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    GUIDE BUSH-LESS OPERATION AND CHIP BREAKING SOFTWARE TRANSFORM TURNING OF ALUMINIUM

    “We believe that investment in the very latest technology is the key to quality, reliability and competitiveness,” said Dave Zollo, joint owner of contract machinists IML (UK). He and Jerry Way started the business in 1995 and moved into the current, 14,000 sq ft premises in Weymouth in 2011. One year later the first sliding-head lathe arrived, a Citizen Cincom A32-VII with 32 mm bar capacity, followed in 2013 by a 16 mm bar model, a Cincom C16-VI.

    The early investments were triggered by an increase in contracts from the medical industry and a desire to be able to manufacture components in one hit, such as endoscope cleaning equipment parts. To cope with an ever increasing level of work, including for the high-end automotive sector which has grown over the past couple of years to become more than 50% of turnover, there are now four different models of sliding-head lathe on site from the same supplier.

    The latest two, designated L20-XLFV and L32-XLFV, were installed in 2018 and 2020. Unlike the first two Cincoms, they offer the flexibility to allow removal of the guide bush, as well as having the notable benefit of low frequency vibration (LFV) software built into the operating system of the control. Mr Zollo noted that the more modern machines are also more user-friendly, allow better access and are quicker and easier to set.

    He explained, “These advanced, twin-spindle, sliding-head lathes are helping to keep us competitive on the world stage, as is automation throughout the factory.

    “All of our lathes including four fixed-head models are bar-fed and work 24/7, with the sliders able to accommodate a wide range of batch sizes from typically 50- to 30,000-off. Dimensional tolerances of less than ± 10 microns may be easily held.

    “Even smaller quantities are economical to produce, partly because we have adopted a policy of standardising on one size of stock on each of the Cincoms, so we do not have to waste time changing over bar sets.

    “We have also invested in automation on the milling side of our business, which accounts for more than half of turnover. Our four vertical machining centres are equipped with robotic loading and remote monitoring, while two horizontal machining centres on the shop floor have a twin automatic pallet changer to minimise idle times.

    “It all helps to keep costs down and allows us to quote our customers prices that are very similar to those we were charging two decades ago.”

    Aluminium bar, which accounts for a significant proportion of throughput of turn-milled parts, is the villain of the piece as regards sliding-head turning in the Weymouth factory. The material is often of variable quality in terms of straightness and diameter variation, so can jam in the guide bush of sliders and requires frequent supervision by the operator to adjust the collet.

    The ability to remove the guide bush on the L20 and L32 in less than half an hour allows the subcontractor to turn aluminium bar into shorter components in fixed-head mode without problems. It also has the advantage of reducing the remnant length from typically 275 mm to 100 mm. Completion of one recent IML (UK) contract consumed 300 bars, so it is clear that a lot of material and money can be saved.

    When turning difficult to chip materials, Citizen’s LFV software, which is part of the control’s operating system, breaks swarf into manageable chip sizes, whereas normally it would be stringy and entangle itself around the tool and component. This capability to manage the size of swarf is in addition to any chip breaking features that may be ground into an indexable insert. Mr Zollo singles out aluminium as well as stainless steel bar to be particularly problematic in terms of bird’s nesting.

    To alleviate it, the LFV function can be switched on and off via G-codes in the part program, enabling optimal use of the feature during different parts of a cycle. It is, however, not a pecking macro in the CNC program itself. As one operator looks after the four sliding-head lathes, LFV is helpful in minimising periodic attendance at the machines to disentangle clogged swarf. It is notable that the 8-axis L32 has LFV on both the main and counter spindles, allowing the oscillations that produce the chip breaking action to assist in the production of both front- and reverse-end turned, milled and drilled features.

    LFV oscillation lifts the tool tip clear of the component surface by tens of microns for ultra-brief periods to allow coolant to penetrate the cut more efficiently. It reduces heat and prolongs cutter life, while at the same time enabling depth of cut to be increased, even when processing tough materials. It often eliminates the need for a roughing pass and significantly shortens cycle times. Mr Zollo advised that it is of major benefit during attended day and night shifts and especially so during the weekend when staff are not present.

