Citizen Machinery’s ground-breaking LFV (low frequency vibration) chip-breaking software, which forms part of the operating system in the controls on some of the manufacturer’s sliding and fixed head mill-turn centres, will feature strongly at MACH 2022 as this year marks the fifth anniversary of the technology’s launch. The principle of operation is distinct from, and superior to, pecking macros programmed into individual machining cycles.

The patented system is gradually being rolled out across the company’s Cincom sliding head lathes, initially on the main spindle and more recently also on the sub spindle. To enable this, the construction of the machine models is systematically being strengthened to withstand the rigours of the momentary air cutting that creates the chip-breaking effect. There will be five Cincom machines on show at MACH 2022 equipped with LFV. A pair of Citizen’s Miyano fixed head lathes also benefits from the technology, one of which will also be exhibited.

The chip-breaking functionality can be switched on and off by G-code during a cycle, when deemed expedient, as if it were part of the program. The size of the actual chips can also be predetermined, as close control is maintained over the relationship between spindle speed and LFV oscillation of the tool by tens of microns, which has the effect of repeatedly retracting the tool tip clear of the workpiece. Coolant is able to penetrate the cut more efficiently, so tool life is extended and surface finish is improved.

Stringy swarf is therefore a thing of the past, even when machining difficult to chip materials like stainless steel, aluminium, copper and plastics. The need for manual swarf clearance is avoided, raising productivity and unattended running time, while the risk of damaging the workpiece and tool is removed. Futhermore, depth of cut may be increased substantially, raising productivity.

Three modes of LFV may be selected for machining with static and driven tools. The first is ideal for turning and grooving of outer and inner diameters, the second is best suited to micro-drilling operations that require high surface speed machining, while the third offers vibration-free thread cutting.

Sliding and fixed head lathes on show
(machines in bold are described in more detail below)

A total of 12 bar fed, sliding and fixed head mill-turn centres will be demonstrated under power on the Citizen Machinery UK stand at MACH 2022 (Hall 20, stand 150), including an automated production cell with integrated loading and unloading. Accent will also be placed on high technology software and mechanical enhancements that extend the scope and efficiency of machining on the Japanese-built lathes.

Making its world debut will be the new, 20 mm bar capacity Cincom L20-XIIB5LFV. The series-5 Cincom M32-VIIILFV will appear for the first time at a MACH show, as will the fixed head Miyano BNE-65MYY. Both have been redesigned to offer more power and flexibility and have been fitted with the latest Mitsubishi 800-series touchscreen control. Consequently, the latter machine is Citizen’s first 65 mm capacity lathe to offer superimposed machining, which allows three tools to be in cut together under simultaneous 5-axis control for elevated levels of productivity.

On show for the first time will be a Cincom L32-XLFV with integrated, high-speed laser cutting, a capability that was originally developed for efficient production of apertures in thin-wall stents on smaller Citizen sliding head lathes.

There will be a Cincom D25-VIILFV exhibited for the first time at a MACH show with the proprietary chip-breaking software. As on many other sliding head lathes manufactured by Citizen, the user has the advantage of being able to remove the guide bush for more economical material usage when producing shorter components up to typically 2.5 times the bar diameter.

A further highlight will be a Cincom A20-VIILFV, the first Citizen lathe to be equipped with multi-axis LFV software in a Fanuc-based Cincom control dedicated to this machine model.

The exhibition will also feature the first showing at a national exhibition in the UK of the 12 mm bar capacity Cincom L12-XLFV with five rear-facing static and driven end-working tool positions and the addition of a Y-axis on the counter spindle to mirror the main spindle’s three axis movements. The machine is intended primarily for production of dental abutments and implants, as well as other complex components.

From the Miyano stable, the ABX-64THY with 80 mm bar capacity and an ANX-42SYYLFV with Fanuc control will also make their debuts at a national show in the UK. Making another appearance at MACH to illustrate automated chucking will be the twin-spindle Miyano GN-3200W equipped with a high-speed loader capable of achieving high levels of productivity. The compact, rigid, thermally symmetrical machine offers a wide choice of infeed/outfeed devices, single or double high-speed gantry loaders, and transfer and turnover units, making the machine ideal for automated production.

