Author: Luke

Historically, a majority of subcontractor Reginson Engineering’s turnover came from the aerospace sector, with oil and gas generating most of the remainder. So, when Covid struck in early 2020 and aerospace contracts dried up, the Nuneaton-based, AS9100 accredited, Rolls-Royce approved company was deeply affected by the contraction in business.

It was mitigated somewhat by the company joining the Ventilator Challenge UK. During April 2020, Rolls-Royce asked Reginson Engineering to manufacture 113,000 components in 10 days to support the build of 8,000 ventilators. Towards the end of that month, within 36 hours of an order being placed for a pair of Cincom A20-VIIs sliding-head CNC turning centres to enable the medical contract to be fulfilled, the machines were delivered by Citizen Machinery UK. Both have LFV (low frequency vibration) chip-breaking capability, which not only improved swarf control, raising reliability and reducing the need for operator intervention, but also enhanced the surface finish on components.

The medical work was only temporary, however, so the family-run business owned by Steve Hatch set about finding business elsewhere. What transpired altered the company’s fortunes entirely, as a contract from a jewellery manufacturer combined with strong growth in aerospace conspired to increase turnover so dramatically that by 2023 it was 447% higher than before the pandemic.

Even better is to come. The jewellery company is so pleased with the quality of the mainly titanium jewellery pieces already supplied that it has signalled its intention to increase the annual quantity of parts from 100,000 to 1 million per month over the next few years. The machine tools underpinning both the quantity and quality of the jewellery parts produced at the Nuneaton factory are yet more Citizen Cincom sliding-head lathes.

Reginson Engineering is a long-time user of these Japanese-built sliders dating back to the early 1990s. In October 2020, the lathes were joined on the shop floor by the subcontractor’s first Citizen fixed-head model, a 64 mm bar capacity Miyano ABX64-SYY twin-turret, twin-spindle turn-mill centre. The user describes the machine as being fantastic, as it has allowed cycle times to be slashed compared with using other turning plant on site. Shortly after its arrival, it more than halved the cycle time for producing a component from 4 minutes 30 seconds to 117 seconds complete.

The upturn in throughput generated by the jewellery contract required much more sliding-head capacity, so the subcontractor has bought 14 new Cincoms in the last couple of years. They are seven 20 mm bar capacity A20-VIIs and the same number of 12 mm capacity L12-VIIs. Twelve of them are devoted to jewellery component manufacture and the other two were acquired to boost production of smaller aerospace parts. The latest influx of new lathes plus the recent purchase of two new 5-axis machining centres brings the total number of CNC machines in the Nuneaton factory to nearly 100.

Machine shop manager and family member Tom Hatch said, “We chose twin-spindle sliders for the jewellery work because positioning cutters on gang toolposts for the next operation is much faster than indexing turrets in a fixed-head lathe. It means we can produce components more quickly, not only because there is less idle time, but also because there is more scope for reducing the number of second and subsequent operations.”

He added that the machines are easy to set and operate, to the extent that he and one other staff member run 12 Cincom’s located in an adjacent factory unit that has been leased recently for the new project. The finish of the turned surface achieved on the lathes is 0.2 µm, which lessens the amount of polishing that has to be done in Nuneaton or by the customer.

Similarly, the performance of the Cincoms when producing aerospace parts is excellent due to the extreme rigidity of the machines, despite having to cut materials ranging from tough nickel alloys to titanium and stainless steels. Tolerances down to ± 3 µm are often turned, saving the time and expense of grinding parts in another operation. Surface finish is also high at up to 0.8 µm when required.

Reginson Engineering additionally runs UPR, a subsidiary company in Pune, India, which it set up in 2014. The facility has more than 20 CNC machines and 60 employees, enabling the firm to offer low-cost components to customers worldwide, mainly in the aerospace, wind turbine, medical and oil and gas industries.

An increase in annual turnover from £3 million in 2016 to £8 million currently is reported by contract machining specialist Unicut Precision Engineering, Welwyn Garden City, which has spent £1.7 million in the last two years on new production and inspection equipment.

