Dowty Aerospace halves testing time
Dowty Aerospace halves testing time
Keywords Hardness testing, Indentec
Purpose-built fixturing at Dowty Aerospace Wolverhampton has reportedly helped to halve the time spent on hardness testing precision-made shearout pins.
Manufactured in steel to stringent US specifications, the pins are designed to fracture under excess loadings to provide fail-to-safety protection against stress in flight-control gearbox systems.
Approximately 19mm long and 16mm in diameter, each pin must pass six Rockwell hardness tests three on each end-face to within one or two Rockwell points.
Originally, the pin was manoeuvred by hand on the test table to position it for each test on one end-face. Any small "dimples" left by the test indentations were then polished or ground off to ensure a flat and uninterrupted bearing surface for the three tests on the opposite endface.
Re-engineering of the process by Dowty, incorporating special fixtures by Indentec, has speeded up testing by eliminating any need for hand positioning and for polishing the end-face.
Based on a vertical vee-block, each fixture locates the pin positively in relation to the test indenter, allowing the pin to be rotated about its axis so that each test can be made accurately at a predetermined circumferential point on the end-face. An annular groove cut in the test anvil at the same circumference accommodates any"dimples" when the pin is inverted for the test on the other end-face.
The fixtures are used in a 100 percent inspection operation, the hardness tests mostly being made with a diamond indenter on the 150kgf Rockwell C scale. The testing machine is a standard Indentec digital model with a touchscreen for control and monitoring.
Further information is available from: Indentec Hardness Testing Machines Ltd. Tel: +44 (0) 1384 896949.
