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    AIRCRAFT EQUIPMENT MANUFACTURER IMPROVES MACHINING EFFICIENCY FOR LARGER COMPONENTS

    Father and son team Andy and Owen Phillips, both of whom are pilots and aviation engineering enthusiasts, started a subcontract machining business in Havant in 1994. After four years, they applied their extensive knowledge acquired over many years of building and flying aircraft to transition their firm, Andair, into a manufacturer of fuel system components for light aircraft in the sport, amateur-build and commercial aviation sectors.

    The business, which is certified by QAS International and to ISO 9001:2008, is now a leading global producer of such equipment, with 90 percent of its fuel selectors, filters, check valves, gascolators and fuel pumps going to export markets. Regular customers include Cessna, Cirrus, Czech Sport Aircraft, Diamond, Grob, Grumman-Northrop, Rotax/Bombardier, Scaled Composites, Technam and Vans.

    Miyano fixed-head, twin-spindle CNC lathes from Citizen Machinery UK have underpinned production of Andair’s turned and milled parts since January 2005, when the first turning centre with sub spindle was delivered to the Havant factory, a 5-axis BND-42S. It proved so efficient that a second, identical model was ordered six weeks later. Fast-forward 16 years and the company has bought a total of seven Miyanos, the latest being the first 80 mm bar capacity ABX lathe to be installed in the UK. It arrived on the shop floor in June 2020 equipped with an Iemca KID 80 short bar magazine.

    Andair had been waiting eagerly for the launch of the 80 mm version of this twin-spindle machine with two Y-axis turrets, having since 2015 been producing 3 inch and 2.75 inch diameter components from billet held in a Hainbuch chuck in the main spindle of a smaller ABX-64SYY, of which there are two in the Havant factory. The high requirement for components of this size meant that the lathes were being used for chuck work 60 percent of the time.

    Owen said, “Production efficiency of our larger components used to be lower because we could only manufacture a limited number of components from a billet, say five or perhaps seven. In the case of the aluminium body for an oil-air separator we are currently machining, we could only produce one per billet.

    “Now all these parts can be machined from bar using the 80 mm capacity lathe, saving a lot of time. It runs continuously throughout the day and although we are not set up for 24/7 operation at present, with this machine and our other Miyano bar autos is it is feasible in the future.”

    The other lathes in the factory all have twin turrets and Owen had ordered a similar specification for the 80 mm model. Due to the cancellation of the MACH 2020 machine tool exhibition, however, which should have been held in Birmingham last April, Citizen Machinery had in stock a triple-turret ABX-64THY (80 max dia) 12-axis model with a Fanuc control system that it had intended to launch at the show. Owen was initially hesitant when offered the machine, having never used a lathe of that configuration before, but decided to buy it anyway as it was available immediately. It turned out to be a revelation.

    He enthused, “I would not buy another twin-turret machine in future, because having three turrets is so much more productive. I would like a four-turret version if Miyano made one.

    “It is no problem to transfer work to the more complex lathe, as a new program can be checked easily using the manual retrace function in the control, avoiding any possibility of interference between tool and workpiece.”

    He explained that the two turrets positioned above the spindle centreline, each with 12 live stations, are dedicated to working at the main and counter spindles respectively. The third turret is located below and has unrestricted travel to operate at either spindle to provide flexibility for balancing front and reverse end machining. Three tools can be in cut simultaneously to achieve very high levels of machining efficiency.

    About 60 different parts have so far been produced on the new lathe, all from 3 inch diameter bar. In fact, in one instance where a customer required a large valve machined from a 4.5 inch diameter billet, Owen turned the end of it down to 80 mm so that it could be machined in the collet.

    In the case of the oil-air separator body, it is now possible to machine five from bar in 30 minutes whereas before, with an operator loading billets manually into the chuck of an ABX-64SYY, it took at least 45 minutes to achieve the same output. In other words, productivity has been boosted by more than 50 percent. A further benefit to Andair is that the two 64 mm bar lathes can now be devoted to the collet work for which they were originally intended.

    Another example of where the 80 mm bar machine has introduced benefits is when machining one of the few Andair components the pilot actually sees, a fuel selector fascia plate that requires a very high surface finish, which is achieved on the aluminium part using a diamond tipped tool. The plate is also engraved to indicate which tank has been selected. Previously, after turning it from a billet, a second operation was required on a machining centre to mill material from the reverse and to drill four holes.

    The method of manufacture has now been altered, whereby milling and drilling as well as turning are carried out from bar on the Miyano, leaving only a small operation to clean the bore on a separate machine. Cycle time has been reduced by at least two minutes and an operation has been eliminated.

    In the case of another component, in fact the first part that was made on the ABX-64THY (80 max dia), all three turrets had almost an identical amount of work to perform. Cycle time is 2 minutes 15 seconds including parting-off and the component comes off finished, whereas previously the cycle was 4 minutes, plus there was a need for a second operation, requiring extra time for both metalcutting and inter-machine handling.

