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.”
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.”
When turning long-chipping malleable materials, Citizen’s low frequency vibration (LFV) software fragments swarf into manageable chip sizes, whereas normally it would become a stringy bird’s nest entangled around the tool and component. The latest sliding-head bar auto on which the technology has been made available is the new Cincom A20-VIILFV, while it can also be found on one of the company’s Miyano fixed-head models.
All machines have been fundamentally redesigned with uprated ballscrews, lubrication system, guarding and other elements to provide additional strength for withstanding the oscillation caused by very short periods of intermittent air cutting that produce the chipbreaking action. Productivity is maximised by avoiding having to stop the machine repeatedly to remove clogged swarf, facilitating minimally attended operation and enabling lights-out running.
A further advantage is the avoidance of the need to fit a high pressure coolant system to encourage swarf breakage, which involves high capital investment and increased running costs.
Embedded in the operating system of the control system, the chipbreaking software synchronises axis servo drive motion with the spindle speed. The software version on the A20 is suitable for longitudinal and face turning as well as drilling and involves multiple oscillations per revolution of the main spindle. The function is highly controllable and can be programmed using G-codes to switch on and off during a cycle, as required.
This is distinct from the functionality being part of the program itself, as is the case with alternative CNC pecking macros, which have the disadvantage of rubbing the tool. It raises the temperature, causing workpiece distortion as well as built-up edge on the tool, shortening its life.
In contrast, LFV oscillation of the tool by tens of microns allows coolant to penetrate the cut more efficiently for the brief periods when the tip lifts clear of the component surface, reducing heat and actually prolonging cutter life, in some instances by as much as five-fold. For the same reason, depth of cut may be increased substantially even when processing tough materials, often eliminating the need for a roughing pass and significantly shortening cycle times.
The Cincom A20-VIILFV can be used with a guide bush as a conventional Swiss-type automatic for machining shaft-type workpieces, or without a guide bush for producing shorter parts from less expensive stock with minimal bar remnant wastage. The guide bush can quickly and simply be mounted and removed. In sliding-head mode, machining length per chucking is a generous 200 mm to reduce cycle times when producing long, slender components.
The 7-axis A20 machine platform, which is capable of 2-axis simultaneous cutting, offers a high performance-to-price ratio for the production of parts from 20 mm diameter bar, optionally extendable to 25 mm (1 inch). The main spindle is rated at 3.7 kW / 10,000 rpm for optimal machining of smaller diameter stock and has an opposed 1.5 kW / 8,000 rpm sub-spindle with an X2-axis enabling simultaneous machining on the front and reverse ends of components. Both spindles have one-degree indexing and a 0.001-degree C axis.
Tool capacity is 21, with four driven stations for cross machining having a maximum speed of 6,000 rpm. The four back tool post stations may optionally be live. Positioning speed is fast at 32 m/min for short non-cutting times. Idle times can be reduced further using the pre-processing function in the Fanuc-based Cincom control dedicated to this machine model. It analyses the machining program before it is run to minimise processing and calculation times.
Subcontractor Unicut Precision, Welwyn Garden City, is no stranger to producing large quantities of components, one million items being shipped to customers in the UK and overseas in a typical month. The company operates 22 Cincom sliding-head lathes and eight Miyano fixed-head turning centres from one supplier, Citizen Machinery UK, in addition to other metalcutting plant.
Three-quarters of this capacity was changed over in early April 2020 to manufacture medical components for the government’s Ventilator Challenge UK following a call from a member of the supply chain management team, McLaren, to Unicut’s owner Jason Nicholson.
He said, “Drawings started coming in on a Thursday and we quoted straight away. The first orders for a dozen different part numbers were received on the Friday and Saturday and we started producing them immediately. Within a week the workload had increased to 780,000 components across 31 varieties, which we are currently producing 24/7.”
Less than 20 per cent of this throughput is being machined in Welwyn Garden City using multi-pallet 5-axis machining centres and lathes not supplied by Citizen, with the remainder allocated to the latter machines, mainly sliders but also fixed-head lathes. The supplier’s applications engineers helped by providing optimised cycles for producing a couple of the medical components but the remainder of the new parts were programmed on-site by Unicut’s experienced CAD/CAM team.
