Decommissioning legacy nuclear waste silos on the former UK power generating site at Sellafield requires the machining of large numbers of ‘bins’ to close geometrical tolerances, thus ensuring they can be stacked safely. These bins are three-metre-cube, double-walled, box fabrications that are highly resonant and, to make their production even more difficult, are made from 6 mm thick duplex stainless-steel plate that tends to induce vibrations during milling.

One of the firms leading the Sellafield decommissioning work, Stillington-based Darchem Engineering, had been taking delivery of machined bins from Newcastle-based contract machinist BEL Engineering since 2017.

CEO Jonathan Lamb says: “We wanted to increase productivity but realised that further improvements to the machining process were impossible using conventional machinery and fixturing. When we tried to raise the speed of machining, chatter resulted and it was difficult to hold tolerance. So we engaged with Kingsbury to develop an entirely new machining concept in respect of both work holding and metal cutting, to improve cycle time and hence increase production rate and reduce cost.”

It was not an exercise for the financially faint-hearted. The two companies invested £500,000 in researching and developing an optimal solution for machining two variants of waste bin, known as a PFCS (Pile Fuel Cladding Silo) and an MSSS (Magnox Swarf Storage Silo).

Richard Kingsbury, MD of Kingsbury, says: “Duplex will seek out any weakness in a machining system. We considered every conceivable source of vibration, from the machine bed to the column, guideways, spindle, spindle-tool interface and cutting tools, including their grade and geometry.

“We then turned our attention to a forensic analysis of how best to fixture the bins and it was here that we achieved a breakthrough,” he continues. “By inflating five airbags between the fixture and the box and five more inside the workpiece itself, we managed to muffle the entire unit so it could be milled at high speeds and feeds without vibration. A final piece of engineering involves hydraulically rotating the 12 swing clamps around the face of the fixture – one by one – out of the way of the approaching cutter so that at any time 11 are engaged to maximise rigidity.”

To understand the natural frequencies of the MSSS bin, the company performed modal analysis in 12 different but repeatable locations around the fabrication. A tap test on a fully fixtured bin, with 32 touch clamps and three push clamps engaged – in addition to the 12 swing clamps and with the internal and external airbags inflated – showed that the vibration amplitude fell to below 0.1 g in under 17 ms on average. That is much less time than the four hundredths of a second it takes successive inserts on an eight-tooth milling cutter rotating at 176 rpm to engage with the metal being machined.

The agitation induced in the material during the cutting process has therefore completely dissipated in the elapsed time between one tooth engaging with the workpiece and the next, an outcome that is impossible to achieve under conventional clamping conditions. This solution prevents any resonance occurring and avoids amplifying vibration, thus eliminating chatter and consequent dimensional inaccuracy and poor surface finish. In effect, the resonant frequencies of the bin are now altered to such an extent that the hollow workpiece has properties similar to those of a solid cube of metal.

The project started in March 2018. A Taurus 30 machining centre from one of Kingsbury’s principals, Waldrich Coburg, was the chosen machine-tool platform for the project, and final trials took place at the manufacturer’s factory in Germany in late 2019 and early 2020. Lamb witnessed these trials and was convinced it would save cost and help Sellafield hit its box production rate as legacy nuclear material extraction ramps up over the coming years.

In mid-2020, the UK’s Intellectual Property Office granted Kingsbury an industrial patent covering the design of the novel fixturing system, based on its ability to damp the structures during milling.

The machine has a cast-iron base and incorporates a static column and moving table, a configuration that lowers the centre of gravity and increases stability. The 400 x 400 mm cross section of the ram provides the rigidity needed when machining the lower part of the component at maximum extension.

A hydrostatic guideway with a film of oil between the slide and moving assembly supports each axis. Irrespective of speed and applied load, the distance between the faces remains constant, while the system distributes an unchanging volume of oil to further help suppress vibration. The spindle employs a large bearing pack and an HSK125-B tool interface, providing excellent rigidity and machining capability.