About half of the investment went on two more Cincom sliding-head lathes and two additional Miyano fixed-head lathes from Citizen Machinery UK, bringing the totals of the bar-fed lathes on site to 24 and 11 respectively. The remaining funds were used to purchase three new items of inspection equipment and to extend the automatic pallet storage and retrieval system linking three 5-axis machining centres on site.

Jason Nicholson, owner and managing director of Unicut commented, “Efficient production is not just down to automation but also depends on how well you monitor the machine tools on the shop floor and use the data to make informed decisions.

“We use PSL Datatrack to help with this and will shortly be progressing from manual extraction of production data from our machine tool controls to directly downloading it over a network for remote monitoring.”

Regarding turning, which currently accounts for 85% of Unicut’s turnover, he said that standardisation on Citizen lathes with their user-friendly, intuitive Mitsubishi controls greatly helps to mitigate the current shortage of skilled setter-operators, which he sees as a worldwide problem. Use of this CNC system throughout the factory also speeds the training of staff and allows operators to swap easily between machines.

Programs are normally prepared offline with Esprit CADCAM and also using Citizen Machinery’s own Alkart CNC Wizard programming aid. The latter guides operators through creation of part programs with the help of a built-in code library for machining processes, reducing the amount of time spent typing in G and M codes and consulting manuals or other programs.

The latest turning centre additions were two 65 mm bar capacity Miyano BNE-65MYY models, each featuring a pair of Y-axis turrets and the latest Mitsubishi 15-inch touchscreen control. They joined five smaller fixed-head lathes in the same series to form a seven-machine cell for producing hydraulic and pneumatic components in large volumes, typically from 2,000- to 10,000-off. This industry accounts for about one-fifth of Unicut’s turnover, with the aerospace, high-end automotive, oil and gas, electrical connector and paint spraying equipment sectors also regularly served.

Mr Nicholson continued, “Flexibility of production in a contract machining environment is crucial, as it is the key to profitability and to being able to compete with subcontractors in low-wage countries.

“Having two Y axes in the latest BNEs rather than one enables the preparation of programs that closely balance front and back working cycles at the main and sub spindles.

“It means that a wide range of work can be tackled efficiently and parts come off the lathes faster, as one of the spindles is not waiting around for the other one to finish off the machining.”

Each turret has 12 live stations, so an extensive variety of milling, drilling and other driven tool operations can be carried out in-cycle, almost always enabling one-hit production of parts. Sometimes prismatic machining accounts for more than 90% of a cycle, so at first glance the components look as though they have been produced on a mill.

Two-axis CNC movement of the sub spindle facilitates superimposed machining, whereby tools on both faces of the top turret can simultaneously cut front-end features on bar stock and reverse-end features on a parted-off component. With the lower turret also working at the main spindle performing pinch turning, milling or drilling, for example, or perhaps OD turning while axial drilling is in progress above, three tools can be in cut at the same time.

Both of the BNE-65MYYs have been fitted with an Iemca Maestro 80 low-vibration bar magazine that allows ergonomic loading of stock at waist level. Bar from 10 mm diameter upwards can be turned at the lathe’s maximum rotational speed without having to change over the guide channel, minimising idle time when processing a range of different material sizes.

Mr Nicholson is also a long-time user of sliding-headstock lathes from Citizen Machinery, having bought his first one in 2000. In 2018 he was an early adopter of the lathe manufacturer’s LFV (low frequency vibration) software, which was included in the operating system of the Mitsubishi control on one of two 12 mm capacity sliders bought in that year.

At the time, he said that the ability of the programmable function to break stringy swarf into shorter chips was eliminating the need to periodically stop the lathe to clear away clogged swarf, raising productivity. The LFV lathe was therefore left with confidence to run unattended, including overnight and at weekends, even when turning ductile metals and plastics, increasing throughput further. Impressed with the trouble-free performance, he bought two similar, improved versions of the lathe with LFV in 2022.

Mr Nicholson concluded, “On this type of machine, productivity is all about getting the material to chip, because otherwise you have to keep stopping the spindle to remove swarf from around the workpiece and tool.