Mr Nicholson continued, “It is testament to the flexibility of modern CNC plant that it can be converted so quickly to produce entirely different components. Only around two per cent of a typical year’s output from here goes to the medical sector, whereas at the moment it is the vast majority.”
Unicut’s employees were keen to meet the ventilator challenge and it has not been necessary to furlough any staff, although a few are self-isolating due to underlying health conditions or through having a vulnerable family member at home. Employees willingly worked throughout the whole of the Easter long weekend and discussion is being postponed to a quieter time as to whether the overtime will be paid or added to an individual’s annual holiday entitlement.
Social distancing on the shop floor and in the offices is working well, staggered arrival times help to minimise the number of people in any given working area at one time, and the ubiquitous hand sanitising gel can be found hanging from every operator’s belt.
Mr Nicholson concluded, “It has been a surreal time, but everyone here is helping out, as they are in machine shops all around the country, to make much-needed ventilator components.
“We have already produced big quantities of the smaller diameter parts, so we have now been able to reallocate many of the Cincom sliders.
“The latest L12 model with Citizen’s LFV chipbreaking software has been useful when machining plastics and certain grades of aluminium for medical parts by breaking the stringy swarf into smaller chips, so we do not keep having to stop the machine to clear it.
“Overall I estimate that around half of our capacity across the lathes and machining centres is still running around the clock on work for Ventilator Challenge UK and will be for some time to come.”
Like most turned parts subcontractors, Sub CNC Precision uses its 14 twin-spindle, multi-axis bar autos, in this case all from Citizen Machinery UK, to turn-mill parts in one hit from a wide variety of metals, from mild and stainless steels through copper and aluminium alloys to exotics such as Monel, Inconel and titanium. Likewise it produces components from many types of plastic including nylon, PEEK and Delrin.
The list of industries served is also long, encompassing aerospace and defence, telecommunications, motorsport, automotive, marine, agricultural and medical, the latter accounting for 20 per cent of turnover in an average year.
So when Rolls-Royce was trying to find a suitable firm to produce a particularly difficult pair of plastic components for the Ventilator Challenge UK, it is unsurprising that its email list included ISO 9001:2008-accredited Sub CNC, whose name had been passed to the government’s consortium by Citizen, which had been identified as a critical supplier.
Joint owners and managing directors of the contract machining operation, Yian Stavrou and George Dingley, received an email request from Rolls-Royce late in the evening on the last Wednesday in March. Drawings came in the following morning, quotes were issued quickly and by the afternoon provisional orders had been issued. The shaft-type nature of the components meant that they were destined for production on the subcontractor’s sliding-head lathes.
Mr Stavrou recalled, “Everything happened at breakneck speed. We prepared the two programs, bought in cutting tools and ordered plastic bar that had to be ground so it would feed through the guide bushes on the sliders. Citizen loaned us a number of milling toolholders that we did not have and we were in production around the clock by the Friday morning.
“Process capability studies were completed, the paper trail put in place and the 9,000 plastic parts were machined, inspected and delivered on the following Monday to meet the contract conditions.”
One of the reasons for Sub CNC winning this plastic turn-milling work, as well as subsequent urgent medical contracts, is the option to use on four of its 12 Citizen sliding-head lathes the manufacturer’s patented LFV chipbreaking software. Plastic materials as well as many metals, when machined, result in stringy swarf wrapping itself around the tool and component, forcing the operator to stop the machine frequently to remove it, compromising productivity. LFV avoids this by oscillating the tool by a few tens of microns to break the swarf into small, manageable pieces, the length of which can actually be programmed.
The two components for Rolls-Royce required the use of sliders capable of turning 32 mm diameter bar. The only machine of this capacity at Sub CNC equipped with LFV is an L32-VIII, which was deployed for producing the most difficult part with drilled and milled features. The other, less challenging component was put on a Cincom M32, with the long swarf broken traditionally using high pressure coolant to prevent machine stoppage.
The three other LFV Cincoms on the shop floor are for turning bar of either 12 mm or 20 mm maximum diameter. These are being extensively used to fulfil other ongoing medical work in a various plastics and long-chipping metals for which component quantities are ramping up. New contracts are also coming in, including one for the production of 70,000 medical parts in a six-week period to mid-May.
