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    AEROSPACE TURNED PARTS SUBCONTRACTOR RAISES PRODUCTION EFFICIENCY WITH TECHNOLOGY FROM CITIZEN

    Founded in 1965, subcontract machining firm Apel specialises in the manufacture of precision components for the aerospace industry. The company began investing in Citizen CNC turning centres in the 1980s to help raise efficiency and over time has continued to re-invest in modern, highly productive lathes purchased exclusively from Citizen Machinery UK.

    Today at its Wilmslow facility, Apel operates nine Cincom sliding-head lathes and one Miyano fixed head model. Together they produce around 50,000 components per month across more than 3,000 part numbers. Utilisation of these Citizen CNC lathes and related technologies has led to much increased levels of productivity and profitability.

    The technology that has contributed most to raising efficiency of production at Apel is Citizen’s proprietary LFV (low frequency vibration) chip breaking software, which is part of the operating system in the control of three of the six 20 mm capacity Cincom L20s on site. When activated, the function breaks what would otherwise be long, stringy swarf into short, manageable chips. Around 50% of material processed by Apel is aerospace grade stainless steel bar and LFV is especially effective when processing this alloy.

    Paul Bowker, Apel’s quality director said, “We were an early adopter of LFV in 2018 following a visit to Citizen Machinery’s technical centre in Bushey to witness demonstrations.

    “The function reduces metal removal rate slightly, so we don’t use it all the time, but it’s really useful to be able to pick and choose when to program the function to start and stop.

    “We switch it on mainly when turning stainless steel components on the LFV-equipped machines, especially when processing parts shorter than one inch (25.4 mm). It is normally chip breaking the metal for up to half of a typical cutting cycle.”

    He further explained that the decision to use LFV is also based on the surface finish required on components. Some customers’ drawings stipulate a very high surface tolerance and machining with the LFV function switched on allows this to be achieved by turning alone, avoiding the need to centreless grind parts afterwards, thereby reducing unit manufacturing cost and raising profitability. Dimensional and surface finish tolerances on many component drawings can be met and maintained when using this facility.

    Apel also uses the Citizen Machinery’s adaptive guide bush (AGB) system, which automatically compensates for variation in bar diameter, preventing stock seizing in the bush. It also constantly maintains concentricity to prevent run-out. Downtime is avoided and tight machining tolerances are maintained. The system is used not only on the 20 mm capacity sliding-head lathes but also on three 32 mm capacity Cincom models on the shop floor.

    The aerospace sector is very busy presently and Apel is well placed to win work due to the quality management system it operates, competitive pricing and the many industry and customer approvals it holds. Exports account for 20% of turnover, with India and Saudi Arabia being major overseas markets.

    The AGB systems ensure reliability during unattended operation by compensating for bar diameter inconsistency and preventing stoppages. Additionally, the LFV machines do not have swarf clogging the working area when processing stainless steel. It contributes further to reliability and eliminates the need for an operator to be in attendance to untangle ribbons from the components and tooling.

    Mr Bowker concluded, “Our nine Cincoms, as well as the Miyano for turn-milling larger components up to 50 mm diameter, support all of our production and will continue to do so as we increase our volume of work in the expanding global aerospace industry.”

    RAPID SET-UPS DECIDE SLIDING-HEAD LATHE PURCHASE

    Last autumn (2023), motorsport subcontractor h2m needed to replace an ageing sliding-head CNC turn-mill centre in its Hinckley factory. Joint managing directors and owners, father and son team Andy and Martin Forryan, considered buying a replacement from the supplier of the original twin-spindle, 32 mm capacity slider, but opted instead for a Cincom M32-VIIILFV from Citizen Machinery UK.

    3,000-off is a large run for sliding-head turned parts at h2m, while production of batches of relatively simple components up to 500-off is typical for unattended overnight running. However, trickier jobs are completed during day shifts in batch sizes as low as 10-off, so speed of programming is essential to minimise machine downtime. Otherwise the reduction in productivity would lower profitability.