The solution developed for the MSSS box applies equally to the MSSS skip and the PFCS box, each of which takes advantage of its own fixture, complete with airbags. Automation on the Taurus 30 sees two fixture assemblies capable of holding six different part variants for both boxes. It means that a complete ship set of parts needed for all MSSS and PFCS bins are fixtured across the two pallets. While one pallet is within the machining area, the operator has free access to unload and then reload to the fixture assemblies on the other pallet, so downtime is limited to the pallet changeover time.

Lamb concludes: “I’m certain that the combination of Kingsbury’s patented fixture solution and the Waldrich Coburg Taurus machining centre will provide Sellafield with a reliable and cost-effective long-term solution for the manufacture of the MSSS and PFCS boxes.”

For further information
www.kingsburyuk.com

Wisconsin-based Integrity Saw & Tool has purchased a Vollmer CHX 840 circular saw blade sharpening machine with the Vollmer HS automated loading station to provide capacity for a significant order the company has won from a new pallet manufacturing customer. The Vollmer machine has increased productivity by 60%, permitted unmanned running and improved blade quality. Without the new CHX 840, fulfilling the new order “would have been impossible”.

It is a familiar tale when an engineer leaves his job and sets up a business from his garage. In the case of Integrity Saw & Tool, a saw sharpening, HSS drill and end-mill regrinding company, the story begins in a basement in 1986. However, it was the move to a 13,000 sq ft factory in 1998, the appointment of Paul Reetz as the fresh-faced sales engineer (now the company’s owner) and investment in its first Vollmer CNC sharpening machine in 2000 that set the company on a new growth trajectory. With 13 staff and an output of 100 saw blades a week back in 2000, this figure quadrupled to almost 400 blades a week by 2005.

“We bought our first machine in 2000, a Vollmer Akemat B4 and, over the next eight years, more Vollmer machines followed,” says Reetz.

In fact, the company acquired a further three machines, with an Akemat U10 and B10 arriving in 2005, followed by an additional Akemat U10 in 2006.

The Vollmer Akemat machines sharpened TCT saw blades while the company’s manual machines manufactured and serviced HSS blades. This investment completed the purchasing of Vollmer machines until the 2019 arrival of the CHX840+HS.

Says Reetz: “The saw sharpening side of the business had grown for almost 10 years, but unfortunately the 2008-09 global recession wiped out a lot of small businesses. Many of our circular saw blade customers witnessed the collapse of their companies. However, the production of round tools such as drills, end mills, router bits and special tools for the manufacturing industry weathered the market far better. Round tooling for industry currently accounts for 80% of our business. With the COVID-19 pandemic, our round tooling business has slowed down. However, as more people are confined to staying at home, they are investing in their homes and the saw division of our business is once again benefitting.”

The pandemic situation has seen people confined to their homes all around the world, with everyone spending more time and money on groceries and eating at home. This situation has delivered a unique opportunity for Integrity Saw & Tool. With millions of wooden pallets in circulation in the US food industry, Integrity is regrinding TCT saw blades for a leading pallet manufacturer. This new customer has ambitious plans to build multiple manufacturing facilities across Canada, the US and Mexico, with each plant capable of producing a pallet every minute.

Integrity Saw can support the new customer with its five-axis Vollmer CHX840+HS for machining the tooth faces and tooth tops of the TCT saw blades in a single clamping. The HS automation solution enables Integrity Saw to load and process 28 blades unmanned. With a customer that will run its operations 24/7 and will require a new saw blade for every shift at every facility, the opportunity for Integrity Saw & Tool is considerable.

Following the arrival of the Vollmer CHX840+HS, Integrity has rapidly ramped-up to the stress-relieving and re-grinding of 400 TCT blades every week from May 2019 – an impossible feat without the new machine.

The 457 mm (18”) diameter TCT blades have 70 teeth per saw and it is possible to re-grind each blade up to seven times before being replaced or re-tipped. Before the arrival of the CHX840+HS, Integrity Saw was conducting four operations on three machines to complete a saw blade in 75 minutes – a machining time not inclusive of set-ups and changeovers.

“When it came to programming time and repeated set-ups, it was approximately 90 minutes for each blade,” says Reetz. “The Vollmer CHX840+HS has cut this time by more than 60% to 35 minutes with just one stress-relieving operation before the CHX840 completes all tooth and face grinding in a single set-up.”