Rounding off the exhibits on the stand will be an educational area explaining the latest Citizen software. It includes Eco Function hybrid technology that automatically saves energy through the intelligent use of power during non-cutting periods, underpinned by clear, on-screen graphical information showing present, maximum, cumulative and historical power consumption values. The next iteration of Alkart Wizard for off-line programming will also be in evidence, as well as Citizen’s Industry 4.0 capabilities encompassing the latest machine networking and monitoring functionality.

Debut of the new L20-XIIB5LFV sliding head lathe

The Cincom L20, Citizen’s best-selling sliding head lathe, has been upgraded to simultaneous 5-axis control via the improved, super-fast M850VM CNC with 15″ touchscreen. The new L20-XIIB5LFV allows multi-axis programming for superimposed machining with up to three tools in cut at the same time. It makes the machining of complex parts faster and easier and improves process stability.

The machine has a B-axis whose swivel range has been increased to 110 degrees, allowing more complex machining to higher accuracy at the main spindle, while the number of turning tools has been raised to six. Other improvements include a larger pitch between adjacent tools on the opposing and back tool posts to facilitate setting and reduce set-up time, a higher specification sub-spindle for improved productivity and the ability for LFV to be used when reverse-end machining.

First national showing of the Cincom L12-XLFV

For efficient machining of dental abutments, a minimum of five rear-facing end-working tool positions including driven stations is required, as well as the addition of a Y2-axis to the X2 and Z2 movements on the counter spindle to match the three degrees of freedom on the main spindle. All these features are provided on the 12 mm bar capacity Cincom L12-X. Previously, to obtain this level of functionality, a user would have had to purchase a 16 mm or even 20 mm capacity lathe, unnecessarily large and expensive for production of such slender components.

In this latest type-10 lathe, a built-in 12,000 rpm motor drives the counter spindle and acc/dec times have been reduced, promoting higher productivity. Rapid traverse at 35 m/min in all axes contributes further to minimising idle times. A modular tooling system has been adopted for the gang and back tool posts and an extensive variety of tooling layouts up to a maximum of 38 cutters is possible, including the ability to drill angled holes.

L32-X sliding head lathe exhibited for the first time with laser cutting

Launched in mid-2019, the Cincom 8-axis L32-XLFV will be on show for the first time at a MACH exhibition, without the optional LFV software but with the addition of high-speed, in-cycle laser cutting. The technology, which was originally developed for efficient production of apertures in thin-wall stents, is capable of fulfilling a wide variety of additional operations when machining tubular stock, or bar after it has been drilled longitudinally.

The development provides the option of in-cycle production of burr-free holes as small as 0.2 mm diameter and features such as spiral cuts with a 0.025 mm kerf. Consistent and accurate radii of less than 0.1 mm in the corners of slots can be achieved without risk of tool wear or breakage and at a far faster rate than is achievable by a separate EDM process. The non-contact, deflection-free, swarfless machining unit, deployed in the gang tool post, greatly expands freedom of design in the medical, electronics and many other industries.

Redesigned M32-VIIILFV sliding head lathe offers 5-axis machining

Although already shown elsewhere, for example at EMO 2021 in Milan, the new flagship series-5 M32-VIIILFV sliding head lathe with Mitsubishi M850W control will occupy a prominent position on the Citizen stand. The 10-axis machine has undergone a fundamental makeover and is considerably more robust than its predecessor, with larger and more rigid ballscrews and a bed that is 500 kg heavier, bringing the total installed weight to 4.3 tonnes.

The 10-station turret, which runs on hardened box ways, incorporates a new tooling system employing a single, heavier duty, 2.2 kW drive to an increased number of live cutters. Only the selected tool rotates – a world first for Citizen. The gang tool post has been equipped with 1.5 times faster live tools powered by a 2.2 kW motor, as well as a programmable, 9,000 rpm B-axis to enable simultaneous machining in five CNC axes rather than four; while the back tool post with Y-axis now has adjustable-angle tooling. Both features enable production of more complex parts, with three tools in cut at the same time.

Cincom D25-VII gains LFV

Since it was launched at the last MACH exhibition in 2018, Citizen has incorporated its chip-breaking software into the 12-axis, 25 mm capacity Cincom D25-VIILFV CNC mill-turn centre, which will be on show this year. The optional upgrade considerably enhances the lathe’s production efficiency. Operational flexibility is maximised by deploying up to 59 tools in the cutting area.

