Subcontractor maximises productivity and quality

Subcontractor maximises productivity and quality

Subcontractor maximises productivity and quality

By investing in four G-90C co-ordinate measuring machines (CMMs) from LK, civil and military aerospace components producer, John Huddleston Engineering, is reportedly reaping benefits not just in the inspection departments but on the shop floor as well (Plate 1).

One of the machines has a large measuring envelope of 4m × 1.2m × 1m, another is the smallest in LK's range offering 0.8m × 0.7m × 0.6m capacity, while the other two have axis travels of 1.5m × 1m × 0.8m. They were purchased and installed in the Spring of last year (2002) as a part of a major investment program in high technology machinery and facilities that has positioned the company – which has factories in Newtownards, Northern Ireland and Blackpool, England – as a highly capable and leading UK aerospace supplier.

Plate 1 One of the LK G-90C CMMs helping to maximise machine tool usage at aerospace subcontractor, John Huddleston Engineering

Managing Director Robert Huddleston commented, "We require production to be as lean as possible so a smooth throughput is highly important to us and component inspection needs to be integrated with machining processes. Whereas military production essentially involves small quantities, our supply commitment to civil airliner manufacturers can be up to 20 aircraft sets per month. Both programmes are subject to stringent quality procedures."

"We therefore require inspection facilities that cover all of our machining capabilities and component sizes, have the flexibility to cope with a wide variation in production volumes and perform these duties with minimal impact on our manufacturing schedules."

He continued, "We previously operated manual CMMs which could not support our production programmes efficiently. The LK machines offer much higher levels of inspection productivity, for example replacing a 10h manual cycle with a 30min CNC controlled routine. Moreover, the new machines, using LK Launchpad software, can be set and operated by our machinists; and the CAMIO software offers us the means to import CATIA CAD models directly and develop inspection programs concurrently with, or ahead of, machining".

The company produces a wide variety of airframe parts, mainly machined from aluminium although hard materials are also processed. Machining capacity ranges up to 3.1m × 1.2m at Newtownards, which concentrates on more complex components requiring up to 5-axis, high speed machining. Blackpool produces higher volumes of smaller components up to 1.5m utilising 3- and 4-axis machining.

Tolerances applied to these components are wide ranging; a bore intended to accommodate a bearing may need to be within 20 microns of its nominal diameter whereas on larger components, the dimensional tolerance may be expressed as a ratio per metre.

"Generally we look for consistency in dimensional accuracy across and between batches", Robert explained. "However our overall aim is to maximise the quality of supply to customers by developing capable, cost effective processes. The four LK CMMs offer enabling technology in that respect and they are helping to maximise the productivity of our machine tools. As many of our customers use similar equipment, the CMMs will also help to integrate our operation with theirs."

Bill Leonard and Eddie Rawlings, the Quality Managers at Newtownards and Blackpool, respectively, were responsible for choosing the CMMs. Bill commented, "One main constraint on the selection process was the need for a large, high quality machine. Not every supplier could offer a CMM as large as the 4m × 1.2m × 1m G-90C. Ultimately we narrowed the field to three suppliers".

Despite having different requirements, both quality managers agreed that the overall package for the four machines regarding capacity, capability, software, after sales support and cost, along with a short delivery lead time, gave LK the edge over their competition.

"At Blackpool we have a number of families of parts", Eddie explained. "In addition, batch quantities are higher so the emphasis is on minimising delay in the production process. Launchpad offers us this capability as the operator can do his own inspection rapidly using the smaller of our two machines, which is installed on the shop floor. This frees up the system to a degree that would not have been possible with manual inspection. For instance, our duty inspector on the night shift has been able to benefit greatly from the machinist's use of Launchpad to free his time for other duties."

All components produced on the site are subject to rigorous inspection; this is particularly the case with first-off parts. In productivity terms, the LK G-90C is said to complete an inspection cycle in around 5min whereas a like-for-like manual inspection routine could absorb around 30 min. As the applications develop, the intention is to apply automatic SPC analysis across repeat batches of components and capability studies are already under way.

Newtownards inspection requirements are slightly different as they include components that are generally larger and more complex. Bill said, "Without the availability of machines like the LK G-90Cs, it would not be possible to adequately support our 5-axis machining capabilities. The complexity of our components is reflected in inspection cycle times approaching 30min for some of our components – similar parts would either have been impossible to inspect manually or need up to 10 or 12h, tying up a fully skilled inspector".

Around 120 inspection programs have been written for the Newtownards CMMs, reflecting the wide variety of components produced at this factory. Inspection cycles range between 5min and 1h. The CAMIO software has proved to be very user friendly while the direct CATIA interface has integrated perfectly with our customers and our CAD models.

Bill continued, "From our perspective, the depth of capability within the CAMIO software and its ease of use were essential for the Newtownards site; Launchpad may be less so, although we will be introducing it for certain families of components soon".

"Many of our customers use CATIA for design and the ability to read their CAD files directly is a great asset. Moreover, the off-line program development capability greatly improves our response times when a new component is introduced. As many of our clients also use LK machines, we have the benefit of being able to exchange inspection programs during the product development phase."

At both sites, the flexibility offered by the machines' CNC indexing probe heads has improved inspection access. Each factory has its larger machines equipped with six-stylus magazines that allow seamless inspection of highly complex components and uninterrupted sequential processing of components with different probing requirements.

Bill commented, "Probe exchange is one of those optional 'add-ons' that proves extremely useful on those occasions that you need it. We do some very complicated work where it has proved to be an asset. The JHE Group has been extremely happy with the LK machines and operating software. Our application is still in its infancy but the benefits have already started to come through at a very early stage".

It is a view echoed by Robert who concluded, "The LK measuring machines were a necessary investment to maximise the productivity of our manufacturing processes and the quality of output. LK's training and after sales support have helped us to climb a fairly steep learning curve while at the same time introducing some fundamental changes to the way we manufacture. However I am convinced that, had we not taken this route, our company would not have been as capable of competing at the level that it does today".

Details available from: LK Limited. Tel: +44 (0)1332 811349; Fax: +44 (0)1332 850149; E-mail: sales@lkuk.co.uk; Web site: www.lk-cmm.com