Machining cell meets increased demand

Citation

(1998), "Machining cell meets increased demand", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 4. https://doi.org/10.1108/aeat.1998.12770dab.005

Machining cell meets increased demand

Machining cell meets increased demand

Keywords Dunlop Equipment, Lead times, Machine tools

When Dunlop Equipment faced a year-on-year work upturn averaging nearly 20 per cent for its range of aircraft hydraulic and pneumatic control valves the company had to rethink its existing production facilities. As well as providing capacity to meet the increased demand there is also the problem that customers are demanding smaller batches at shorter delivery times.

Although equipped to carry out most machining on the product range the technology needed to be upgraded to meet the changing market requirements.

Even with existing order levels lead times of four months for many products were common and this had to be eliminated. After analysing the future production breakdown a number of machine tool suppliers were asked to provide solutions. All but one suggested, in effect, more of the same. That is to say increasing the number of machines already used by existing methods to meet the perceived need.

RMT Mechatronics was the exception. This company suggested that a Kitamura machining centre set up as a self-contained cell would allow machining in one set up using a pre-prepared billet. In fact, for operational reasons, machining will be in two stages with wet processing carried out in between.

To meet the new output rates the preparation of the billets had to be speeded up. To achieve this two new CMZ520 CNC lathes with a powered 12 tool turret representing an investment of £200,000 have been purchased. Since the machines have been installed lead times have been reduced on average to approximately two weeks.

The machining cell selected was the Kitamura Mycenter H300SC Supercell. With a work envelope of 300mm diameter by 300mm high it has the capacity to handle the majority of Dunlop Equipment's components. The cost of installing this machine was over £500,000. It has a number of features. Each fixture, which often carries several components, is mounted on one of 20 pallets which are carried into the machining area by conveyor. Pallets are individually identified by binary code so that the computer recognises which programme is required and machining commences as soon as the pallet is in position.

This means that jobs can be loaded in a random fashion as required and small batches of a number of components produced, say on a weekly basis. Tools are called up from the 200 position tool magazine as required.

Toolsetting is carried out off-line using a £30,000 Komeq digital camera-based computer-controlled toolsetter which is linked into the CAD/CAM/DNC system. Because of the high accuracy of setting using this machine it avoids the need for putting in manual offsets when setting up the machine.

It also aids in unmanned running which has become a vital part in Dunlop Equipment being able to meet the latest production schedules. To achieve this effectively, back up tools are required. Duplicates of particularly vulnerable tools are loaded in the tool magazine. A typical example is a deep hole drill which measures only 4mm diameter but produces a hole over 120mm long. In the event of excess tool wear or breakage the spare tool is automatically brought into action.

The life of small tools is determined by machining hours and large tools are also fitted with torque sensing equipment. If machining still cannot proceed then that component is automatically rejected and the next pallet brought into the machining station.

All production is planned and tooling produced by the skilled operators actually on the shopfloor. Using a nearby workstation. Following successful introduction of the new machines, work has continued to expand. To meet upcoming market needs a further two Kitamura Supercell H400 (400mm by 400mm cylinder work envelope) are being purchased. This requires in excess of £1.2 million investment by the company but means that virtually all its current production including air/oil separators and other precision aerospace control products will be produced on these new machines.

Apart from greater efficiency and lower cost there are considerable savings in factory space and there are subsidiary gains in environmental performance and workshop cleanliness.

Further details are available from Dunlop Equipment. Tel: +44 (0) 1203 682000; Fax: +44 (0) 1203 683407.