The latest D25-VII features the Industry 4.0-ready Mitsubishi 800 CNC system with touchscreen and QWERTY keyboard, which also provides triple axis control groups for simultaneous cutting with three tools. The contact angle between each cutter and the component is optimally maintained during production, enhancing surface finish, reducing cycle times and extending tool life.

New Miyano BNE-65MYY fixed head lathe with Mitsubishi 5-axis CNC for superimposed machining

Complex components up to 65 mm diameter may be turned and milled from bar on the new Miyano BNE65-MYY 10-axis fixed head lathe. Equipped with two Y-axis turrets, one positioned above and the other below the centreline of the twin-opposed spindles, considerable flexibility is provided for balancing front and back working cycles. The 8-tonne machine was introduced in the autumn of 2020 and is therefore making a first appearance at a MACH show.

Two-axis movement of the sub spindle facilitates superimposed machining under the control of a Mitsubishi M830W. Tooling on both faces of the top turret can simultaneously cut front-end features on bar stock and reverse-end features on a parted-off component. With the lower turret also working at the main spindle performing pinch turning, milling or drilling, for example, or perhaps OD turning while axial drilling is in progress above, three tools may be in cut at the same time.

ANX-42SYYLFV with Fanuc control

Also of double Y-axis configuration, the ANX-42SYYLFV is one of just two Miyano lathes currently to offer LFV, the other having only one Y-axis. The compact, 42 mm bar capacity, 10-axis machine is ideal for OEMs and subcontractors 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.

In addition to LFV software, the 15-inch XGA (extended graphics array) touch panel Fanuc 31iB control features a new Citizen HMI and incorporates the company’s multi-axis technology to allow 3-axis simultaneous cycles, double Y-axis cutting and superimposed machining with three tools. 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.

First national showing of 80 mm capacity Miyano fixed head lathe

The largest bar capacity CNC lathe in the Citizen Machinery product portfolio is the new 12-axis Miyano ABX-64THY, a fixed head model also launched in the autumn of 2020 and therefore new to MACH. It has twin-opposed C-axis spindles and three Y-axis turrets moving over hand-scraped box ways, providing maximum rigidity. Originally designed for mill-turning parts from 64 mm diameter stock, the lathe can now be uprated for continuous, automated, unattended production of components from bar up to 80 mm diameter. Maximum billet size when chucking is 165 mm diameter.

The three 12-station live turrets can be in cut simultaneously to achieve very high levels of productivity. Two turrets are positioned above the spindle centreline and are dedicated to working at the 15 kW / 2,750 rpm main spindle and 7.5 kW / 5,000 rpm counter spindle respectively. The other turret is located below and has unrestricted travel to operate at either spindle and provide flexibility for balancing front and reverse end machining operations, or to deploy a tailstock centre to support shaft-type components being machined in both spindles. Again, control is by a Fanuc Series 30i-B.

Aerospace component manufacturer reinvents itself during the pandemic

Rugby-based subcontractor Technoset, with 70% of turnover in the aerospace sector, was not a good situation last March (2020) when COVID-19 grounded most aircraft and orders plummeted seven-fold. Towards the end of 2021, the company’s production of aircraft parts is still below one-quarter of previous volumes.

With the business facing an existential crisis, managing director Kevan Kane and the firm’s owners set about restructuring the operation, positioning Technoset as a solutions provider rather than a supplier of components. It also started targeting challenging contracts for the supply of tight-tolerance components to more industries, notably lasers, fibre optics and telecoms.

The success of these policies has seen the number of components going through the shop floor for the first time for both existing and new customers more than treble from 10 to 33%. A large proportion have benefited from design-for-manufacture expertise from Technoset engineers to reduce piece part costs for customers.

The first new machine tool the company has bought since the onset of the pandemic was a highly specified, twin-spindle Cincom M32-VIIILFV bar-fed, sliding-head mill-turn centre, which was delivered by Citizen Machinery UK in spring this year (2021). Replacing two smaller M12 and M16 Cincoms that were about 20 years old, it joined a previous-generation M32-VIII bought in 2017, all numbers representing maximum bar capacity. There are also eight twin-spindle, fixed-head Miyano bar-fed lathes on-site from the same supplier for turning and milling components from stock up to 64 mm in diameter.