    Andy and Martin paid particular attention to this issue and came to the conclusion that the Cincom lathe with Citizen’s Alkart Wizard programming system would be less expensive and several times faster than if the other lathe had been purchased. The wizard assists and simplifies the creation of even complex cycles using a built-in code library, reference material and diagrams.

    Sharing some detail of their deliberations, Martin said, “Alkart Wizard is an inexpensive option. We use it to prepare programs and prove them out off-line for virtually every sliding-head part we produce. Only the occasional simple component is programmed directly at the control.

    “Even complicated components take just 30 to 40 minutes to program in Alkart and it then takes 15 to 20 minutes to high-speed check the cycle virtually in the wizard, so a new job is always up and running in under an hour.”

    He contrasted this with the much longer and more expensive route that would have been needed with the other slider, for which a similar wizard was not available. First, it would have been necessary to purchase a sliding-head turning software licence for h2m’s seat of EdgeCAM, as well as a post processor for the lathe.

    Furthermore, creation of the program would have been longer before it could be downloaded to the control, added to which checking the cycle by hand on the lathe would have been very time-consuming, tying up the machine for several hours if it was a complex part. The alternative would have been to acquire third-party verification software, again entailing extra cost. Even then, program creation and prove-out would have taken considerably longer.

    Jack Simms, setter-operator of the M32-VIIILFV added, “Basically, the Alkart Wizard is a CAM system and post processor for the Cincom lathe all in one. It is very quick to use and the next program is always ready as soon as the previous batch has finished.

    “We also like the LFV (low frequency vibration) chip breaking software in the lathe control, which is built into the operating system rather than being macro-based.

    “It works at both spindles and is an absolute dream. We use it on most jobs, mainly for G71 roughing cycles which tend to produce stringy swarf, particularly when machining heat-treated stainless steels and titanium.

    “LFV is programmed by G-code to turn on when roughing starts and off again when it finishes and is typically used for one-quarter of a cutting cycle. You always end up with short chips, so there are no ribbons tangled around the tool and part.”

    Everyone at h2m agrees that the Cincom is a stable, repeatable machine that produces parts to within 10 µm total tolerance all day long – and to within 5 µm with operator supervision. The machine was supplied with a kit that allows oversize bar up to 35 mm diameter to be fed into the machine for sliding-head mill-turning. A further benefit is the ability to remove the guide bush, enabling parts up to 2.5D to be machined more accurately from less expensive bar, in multiple passes if desired, while reducing remnant length threefold. Neither facility had been used by the time the firm was visited in mid-March 2024, by which time 74 different components had been produced on the M32-VIIILFV.

    The machine has rapidly proven to be a key facility on the turning side of the subcontractor’s business, supplementing CNC milling, much of it automated, as well as both die-sink and wire-cut electric discharge machining. The latest lathe acquisition is helping to further the subcontractor’s success, which is already evident from its current headcount of 49, despite the company having been established by Andy Forryan as recently as 2015. Today, 80% of the firm’s throughput is destined for the motorsport sector, but aerospace work has started to grow and the company is already an established tier-two supplier.

    FABRICATOR REBALANCES BUSINESS TOWARDS SUBCONTRACT MACHINING

    Twenty years ago, Gareth Davies started Burton-on-Trent company TAS Engineering as a steel, stainless steel and aluminium fabrication shop serving food and beverage customers, the pharmaceutical and automotive sectors, and industry in general with fire escapes, factory staircases and secondary steelwork.

    In 2014, he established a machine shop to add extra value to the products the company was shaping and welding. Today, there is a pair of 3-axis, vertical-spindle machining centres on-site and three CNC lathes, the latest of which is a second-hand Cincom L20 sliding-head turning centre from Citizen Machinery UK.