For the 27-employee company to have just two skilled operators running four Vollmer Akemat machines and the CHX840+HS; the new machine has doubled the weekly output with the same number of staff.
“The two operators previously had the capacity to do 40-50 TCT blades a day on the Akemat machines, but adding the Vollmer CHX840+HS means we can now re-grind over 100 blades a day,” explains Reetz. “We work from 05:00 to 15:00 and the HS automation system allows us to set the CHX840 machine so it processes up to 28 saws unmanned throughout the evening.”

Although the new Vollmer has increased productivity and capacity; the benefits reach much further. Integrity Saw has recognised that the ability to grind tooth tops and faces in a single operation has the potential to make single-purpose machines redundant in the future. With a single ‘compact-footprint’ Vollmer machine, Integrity can significantly increase output while reducing machine inventory and running costs.

From a programming perspective, the operators undertook 2½ days of training on the CHX840+HS.
“While the older machines have all the programs stored, the Vollmer CHX840+HS didn’t initially have that luxury,” says Reetz. “However, the easy-to-use CNC interface means our operators don’t have to program every blade from new – they can simply edit one of the hundreds of stored program templates within the software to generate a suitable wheel path. This means it is possible to program a stack of 28 saws for unmanned running in just over 5 minutes.”

Additionally, the operators no longer have to be concerned about grinding wheel offsets as the CHX840+HS automatically compensates for wheel degradation. The combination of probing, automated wheel offset calibration and the intelligent software on the CHX840 also eliminate the potential for operator error and collisions.

With the pandemic gradually subsiding, the Vollmer CHX840+HS will eventually reach capacity in line with customer demands for more saw blades. Integrity already has its sights set on a second Vollmer TCT saw sharpening machine with automation to meet these production demands. Furthermore, the company has been so impressed with the CHX840+HS that it is now considering the latest generation Vollmer machine for its rotary tool division.

For further information
www.vollmer-group.com

Mills CNC, the exclusive distributor of Doosan machine tools in the UK and Ireland, says it is not only the supplier of choice for many OEMs, tier-one suppliers and precision subcontractors, but increasingly the first port of call for many new engineering start-ups. One such company is Gateshead-based EAG Precision. Established in March 2019, the company invested in 10 new Doosan machine tools from Mills CNC within its first three months of operation.

Operating from a 14,000 sq ft facility, EAG is a privately-owned company specialising in the small and medium batch production of complex, high-precision parts for sectors such as defence, marine, medical and renewable energy. To differentiate itself in the market, EAG has achieved ISO 9001 approval and specialises in machining complex components (including prototypes) to tight tolerances and exacting surface finishes for customers based in the UK and the US. The company also designs, manages and implements complex turnkey projects for its customers.

To maintain its growth and profitability EAG relies on the dedication of a highly skilled workforce, the experience and expertise of its directors and senior management team and, of course, the advanced machine tool technologies it has at its disposal.

Not many new companies have the confidence or wherewithal to invest in 10 new machine tools straight out of the gate, but EAG is unlike other start-ups.

Says Dave Graham, EAG’s managing director: “Although the new enterprise started trading in March 2019, a great deal of preliminary planning was initiated and completed well before then. The strategic business plan we created, and which we used to help obtain funding for the new company, was both robust and ambitious.”

Covering all aspects of business, the plan identified key markets and customers, and how EAG would approach and build business relationships. The plan highlighted, in depth, the company’s key capital equipment investment criteria, which included the number and type of CNC machine tools it wanted to acquire initially and in subsequent years. EAG’s plan also set out and reinforced the company’s mission, vision and values.

Says Graham: “There were, and still are, three guiding principles that direct our company operations: delivering high-quality manufacturing solutions to customers; providing a rapid response in order to meet customer requirements efficiently and effectively; and ensuring value for money and achieving cost efficiencies. Everything we do is measured and benchmarked against these principles.”
The directors and senior management team at EAG can offer over 100 years of collective experience in the precision manufacturing sector. Their knowledge and expertise was invaluable when approaching potential customers to secure new machining contracts, and critical in identifying and selecting the right machine tools that would meet EAG’s immediate and future capacity and capability requirements.