    Aluminium accounts for three quarters of throughput at the Havant factory, with a wide range of other materials also machined including brass, bronze, plastics, tool steel and other steels including stainless. Batch sizes are relatively low, normally between 100- and 500-off, so there is a lot of machine preparation.

    The Miyanos are quick to set up however, as they have built-in tool setters and programs are prepared off-line using an Esprit CAM system. Typical tolerance that needs to be held is ± 0.02 mm and Owen declared that if it is exceeded on any occasion, it is always the tool that is at fault, as the machines do not move.

    He concluded, “I am a big fan of Miyanos. They are very productive, accurate machines and have beautiful spindles that produce excellent surface quality. I wouldn’t look at another make of lathe.

    “Support from Citizen has been fantastic, from sales to delivery, installation and commissioning – they are absolutely incredible.”

    AIR BEARINGS MANUFACTURER BRINGS SLIDING-HEAD TURNING IN-HOUSE

    The first sliding-head turn-milling centre to be installed at the Ferndown, Dorset factory of Air Bearings Ltd (ABL) is a Citizen Cincom L20-VIII LFV. Delivered in June 2019, it has brought in-house the production of nearly all shaft-type components, saving around £8,000 per month previously spent on subcontract Swiss-type turning. As a consequence, the machine paid for itself within 18 months.

    Speeds up to 350,000 rpm are attained by ABL’s air bearings, which are used globally in machinery for semiconductor wafer slicing, printed circuit board drilling, and micro-machining applications as diverse as polymer lens manufacture for cataract operations, edge grinding of toughened glass for mobile phone screens, watch component manufacture and milling of coining dies. The high rotational speeds demand that sub-micron tolerances be held on some turned bores and other features of component parts of the air bearing.

    This in turn means that operations prior to diamond turning and grinding of the bore and outside diameter must also be very accurate to meet pre-finishing requirements. In this department, ABL operates two vertical machining centres, seven 2-axis chuckers, two multi-axis, bar-fed, fixed-head lathes and now the Citizen L20 slider.

    Only top-end machine tools are purchased by ABL to meet the levels of precision required to ensure rotational motion of the air bearing spindle to within a couple of microns. The shaft assembly with its six key parts is especially critical.

    ABL’s senior production controller Dave Stacey advised, “Take the collet, for example, produced from 13 mm diameter tool steel bar. The concentricity of the front bore to the taper is tied up to 30 microns TIR (total indicator reading).

    “Dimensional tolerances on diameter and length need to be within 50 microns or sometimes 25 microns to allow post machining to sub-micron accuracy, while there is a 6-micron limit in the bore.

    “Originally, before our decision to use subcontract services, these collets were machined in-house in two operations – turning and boring on a fixed-head lathe and then drilling of eight radial holes on a machining centre.

    “The time-consuming process led to our pre-finishing department only producing the quantity that was needed, which could be as low as 15-off, yet external heat treatment and stress relieving before final finishing still cost £250 a time, irrespective of component quantity.

    “Now, with single-hit turn-milling of the collets on the Cincom L20, we run off typically 500, representing three months’ supply, at a fraction of the cost of subcontracting them out, added to which we can take full advantage of the fixed-cost heat treatment service.”

    It is a similar story with the other rotational components in the shaft assembly of an air bearing spindle, such as the EN57 stainless steel collet studs and guide pistons, of which there are six variants. All are produced more economically on the slider, as they involve classical Swiss-type turning from bar less than 13 mm in diameter.

    The largest part produced on the Cincom L20 is a 250 mm long push rod turned from 16 mm silver steel bar down to 7 mm diameter in one pass. It would not be feasible to turn the component in several passes, as it is longer than the guide bush; while recourse to turning between centres using the sub-spindle would unduly extend the cycle time and leave a witness mark.

    Taking a 9 mm depth of cut in this high carbon steel over much of the component’s length is an ideal time to activate Citizen’s patented LFV (low frequency vibration) chipbreaking software in the Mitsubishi control. It allows what would normally be long, stringy swarf to be broken into shorter lengths, the size of which is determined within the program, to avoid birds-nesting around the component and tool and the need to remove the swarf repeatedly from the machining area by hand. Economy of production is greatly increased, as there are no stoppages for swarf clearance, and the lathe can be left to run unattended. Additionally, absence of chatter improves the surface finish on machined components.

    Notably, LFV may be switched on and off during a cycle by G-code command, but is not a chipbreaking macro within the program itself. Instead, and distinct from other systems, it is part of the CNC operating system and as such does not compromise tool life.

    Mr Stacey concluded, “The Cincom lathe is so fast at producing rotational parts from bar for our air bearings, even with the larger batches we are running, that the machine is often waiting for work during the day.

    “We are therefore looking at putting classical fixed-head work onto the machine, parts that are shorter compared with their diameter, which will provide an opportunity to bring further subcontracted turning in-house.

    “For this purpose, the ability to run the Cincom L20 in guide bush-less mode to save material by shortening the minimum bar remnant will provide an additional saving.”