A primary reason for acquiring the latest M32 was a need to machine complex telecoms components, in particular a family of 12 mainly aluminium connector parts for use in the defence industry. Many of them are complex, with a lot of milled detail, and drawing tolerances are below 10 microns.

That level of accuracy is achieved reliably, even when running lights-out, partly because the lathe incorporates Citizen’s LFV (low frequency vibration) software in the Mitsubishi control’s operating system. Variants of the LFV function can be called up automatically in any part program to break what would normally be stringy swarf into manageable chips. It is no longer necessary to stop the lathe to untangle and clear potentially harmful swarf from the tool and/or component.

Productivity is therefore maximised, the operator is freed to carry out other tasks on the shop floor and the machine can be left with confidence to run unattended. The programmable chip-breaking software is not only beneficial when machining the aluminium connector parts but will also prove invaluable when Technoset restarts producing aircraft components in significant volumes from Inconel, titanium, Waspaloy, Nimonic and other superalloys, all of which tend to birds-nest when turned and drilled.

In anticipation of acceleration in the return of aerospace work, the subcontractor introduced a second shift in early September 2021. It is to ensure that contracts for aircraft components, which typically involve batch runs of 1,000 to 2,000-off, do not dominate the shop floor and dilute the production of new work that has been taken on in other industries. Consequently, aerospace work at the AS9100-accredited contract machinists is unlikely to exceed 50% of throughput in the future.

Rapid development of turning machine technology

Mr Kane commented “Citizen Machinery’s M32 sliding-head lathe, the manufacturer’s flagship model, has been the most important contributor to Technoset’s business since we bought the first one in 2000.

“Something that has surprised me is the speed with which the machine technology has advanced. Our latest M32 is of the fifth generation, which has been beefed up and completely redesigned since we installed the last, fourth generation model in 2017.

“The result has been a step change in performance. I regard the machine as the epitome of sliding head-technology in terms of productivity, flexibility and speed. It is ideal for mill-turning high value piece parts.”

Improvements to the turning centre include 1.5 times faster live tools powered by a 2.2 kW motor and a programmable, 9,000 rpm B-axis to enable simultaneous machining in five CNC axes rather than four. Combined with the back tool post whose Y-axis now has adjustable-angle tooling, it enables faster production of more complex parts. Superimposed machining allows three tools to be in cut at the same time, further shortening cycle times and raising productivity.

The 10-station turret incorporates a new tooling system employing a single, heavier duty drive, also rated at 2.2 kW, to an increased number of live cutters. Only the selected tool rotates, suppressing heat generation and vibration to enhance machining accuracy and surface finish. As nearly every part that is turned in the Rugby factory also requires prismatic operations such as milling and drilling to achieve one-hit manufacture, the improvements to the driven tool stations are of considerable benefit.

Mr Kane added, “The upgraded specification of the M32, which includes an 8,000 rpm main spindle uprated to 5.5 / 7.5 kW and an identical counter spindle, much more powerful than before, means that the machine is able to match the speed of the M12 and M16 that it replaces.

“Normally, to achieve cost-effective levels of productivity when mill-turning components from smaller diameter bar, you would not put that work on a lathe with double the bar capacity or more, as you would expect it to be slower.

“That is not the case with the fifth generation M32, which means we can consolidate jobs onto one platform. The reduced mix of machines on the shop floor promotes knowledge transfer and helps to mitigate manufacturing’s industry-wide skills shortage problem.”

He singled out Citizen Machinery UK’s engineering backup as worthy of special mention; it is applicable not only to Technoset but also to group member Technoturn, St Leonards, where a similar number of Cincom and Miyano lathes are in operation. Responsive service is appreciated, but especially beneficial is the application support.

Recently, Technoset found itself pitching for work and were stuck on a cycle time of 90 seconds, which was too long to achieve the target price. Mr Kane contacted the supplier’s Bushey headquarters by email and an engineer came back within 24 hours with an application-optimised cycle time of 60 seconds. The one-third decrease resulted in the subcontractor winning the new business.

