EDM boosts quality and lead times

Excel Precision Group has enhanced its wire and spark erosion capabilities by acquiring two new Sodick machines from Sodi-Tech EDM. Installed at the company’s Gloucester facility, which has AS9100 rev D and NADCAP AC7116/3 Rev B approval in place for both spark and wire erosion, the arrival of the Sodick ALC600G wire EDM and AG60L die-sink EDM will underpin a number of important contracts across both the civil and military aerospace markets.

Established in 1978, Excel Precision Group operates from two modern facilities in Gloucester and Leeds, which together house over 30 CNC wire and spark erosion machines. This capacity, along with its accreditations, make Excel one of the leading EDM subcontract operations in the UK, with particular emphasis on aerospace and defence.
“Few EDM subcontractors have both AS9100 and NADCAP approval,” states Steve Batt, operations director at the Gloucester facility. “This level of process control allows us to serve an extensive number of aerospace and defence customers. In addition, we currently hold company approvals from BAE Systems, Rolls-Royce, Goodrich, Safran Landing Systems, Dowty Propellers, Messier Dowty, MT Satellite, GE Aviation, Moog Aircraft Group, UTC Aerospace Systems, Mettis Aerospace and Triumph Actuation Systems.”
Along with the need to replace older machines, part of the reason behind the company’s investment in Sodick technology was due to the imminent ramp-up of an existing defence contract that is currently scheduled to run until 2022. An NDA has been signed, so details are scant, but the parts involve the intricate wire erosion of titanium stock.
“We looked at both Sodick and our existing supplier of EDM machines, but the test cuts provided by Sodi-Tech EDM were simply better,” says Batt. “In particular, the surface finish produced by the AG60L spark eroder really caught our attention. Due to the presence of debris, some machines struggle to replicate the surface finish achieved on the sides of parts, on the bottom face. However, this proved no such issue for the AG60L.”

Excel Precision’s AG60L has been set to work producing a variety of aerospace parts, including stainless steel actuator components. In total, the aerospace sector commands about 40% of the machine’s time. The other Sodick machine, the ALC600G wire EDM, has around 50% of its output sent to aerospace customers, including the titanium defence part.
“Compared with our old machines and process, using the ALC600G has transformed our operation for this component,” says Batt. “For a start, we previously needed two machines, whereas now the part is completed in its entirety on the ALC600G. Also, our old machine would only achieve a 90% pass rate on an angled face with a
5 µm tolerance. With the Sodick machine, the pass rate is 100%. That step-up in quality makes a real difference on high value-added parts such as these.”
Excel Precision is currently tasked with producing 200 of the titanium defence parts every month, although this figure will shortly rise to 600. Using the ALC600G, the company can produce around 24 per day. However, with work for other sectors, both Sodick machines run 24 hours a day, four days a week, with long cycle-time jobs loaded at the weekends. Aside from aerospace and defence, the company serves further high-end industries such as motorsport, nuclear, oil and gas, and medical.
“We’ve not had Sodick machines at Excel since before 1995, but we’re very pleased to make the switch back,” says Batt. “The technology has moved on considerably and we cannot fault the machines or the team at Sodi-Tech EDM, who have been very supportive since installation in early 2019. Through our own mistake, we once accidently set off the fire extinguisher on the AG60L, but the response was excellent and we were back up and running the next day.”
Excel Precision actually began life in Leeds, but started the Gloucester operation seven years ago through acquisition. The machines at Gloucester were around 20 years old and the company has since been progressing its way through a steady replacement programme.

“One thing we’ve noticed is the compact nature of the Sodick machines,” says Batt. “We were able to fit both Sodicks into the space previously taken up by one older EDM. Also, while we didn’t buy the machines for speed, it’s difficult not to notice the gains we’ve achieved. The titanium defence part previously had a cycle time of 65 minutes, but it’s completed in just 35 minutes on the ALC600G wire EDM, a 46% improvement. As for the AG60L die-sink machine, the results we get, particularly on deep cavities, is like nothing we’ve seen before. We have also reduced our electrode consumption dramatically; we now complete many jobs using just one electrode.”
Good growth over the past two years has seen Excel Precision Group hit an annual turnover of £2m, and more growth is expected moving forwards.
“There are many factors that set us apart from competitors, not least the capacity we offer and the accreditations we hold,” concludes Batt. “In addition, we believe the level of work and service we provide is second-to-none. It’s all about quality, on-time delivery and customer communications, all backed up by investing in the latest technologies.”
For further information www.sodick.org