Although the company canvassed the market looking for the best performing and best value machine tools, the directors’ previous positive experiences of dealing with Mills CNC and of using Doosan machines (gained prior to EAG being established), put Mills in the box seat.

“We knew that owing to the depth and breadth of the Doosan machine tool range we would be able to find solutions perfectly suited to our requirements,” says Graham. “It was also a big positive, especially for a new start-up in terms of time and logistics, if the machines could be acquired from a single source.”

Although many start-ups initially invest in used/pre-owned machines to get up and running, EAG opted to invest in new machine tools from day one.

“We decided on new machines from Mills CNC as they were competitively-priced and were backed by full warranties and the company’s reputable applications and aftersales support,” says Graham. “In addition, we were able to take advantage of Mills CNC’s machine tool financing, which gave us access to flexible capital equipment funding packages.”

Mills CNC’s stock policy means that many machines (over 70 at any given time) are available from its campus facility in Leamington ready for immediate delivery to customers in the UK and Ireland.

“It was important that we hit the ground running from day one as we had already secured machining contracts from a number of customers,” explains Graham. “The ability to order and get our machines delivered, commissioned and installed in double-quick time was critical.”

To improve operational efficiencies, optimise manufacturing flexibility and help with lead-time fulfilment, EAG invested in a number of multi-tasking Doosan machines. The models now on site include: Lynx long-bed lathes with Y axes, sub-spindles and driven tools; a large-capacity Puma lathe with full mill-drill capability; Doosan DNM machining centres supplied with 4th-axis units; and a high-productivity twin-pallet vertical machining centre.

All 10 Doosan machines acquired by EAG are equipped with Fanuc controls. These CNC units facilitate quick and seamless program transfer between machines when required. This capability prevents production bottlenecks from occurring if, for some reason, a machine is out of action for maintenance or repair.

EAG produces precision components for a wide range of sectors and customers. As a consequence, the company machines materials that include steels, aluminium alloys, duplex and standard stainless steels, plastics, Inconel, and titanium. Mills CNC says that the Doosan machines, with their rigid structural characteristics and high-specification spindle technology, are sufficiently versatile and capable of machining this diverse range of materials to high geometric tolerances and surface finishes.

Graham shares this sentiment, stating: “Our DNM machining centres enable us to machine prismatic parts up to 1 x 1 x 1 m, while the largest of our Doosan lathes provides us with a maximum turning diameter of 550 mm.”

Mills CNC reports that new start-up companies are increasingly turning to the company for help with their machine tools and, more recently, their automation requirements. Attracted by the depth and breadth of the Doosan machine tool range, competitive pricing, immediate availability from stock, and the company’s aftersales support services, it is a trend that looks set to continue.

Concludes Graham: “We are delighted with our Doosan machine tools and the level of service we receive from Mills CNC.”

For further information
www.millscnc.co.uk

Having installed a Brother production cell at the end of 2019 comprising two five-axis Speedio M140X2 mill-turn centres served by a Feedio vision-based robotic unit for component handling, Worthing subcontractor Roscomac has ordered a second identical cell. Due for delivery in April 2021 by Brother’s sole UK agent Whitehouse Machine Tools, the latest acquisition is symptomatic of a fundamental change in the way Roscomac’s owner Joe Martello views automated manufacture.

“About 20 years ago we installed a large flexible manufacturing system consisting of six three-axis, 40-taper, half-metre-cube machining centres linked by a three-level storage and retrieval system for 104 machine pallets,” he says. “Having served us well, it is being decommissioned in February 2021. We will relocate the first Brother cell into part of the space it releases, with the second placed alongside it, all in a relatively small footprint.”
Since 2018, Roscomac has instigated a major shift towards five-axis machining. The company has spent the majority of a £4m investment in that period on multi-pallet pool systems with large tool magazines.

