Machining cell completely machines seeker parts

A new machining cell has been installed in a temperature controlled environment for volume manufacture of high-tolerance metalwork for a missile system's infrared seeker assembly.

A new machining cell has been installed in a temperature controlled environment at the Basildon factory of BAE Systems Avionics for volume manufacture of high-tolerance metalwork for the infrared seeker assembly fitted to the front of the Javelin, a shoulder-launched, anti-tank missile developed jointly by Lockheed Martin and Raytheon in the US.

NCMT was chosen to supply the turnkey cell, which comprises two Makino twin-pallet machining centres and two Okuma lathes, at a cost of GBP 1.2 million.

The latest project is an expansion of the seeker machining cell within Basildon's 'centre of excellence' Machined Component Centre.

The company set up the facility in 2000 to produce similar parts for the seeker for Stormshadow, a project that is on-going with regular monthly deliveries.

The contract from Lockheed Martin is for seekers for Javelins ordered by armed forces worldwide, including the UK MOD.

BAE Systems is producing machined parts for seekers assembled on their own Basildon site as well as for seekers to be built by Lockheed Martin in Florida.

This level of investment is a testament to the international reputation that the Basildon site has in this sector.

By the end of April 2004, the first requirement of seekers and sets of machined parts were delivered to Lockheed Martin.

Volume production has now commenced at the Basildon facility.

Three high-precision aluminium parts are key to the Javelin seeker's construction, two machined from solid (referred to as A and B) and one from a casting (C).

All undergo heat treatment within the cell prior to final machining.

These three parts form the chassis for the stabilised IR imaging assembly.

Multiples of both A and B are fixtured on each pallet of the Makino a51 machining centres, which have 128-tool magazines and are identically set up so there is cover should one machine be down temporarily.

The parts undergo two roughing and two finishing operations, pallet time being about four hours.

In addition, component A is transferred to an Okuma Soarer CNC lathe equipped with a permanently-mounted fixture for turning an optics feature to within one micron positional tolerance.

Component C is machined entirely on the Okuma MacTurn 250 turn-mill centre with B-axis and 44-tool magazine, and also requires two roughing and two finishing operations.

Cycle time is evenly split between turning and prismatic metalcutting.

Tolerances are again challenging at +/-2.5 microns on diameter.

Despite the high accuracies, the cell runs unattended for between 20 and 25 per cent of the time, 24 hours a day, six days a week.

Parts come off the machines complete, with most of the deburring having been completed within the machining cycles, this having been part of NCMT's remit to supply a turnkey solution including programs for machining the three key Javelin components.

Partners on the project were BIG Daishowa for the toolholders (also through NCMT), Bartling Designs which produced the fixtures, and Technicut for the cutting tools.

The decision to opt for the same group of suppliers as were chosen for the Stormshadow contract was based on the smooth running of that project and the competent back-up provided by all concerned, which is crucial for the successful operation of such production cells.

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