    He concluded, “Swarf build-up is really the only thing that stops modern bar-fed CNC lathes, which are inherently very reliable. LFV on the Citizen sliders virtually eliminates the hassle of clearing away swarf and consequent loss of production, especially during minimally attended operation.

    “Even when we are running them unattended at the weekend, it is unusual for them to stop before the bar runs out. Should there be a problem, however, the on-board cameras allow us to monitor production and come into the factory if necessary to take remedial action.”

    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.

    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.”

    FIXED-HEAD TURNING UP TO 40% FASTER AND TOOL LIFE DOUBLED ON SLIDING-HEAD LATHE

    In August 2020, Merseyside subcontractor Bryken took delivery of its sixth Miyano BNE-51MSY turn-mill centre, having bought its first as recently as June 2018. Operations director Phillip Taylor says that regular investment in new plant is key to thriving in a competitive global marketplace and he makes sure that no machine tool stays on the shop floor for more than 10 years. The company, which has 95 employees and a £10 million annual turnover, derives 40 percent of its business from the oil and gas industry and is also a major supplier to the high-voltage power sector, amongst others.

    Citizen Machinery UK, which supplied the fixed-head Miyanos, is also the source of four Cincom CNC sliding-head lathes currently on site, which have been in use at the Prescot factory since the mid-90s. A dozen older models, which took over from six times as many cam autos, have all now been replaced. It leaves three 32 mm capacity Cincom sliders installed since 2014 and a more recent 20 mm capacity model that uses Citizen’s proprietary LFV chipbreaking technology.

    Mr Taylor, son of one of the company founders, runs the subcontracting business together with his brother Stewart and sister Natalie Lund. He explained, “Ninety percent of our turnover comes from producing precision turned parts, many of which require a lot of prismatic machining as well, so choice of turn-mill centre is crucial to our success.

    “We started to upgrade our fixed-head lathes by replacing them with Miyanos in 2018 in response to an upturn in demand, which gathered pace at the beginning of this year when we bought three more BNE-51MSYs in the space of two months. The 51 mm bar capacity, twin-spindle turning centre with its two 12-station live turrets, the upper one with a Y-axis, is ideal for our needs.

    “It is highly efficient at balanced machining of complex routines at both spindles, so we can take chunks out of cycle times, which are between 20 and 40 percent faster than on previous lathes. It meets the increasing demand for the supply of high added value parts at competitive prices.”

    He added that other makes of lathe were looked at during the plant renewal process. In comparative trials, the BNE-51MSY offered the quickest TAKT times and was also much better value for money than others he considered. The lathes were also shown to hold 20 microns total tolerance easily on machined dimensions.

    One reason for the lathe’s impressive speed is Citizen’s superimposition control technology, which allows the sub spindle to track the upper turret for cutting reverse-end features while the same turret is performing front-end operations on bar at the main spindle. If the lower turret is operational at the same time, three tools are in cut simultaneously, delivering the performance of a triple-turret lathe for a significantly lower capital outlay.

    Another benefit that Bryken operators appreciate is their ability with the Mitsubishi control to use the handwheel to run through an entire machining cycle to verify the program and detect any potential clashes.

    Over the years, market forces have dictated a move at Bryken towards more fixed-head turning for the production of larger diameter, complex components, the simpler work having largely disappeared overseas. Nevertheless, nearly one-third of the lathes on-site are still of the sliding-head variety. The four Citizen Cincom models are the most recently installed, three M32-VIII lathes and an L20-XIILFV, the cardinal numbers representing maximum bar diameter.

    The latter machine, installed in May 2018, was bought to produce sub-sea oil and gas components from tough materials such as Monel, Inconel, titanium alloy and 440C stainless steel. These metals produce stringy swarf that benefit greatly from the low frequency vibration (LFV) functionality built into the operating system of the Mitsubishi control.

    Mr Taylor continued, “We saw a demonstration of LFV in Citizen’s Bushey showroom and were impressed with the way chips break up and do not clog the machine, or wrap around the component or tool. It means we can leave the machine running unattended for long periods.

    “LFV can be simply switched on and off by G-code in a program. We use it for turning at the main spindle and axial drilling at the sub spindle of the L20 and switch it off to maximise metal removal rate when milling with the live tools.