    SLIDING-HEAD LATHE WITH TWO TOOL PLATENS SLASHES PRODUCTION CYCLE TIMES

    At the subcontract machining facility of Witon Engineering, Barnstaple, turn-milling of relatively complex components from 16 mm diameter bar used to be carried out on 32 mm capacity sliding-head lathes, rather than smaller capacity models, to take advantage of the extra CNC axes and tools available on the larger machines. This type of work has now been transferred to a more nimble, 25 mm bar capacity Citizen Cincom D25-VIIILFV sliding-head turning centre, installed in January 2021. The first two jobs have shown significant cycle time reductions of 20 percent or more.

    Since the mid-90s, the contract machinist has bought 17 bar-fed lathes from this supplier, of which one was a 42 mm bar capacity Miyano fixed-head machine, the others being various Cincom sliding-head models for turning up to 32 mm stock. There are currently 11 Citizen machines on the shop floor, earlier models having been exchanged over the years. Lathes from this supplier therefore account for approaching half of the 25 of bar autos in the factory, comprising 13 sliding-head models, eight single-spindle fixed-head turning centres and four CNC multi-spindle automatics.

    The first component to be transferred to the D25 was an EN1A steel shaft for a lawnmower. The part was formerly produced on an L32-VII, of which there are three on site. As 180,000 have to be produced to fulfil the current contract, the 20 percent cycle time reduction leads to a significant production cost saving.

    The second component benefiting from being machined on the D25 is a 304 stainless steel fuel inlet fitting for an automotive customer. It used to be turn-milled on one of a pair of Cincom M32s in a cycle time of 72 seconds. This has been cut to 53 seconds, representing a 26 percent saving. With 55,000-off needed, the economy gained is significant.

    Ian Clapp, workshop manager at the Barnstaple factory explained, “We operate a couple of 20 mm capacity, dual-platen sliders of another make and knew this configuration offered quick cycle times.

    “However, we saw what our longstanding sliding-head lathe supplier Citizen was offering in the D25, a machine with larger bar capacity plus the ability to carry out work up to 32 mm diameter without the guide bush for more economical material usage when producing shorter components.

    “The model also has the benefit of a programmable B-axis, so we decided to go for this option.”

    The gang tool platens are in front of and behind the spindle centreline, with Z-axis motion provided on the rear carrier to allow balanced turning, milling or drilling, or simultaneous rough and finish turning. The B-axis on the front post, carrying up to four driven tools on either side to service either the main or counter spindle, swivels by up to 135 degrees. A further feature of the lathe is that three axis groups can be controlled simultaneously by the Mitsubishi 800 CNC system, so three tools can be in cut at the same time.

    Another potential benefit of this 12-axis CNC turn-mill centre is that it incorporates Citizen’s programmable LFV (low frequency vibration) chipbreaking technology in the control. It automatically breaks into smaller pieces the long, stringy swarf produced when machining materials such as copper, plastics and high alloy steels. Birds-nesting around the tool and component and the consequent damage that may be caused is therefore avoided. Although LFV cycles have not been included in programs run so far on the D25 at Barnstaple, it is nevertheless there to use when appropriate jobs come along.

    Witon Engineering underwent a change of management at the end of 2016 when second-generation owner and managing director Ian Sheldon retired. The firm is now run by Ian’s son-in-law Tom Courtney, who is the general manager and Ian’s daughters, directors Hayley Neate and Gemma Courtney. Operations still predominantly centre on precision turned parts production on CNC lathes, the cam multi-spindle auto shop having closed in 2018. Two 3-axis, vertical-spindle machining centres are also in use.

    Large batch runs are the norm: one electrical connector part is produced at a rate of 100,000 per month and even one of the machining centres is currently completing a contract for 500,000-off prismatic components.

    Mrs Neate commented, “We are keeping Witon Engineering basically on the same trajectory, with the accent on turning and long periods of unattended running of our bar autos during the day and to the end of a twilight shift finishing at 12.30 am every weekday.

    “The onset of the pandemic reduced business early on, especially as work for the automotive sector, traditionally a large proportion of our business, was badly affected. However, we have gained extra contracts in other sectors to compensate, such as parts for lubrication systems and household goods.

    “When the automotive work returns, our production throughput will be at a record high and we will carry on investing in top quality plant like Citizen lathes to meet the demand.”

    MEDICAL WORK OFFSETS SHORTFALL IN AEROSPACE CONTRACT MACHINING

    Over the past decade, Managing Director Nick Street has driven the growth of Trust Precision in Eastwood, near Nottingham, which has become one of the leading providers in the Midlands of sliding-head turn-milled components. He said, “With a can-do attitude and living up to our slogan ‘where reputation is everything’, we have established ourselves as a benchmark for quality and reliability.”

    Last year the company more than doubled its production area to 8,500 sq ft by moving into an adjacent factory unit. Part of the reason for expansion was to dedicate space for training and developing the skills of the subcontractor’s workforce, apprentices and operators from one of its largest aerospace customers that utilises similar machines.

    When he started his contract machining business, Nick took the view that for one-hit production of turn-milled parts, sliding-head lathes were able to hold size better than equivalent fixed-head twin-spindle lathes. It is possible to hold five microns total tolerance on most turned and interpolated features.

