When a customer of Apsley Precision Engineering stopped manufacturing components in-house, one of its redundant machine tools — a Miyano BND-51S — was purchased by the sub-contractor’s managing director, Peter Aymes.

Its installation (in 2012) in Apsley’s 12,000ft² facility in High Post (near Salisbury) heralded the start of a big improvement in the firm’s CNC turning capability.

There followed the purchase of two more second-hand Miyanos.

Mr Aymes said: “We were aware of this make of bar auto and knew that they rarely come onto the second-hand market, so we were lucky to be able to buy the first Miyano machine — a twin-spindle lathe with live tooling in the turret.

“Compared with our single-spindle bar-fed lathes without driven tools, it virtually halved cycle times for machining parts up to 51mm in diameter.

“It meant that we could generally produce components ‘in one hit’ rather than two or three operations, which in turn reduced handling and work-in-progress — and improved accuracy.

“This machine allowed us to manufacture more cost-effectively and become more profitable.

“It is difficult to overstate the improvement it made.”

Another notable benefit was that an operator could set this Miyano and walk away for long periods to carry out other tasks, as its consistency of machining was such that changes to offsets were rarely needed.

That was not the case with Apsley’s other bar autos, which Mr Aymes says “tend to occupy an experienced setter for much of the time”, raising the labour cost content of manufacture.

Based on these advantages, a second Miyano BND was installed a year later.

Bought at auction, it turn-mills parts from bar up to 42mm in diameter but is otherwise similarly specified to the first machine; and despite being 12 years old at the time, it was — and still is — capable of holding tolerances down to ±5µm.

Mr Aymes said: “By that time, it was abundantly clear just how good these machines are.

“They are heavy, compact and very robust, which leads to high accuracy, repeatability and reliability. They need very little money spent on them for repair, so the cost of ownership is low.

“In 2015, we bought our third Miyano — another 42mm machine, of a similar age — from another sub-contractor.

“This machine, a BNJ model with two turrets, was needed to cope with the increasing amount of work these machines were generating.

“With access to even higher productivity — thanks to a second turret to serve the sub-spindle, while the first turret operates at the main spindle — we were able to offer customers even better prices and shorter delivery lead times.”

A ‘new’ venture

With a view to increasing production output still further, as well as accessing the latest technology and providing back-up for its 51mm-capacity lathe, Apsley bought its first new Miyano — a BNJ-51SY twin-spindle twin-turret lathe with a Y axis — from Bushey-based Citizen Machinery UK Ltd (www.citizenmachinery.co.uk) in July.

Mr Aymes says the capability that this machine offers is proving invaluable for machining off-centreline and providing flexibility and accuracy of milled features.

He cited one component that is produced much more efficiently with this Y-axis feature.

It is a tubular thin-wall aerospace part machined from 38mm-diameter solid 304 stainless-steel bar that requires a blind longitudinal hole to be drilled and bored and the outside diameter turned to leave two lugs.

“Not only does the Y axis allow the lugs to be drilled in-cycle, instead of the component having to be transferred to a machining centre for completion, but by being able to program both Y- and C-axis movements into the OD turning, cutter deflection is minimised — and accuracy improved.

“The component is required in batch sizes ranging from 200 to 800, so the benefits are considerable.

“Even more advantageous with the new machine is the ability to take advantage of ‘ghost shift’ running, which is theoretically possible with the other Miyanos but practically not feasible due to the absence of load monitoring to detect worn or broken tools and automatically stop the machine.

“The latest lathe, with its fail-safe features and reliability, is regularly left to operate unattended overnight.”

When Citizen installed the BNJ-51SY, it also supplied the latest version of its Alkart CNC Wizard programming software.

This assists and simplifies the creation of even complex cycles, using a built-in G-code and M-code library — plus reference material and diagrams.

Inexperienced users in particular benefit, such as Apsley’s Jay Pritchard, who is halfway through a four-year mechanical-engineering apprenticeship.

He said he finds the Wizard useful when operating the new Miyano, as it helps with understanding how to best use the machine.

Founded in 1984 by Peter Aymes’ father (Graham), the sub-contract engineering firm has always split its machining almost equally between turning and milling.

The industry sectors supplied include aerospace, defence, medical and pharmaceutical.

Batch sizes typically range from 20 to the low hundreds; the company also operates a tool-room facility for smaller batch runs, prototype production and the manufacture of tooling and fixtures.

That said, about one third of the company’s business comes from supplying components and assemblies on a just-in-time basis, with customer call-off typically at a rate of 1,000 pieces per week.