    “We tried making parts from these exotic materials on other sliders but the swarf was not chipping, even with high pressure coolant. Tool life was so poor it was taking away a lot of the profit. Now cutters last at least twice as long, plus there is less machine downtime and scrap is more or less eliminated.”

    Low frequency vibration technology has started to be rolled out across the Miyano fixed-head lathe range with the introduction of the BNA-42GTYLFV and Mr Taylor is keeping a close eye on this development. He pointed out that subcontractors rarely know the orders that will be coming in next and which materials they will be asked to machine. As LFV is not a pecking macro that tends to prematurely wear out tools, but is integral within the control system, having this built-in chipbreaking capability is of great benefit when machining stainless steels, copper and plastics as well as the nickel and titanium alloys.

    Mr Taylor concluded, “We source a lot of lathes from Citizen because they have a wide range of machines that use advanced technology. We also receive good support from them, especially the applications engineering and training they provide. They and their equipment have made a big improvement to our operational efficiency.”

    LUBRICATION EQUIPMENT MANUFACTURER PRODUCES PRISMATIC AND PRESSED PARTS ON NEW LATHE

    Established in 1942, Coventry-based Adams Lubetech is member of a leading European group of specialist manufacturers of single-point and centralised lubrication equipment for OEMs in the food and beverage industry, compressor and conveyor sectors, and across industry in general.

    Consistently rising sales worldwide meant the company needed extra production capacity. So in early 2020 the firm purchased its first lathe from Citizen Machinery, a fixed-head Miyano BNJ-51 turn-mill centre, to machine not only rotational parts but also components that were previously produced on a manual mill or a power press.

    Eric Chambers, Factory Manager at Adams Lubetech explained, “With these parts in mind, we wanted a powerful, rigid turning centre that was equally capable of milling. We selected the Miyano bar automatic primarily due to its competitive price.

    “The first purely prismatic component we produced on it was an anchor block for our sister company in Belgium. We were milling and drilling the steel blocks manually in several operations, which was time-consuming, so we decided to use the Miyano as a chucker to produce them automatically.

    “The support provided by Citizen’s applications engineers was brilliant. They helped us enormously by developing the process, writing the program, and setting up the machine including replacing the chucks and jaws to fixture the part. They even came on site for three days to oversee production of the first-off components.”

    The lathe effectively doubles as a CNC machining centre in this application. Each part, which has large threaded holes and smaller diameter holes machined into multiple faces, comes off the machine complete in a cycle time of 139 seconds.

    The Miyano is also taking work from a power press in the Coventry factory, resulting in even greater advantages. A deep-drawn part previously required seven sequential operations, removal for skimming on a capstan lathe and return to the press to be slotted. Lead-time was more than one month to produce a typical batch of 8,000 and there was a lot of manual intervention for inter-machine handling. The same part is now produced in one hit from bar on the twin-spindle Miyano in 2.5 minutes, so the entire batch can be finished and shipped in a fortnight if the job is left to run 24/7.

    Mr Chambers concluded, “We operate in a global marketplace and need to reduce costs internally to compete. Production equipment like the Miyano, which has reduced cycle times on average by 20 per cent and has expanded the variety of parts that can be machined, is helping us to keep manufacturing costs down.”

    USED SLIDING-HEAD LATHE RECEIVES FULL SUPPORT FROM THE MANUFACTURER

    Despite starting out more than 25 years ago, Dudley-based TWP Manufacturing opened its CNC machine shop as recently as the beginning of 2019 to produce in-house most of the components needed for its proprietary products. They include photographic darkroom and studio equipment, gardening products including wheelbarrows, and security anchors. The firm also provides subcontract pressworking and injection moulding services to a wide range of industries, particularly the automotive sector.

    Vertical machining centres and a single-spindle, fixed-head bar auto are to be found on the shop floor, but in May 2020 the company bought its first sliding-head twin-spindle lathe, a 20-year-old Citizen Cincom M32 equipped with an Iemca Boss 432r barfeed. It was originally sold in 2000 by the Japanese manufacturer’s agent for the British and Irish markets, NC Engineering, which in 2008 became a wholly-owned subsidiary, Citizen Machinery UK.