    He already had considerable experience of Citizen Cincom as well as other sliding-head lathes at various subcontract firms in the area, so in 2011 he ordered the first Cincom M32-VIII, which was delivered fitted with a pneumatic guide bush that improves the machine’s ability to accept bar stock of variable quality and extends the bar capacity from 32 to 35 mm diameter.

    Mr Street said, “With B-axis movement of one of the tool carriers and a total of nine cutters facing the sub spindle, the machine was at the time more advanced than most other lathes on the market, either sliding-head or fixed-head, so it was a straightforward choice to purchase the Cincom.”

    It proved ideal and there are now six similarly equipped models operating around the clock at the Eastwood facility, lights-out overnight. All are fitted with 130 bar high-pressure coolant and a 3.6-metre bar magazine. The latest M32 addition, plus a 20 mm bar capacity Citizen L20-XII with a programmable B-axis and the manufacturer’s low frequency vibration (LFV) chip breaking software, were delivered in January 2020 directly to Trust Precision’s factory extension. Alongside them, the subcontractor operates the latest M32 variant that Citizen Machinery UK asked him to beta test.

    Until the pandemic took hold in early 2020, up to 60 percent of turnover was derived from aerospace contracts, but the proportion is more like one-third of that now. The current shortfall in commercial aerospace work, due to Covid-19, has been largely offset by winning new business, primarily from the medical industry. The fall-off in work from the aerospace sector has presented the opportunity to focus more on training, which had been identified as the crucial element for the future development of the business. Mr Street commented that Covid-19 has been a benefit in this respect, giving the company the opportunity to focus more on this important element for the development of the business.

    Fortuitously, the presence on the shop floor of the L20-XIILFV meant that its superior chip breaking ability could be harnessed for more efficient turning of medical parts from stainless steel bar. The material normally forms stringy swarf that wraps itself around the component and tooling, risking damaging both, but programmable LFV avoids the problem by breaking the swarf into a short, manageable length. The chip-forming functionality in the operating system of the Mitsubishi control is switched on automatically by G-code command for those parts of cycles where it is expedient to use it, and then switched off again automatically, resulting in significant improvements in productivity and yield.

    In the case of an early medical job whose dimensional tolerances needed to be within ± 25 µm, LFV was switched on for about 25 percent of the cycle. After 1,000 components had been produced, there was no swarf damage to components or tool breakage, even though a 0.8 mm diameter hole was being drilled and reamed in the reverse end of the part.

    Mr Street continued, “LFV is a must if you are buying a Citizen lathe that offers the option. It is a major technological advance, the more so because it can be activated by the part program. So the slightly lower metal removal rate during LFV can be restricted to those elements of the cutting cycle that benefit most from the chip control.

    “Although the volume of our aerospace work diminished at the start of last year, just after we acquired the L20, the machine is proving useful for fulfilling medical contracts. The benefits will be felt even more in the future as the aviation sector recovers, as the stainless steels, titanium alloys and plastics we turn-mill for those customers all benefit from the chip breaking technology.”

    Another feature of the machine that Mr Street appreciates is its ability to operate in guide bush-less, fixed-head mode for producing shorter parts economically. It also allows the machine to accommodate free-issue bar of indifferent quality. There is the added advantage of reduced remnant length and hence material savings. Only about 5 percent of throughput is currently machined without the guide bush in place, the remainder being shaft-type work, but for those contracts where it is possible the benefits are considerable.

    With tongue in cheek, Mr Street concluded that LFV has one downside for experienced sliding-head lathe programmer-operators. It takes the black art out of chipping troublesome malleable materials so comprehensively that the playing field is levelled in favour of less skilled machinists.

    CITIZEN MACHINERY HIRES FIVE NEW STAFF

    To satisfy the needs of its widening customer base, Citizen Machinery UK has recently taken on five new employees. The ongoing recruitment campaign is essential to underpin the company’s position as the largest supplier of sliding-head (Cincom) and fixed-head (Miyano) bar-fed CNC lathes into the UK and Irish markets.

    Citizen Machinery UK’s managing director Edward James commented, “We have expanded our business dramatically over the past few years. It is essential we keep our headcount commensurate with the increasing level of business to ensure our long-term success.

    “This is especially important for our UK operation, as we are also the distribution hub for Citizen machines going into France, Spain, Portugal, Scandinavia, the Middle East and Africa.

    “We are continually looking for candidates to strengthen our departmental teams and fervently believe that investment in staff is a top and ongoing priority, both to sustain growth and for succession planning and promotion.”

    The level of success achieved by the UK operation enabled the management team to persuade the Japanese parent company to invest more than £3 million in a new turning centre of excellence in Brierley Hill, which opened in 2019 and concentrates on preparing deliveries to customers. It operates alongside the headquarters in Bushey, which has been made the centre for configuring and supplying bespoke manufacturing solutions.

    The first new recruit, who joined as a service engineer towards the end of last year, is Gloucestershire-based Timothy Baldwin. He has a strong background in CNC turn-milling machine programming, setting and operation in the aerospace, motorsport and toolmaking sectors.

