenic models require surfaces to be polished to a near mirror finish. There is an increased test productivity since all model parts are trial assembled.