“On a fixed-head lathe it is possible to increase the feed rate to promote chipping, but that is not possible when turning smaller diameter parts on a slider.

“With LFV programmed correctly, the swarf never fails to chip whatever the material, even when OD turning long components.

“The function is only needed for between 10% and one-third of a typical cycle, after which it is switched off by G-code to take advantage of slightly higher productivity without the air cutting caused by LFV tool oscillation.

“After five years’ experience using this technology, I would not consider buying another slider without it – and I am looking forward to its wider adoption on the Miyano fixed-head lathes as well.”

A large proportion of work going through subcontractor C&M Precision’s Maldon factory involves machining copper bar fed into CNC mill-turn lathes. Two sliding-head models out of the nine turning centres on the shop floor, all of which have been supplied by Citizen Machinery UK, have LFV (low frequency vibration) functionality in the operating system of their Mitsubishi controls. It results in much higher productivity and increased yield when converting malleable copper into high-end electronic components for OEMs in the medical, radar, satellite and broadcasting sectors.

Owner John Cable explained that for many of these jobs, a particular grade of copper known as OFHC (oxygen-free high conductivity) has to be used, which is more than 99 percent pure. One 60 mm long, tight-tolerance component previously produced from 3 mm diameter bar on an early Citizen Cincom M16 slider without LFV had to be turned in one pass through the guide bush down to 1.20 – 1.22 mm diameter along half its length. The continuous string of copper swarf frequently damaged the component and often became lodged in the counter spindle, preventing synchronous transfer after part-off and causing the machine to alarm out. Productivity was severely impacted and up to 20 percent of parts had to be scrapped.

Mr Cable enthused, “Transferring the job to a Cincom L12-VIILFV we bought in 2019 was a real winner. With the LFV function turned on, the copper chips like brass. Yield is now 100 percent, throughput is high and we can even leave the machine to run unattended.”

The other Cincom slider on site with this chip breaking functionality, a nominally 20 mm capacity L20-VIIILFV, arrived on the shop floor in 2017, making the subcontractor an early adopter of this novel technology. Supplied with a kit that allows feeding of oversize bar up to 25 mm diameter, the lathe is also proving useful for machining other materials that tend to generate stringy swarf, like nickel alloys and plastics, which are regularly turned in the Maldon facility.

C&M Precision was established in 1992 as a CNC sliding-head, twin-spindle, mill-turning shop, following research at the time indicating that four-fifths of rotational parts produced in the UK were less than 25 mm in diameter. After starting out with a different brand of slider, Mr Cable quickly changed to Cincoms, describing the transition as “a breath of fresh air”.

The first model to arrive in 2001 was a now discontinued M12, which has been sold on. The first job it tackled was the production of 120,000 brass connectors requiring the milling of 3/8-inch hex flats. Amazingly, due to the rigidity of the lathe that Mr Cable described as “rock solid”, one 6 mm diameter carbide milling cutter completed all of the flats, 720,000 of them, and still had not worn out.

The subcontractor is an enthusiastic user of Cincom M-series machines due to their inclusion of a tool turret as well as a gang tool post, allowing the production of complex components. A 16 mm diameter bar model installed in 2004 was joined three years later by a pair of 32 mm diameter bar capacity lathes. The latter, third-generation M32 lathes have since been replaced by fifth-generation models to take advantage of Y-axis motion on the turret and an overall higher specification.

2014 and 2015 saw the arrival of three more 32 mm sliders, this time in the Cincom A-series. They have only gang tool posts, so are faster when manufacturing less complicated parts. One of the lathes does not have a guide bush, as it is devoted to relatively limited runs of short components such as mining industry connectors. The other two sliders with a guide bush produce tens of thousands of parts per week, 24/5. One example is a mild steel gas meter part which the customer orders at a rate of one million per year, with the subcontractor making weekly deliveries.

C&M Precision’s latest two acquisitions are from Citizen’s Miyano range of fixed-head lathes. Installed in January and March 2022 respectively, the twin-turret BNE-65MYY models with Y-axis motion on each tool carrier replaced two ageing lathes that had one Y-axis turret apiece.