    The newest member of Citizen Machinery UK’s applications engineering team arrived shortly afterwards. Martin Gregory lives in Birmingham and is well located to serve customers in the Midlands and to support the Brierley Hill operation. He has several years’ directly relevant experience working in the machine tool industry and is a valuable addition to the team.

    Mark Harris, whose first day with the company was during early November, has considerable experience as a field service technician as well as having extensive knowledge of machine tool technology. Living in Solihull, he has been recruited into the servicing and installation team.

    Rebecca Hancock joined as another service technician. She completed her apprenticeship during a five-year term at a superabrasives company in Gloucestershire and has experience working in the aerospace, F1, nuclear, defence and petrochemical industries. During that time she learnt to program, set and operate various machine tools including twin-spindle CNC lathes. She recently relocated to Walthamstow in north London.

    That three of the first four new arrivals were recruited to the CMSure service and maintenance side of the business is no surprise. Citizen Machinery UK is finding that, due to uncertainty caused by Covid-19, there is a nervousness in some manufacturing companies to invest in new plant. It has resulted in a corresponding increase in the popularity of keeping existing machines in the field in peak operational condition and demand for service and maintenance support has never been higher.

    The fifth recruit was north London-based Aaron Lewis, who joined from a leading workholding equipment supplier where he was a design/project engineer. Prior to that he studied design engineering at university. He is now supporting the customised production solutions team in a systems role at Citizen Machinery UK’s Bushey headquarters, working on integration projects and machine modifications.

    FIRST CITIZEN SLIDING-HEAD LATHE WITH AUTOMATIC TOOL CHANGE

    A fourth variant has been added to the versatile Cincom L20 sliding-head CNC turning centre range from Citizen Machinery UK. The top model, L20-XII, which has a 135-degree swivelling B-axis mounted on the gang tool post for working at either of the opposed spindles, is now available with an automatic tool changer (ATC) for swapping up to 30 mm diameter cutters in a chip-to-chip time of four seconds. Both the tool carrier and magazine move in the Y1-axis to effect tool change.

    Believed to be a first in a Swiss-type turning machine, the ability to exchange 12 different cutters in the lower position of the B-axis carrier greatly extends the machine’s versatility when executing angled crossworking or end facing operations. A 13th tool is fixed in the upper position on the carrier. While the cutters are normally live for performing drilling, slitting, hobbing or multi-axis milling, positions may be filled by turning tools if expedient.

    The total number of tools that may be mounted in the working area of the Cincom L20-XIIATC is 34, providing considerable flexibility to ensure that components are machined in as few set-ups as possible, normally one. Cutters are driven by a 2.2 kW motor at up to 12,000 rpm, so even small diameter mills are capable of productive metal removal rates.

    As its designation implies, the lathe is designed to turn components from 20 mm diameter bar, although oversized options allow up to 25 mm diameter material to be accepted. Another feature contributing to the lathe’s versatility is the ability to switch over quickly between Swiss-type operation and non-guide bush turning for more economical production of shorter components up to 2.5D. This mode results in less bar wastage due to the shorter remnants and is well suited to coping with tight drawing tolerances and close bore-to-OD geometry. The removal of the guide bush also means that the diameter of the stock material does not have to be tightly controlled.

    To underscore the flexibility of use that is possible with this machine, it is noteworthy that it can be supplied in an LFV version with Citizen’s patented, programmable, low frequency vibration chipbreaking software. Furthermore, laser processing can be integrated to provide almost limitless possibilities for creating burr-free geometric shapes or precision holes as small as 0.2 mm diameter in tube or predrilled solid bar.

    DOUBLE Y-AXIS MILL-TURN CENTRE WITH FANUC CONTROL AND CITIZEN’S CHIPBREAKING SOFTWARE

    The first fixed-head lathe in Citizen Machinery UK’s Miyano range to have the company’s patented LFV (low frequency vibration) chipbreaking software in a Fanuc control system is the new, 42 mm bar capacity ANX-42SYY. It features 10 CNC axes including a ±35 mm Y-axis on both the upper and lower turrets in addition to X- and Z-axis movements, enabling the production of complex components to tight geometrical tolerances.

    The new, compact mill-turn centre is ideal for OEMs and subcontractors in Britain and Ireland keen to leverage the quality and productivity of a Miyano lathe and at the same time standardise on Fanuc controls on their shop floor for the sake of operator familiarity and compatibility with other machines.

    LFV involves synchronising the rotation of the spindles with high-frequency oscillating motions of the tools in the X and Z axes to break what would normally be stringy swarf into manageable chips that can be disposed of easily. During turning and drilling, swarf is prevented from entangling around the component and tool, which would otherwise risk damage to both and is time-consuming to remove. Machine stoppage for swarf clearance is not needed, even when machining such materials as stainless steel and plastics, so productivity levels can be raised.