“They machine parts in fewer operations while achieving a high level of automation, without the complexity of an FMS based on three-axis capacity,” explains Martello. “Had we not gone down the five-axis route we would be dead in the water by now. With the two Brother systems, we have gone a step further by installing our first 30-taper five-axis capacity for the automated, ultra-fast machining of aluminium components in fewer set-ups.”

He says that while the FMS was an efficient production facility, the three-axis CNC technology often required the multiple clamping of several parts in expensive staged fixtures for undertaking several separate machining operations. The system’s utilisation dropped because the type of work coming through the door was changing; it was becoming lower volume and more complex. Production was more difficult to control and the increasing number of set-ups raised the labour cost content of component machining, as operators were frequently at the load/unload stations.

The timing of the arrival of the first Brother cell, a matter of months before the start of the COVID-19 pandemic, could not have been more opportune. Nearly a quarter of Roscomac’s turnover normally comes from the medical industry, but in 2020 that proportion doubled, leading to an increase in annual turnover of £2m despite the virtual disappearance of aerospace work, which historically has accounted for 10% of Roscomac’s throughput.

For many years the subcontractor had been machining four different components for hospital syringe pumps from aluminium castings and extrusion. Machining previously took place at a rate of 4000 per month per part number on 40-taper machines in the FMS, but were ideal candidates for transfer to the first Brother cell. The cell therefore features a turnover station so that one Speedio can carry out Op 10 while the other completes Op 20 after the component rotates, all fully automatically.

These 30-taper, five-axis machines could produce the parts much more cost effectively in two operations, 24/7, without operator intervention, apart from placing raw material on to the input conveyor and unloading finished parts from the output conveyor. Conversely, unattended and lights-out running was impossible on the FMS due to the constant loading and unloading. In practice, for these components, the system was only capable of one-quarter of the output compared with the Brother cell.

Within a month of the pandemic starting the customer quadrupled the order quantity to 16,000 per month per part. Martello says that it would not have been feasible to achieve even half that amount using the other plant in the factory, which would have meant turning away business. As it was, the Brother cell was able to cope and started paying for itself and making a profit from day one. The operator only had to load and unload the conveyors and keep an eye on production, so was free to run other machines.

By the middle of 2020, due to the success of the cell, Roscomac transferred all the remaining work from the FMS and started planning for its removal. As the Brother cell was working flat out, this work was initially put on to 40-taper machining centres, but to add more high-speed capacity, a third Speedio M140X2 was hired from Whitehouse Machine Tools and operated as a manually-loaded machine.

“It really focused the mind, seeing the operator having to attend the machine almost continuously during the relatively short Op 10 and Op 20 cycles, so we decided to purchase a second fully automated Brother cell, exactly like the first,” says Martello. “Whitehouse supplies them as turnkey installations with time studies, programs, fixtures and tooling. We have the skills to do this in-house, but we are very busy at the moment with the surging medical work. In any case, we find that we learn a lot from Whitehouse each time they prepare and supply a fully functioning production cell, so we get the benefit of knowledge transfer, along with their experience of the best way to produce parts most efficiently.”

The Speedio M140X2 has a machining volume of 200 x 440 x 305 mm and incorporates a 2000 rpm turning table. Together with the +120° to -30° swivel of the trunnion carrying the table, the two extra rotary CNC axes are useful for automatically positioning components in-cycle for predominantly three-axis machining, although there is some four- and five-axis simultaneous metalcutting within certain cycles.

High machining productivity comes in part from simultaneous movement in the X, Y, Z, A and C axes, plus tool change when the machine is not cutting. Tool change time from the 22-position magazine is 0.9 seconds, giving 1.4 seconds chip-to-chip, while spindle start/stop is completed in 0.2 seconds. Cutting feed rate is up to 30 m/min, with 50 m/min rapids.

The Feedio robotic component handling system option exploits this speed to the maximum by delivering parts to the spindle faster than an operator is able to, and without interruption. The plug-and-play automation unit, which communicates with the machining centre via a Profibus interface, features a six-axis ABB robot and the manufacturer’s smart teach pendant incorporating a customised Speedio page.

A camera-based vision system and built-in PC allow the robot to detect raw material on the upper input conveyor. After machining, components return to an output conveyor positioned below the first.