Mr Cable continued, “It made sense to go the Miyano route in view of our good experience with the Cincom lathes. People say it is not good to have all your eggs in one basket, but in Citizen’s case it is. We now have a single point of contact for applications, backup and service and the supplier is very capable and responsive to our needs.”

He added that the Miyano lathes have similar capability at both spindles and are highly productive, with advantage taken of Y-axis machining for a large proportion of the time. Simple off-centre holes are frequently drilled and bored, flats are easier to mill up to a shoulder and roll marking is often done using the Y-axes. Parts coming off the lathes are accurate due to one-hit production. It is possible to program cycles involving superimposed machining, where three tools are cutting simultaneously, although this facility has not been used so far in the Maldon factory.

Some parts could not be produced at all on driven-tool lathes without Y-axis motion on at least one turret and would have to be put onto a machining centre for a second operation. Others, such as a pair of components – one aluminium and the other brass – for a broadcasting microphone, are produced much faster on the twin Y-axis Miyanos compared with the lathes they replaced. The more complex of the two, the aluminium part, is produced in 4.5 minutes compared with 7.5 minutes previously. As batch size is 2,000-off, the saving is considerable.

As to the future, Mr Cable sees continued purchase of LFV lathes inevitable. While high pressure coolant systems break swarf adequately on his current larger lathes, as they mainly process free-cutting materials, there is one job presently produced from malleable, oversize, Swedish iron bar on the L20-VIIILFV that would profit from being put onto a 32 mm Cincom in the same series with the chip breaking technology.

Located in Chard, Somerset, subcontract machining firm Metaltech Precision has increased the number of sliding-head mill-turn centres on its shop floor from 6 to 13, of which 10 are Cincom models from Citizen Machinery UK. It follows the purchase by the company’s owner, Expromet Technologies Group, of another subcontractor nearby, NC Precision, which specialised in this area of production.

The strategic acquisition in May 2022 underlines the intention of the UK casting and machining group to strengthen its Swiss-type mill-turning capability. Nevertheless, Metaltech is also strong in fixed-head turning as well as prismatic metalcutting on numerous machining centres, there now being a total of 58 CNC machine tools in operation, providing an extensive suite of machining capabilities to meet customer needs.

The latest sliding-head lathe was installed in September 2022, having originally been ordered by NC Precision. It is a Cincom L32XIILFV capable of mill-turning parts from bar up to 35 mm diameter. Notably, the machine has LFV (low frequency vibration) functionality. It can be switched on by G-code during sections of a machining cycle that would normally result in stringy swarf being generated. Instead, it is broken automatically into chips of manageable size that fall away from the machining area for easy extraction.

Steven Ward, operations manager at Metaltech said, “We were already familiar with and impressed by LFV, having installed a smaller Cincom L20XIILFV four years ago to simplify the production of a particularly difficult component.

“The ongoing job involves machining a tough, malleable iron that has a high tendency to cause bird’s-nesting when turned, but LFV completely solves the problem by allowing the chipping to be controlled.

“It means that we are able to leave the lathe running unattended for long periods, whereas before an operator needed to be in attendance virtually all the time to constantly clear away the swarf.

“This labour cost element, which has now been removed, was contrary to the whole concept of bar turning, yet was necessary to maintain consistency of production and minimise scrap.”

During the acquisition process of the L32XIILFV, the order was placed by NC Precision and honoured by Expromet. It is a clear sign of the group’s ongoing commitment to development and continual investment in up-to-date plant, allowing Metaltech to remain at the forefront of technological advances and providing extended capabilities along with capacity.

The purchase of the second LFV lathe last autumn, with its chipbreaking function, facilitates more options for fulfilling contracts that may come along involving titanium, nickel alloys or other metals that tend to result in stringy swarf. Until now its full potential has not been utilised, except to assist the smaller LFV lathe in producing more of the malleable iron components to cope with rising production volumes.