    What prompted the purchase in October 2023 of this 20-year-old lathe, the company’s first sliding-head model, was a desire to turn more efficiently components in a range of materials from bar up to 20 mm in diameter. A case in point is the ongoing production since 2020 of a 16 mm diameter, 316 stainless steel magnet holder, which is welded to a small, laser-cut and bent plate to form part of a safety unit for industrial switchgear. The turned component, of which 200 are required per month, was previously produced complete on one of two fixed-head, twin-spindle lathes (that have since been sold) in a 2.5-minute cycle.

    Mr Davies had previous experience of programming and setting sliding-head lathes, albeit from 40 years ago working for a subcontracting firm in London that happened to be the first ever customer of the Citizen sales agency at that time. The lathes were equipped with servo-driven cams and while the technology has moved on enormously over the decades, the underlying principle of operation is still similar.

    It was apparent that the steel magnet holder could be produced more quickly on a modern Citizen L20 twin-spindle, sliding-head turning centre than on a fixed-head lathe due to the faster axis motions of the gang tool carriers on the former compared with the turret movements on the latter. However, Mr Davies was surprised to find that the part could be machined more than three times faster on the Cincom, the cycle now taking just 48 seconds.

    The sliding-head turning centre was installed and commissioned in October 2023, so it is still early days. Nevertheless, four additional jobs had been won by the end of the following January as a result of having the capacity available on the shop floor. None of this new work has anything to do with the fabrication side of the TAS Engineering’s business. One contract involved the production of 1,000-off brass parts for a customer in industrial gases, which ran 24/7 for one week, despite Mr Davies being new to sliding-head lathe operation.

    The other jobs were 70-off engine parts produced from steel bar in one hit rather than in two operations on a fixed-head lathe plus another on a mill; 3,000-off heritage railway carriage brass fixing pins; and another component for the industrial gases sector machined from 0.75-inch diameter CZ121.

    Mr Davies commented, “Although all the parts are relatively simple, some tolerances are tight. The bore on one of the components for industrial gases has to be held to 0.05 mm total and the engine shaft OD must be within 0.04 mm.

    “Despite the Cincom being 20 years old, provided we run it at sensible feeds and speeds we achieve this level of accuracy easily.

    “Not only that, but we have confidence leaving the machine running unattended to get on with other tasks, as all dimensions repeat from part to part to within 15 microns.”

    He went on to mention that although the purchase price of the lathe was only about one quarter of the investment needed for a modern 20 mm capacity Cincom in the manufacturer’s L-series, he was treated by all Citizen Machinery UK staff as though he were purchasing a new L20. “They went above and beyond what would normally be expected for the sale of a used machine and the delivery, commissioning and training were exemplary,” he said. “I cannot sing their praises highly enough.”

    TAS Engineering is currently undergoing a metamorphosis whereby, while fabrications will continue to play a part in the business, in the future it will only be if they undergo prismatic machining or contain turned parts. Already this policy has seen the contribution of chip removal, mostly metal and but also plastic, in the factory rise from 10% to 90% of turnover. It is a progression that was accelerated by the Covid pandemic, when on-site visits to provide customers with fabrication services were forbidden.

    Another insight offered by Mr Davies is the formidable financial advantage of purchasing a good quality used machine tool, provided that one can be sourced, which is not always easy. His L20 had only 40,000 hours on the clock when it arrived, equivalent to having run for a single shift every weekday. It is notable that, for the jobs completed so far, repayments on finance for a new Cincom would not have been viable.

    On the other hand, paying back only one-quarter of the amount puts TAS Engineering in a strong position to quote for work very competitively, especially if it is not especially complex. Moreover, small quantities are also practicable, provided that the machine can be set up quickly. Mr Davies often uses Citizen’s Alkart Wizard software running on his laptop to speed programming and downloads the code to the control.

    Applications engineers at Citizen Machinery UK are always on hand to assist when needed. A recent instance was when Mr Davies was worried about possible damage to the steel engine shaft as it was ejected from the sub spindle. Within an hour, a response was received advising him to omit an M-code at the end of the cycle and replace it with a specific line of alternative code that worked perfectly as soon as it was implemented. “Such after-sales engineering back-up is invaluable, especially if you are new to sliding-head turning,” he concluded.