Overall, about half of the subcontractor’s lathes have been made over to producing parts for ventilators and other medical products, including its two Citizen Miyano fixed-head lathes, which produce parts from bigger diameter bar up to 42 mm and 51 mm diameter respectively. The latter was devoted for 20 days to producing 10,000 actuators for ventilators and is currently producing 4,000 of the more complex valves, while the former is turn-milling 316 stainless steel medical parts. The remaining half of the turning capacity serves manufacturers in other industries that are continuing to operate during the Covid-19 crisis.
Co-director Mr Dingley added, “We are fortunate that our activities are split across two sites in Dunstable and one in Luton, so machines are fairly spread out and our operators can socially distance easily. It is a credit to our staff the way they have stepped up to tackle this urgent medical work, which involves coming in at nights and weekends, including over the whole of Easter. Day to day it is more or less business as usual for Sub CNC, except that the workload is unusually high.
“The only real difference is that we are not allowing external people to visit. We did however make an exception by asking a Citizen engineer to realign a Cincom L20 so that we could guarantee to produce a high accuracy medical component requiring a 10-micron total tolerance on cross holes and a slot. The alignment was completed within 24 hours of issuing the request – and our email was sent out on a Sunday. Everyone is pulling together at this difficult time.”
In the opinion of Citizen Machinery UK’s managing director Edward James, the Covid-19 pandemic has united the whole of the manufacturing sector to an extent never seen before in terms of the levels of selfless application by huge numbers of people to boost production of much-needed medical equipment. In this article he describes how the company he runs, a turning solution provider, is contributing in the battle to deliver more ventilators to the front line in hospitals.
Citizen became involved early on when it was contacted by the UK government’s consortium for ventilator production, which became known as Ventilator Challenge UK. The committee included representatives from the AMRC (Advanced Manufacturing Research Centre) and Renishaw, who identified Citizen as the largest supplier of bar automatics in the UK and Ireland. This type of machine tool, especially the sliding-head variety with turn-milling capability, is critical to the rapid, efficient manufacture of components in very high volumes for making the extra ventilators needed by the NHS, 30,000 being the current target.
Accordingly, Citizen was given critical supplier status for the medical as well as the aerospace and defence sectors, although priority is being given to medical applications and is the only one being serviced at the moment.
Mr James commented, “At the outset, the government was considering building a factory to make ventilators parts and assemble them. However, we and others advising them suggested that the best route would be to enlist the help of the existing pool of first-class manufacturers and their supply chains already using our lathes and production equipment from other leading machine tool suppliers.
“I gave them a list of about 50 companies that use Citizen turning centres, choosing firms that operate sufficient numbers of machines, hold ISO accreditation and have the right level of expertise and metrology capability. We knew many of them already make ventilator parts as well as similar types of medical and non-medical parts out of both normal materials and special alloys.
“We had told all of our customers via social media that Citizen Machinery UK was still open for business and continuing to operate under government guidelines to support customers and prioritise any request for help in producing medical components.”
Nearly all of the recommended contacts were approached by multinational firms, including Rolls-Royce, GKN and BAe, appointed by Ventilator Challenge UK to oversee supply chain management from purchasing through to ventilator assembly. The manufacturers were asked to change over their production to machining medical components and they immediately agreed to do so. As many of the firms recognised that additional capacity would be needed, it triggered multiple orders for new Citizen bar automatics from several companies and from additional manufacturers that became involved in the initiative through word-of-mouth recommendation.
In just over three weeks to mid-April 2020, 17 machines were prepared and delivered from stock, all of which are devoted to the production of medical parts. Transport is provided by Citizen’s dedicated team, J Parrish & Son, and for the rest of April sliding-head lathe deliveries are running at one per day. Extraordinarily, each is commissioned and operating on a customer’s shop floor in approximately 36 hours from receipt of the order, such is the urgency. Overlaid on this already hectic workload is a significant amount of re-purposing of existing turn-mill centres in the field to manufacture medical equipment.
There are examples of Citizen lathes having been reconfigured for making metal parts that are normally produced from stampings, forgings and castings. By far the largest proportion of resetting, however, has involved writing programs and providing tooling packages for turn-milling large quantities of plastic components from bar that are normally injection moulded, such as tubing connectors for ventilators. Often they are supplied from overseas, including China, but deliveries may have either stopped or the numbers available are insufficient.