Another area where the L32XIILFV has benefited Metaltech is in taking the load off a higher specification M-type 32 mm capacity Cincom on site that incorporates cutters in a turret. The gang tool-only L-type machine with its more nimble axis motions is quicker at producing relatively simple parts, leaving the M32 free to concentrate on more complex work.

One example was the transfer of production from the M32 to the L32 of a brass component on which only about 10% of the cycle involves turning operations, the remainder being milling and drilling. Although the spindle drives and driven cutter stations in the gang tool carrier lathe are a little less powerful than in the turret-type machine, it was nevertheless possible on the L-type lathe to produce the part from free-cutting brass in four minutes and four seconds, 20 seconds faster than on the M32.

Mr Ward explained, “Although this represents a reduction of only 7 to 8%, the batch size was 6,000-off, so a significant saving was made. Measures like this help us to maintain our reputation as a rapid response, short lead-time service provider with excellent on-time delivery results.

“It also helps us to control costs, even on parts like this that are predominantly prismatically machined on a driven-tool lathe yet require 20 µm positional tolerance to be held in certain areas, ensuring we provide best value and quality to our customers.”

Metaltech has been using sliding-head lathes from Citizen since 2008, when it installed its third machine, a Cincom A20. Purchase of another two and acquisition of seven more from NC Precision has brought not only increased capacity, but knowledge from the latter company as to how to lower production costs on the more recently installed sliders on which it is possible to swap the guide bush in and out in about half an hour.

Historically, the technique had not been available to the subcontractor owing to the age of the first two Cincoms and the dedication of the third to a single, awkward job. However, the newer lathes from NC Precision do incorporate a swappable guide bush.

When removed, it allows less expensive bar to be turned and results in much shorter rest lengths when the material has been used up, leading to significantly more economical production of shorter components up to typically 2.5 times their diameter. For the right type of work, Metaltech will harness this benefit in the future.

It is often said that a subcontractor does not know what type of work will be coming through the door the next day, so needs versatile machine tools to be able to produce a wide variety of components. The diversity of work is particularly large in the case of contract machinists Repro Engineering, 80 percent of whose turnover derives from turn-milling, components being mainly in the diameter range 19 to 51 mm. Throughput in a variety of different plastics typically accounts for one-third of the total, but at times is as much as 50 percent, the remainder being mainly mild and stainless steels.

The mainstay for production of a large proportion of the turned parts are CNC turning centres from Citizen Machinery, both Miyano fixed-head lathes and Cincom sliding-head models. The first Miyano to be installed was a BND42S twin-spindle lathe with live tooling. It arrived in 1997 and departed just three years ago after 23 years of service, having produced more than 2 million components, most in one hit and a large proportion in lights-out operation. The second Miyano, a BND51S, was bought in 1998 and sold in mid-2022 after an even longer period on the shop floor.

Repro Engineering’s owner and managing director Richard Palmer said, “We have a policy of regularly reviewing our capacity and keeping plant up to date. In the case of the Miyanos, however, earlier exchange simply wasn’t necessary, as the machines continued to hold tolerance. Not having to spend money on replacing them earlier helps to keep costs down for our customers and makes us more competitive.”

The replacement for the BND51S was a more capable BNJ-51SY, which arrived in May 2022. Featuring two turrets and Y-axis movement of the main turret, the lathe allows complex machining operations to be carried out at the main and sub spindles simultaneously. The turning centre also sports many more tool positions than the older model, so fewer tool changes are needed. It is normally possible to put the next part up without any cutter exchange at all.

Nine Miyano machines have been purchased over the years and many have been replaced by newer models. The subcontractor’s current tally of bar-fed lathes of this make is five, accounting for nearly half of its fixed-head lathes. Three of the Miyanos have a Y-axis function and all are fitted with short bar magazines for feeding one-metre stock up to 51 mm diameter. Additionally, the subcontractor operates a Miyano LZ-01R chucker for billet work, especially components that need hard turning.

