Aerospace Case Study - Spool & Sleeve

Component: Hydraulic control spool & sleeve for use on the Airbus A380

Material: 440C Matt 119

Challenge: The challenge with this component is that the bore tolerance is straight round and has to be within 0,005mm along the whole length. To achieve this, the air temperature has to be carefully controlled at the specified 68.4°F, because just 1° of temperature change, would be 2.5 times the tolerance.

We believe that fewer than five companies in the UK are capable of achieving this requirement.

Process: Turn, mill, harden & temper, Grind, Hone & Sleeve lap, match grind to 0,001mm tolerance.

Success factors: In addition to having a workforce with the right skills and aptitude, there is a need for the necessary equipment, suitably well maintained. The biggest issue for us was to develop a technique of measurement and controlling the environment and temperatures both on the grinder and in the workshop. We had to work closely with the customer on the air-guage system to ensure their equipment could measure the tolerance to the required standard. Final calibration was carried out by NAMAS.

Finally, conventional precision engineering companies would have ground the O seal grooves, whereas we used a different technique.

To discuss your precision engineering requirements, contact us on +44 (0)1329 232795.