    SEVEN OPERATIONS DOWN TO TWO VINDICATES SECOND SLIDING-HEAD LATHE PURCHASE

    It is only within the last five years that Nuneaton-based subcontractor Oaston Engineering, which specialises in work for the aerospace and biotechnology industries, has embraced sliding-head turning, although it has used numerous fixed-head lathes since the company was formed in 1988. July 2018 saw the arrival of the firm’s first sliding-head lathe, a 20 mm bar capacity Cincom L20-VIIILFV from Citizen Machinery UK. It was followed in October 2022 by a second, larger model, a 32 mm capacity Cincom L32-VIIILFV.

    Oaston Engineering’s managing director Sean McCarthy commented, “We were always led to believe that sliding-head lathe operation was a dark art and that you need to produce large batch quantities, say 50,000, to justify setting them for a new run. We had been looking at the technology since MACH 2008 and a decade later, when the Cincom L20 was delivered, we discovered the myths were untrue.”

    He found that setting the machines was quick and so also was programming using Citizen’s Alkart CNC Wizard. It has a built-in library for machining processes to reduce the amount of time spent typing in G and M codes, together with internal reference material and diagrams to guide the programmer. The subcontractor’s setter / operators also frequently refer to the machine manual, which McCarthy describes as excellent. In the first few weeks, Citizen’s applications team provided help with preparation of the initial programs.

    The ease and speed with which the lathe could be prepared for the next production run meant that batch sizes of as low as 200 are economical to machine. As it happens, though, the quantities the company is being asked to produce are steadily rising. One example is a contract to mill nuts and olives for an aircraft de-icing equipment manufacturer. In 2008, the typical annual quantities required were 2,000 and 5,000 respectively, whereas today they are five times higher. Both components are now machined on the L20, with typically parts for five months’ supply produced and consignment stocked to save repeated machine set-ups throughout the year.

    Mr McCarthy continued, “We have always known that continuous investment in modern plant is essential to remain competitive in a global marketplace and we invested £500,000 in new plant over a 12-month period alone in 2022 to 2023.

    “We had a strong competitor in Poland vying for the de-icing equipment contract, but the efficiency with which the L20 produces the parts puts the business out of their reach.”

    He added that when it came to selecting which make of slider to buy, they carefully reviewed different suppliers’ offerings. Two factors swayed the decision towards Citizen Machinery. One was the availability of the LFV (low frequency vibration) chipbreaking function in the Cincom control’s operating system. The other was the knowledgeable response to questions, evidenced by the Citizen sales engineer being able to provide all answers on the spot, rather than having to refer back to head office every time. As Oaston Engineering was new to sliding-head turning, this was a major advantage.

    It was also notable that the machine supplier was the only one offering to deliver the lathe with a bar magazine that was two metres long, rather than the more standard three or four metres. This was also important to the subcontractor, as space is limited on the shop floor and there would not have been room for a longer bar feeder.

    Of the work put onto the L20 since it was delivered, 95% has been to fulfil aerospace contracts. One of the first jobs was a 303 stainless steel inlet connector, which came off complete in one hit in 3.5 minutes. Previously, four separate operations were needed. The part had to be turned on a lathe in a 3.5-minute cycle, transferred to another lathe for a second, 3-minute turning operation, undergo a 2-minute manual operation and then have a hole drilled on a milling machine, taking 1.5 minutes. Transfer between each stage took about 30 seconds.

    The overall floor-to-floor time was 11 minutes 30 seconds, more than three times longer than on the slider with its very quick gang toolpost motions. The new process route allows a considerable saving to be made in the cost of production and the parts are perfect due to the absence of tolerance build-up through having to repeatedly clamp them. It enables the subcontractor not just to hold the price of the component to the customer, but to actually lower it by 5%. As is commonly known, cost-down is a widely sought throughout the aerospace industry.