Looking to the future

Focusing on digitalisation and automation, Technoset’s plans are wide-ranging. The turning side of the business, which currently accounts for around two-thirds of turnover, is already automated through the use of bar magazines. The milling side will take a significant step forward in spring 2022 with the installation of a 5-axis machining centre with built-in robotic component load/unload and on-board part probing. It will be the first automated prismatic component manufacturing cell on-site.

Helping to fund the purchase is a £100,000 Aerospace Unlocking Potential (Aerospace UP) grant recently awarded to Technoset. Delivered through the University of Nottingham and the Midlands Aerospace Alliance, the initiative aims to support the aerospace supply chain in the Midlands.

Part of the money will also be spent on acquiring a CADCAM suite for off-line programming, a function that is currently performed mainly by manual data input at the machines. Consideration will also be given to investment in laser cutting, part marking, a painting facility and special deburring equipment to achieve the high standards demanded by the aerospace and laser industries.

As any manufacturer knows, use of the best machine tools comes to nothing without skilled people to run them. Mr Kane ensures that highly trained setter-operators are always coming through the system by continually taking on apprentices. Thre are progressing through a four-year program with Midland Group Training Services and two are aligned with the programme delivered by the Manufacturing Technology Centre.

The leading supplier of bar-fed sliding-head and fixed-head CNC turning machines to the British and Irish markets, Citizen Machinery UK, has reported a successful open house. The first since the start of the pandemic, excluding a few virtual events, it was held at the company’s headquarters in Bushey from 12th to 14th October 2021.

There was a steady stream of visitors over the three days. Numbers were down compared to previous shows, with 100 visitors representing 52 companies attending. Some people are still wary of travelling due to coronavirus, but by far the main reason given for not visiting was pressure of work.

Orders for 15 machines valued at £2,321,000 were either placed or committed to verbally during the show. Three of the orders were from customers who had registered but could not attend or who had not planned to visit.

More than two-thirds of the lathes will be supplied with the manufacturer’s proprietary LFV (low frequency vibration) programmable chip breaking software. Launched five years ago, it has transformed the ability of manufacturers to manage swarf when turning, threadcutting and drilling malleable metals and plastics.

Managing director Edward James enthused, “Our open houses are known for their feelgood factor and we like to entertain as well as take orders.

“The customary curry evening on Wednesday was very popular as usual and boosted attendance that afternoon and on the Thursday.

“We organised a Six Nations rugby draw each day for a pair of tickets to see the England v Ireland match in March 2022. There was also a daily prize draw for a Citizen watch.”

Visitors to the open house were additionally able to see the activities of Citizen Machinery UK’s Solution Centre in Bushey. It has transformed the traditional showroom into a facility for configuring and proving out complex automated machining cells, often with special functions such as in-cycle laser cutting, peripherals, software and robotic cleaning and packaging. The centre also doubles as a permanent exhibition of mill-turn solutions and software.

Citizen Machinery UK has announced that it will hold an open house at its Bushey, Hertfordshire headquarters and recently opened Solutions Centre from 12th to 14th October 2021, the week after the EMO international machine tool show finishes in Milan.

The company sells its Japanese parent company’s sliding-head (Cincom) and fixed-head (Miyano) bar-fed CNC turn-milling centres into the UK and Irish markets, as well as being the distribution hub for Citizen machines going into France, Spain, Portugal, Scandinavia, the Middle East and Africa.

Managing director Edward James commented, “We are delighted to be able to reintroduce the physical in-house exhibition format, where people can actually attend and network with others, rather than having to contend with the virtual shows we organised during the pandemic.

“We will not only be celebrating the return of this annual event but also commemorating a true milestone in the development of Citizen Machinery UK, as the open house will mark the fifth anniversary of the launch of our ground-breaking LFV (low frequency vibration) chip breaking software.”

This innovative, game-changing technology is to be showcased and there will be demonstrations to explain how it has helped boost CNC machining productivity globally. The company is also offering a sneak peek at some of the projects it is working on in the newly opened Solutions Centre.

Anyone interested in attending is invited to register via the company’s website: www.citizenmachinery.co.uk/open-house-registration

“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.”

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.”

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.”

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.”

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.