    Phil Stanley, a director of TWP Manufacturing said, “We were previously outsourcing the production of a lot of our turned parts, including to subcontractors in the Far East.

    “However it became apparent that, the way we were expanding, it would be necessary to bring component manufacturing in-house to cope with the higher volumes as well as to have more control over production.”

    To fulfil the predicted quantities, the company recognised that it needed a turning centre with more speed and capability than its fixed-head lathe without driven tools, as when using this machine there was frequently a requirement for additional operations.

    Sometimes a component needed to be parted off and inverted in the chuck if it required machining on the reverse end. If milling and drilling were involved, they had to be accomplished by setting up the job on a machining centre. Furthermore, many components formerly required manual depipping, adding a lot of labour cost content to their production.

    None of this is necessary on the Cincom. It is able to synchronously and automatically transfer a component from the main spindle to the counter spindle for back-end machining while front-end operations are carried out simultaneously on a new length of bar. Prismatic features are added in the same cycle using live cutters and the tool carrier’s Y-axis. Components come off the lathe pip-free after parting off due to close control over the machine’s spindle speeds and feed rates. Production times have drastically reduced from, for example, 3.5 minutes down to a single one-minute cycle without any manual intervention, allowing parts to go straight to plating.

    Director Phil Stanley added, “The speed and surface finish we are achieving are just incredible and the fact that there is no operator intervention means that we are able to implement lights-out production, which we are looking to do later this year.”

    In the first few of months of operation, the Cincom M32 was devoted to large volume production of one particular component but another four part numbers have now been added. All are machined from 1 inch hexagonal steel bar and annual production will exceed 200,000-off.

    Pre-sales time studies and cutting trials carried out by Citizen Machinery UK showed that all five components could be produced within tolerance at the required speed. The calculations were carried out following a visit by managing director Edward James and regional sales engineer Warren Garratt to the Dudley factory, during which the company was advised on how best to proceed with its in-house turned parts production strategy.

    Mr Stanley concluded, “Even though the machine was 20 years old and we bought it independently on the second-hand market, from the outset Citizen have been behind us.

    “First they demonstrated the same type of machine in their showroom, which I would say was a light-bulb moment for us, following which they wrote the first program and carried out a cycle time calculation, repeating the same procedure for four further components.

    “They supported us through machine installation and commissioning, helped with tooling, setting-up and maintenance, and trained us to operate the lathe and their Alkart CNC Wizard programming system.

    “If their assistance had not been forthcoming, without a shadow of a doubt we would not have been able to progress, especially as some of our operators have never used a machine like the Cincom before.

    “The support we have received all the way through these processes has been brilliant and has enabled us to take a massive step up the ladder in respect of in-house production of turn-milled components.”

    PLASTICS MACHINING SPECIALISTS INVEST IN SLIDING-HEAD LATHE WITH NOVEL CHIPBREAKING SOFTWARE

    Gloucester subcontractor Stratos Precision Engineering, a majority of whose business comes from machining plastics, has strengthened and diversified its turning department with the addition of its first sliding-headstock lathe, a Citizen Cincom L32-VIIILFV. Installed in September 2019, the twin-spindle, 35mm capacity, bar-fed turn-milling centre joined an already impressive plant list of five fixed-head, single-spindle chucking lathes for turning parts up to 650mm in diameter.

    Purchase of the 7-axis CNC Swiss-type lathe was part of an investment of more than £1 million since the fourth quarter of 2018, which has also seen the arrival in Gloucester of a new big bore lathe and a 3m x 2m automatic tool change CNC router as well as refurbishment of the 8,000 sq ft premises. During the same period, the number of staff has doubled to 16 and in the last financial year, turnover increased by nearly 50 per cent over the previous 12 months.

    Stratos’ managing director Jonathan Caple said, “For some years we had been looking at buying a bar-fed lathe to increase our competitiveness, win new business and enter new industries by machining larger quantities of parts with tighter tolerances. We favoured the sliding-head type over fixed-head lathes, as the short axis movements lead to higher productivity.

    “The twin-spindle configuration and extensive driven tooling on the machine means one-hit production often supersedes two or three operations on different machines.