    In addition to LFV software, which is programmable via G-codes in the part program, the 15-inch XGA (extended graphics array) touch panel Fanuc 31i control features a new Citizen HMI and incorporates the company’s multi-axis technology. It allows 3-axis simultaneous cycles, double Y-axis cutting and superimposed machining whereby three tools can be in cut at the same time thanks to X-axis movement of the sub spindle. Metal removal rate is therefore maximised and the technology also helps to share operations between the two spindles more evenly, all designed to increase production efficiency and throughput.

    The 6.2-tonne machine occupies only 2,650 mm x 1,630 mm of space on a 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. The turrets have 12 live tool stations each rated at 6,000 rpm / 2.2 kW / 20 Nm. Rapid traverse rates are fast at up to 30 m/min, again with high productivity in mind. This has been achieved by adopting linear guides in all axes. Commonality of tool holders with Citizen’s popular BNA range of Miyano lathes leads to cost savings for existing users of the supplier’s equipment.

    The only other LFV model in this fixed-head lathe range is a single Y-axis model of the same bar capacity with a Mitsubishi control, although the chipbreaking software has been extensively rolled out across six of the Japanese manufacturer’s Cincom sliding-head mill-turn centres.

    NEW MILL-TURN CENTRE PREPARED FOR AUTOMATION

    Building on the strengths of previous generations of Miyano fixed-head mill-turn centres, the BNA-42SY is Citizen Machinery’s latest addition to the range. The CNC lathe is the first BNA model to have a 12-station turret giving ± 35 mm of Y-axis movement, all tool positions now being live, and a new design that lends itself to easy automation.

    Compared with current BNA models, machining efficiency has been upgraded by more powerful spindle motors, which are rated at 7.5/5.5 kW (15min/cont) for the 6,000 rpm main spindle and 5.5/3.7 kW for the 5,000 rpm sub spindle. Acceleration and deceleration are quicker on both spindles, improving productivity further by minimising idle times.

    The machine’s rigid bed, the weight of which has been greatly increased to 1,823 kg, brings thermal control advantages and more capacity to house a larger coolant tank. The base casting has been prepared with space at the right hand side for robotic load / unload equipment. If a user intends to take advantage of automation, the machine can be supplied with a swarf conveyor that exits to the rear as an option.

    The automation may be employed solely for unloading components that have been mill-turned from bar stock up to 42 mm diameter, either directly from a spindle or via a parts catcher and conveyor. Alternatively, or in addition, it may load and unload billets or near net shape workpieces like castings or forgings up to 135 mm in diameter. A workpiece stocker is positioned at the right hand side of the machine to accommodate the finished components.

    Mounting points have been included to provide an option to add an overhead gantry if only chucking is to be carried out, in which case a raw material stocker can be positioned to the left of the machine in place of the bar magazine. For complete flexibility in layout, top shutter and auto door options are offered.

    At 285 mm, the turret’s Z-axis travel has been increased by more than 20 percent, expanding the machining range of this compact, space-saving lathe. The turret and spindles are mounted on hand-scraped box slideways for improved rigidity and damping characteristics, leading to high metal removal rates, prolonging tool life and maintaining high accuracy.

    The diameters of the X- and Z-axis ballscrews have been upsized from 25 mm to 32 mm, increasing rigidity further. Forced lubrication is provided to the ballscrews in all axes, the BNA-42SY being the second Miyano lathe to benefit from this feature.

    The latest FANUC 0i-TF Plus CNC system with 10.4″ colour LCD screen controls the machine. Cutting times can be shortened by simultaneously completing complex reverse-end turning and milling at the sub spindle while front-end machining is ongoing at the main spindle, despite there being only one turret. It is achieved by superimposed machining, where the sub spindle tracks the turret and compensates for its movements while it is cutting at the main spindle, enabling a machining cycle on a parted-off component to be executed using tools mounted on the reverse face of the turret. This can be accomplished due to the ability of the sub spindle to move in the X-axis.

    As with all modern lathes from Citizen Machinery, both Miyano fixed-head and Cincom sliding-head models, the BNA-42SY is an environmentally friendly machine. Use of an inverter controlled hydraulic unit results in a large reduction in power drawn. Standby power consumption is just 0.661 kW, as servomotor readiness is automatically turned off when it is not needed, for example during program editing. Overall energy consumption can be visualised via a power monitor window on the control screen.

    SUBCONTRACTOR STARTED WITH ONE SLIDING-HEAD LATHE: NOW THERE ARE TEN

    When physics graduate Paul Cobb asked his father Reg in 1997 to help him invest in a subcontract machining business specialising in CNC sliding-head turning, Mr Cobb senior groaned; he knew it would mean a sizeable investment. At the time, both father and son were partners in the family’s subcontracting firm in Stapleford, Hemlock Engineering, which specialised in producing mainly prismatic parts and continues to do so.

    However, Paul was keen to embark on a project of his own. He chose not to become a computer programmer or geological analyst but instead started HPC Services. A small factory unit was rented in nearby Ilkeston and a Japanese-built Citizen Cincom L25 sliding-head, bar-fed, turn-mill centre was installed. At the time it was the first of a new, updated design to arrive in the UK.