Mr James added, “The six-week lead-time to produce a new injection mould tool is too long – the parts are needed much faster than that. Our multi-axis sliding-head bar autos are ideal for turning such components at both ends and milling and drilling them in the same cycle so they come off complete, without the need for special fixturing and with minimal material wastage.
“It is actually a lot of work to identify parts that can be re-engineered in this way and then re-purpose a lathe to make them. A significant amount of CAD effort is required, plus complex CAM programming and post-processing.
“Our applications department has been doing a lot of this in-house and at our customers’ factories, outsourcing what it cannot handle. One of our applications engineers has been working pro bono at a customer’s site for three weeks to help out with re-engineering medical components due to staff shortage.”
There are several reasons for Citizen fortunately finding itself in a good position to ship such a large number of lathes at short notice. One was the opening last year of a new turning centre of excellence in Brierley Hill with a showroom containing many demonstration machines. These together with those on show at the Bushey headquarters are available on short delivery.
The company in any case has a policy of supplying its machines and accessories from UK stock and more were available than usual, as extra had been brought in due to the possibility of a hard Brexit. Additional machines were in the UK, including some of the very latest models, ready to be shown at the now-postponed MACH exhibition.
Moreover, a bull run of sales had led to a backorder book of about eight weeks, with turning centres that were nearly ready for delivery able to be re-purposed at short notice and diverted urgently to medical component manufacturers. The original machine packages are being replaced from stock.
Naturally, these activities are only possible with healthy Citizen staff to implement them. Seeing the speed with which Covid-19 was spreading, Mr James had pre-empted government advice by putting on hold in February all overseas travel, isolating the Bushey and Brierley Hill centres to avoid movement between them, and instigating working from home where feasible. The result is that of the 56 members of staff, 20 are furloughed but the other 36 are able to work, including all of the applications engineers, half of the service staff and many back office support personnel.
Mr James concluded, “I am told that most of the turned parts have already been manufactured for the 30,000 extra ventilators, which is testament to the effort put in by us, other lathe suppliers and an army of willing and capable manufacturers in Britain and Ireland.
“I would like to offer a big thank you to all our staff and suppliers who are helping to make this happen. Everyone is volunteering to work tirelessly around the clock, at weekends and even through their holidays.”
He added that when the country finally comes through the pandemic, Citizen Machinery UK will find itself in a stronger position than previously as he predicts that demand for new machines will grow. It will be due to companies that are acquiring modern sliding-head turn-mill centres now, where in normal circumstances they would not have done so for several years, recognising earlier the benefits of the tighter tolerances and better surface finishes achievable compared with using their older lathes.
Additionally, most of the new turning centres currently being supplied have Citizen’s proprietary LFV programmable chipbreaking software built into the control’s operating system. Manufacturers are seeing the productivity benefits of this technology when machining traditionally long-chipping materials such as plastics, stainless steel and titanium.
Edward James, Managing Director of sliding- and fixed-head lathe supplier Citizen Machinery UK, posted on social media on 16th March 2020 that the company is continuing to operate under the UK Government’s recommended health guidelines and was available to support firms in the production of ventilator parts. He regards this as a priority following Prime Minister Boris Johnson’s appeal the same day for the manufacturing community to help urgently to make 20,000 extra ventilators.
One of Citizen’s nearly 4,000 followers on LinkedIn, an existing user in the West Country with five Cincom sliding-head bar autos in operation dating back to 1999, responded at lunchtime the following day. A medical equipment OEM was asking it to increase fourfold its capacity to produce critical ventilator components.
The subcontractor ordered two additional Cincom machines for urgent delivery. The first, a 32 mm capacity L32-XLFV, was installed two days later on Thursday 19th March. Citizen’s engineers worked around the clock to commission the machine so it could start making the ventilator parts. The second machine, a 20 mm bar capacity Cincom L20-VIIILFV, was installed the following Friday, 27th March and was similarly fast-tracked into production.
By then, in the space of a fortnight, Citizen had received further orders from another four customers for five more machines to be delivered at short notice for ventilator parts manufacture and there is no sign of the demand slowing.
Mr James commented, “I would like to offer a big thank you to our staff and suppliers who helped to make this happen. Let’s all work together to come up with solutions to this terrible COVID-19 pandemic.
“If any of our customers make ventilators, respirators, personal protective equipment or other medical items that are in high demand, we may be able to help them as a matter of urgency to manufacture the necessary components, as we have a number of fixed- and sliding-head turn-mill centres in stock ready for immediate dispatch and installation.