    According to night shift supervisor John Shirley, a substantial further saving is made in the cost of tools. Owing to the rigidity of the Cincom lathes and their use of neat oil rather than a water-based coolant, cutters tend to last a lot longer. For example, for the above job an HSS (high speed steel) twist drill only managed to complete 100 pieces before it dulled, whereas Mr Shirley finished a batch of 4,000 on the slider using the same tool and it was still sharp.

    The LFV function is also proving valuable. It is used on most jobs to assist breaking stringy swarf into shorter chips, preventing entanglement around, and damage to, the tool and workpiece. LFV, which is switched on and off automatically within the program, is used sparingly as the microsecond periods of air-cutting due to the tool oscillation that creates the chipbreaking action also diminishes very slightly the metal removal rate. Nevertheless, its advantages far outweigh this small effect, especially when cutting oxygen-free copper, 316 stainless steel, aluminium (often 6082T6) and plastics including PEEK, all of which tend to generate bird’s nests of long swarf.

    The Cincom L32 would have been purchased earlier had it not been for the pandemic; it was delivered by Citizen Machinery in July 2022. The subcontractor had a particular job in mind for it – the production of a light aircraft pump camshaft from 431S29, a martensitic stainless steel.

    The component, which is produced from 1.25-inch bar, formerly needed seven separate operations: outside diameter turning and grooving; milling on a machining centre; two separate turning operations in offset fixtures to machine the cams to a dimensional tolerance of 0.07 mm; drilling a longitudinal bore on a machining centre; cross drilling a tooling hole in another operation; and off-site grinding of two spigots to within 0.015 mm.

    The camshaft produced in this way required a total of 18 minutes 30 seconds of cutting time, plus inter-machine handling as well as 30 to 60 seconds for deburring and more time for inspection at each stage, all of which added up to several more minutes per component. Now, six of the operations are performed in one hit in less than 15 minutes on the Cincom before the part goes out for grinding. It had been hoped to complete the latter operation in-cycle as well, and indeed it was demonstrated that it is possible to turn the spigots to within 15 µm on the L32, but it is a tight limit that needs care to achieve and would have slowed production.

    More than 20 jobs have already been through the L32, which is also fitted with a two-metre Iemca bar magazine and standardised to the use of 30 mm diameter stock to avoid having to change collets. Some work has been transferred from the L20, easing the pressure on that machine. The sliders operating in tandem provide security should one be out of operation. Mr McCarthy stresses, however, that neither Cincom has gone down since they were installed, which is a refreshing change from other lathes on site that are considerably less reliable.

    Many components need hexagonal flats, but hex bar is never used as it would cause vibration and not be commensurate with producing accurate parts for aerospace and biotech. In any case, the driven tools on modern Cincoms are so powerful that milling of spanner flats is rapid. Oblique cross holes are required in that area of many components and to prevent the drill wandering, the milling is completed afterwards. Both Cincoms run continuously from 6.00 am on Monday to 1.00 pm on Friday, with night shifts always attended due to the nature of the work carried out.

    The two sliding-head lathes not only hold the limits asked of them but are also highly productive, so much so that time has been freed up within the factory to begin assembly work for the first time. From November 2023, the body for the aircraft pump will be milled on one of Oaston Engineering’s 5-axis machining centres and assembled with five other mechanical parts produced on the shop floor, including the camshaft, before delivery to the customer. More such added-value contracts are expected in the future.

    SUBCONTRACTOR’S TURNOVER MORE THAN QUADRUPLES IN THREE YEARS

    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.

    AUTOMATION AND PLANT MODERNISATION SUPPORT CONTRACT MACHINIST’S GROWTH

    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.”

    CHIP BREAKING SOFTWARE MAKES TURNING COPPER AS EASY AS BRASS

    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.

    SUBCONTRACTOR MORE THAN DOUBLES SLIDING-HEAD TURNING CAPACITY

    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.

    LONGEVITY OF LATHES PROMPTS REPEAT PURCHASES

    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.

    HIGH-LEVEL TURNING TECHNOLOGY RAISES SUBCONTRACTOR’S PRODUCTIVITY

    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.

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