    “However, to reap the full benefits of the investment, we need to be able to leave the machine to run 24/7 either unattended or with reduced labour overnight to maximise production output.

    “That was previously impossible for us due to the stringy swarf that is produced when machining plastic, which regularly needs to be manually cleared by an operator.”

    The situation continued until 2016, when Citizen invented and patented its LFV (low frequency vibration) software. Part of the operating system in the Mitsubishi control of Cincom machines, and switchable on and off if required during the program, it vibrates the servo axis in the cutting direction so that the tool tip leaves the surface of the material being machined for regular, ultra-brief periods.

    The effect is to break the long strands of swarf normally generated when turning plastics into short lengths of just a few millimetres, preventing it from birds-nesting in the machining area and melting back onto the workpiece, which normally means scrapping the part.

    A recent trend in the subcontractor’s business has been a shift to machining more metals, notably aluminium for a large packaging machinery contract but also ferrous metals including stainless steel. This material also results in stringy swarf forming around the tool and workpiece and therefore benefits greatly from using Citizen’s chipbreaking software.

    Mr Caple and Stratos’ co-owner, operations director Mark Vine, recognised how beneficial LFV technology would be for the business when turning plastics. Unlike metals, whose finish can be adjusted by fettling after machining, this is not practical with plastic as it needs to come off any machine tool in a finished condition.

    The importance of improving turn-milling efficiency to increase competitiveness was reinforced when Stratos was required to produce 2,000 parts over a short period and the existing machinery would only achieve 400 per day. However with the new sliding-head machine and LFV technology, Stratos is now able to produce the 2,000 parts in 48 hours.

    With a new sense of urgency, the directors’ research took them to MACH 2018 and to online testimonials from other users. A series of demonstrations at Citizen’s technical centre and showroom in Brierley Hill decided the directors in favour of LFV over other chipbreaking methodologies that involve macros in the program. Additionally, as Mr Caple pointed out, Cincom machines are built from the ground up to withstand the high-frequency, low-amplitude vibration caused by the intermittent, chip-generating cutting action.

    The transition on the shop floor at Stratos to the new turning technology, as well as to the first Mitsubishi control on site, has been seamless. One of the sliding-head lathe operators, who normally runs five machining centres at the Gloucester facility, quickly picked up programming of the L32 using Citizen’s Alkart Wizard off-line software. He and others received two days’ instruction at Brierley Hill, followed by a week of on-site operator training. In the period from machine installation to the end of January 2020, more than 30 jobs had been produced on the new lathe, which included some around-the-clock running.

    A major benefit of a twin-spindle lathe is the ability to produce components machined at both ends in a single cycle that would otherwise require two separate operations. This is assisted by the availability of a multitude of tools including driven cutters that enable the inclusion of extra operations such as deburring, eliminating further subsequent processes.

    Speed of production is consequently much higher on the bar-fed Citizen compared with the fixed-head chuckers. For example, a 400-off contract that used to take a full day is now finished in a couple of hours on the slider. It also means that Stratos often manufactures in bulk, as the bar does not need to be changed as frequently as for multiple jobs. Stratos can now run, say, 1000-off, deliver 400 to the customer and stock the remainder on consignment. The customer benefits through more flexible supply and the certainty of prompt deliveries, while Stratos gains through more economical cost-per-part manufacture, which is passed on to the customer through improved rates and prices.

    Another recent example of accelerated production was the machining of 5,000-off steel pins for a chain conveyor, which was completed in five days working a single shift. The job would previously have needed two operations on a pair of chuckers requiring two operators. Either the contract would not have been economical or the margin would have been unacceptably small.

    Mr Vine concluded, “The accuracy and surface finish we are achieving on the slider are fantastic.

    “We recently ran the machine unattended around-the-clock with LFV, with coolant running to keep the temperature stable, and produced 3,000 Ultem® Polyetherimide thermoplastic parts for a customer in the flow control sector.

    “All of them were within the required -0 / +0.05 mm tolerance band, which is impressive and can be difficult to achieve in this material, without having to make any adjustments whatsoever to the machine.

    “Overall, our new machinery has enabled us to be a more competitive subcontractor for plastic and metal machining and is contributing towards the impressive growth of our business.”

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