Martello regards the Brother cell, based on very fast 30-taper machines, as being the ideal solution for machining aluminium components, in this case for medical applications. The five-axis capability and turnover station enables the completion of mainly 3+2 machining in two operations without manual handling. Some fully interpolative five-axis sequences are also completed. Jobs requiring straightforward three-axis prismatic cycles without any need for the rotary axes will in future be machined in the cell, if expedient, simply to take advantage of the automation.

“This was new technology for Roscomac and we leant quite heavily on Whitehouse in the early days,” concludes Martello. “We have received very good support from this supplier throughout, with their engineers sometimes on-site at weekends, which was especially important in view of the urgency of the COVID-related work. As the very large volumes associated with the pandemic subside, there will still be a lot of medical work around due to the backlog of elective surgical procedures. We can use the Speedio/Feedio cells to fulfil these contracts more economically.”

For further information
www.wmtcnc.com

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

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

From that moment onwards, HPC’s approach has been to acquire the latest, most productive CNC equipment available, designed to slash production times, reduce costs and improve component quality.

Over the intervening 24 years, Cobb has bought around 20 CNC sliding-head, twin-spindle lathes of nominally 12, 20 or 32 mm bar capacity, all from the same supplier. Ten Cincoms are in operation, following systematic replacement of the others with newer models. There are also seven fixed-head, twin-spindle CNC lathes on the shop floor of the current premises, which houses around 30 employees.

When Cobb launched HPC, he took with him from Hemlock one production job to get started, a shaft for a sell-by date label printing machine. The food industry still accounts for around one-third of HPC’s turnover. This job previously involved turning the component in two operations, after which it was ground and then milled on a machining centre, all in a total cycle time of seven minutes. On the Citizen L25, he completed the same job in one minute as part of a one-hit set up. Today, HPC machines the parts on a different slider at a rate of 1000 per month.

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

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

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

Today, HPC has some 5000 different part numbers on its books. Components are produced from 38 mm diameter bar or smaller on the Cincoms. Quantities range from 100 to 40,000 in a vast range of materials, from exotic alloys, through stainless steels, brass and aluminium, to plastics. The two million parts machined annually account for two-thirds of the company’s £3m annual turnover, the remainder being fixed-head turning. HPC reinvests some 10% of revenue every year in new plant and equipment, a proportion that also applies to Hemlock’s £7m turnover.

One of the latest components produced at HPC in one hit on a sliding-head lathe requires only milling. The company machines the parts on one of two recently delivered Cincom M32-VIIIs of a radically different design compared with the earlier M32s on site. The first of the new machines arrived in November 2020 and Cobb was so impressed with its performance that he bought another a month later.

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

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

“The difference is amazing,” states Cobb. “It is possible to machine exotic alloys at double the speed compared with a fourth generation M32, and you get four times the tool life, especially as coolant is now delivered through the tool platen as well as the turret. It is a massive step up in performance. A 10 mm cutter purrs into the bar, even using a mill with carbide inserts rather than a solid-carbide tool, which we need to use on the earlier M32s. Any production engineer would know that the new model is a very rigid machine.”

Other aspects of the latest design that he appreciates are the increased number of driven tools and a platen tool post with a programmable B axis, which is useful for producing angled features on components and performing front working.
Cycles for many jobs are significantly quicker. For example, when producing a particular 303 stainless steel flange from 38 mm bar, it was previously necessary to wait for the turret to become available to deburr the component. At 57 seconds, the cycle time is now 25 seconds quicker, representing a saving of 30%.

Just as important for reducing production costs is the ability to swap the machine over in half an hour to guide bush-less mode, thus saving remnant wastage when producing relatively short components like the flanges. In this case, it is possible to produce 262 parts from a 3-m bar, compared with 225 if the guide bush is in place. With 5000 of the flanges produced annually, the saving is significant.

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

Citizen had recently invented its patented, low-frequency vibration (LFV) software that breaks such swarf into short, manageable lengths. Running in the Cincom’s Mitsubishi control, the facility can switch in and out of a programmed cycle by G-code command.

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

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

For further information
www.citizenmachinery.co.uk