Single-cycle mill-turning on the 'Miyano Fleet'

Fixed-head machines play a key role in supporting aerospace contracts — and a move into automotive

Posted on 24 Feb 2016 and read 2739 times

The Miyano Fleet is an ‘affectionate term’ used by the Techno Group’s two sub-contract operations to describe their 16 Miyano fixed-head turn-mill centres.

These machines are playing a key role in the machining of aerospace components for aero-engines, cabin interiors, control equipment and instrumentation for various Tier One companies. They are also allowing the group’s operations to move into other sectors of sub-contract machining — including automotive.

The Techno Group comprises two companies: Technoset, based at the headquarters in Rugby; and Technoturn, which is on the south coast in St Leonards.

Both 35,000sq ft sites have been the subject of recent investment in their infrastructures, with Technoset expanded by 6,500sq ft and Technoturn by 4,500sq ft; a machining-centre capability has been added to each site, along with further equipment aimed at improving productivity and shortening lead times.

Furthermore, the company also offers design-for-production advice and a machining service to help customers with their R&D and prototype projects, allowing them to offer a complete service from part sourcing right through to kit marshalling and assembly.

Operations director John Stretton said: “We have a policy of investing and proving our operational capability, prior to going for new business. This gives customers confidence in our abilities; as a result, we have not only prevented work going offshore but also won business back from overseas.”

New machines

Last year, the group bought four Miyano fixed-head turn-mill centres from Bushey-based Citizen Machinery UK Ltd ( Two BNJ-42SY5 machines were delivered to Rugby early in 2015, and a high-specification ABX-64SYY2 two-spindle twin-turret machine was delivered to Technoset in June. This machine was soon followed by a second ABX machine — a three-turret ABX-64TH5 — for the Technoturn facility.

MWC2Technoset’s managing director, Kevan Kane, said: “We have established a partnership with Citizen Machinery UK that sees us working together to overcome any difficulties — particularly when very complex work is involved. Some components machined on our Miyanos are produced from difficult materials such as Inconel, Nimonic alloys and special stainless steels and can have cycle times up to 30min long. Moreover, most parts require the milling of features and the use of up to 16 driven tools.”

Customer demands on the group as it moves into higher-end machining, are constantly increasing, as Mr Stretton highlights: “We are forever intensifying our focus on quality rather than out-and-out cycle times. Mirror finishes and fully controlled deburring with no marks or scratches when parts leave the machine are now the order of the day; and tolerances of 25µm — sometimes 12µm — are almost commonplace. Achieving these tolerances means having the right machine in the first place — backed by in-house attention to quality control, programming, setting and tooling.

“When you consider the regularity with which we put parts through our Miyano machines and the levels of precision we achieve, supplier relationship is very important. That said, we will always consider competitive machines of a similar standard, but there has to be a logical reason to change suppliers. Moreover, with two busy machine shops and some 70 employees, we need interchangeability of tool-holders and work-holding equipment, as well as familiarity with setting and programming.”

Increased power

The two recent Miyano BNJ-42SY5 machines were the latest upgraded additions to the BNJ family, offering increased spindle power; the main spindle is rated at 11kW 6,000rev/min, while the secondary spindle is rated at 5.5kW 5,000rev/min. These are supported by the main 12-station turret (2.5kW 20Nm of torque and 6,000rev/min for the driven-tool positions) and a six-station sub-turret that offers simultaneous and overlapped machining sequences.

Mr Stretton says: “These latest Miyano machines are already allowing us to avoid bottlenecks and helping us to halve our lead times on some repeat batches. We are also benefitting from faster change-over, which is very important for improving spindle utilisation on shorter batch runs.”

Meanwhile, the nine-axis Miyano ABX-64SYY2 at Rugby is enhancing the company’s single-operation capabilities; it has also introduced a 65mm bar capacity.

Moreover, the optional quick-change bar-to-chuck adapter further enhances the versatility of the machine, which has a 15kW 4,000rev/min main spindle, a 7.5kW sub-spindle and two 12-station Y-axis turrets with a capacity for up to 48 fixed tools (the driven tools are rated at 4.5kW 6,000rev/min).

A prime example of single-cycle work at the Rugby operation is a multi-featured aircraft-grade stainless-steel component produced from 60mm-diameter bar.

Produced in batches of 25, it involves the removal of some 70% of the material. In the centre of the component is a flanged feature that has to be profile-milled to create six external flats with perfect blending of radii on each corner.

Drilled through the flange are three off-centre PCD holes, each with precisely controlled chamfers. There is also an elongated slot that is drilled and finish-milled through the flange.

Further processes involve turning of the part either side of the flange, producing a deep, blind 20mm-diameter hole that is U-drilled and bored to a 15µm tolerance with an 8mm breakthrough from the bottom into the opposite face.

A number of counter-bores, reliefs and chamfers are created in the bore; and on the two outside diameters either side of the flange, a cone, spigot diameter and reliefs are also produced.

The ABX-64TH5 at Technoturn has a different specification to the Rugby machine; in order to provide flexibility, it is compatible with two previous ABX installations at the site.

The TH5 version of the ABX has three 12-station turrets, each with a Y-axis and the ability to apply them as required to overlap sequences and simultaneously turn, mill or drill at both spindles.

David Mcllwain, managing director of Technoturn, says the infrastructure of the business is being enhanced with further key people in sales and production control — and a key account manager.

“We need this infrastructure to not only maintain customer relationships but also protect our turnover — a quarter of which is generated from exports to Germany, India and the USA — and attract highly valuable re-shoring work back to the UK.”

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