Regarding Repro Engineering’s sliding-head capacity, the subcontractor operates three Cincom lathes capable of machining parts from up to 32 mm diameter bar. There are also five smaller capacity sliders of a different make on site. Impressed with the quality and longevity of the Miyano machines, Mr Palmer decided to approach Citizen for larger Swiss-type lathes capable of producing bigger diameter, often shaft-type components. He purchased a Cincom A32-VII in 2009, followed by a more highly specified M32-VIII with a B-axis in 2013, and another A32-VII two years later.

All were bought before the Japanese lathe manufacturer had introduced its novel LFV (low frequency vibration) chip breaking software, otherwise Mr Palmer would definitely have specified it. The programmable function, which breaks stringy swarf into short chips, is ideal for turning plastics and stainless steel efficiently. Instead, Mr Palmer relies conventionally on high-pressure oil to promote chip breaking and prevent bird’s nesting.

Extensive use is made of Citizen’s Alkart Wizard CNC programming software to prepare programs for both the Miyano and Cincom lathes. It guides operators through the creation of part programs, calling on a built-in code library and reference diagrams to optimise machining of different materials. It cuts down the amount of time spent typing in G and M codes, or consulting manuals, and validates the program before it is run.

Repro Engineering also operates four machining centres, which generate the other 20 percent of turnover. One machine is part of an automated cell with robot loading and some are equipped with a fourth CNC axis, but for indexing, not turning. It means that all components produced that require both turning and milling go onto the lathes.

Mr Palmer points out that, in this respect, a twin-spindle bar-fed turning centre is the ideal platform for unattended production in one hit of complex components, even prismatic parts requiring all six sides to be accessed. Cycle times tend to be longer on mill-turn centres, which in any case normally require an operator to be present. He does not hesitate to put onto his lathes parts that require no turning operations at all except parting-off.

Mr Palmer concluded, “All Citizen lathes are real workhorses. They are robust, compact and some have hand-scraped guideways, which leads to excellent machining quality.

“The Miyanos in particular are so heavily built, they are almost over-engineered. They just keep going and going, maintaining their accuracy and repeatability for decades. Consequently for machining parts up to 51 mm, they are our preferred lathes.

“Likewise, for turning and milling in sliding-head mode, we have standardised on Cincom when machining parts from larger diameter bars up to 32 mm.”

Founded by Mr Palmer’s father Davin in 1967 and now operating 24/7 from a 12,000 sq ft premises in Waterlooville, Hampshire, Repro Engineering produces batch sizes typically in the range 1,000 to 50,000, although prototype batches down to 100 are not infrequent. Some parts are machined to very tight tolerances down to 10 microns total.

Customers are mainly in the motorsport, defence, sports and leisure, electronics, medical and fluid power sectors and many take advantage of the subcontractor’s consignment stocking service. The company is accredited to ISO9001:2015 and AS9100 Rev D, ensuring high quality standards. In addition, it is registered on the International Aerospace Quality Group’s OASIS (Online Aerospace Supplier Information System) database.

Prismatic machining on BT30 and BT40 machining centres accounts for a majority of throughput at the Mildenhall factory of subcontractor CTPE, which produces complex, high precision components for the medical, marine, scientific, defence and electronics sectors. However, productivity on the turning side of the business received a significant boost in mid-2022, when an ageing, 2-axis, fixed-head bar auto was replaced by a Miyano twin-spindle turning centre with twin Y-axis turrets and live tooling, fed by an LNS Alpha SL65 S short bar magazine.

Supplied by Citizen Machinery UK, the 10-axis ANX-42SYY lathe is fitted with the latest Fanuc 31i 15-inch touch-screen control incorporating a new HMI. It also features the company’s superimposed machining, whereby three tools can be in cut at the same time thanks to X-axis movement of the sub spindle. Three-axis simultaneous interpolation and double Y-axis cutting are also enabled.

The sub spindle offset has the additional advantage of allowing reverse end machining of long parts with extended tools, while simultaneous machining of the front end of the next component is in progress at the main spindle. Otherwise that would have to wait due to interference caused by back end operations, lowering production output.