    From that moment onwards, HPC’s approach has been to acquire the very latest, most highly productive CNC equipment available on the market, designed to slash production times, reduce costs and improve component quality. Under Paul’s influence, it has become Hemlock’s maxim as well.

    Over the intervening 24 years, he has bought for HPC around 20 CNC sliding-head, twin-spindle lathes of nominally 12, 20 or 32 mm bar capacity, all exclusively from the same supplier. Ten Cincoms are in operation, the others having been systematically replaced with newer models. There are also seven fixed-head, twin-spindle CNC lathes on the shop floor of the current premises, where around 30 staff are employed.

    When Paul launched HPC, he took with him from Hemlock one production job to get him started, a shaft for a sell-by date label printing machine. The food industry still accounts for around one-third of HPC’s turnover. The job previously involved turning the component in two operations, after which it was ground and then milled on a machining centre, all in a total time of seven minutes. On the Citizen L25, the same job was completed in one hit in a one-minute cycle. The parts are machined today on a different slider at a rate of 1,000 per month.

    Due to complete machining in one set-up, the components produced by HPC were of better quality, 5 microns concentricity and 10 microns dimensional tolerance being held reliably. Moreover, the price charged to the customer has consistently fallen in real terms due to the progressively higher level of automation on the newer lathes, which allows longer periods of unattended running, 24/7.

    Paul commented, “Over the years, turned parts subcontractors from around the world have quoted for this work. However, by harnessing the efficiency and accuracy of machines like the Cincom sliders we are globally competitive on price as well as quality, even for large production volumes.

    “In the past that was not the case, but it is possible now with modern, ultra-high speed plant. And of course, our delivery times are much better than Far Eastern competition can offer, added to which control over projects is easier. As a result, we are seeing a strong trend towards reshoring of work.”

    Today, HPC has some 5,000 different part numbers on its books. Components are produced from 38 mm diameter bar or smaller on the Cincoms. Quantities range from 100- to 40,000-off in a vast range of materials, from exotic alloys through stainless steels, brass and aluminium to plastics. The two million parts machined annually account for two-thirds of the company’s £3 million annual turnover, the remainder being fixed-head turning. 10 percent of revenue is reinvested every year in new plant and equipment, a proportion that also applies to Hemlock’s £7 million turnover.

    Fifth generation Cincom M32 lathe increases productivity by typically 30 percent and quadruples tool life.

    One of the latest components produced at HPC in one hit on a sliding-head lathe requires only milling, there being no turning content at all. The parts are being machined on one of a pair of recently delivered Cincom M32-VIIIs of a radically different design compared with the earlier M32s on site. The first of the new machines was delivered in November 2020 and Paul was so impressed with its performance that a second arrived a month later.

    The prismatic component looks as though it has being machined from flat bar but is in fact milled from 303 stainless steel round bar, as it is difficult to source flat bar in that material in the UK. Part of a date-coding machine, it is produced in one operation in a cycle time of 4 minutes 53 seconds on the lathe, whereas it would require four operations totalling 7 minutes on a vertical machining centre.

    A year or so before the arrival of the two new M32s, which have been supplied with kits to allow bar up to 38 mm diameter to be accommodated, the chief designer from Citizen’s Japanese factory visited HPC to ask Paul what he would like to see in the fifth generation of this sliding-head lathe. His response was, “more rigidity”. The Japanese manufacturer obliged, endowing the latest model with box guideways rather than linear slides, a tang instead of a worm drive on the turret and higher power motors throughout.

    Paul explained, “The difference is amazing. It is possible to machine exotic alloys at double the speed compared with on a fourth generation M32 and you get four times the tool life, especially as coolant is now delivered through the tool platen as well as the turret.

    “It is a massive step up in performance. A 10 mm cutter purrs into the bar, even using a mill with carbide inserts rather than a solid carbide tool, which we need to use on the earlier M32s. Any production engineer would know that the new model is a very rigid machine.”

    Other aspects of the latest design that he appreciates are the increased number of driven tools and a platen tool post with a programmable B-axis. It is useful for producing angled features on components and additionally is able to carry out front working so that the turret can be freed up earlier to perform operations on the reverse end.

    Cycles for many jobs are significantly quicker. For example, when producing a particular 303 stainless steel flange from 38 mm bar, it was previously necessary to wait for the turret to become available to deburr the component. At 57 seconds the cycle time is now 25 seconds quicker, representing a saving of 30 percent.

    Just as important for reducing production costs is the ability to swap the machine over in half an hour to guide bush-less mode to save remnant wastage when producing relatively short components like the flanges. In this case, 262 parts can be produced from a 3-metre bar compared with 225 if the guide bush is in place, delivering 37 extra parts, an increase of 16.4 percent. With 5,000 of the flanges produced annually, the saving is significant.

    Programmable chip breaking software is ideal for turning plastic

    Citizen’s advanced technology came to the rescue a few years earlier, when HPC received a contract to produce plastic internal components for a manufacturer of high quality taps. Moulding these top-end parts is not feasible, as flash on the sealing surfaces could cause leakage and removing it would be too time-consuming. Turn-milling the components from acetyl bar was the preferred method of manufacture, but plastics are notoriously difficult to machine, as copious quantities of long, stringy swarf is produced, especially when grooving.