“We are also able to put OEMs and their supply chains in touch with a large number of our customers who can make ventilator and other medical parts using their existing plant.
“In particular, if a manufacturer traditionally relies on plastic extrusions or other bespoke raw materials that are becoming scarce, we are able to re-engineer items so that they can be made from solid bar and would prioritise this kind of requirement.”
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.”
In response to feedback from users, Citizen’s M32 sliding-headstock lathe, a popular model in the Japanese manufacturer’s range capable of economical machining of components in small or large batches, has undergone a fundamental makeover in its fifth design iteration to the extent that half of its constituent parts are new. It is also considerably more robust, with a bed 500 kg heavier than that of its predecessor, bringing the installed weight to 4.3 tonnes. Availability of the 10-axis Cincom M32-VIII in the UK and Ireland is through Citizen Machinery UK.
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 the live cutters. Only the selected tool rotates – a world first for Citizen. The effect is to suppress heat generation and vibration, enhancing machining accuracy and surface finish. Power consumption is reduced and there is less the wear on gears and bearings. The latter have been strengthened, providing extra rigidity to withstand torques twice as high as on the previous machine model, leading to greater productivity.
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, 50 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. Three tools may be in cut at the same time, supported by the Mitsubishi M850W control with 15-inch touch-screen, shortening cycle times and raising productivity.
The 8,000 rpm main spindle has been upgraded to 5.5 / 7.5 kW and the counter spindle is of the same power, representing a 2.5-fold increase. It improves the flexibility with which front-working and rear-working cycles can be shared between the two spindles. The Z-axis feed drive has been uprated to 1.5 kW for more powerful cutting performance, the 32 m/min rapid traverse rate remaining the same. New also is the optional possibility to swap over in half an hour to use the machine in guide bush-less mode to reduce remnant length when turning shorter components up to 2.5 times their diameter and to enable the use of cold drawn bar up to 38 mm diameter.
To improve operability and visibility and reduce set-up times, the machine door and its window have been enlarged by 65 per cent. Other enhancements include reduced overhang of the counter spindle headstock on its slideway to provide more robust support, larger and more rigid ballscrews, and 30 per cent lower air consumption.
The lathe’s ecological credentials, as with other Citizen machines, are impeccable. The M32 is an environmentally friendly product that has undergone stringent assessment by the manufacturer. The use of easily recyclable materials and avoidance of hazardous substances are combined with Eco Function hybrid technology that automatically saves energy through the intelligent use of power during non-cutting periods. Its effectiveness can be monitored on a control screen window that shows graphically the present, maximum, cumulative and historical power consumption values.
A total of 12 CNC Cincom sliding-head and Miyano fixed-head turn-milling centres will be demonstrated under power on the Citizen Machinery UK stand at MACH 2020, including automated production cells 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 these Japanese-built lathes.
On show for the first time will be Citizen’s flagship series-five Cincom M32-VIII and a Miyano BNE‐65MSB, both of revised design with more power and flexibility plus the latest Mitsubishi M800 5-axis touch-screen control. Consequently, the latter machine is the first 65 mm capacity Miyano lathe to offer superimposed machining, which allows three tools to be in cut together under simultaneous 5-axis control for elevated levels of productivity.
New will be a Cincom L32‐X with Citizen’s 2-axis LFV programmable chipbreaking software built into the operating system of the control as well as integrated, high-speed laser cutting capability, a technology that was originally developed for efficient production of apertures in thin-wall stents on smaller Citizen sliding-head lathes.
A further highlight will be a Cincom A20‐VII LFV, the first Citizen lathe to be equipped with patented Fanuc-based, multi-axis LFV software for breaking into manageable pieces the stringy swarf often generated when turning and drilling stainless steel, copper and plastics.
The exhibition will also mark the first UK showing of the 12 mm bar capacity Cincom L12-X LFV with five rear-facing static and driven endworking tool positions and the addition of a Y-axis on the counter spindle to mirror the main spindle’s three degrees of freedom. The machine is intended primarily for production of dental abutments and implants as well as other complex components.
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; the next iteration of Alkart Wizard for off-line programming; and Citizen’s Industry 4.0 capabilities encompassing the latest machine networking and monitoring functionality.