Chipbreaking software is a big benefit

Advantage is regularly taken of the machine’s other stand-out feature, LFV (low frequency vibration) chipbreaking software in the control’s operating system. The function is independent of the programmed cutting cycle, apart from it being switched on by G-code when expedient to break up stringy swarf, which is particularly problematic when taking finishing cuts. LFV may similarly be switched off when it is not needed, avoiding a slight reduction in metal removal rate due to high-frequency oscillation of the tool tip away from the component surface. In practice, at Mildenhall LFV is on for 10 to 15 percent of a typical cycle.

CTPE’s operations director Alex Taylor said, “We saw LFV demonstrated on the Citizen stand at MACH 2022. The function is extremely useful when machining aluminium, which constitutes most of our work, and is even more effective on plastics, which accounts for about 25 percent of our throughput.

“We struggle with bird’s nesting when internally boring both materials, as the swarf tends to leave marks that affect the bore diameter and in the case of plastic can cause burning. LFV avoids these problems, so machine stoppage for swarf clearance is no longer needed, increasing productivity and enabling reliable unattended operation overnight.

“Program preparation is simple using Citizen’s Alkart Wizard software, which offers suggestions for optimal LFV parameters, and activation only requires one extra line of code. We know we have this functionality in reserve if we have to machine exotic alloys or stainless steels, especially 304 which strings readily, although we have not used it yet on those materials.”

One example of the chipbreaking software’s effectiveness involves a defence electronics part regularly produced from aluminium bar. After experimenting with dwells and pecking macros to improve chipbreaking, which require time to insert patches manually into programs, Mr Taylor was only able to run off 50 components before having to stop the machine to clear away the swarf. That was therefore the maximum number that could be produced lights-out. The situation was acceptable when the customer was ordering batches of 250, but as volumes grew steadily to 2,000 per order, it was denting the profitability of the contract.

The problem has been resolved by having the chipbreaking software switching in and out on the Miyano during difficult parts of the cycle, so the machine can confidently be left to run throughout the night. Moreover the cycle time has fallen from three minutes on a twin-spindle, single-turret, fixed-head lathe, or two minutes when the work was put onto a sliding-head bar auto, to just one minute and 40 seconds on the Miyano. So around 400 finished parts are waiting for staff when they return in the morning.

More tools needed

Before he bought the Miyano, Mr Taylor had already moved along the path of fixed-head, twin-spindle mill-turning, having in 2020 purchased the above-mentioned lathe with a single, 15-station Y-axis turret. However, it meant that retooling was often needed when changing over to a new job, as there were insufficient cutters in the working area to cope with a high mix of work, which is characteristic of a subcontractor’s business.

What he really wanted was an increased number of tools so there would be more likelihood of the next job starting as soon as a new program was loaded. The 12 live tool stations in each of the two Miyano turrets provide him with that flexibility. He is able to leave more pre-set tools in the machine, speeding up changeover and maximising spindle uptime.

Most accurate machine ever

The 6.2-tonne machine occupies only 2,650 mm x 1,630 mm of space on the shop floor. Both main and sub spindle have a bar capacity of 42 mm diameter and are powered by 11 kW / 6,000 rpm built-in motors, while the live tools are rated at 6,000 rpm / 2.2 kW. Rapid traverse rates are fast at up to 30 m/min, which has been achieved by adopting linear guideways.

Mr Taylor concluded, “The Miyano is the most solidly built, accurate machine we have ever bought. Lathes tend to suffer more than machining centres from thermal movement when they are switched on in the morning. They are typically 30 microns out for about 15 minutes while they warm up, but not the ANX.

“After we power it up, it immediately starts producing a part we were machining the previous afternoon to exactly the same single-figure-micron accuracy, without any offsets being entered. Some tolerances we hold are down to ± 5 microns, which we have no trouble achieving.”

He added that this was the first machine tool they have purchased from Citizen Machinery and that the supplier has performed well in terms of service and back-up, especially applications training, which is important for a relatively small subcontracting firm. CTPE joined the BTMA in September 2022 and in 2021 was accredited to ISO 9001:2015.