    Citizen had recently invented its patented, low frequency vibration (LFV) software that breaks such swarf into short, manageable lengths. Running in the Cincom’s Mitsubishi control, where it is integrated into the operating system rather than being a macro, the facility can be switched in and out of a programmed cycle by G-code command.

    Paul concluded, “LFV on the Cincom L20 we bought in 2017 is absolutely brilliant for turning plastic. Normally on a lathe we regularly have to remove swarf by hand that has tangled around the component and tooling, which takes ages and risks damaging the part, but that is eliminated by the software.

    “It not only saves a lot of production time but also allows us to run the lathe unattended for long periods, which normally would be impossible when machining this type of material. The software will also be a big advantage if we receive contracts for producing components from ductile, long-chipping metals such as copper.”

    CITIZEN SETS UP DEDICATED SOLUTION CENTRE

    Citizen Machinery UK, which supplies Cincom sliding-head and Miyano fixed-head turn-mill centres into the British and Irish markets, has been providing manufacturing solutions to OEMs and subcontractors in their supply chains for virtually the entire time the company has been in business. However, the degree of customisation that it is being asked to engineer into the equipment it supplies has now reached such a high level that it has decided to centralise this side of the business by setting up a dedicated centre, CMSolutions, at its Bushey headquarters.

    Managing Director Edward James said, “As the largest supplier of bar fed lathes into the markets we serve and being a specialist exclusively in turn-milling, we felt it was fitting for us to raise the bar in terms of the level of support customers can expect.

    “In our industry it is no longer enough to deliver a so-called turnkey package, which is subject to a lot of interpretation and often misunderstood. It can mean simply the supply of a machine, a few cutters and a couple of programs.

    “Customers demand more than that these days. They want a fully worked out, end-to-end solution that has been proven off-site before delivery, complete with attachments, peripherals, in-house-written software and perhaps additional robotic functions such as cleaning and packaging. Projects are often demanding in terms of their scope, level of innovation, the process capability to be achieved and return on investment required.”

    CMSolutions operates from the Bushey premises independently from the applications department there to project-manage such complex, high-level installations, from initial consultation through design, configuration, assembly and prove-out to delivery, acceptance and training.

    The solution could be stand-alone or integrated into a larger manufacturing plant; and it may be a pre-existing package or designed specifically at either the customer’s request or at the instigation of Citizen. In all cases there will be a sound business case for what is delivered. It will be pragmatic, process-optimised and cost-effective, not necessarily the top solution possible, which may be overly expensive and take too long to amortise.

    The Bushey venue will also house a permanent exhibition of turn-mill solutions and software, which will often involve automation such as robotic or gantry loading of billets, forgings, and near net shape parts and unloading of components. Additionally, it will show technology that is less frequently encountered, such as in-cycle laser cutting of apertures in the thin wall of a stainless steel stent.

    Other specific solution examples to be presented will include the mounting of a digital microscope and a 21-inch screen to assist setting of micro tooling on a 12 mm capacity sliding-head lathe used for watch component manufacture; and the provision on a 32mm capacity sliding-head lathe of a pair of high frequency, 60,000 rpm spindles in the gang toolpost, together with mounting adapters, pneumatic and electrical supplies, custom software and displays for spindle speed feedback.

    Mr James added, “We could see the direction of travel towards the need for a greater degree of machine adaptation to meet customers’ production requirements, so we have had this development in mind for several years. It was part of the justification for establishing our Turning Centre of Excellence in Brierley Hill last year.

    “The showroom and technical centre there is now the main location for machine arrivals, configuration and despatch, leaving Bushey free to concentrate on technology advancements and their permanent display and demonstration.

    “Customers are looking for stable running of their lathes over long periods. We already have our LFV non-macro chipbreaking software to assist in that goal, which is programmable and especially beneficial when cutting materials that tend to produce stringy swarf. It is another example of the importance and focus Citizen places on technological progress.”

    As a postscript, he mentioned that Citizen as a group reinvests one-quarter of its annual profit into research and development and is continually launching new machines and technology, such as LFV, which has been extended recently from the main spindle to the sub spindle on many Cincom lathes and is increasingly available on the Miyano range of fixed head lathes also. Another recent innovation is an automatic tool changer on the L20 Cincom sliding-head model.

    There will be a significant and ground-breaking new launch in the first half of 2021 of a lathe designed by Citizen Machinery UK that the Japanese parent company has agreed to manufacture. All of this activity dovetails neatly with the formation of CMSolutions, which Mr James predicts will gain in importance as manufacturing industry moves forward after the pandemic and looks for ever more efficient methods of production and return on investment.

    He also thinks that opportunities will be enhanced by increased reshoring of manufacturing from China and elsewhere, coupled with the emergence of electromobility, which will be beneficial for Citizen and other lathe suppliers in particular, as plug-in hybrid electric cars contain a higher proportion of rotational parts than conventional vehicles.

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