HMCs double productivity and improve accuracy

In its 25th anniversary year, the Plymouth plant of hydraulic motor, pump and valve manufacturer Kawasaki Precision Machinery has seen a far-reaching reorganisation of its K3VL axial piston pump machine shop. This initiative follows the purchase in October 2018 of a pair of twin-pallet, horizontal-spindle machining centres (HMCs) from Heller Machine Tools to replace two ageing, double-pallet models on which it was becoming difficult to hold tolerance.

One of the new Heller H2000 HMCs, which are manufactured at the supplier’s factory in Redditch, is devoted to machining pump cases, while the other HMC mills and drills valve covers. The components are produced from grey iron castings that have had their bores pre-turned on a lathe in preparation for two-operation prismatic machining. Around 20,000 of each component are produced per year.
Production engineer Mark Pellow says: “In the case of the valve cover, the machining time of 50 minutes plus 10 minutes load/unload on the former production centre has been replaced by a 32-minute cycle on an H2000. For the pump case, the former machining time was 48 minutes plus 10 minutes, for handling, while the current cycle takes just 30 minutes.
He adds: “As set-up is carried out on the other pallet during machining, the next component is presented to the spindle within seconds by automatic pallet change (APC), so productivity has been nearly doubled for both components.”
The two process routes have been changed to enable such a significant increase in output. Parts are still loaded two at a time on a tombstone for op 1 and op 2 machining. One difference now is that fixtures have been built into a suite of tombstones to accept the castings directly, rather than first having to mount the parts on to work-holding plates. The latter double-handling procedure used to eat into much of the spindle uptime on the previous machines.

There is a second, even more important difference, however. When nearby Morris Engineering produced the work-holding solutions for Kawasaki, it arranged the two fixtures so that one is on a tombstone face and the other is mounted across the top, improving tool access. The result is that any given tool can machine more features throughout the whole cycle, the program no longer being split into two, so fewer tool changes are needed, leading to less idle time. Tool exchange itself is also faster at 2.8 seconds chip-to-chip, as are rapid traverses at up to 90 m/min around the 630 mm working cube.
In-cut times are shorter as well on the Heller horizontal machining centres due to the faster cutting feed rates and spindle speeds. This cutting data is coupled to the use of Seco’s latest insert-based and solid-carbide tooling having long service life, reducing the need for worn tool replacement. A 6.2 mm diameter solid-carbide drill now produces holes to depth at a fast feed rate, for example, compared with the previous need for a high-speed-steel drill to peck in 5 mm increments up to 20 times at a slower infeed. The use of carbide form drills from UTT also speeds hole production.
Further savings within the machining cycles derive from better probing of more features for establishing workpiece position, which allows most fixed datums to be live, minimising operator adjustments relative to them.
Not only is productivity almost doubled by the new processes, but accuracy of machining is also improved, allowing tolerances to be held easily. For instance, 50 µm valve cover concentricity, 20 µm servo piston concentricity and 0.2 mm dimensional accuracy on bolt holes are held to support a process capability of at least Cpk 1.33. Previously, some tolerances when checked on the Mitutoyo shop-floor CMM were close to their limits and engineering intervention was frequently needed.
Currently, production for one pump frame size is carried out on the Heller H2000s, but a further two sizes will be phased in over the coming months, entailing more than 30 part numbers encompassing all variants.
As to Kawasaki’s choice of Heller HMCs for this latest project, bearing in mind there are already two other brands of horizontal-spindle machine on the shop floor and a fourth was also considered, Pellow says: “As is often the case with machine tool purchases, we constructed a checklist of machine attributes from speeds and feeds, through health and safety features, to price.

“In this appraisal, 19 items were listed on a spreadsheet and Heller’s overall score came out on top,” he adds. “The fact that we use four other Heller HMCs that are about a dozen years old yet are still reliably producing a valve block and two cases for our KV3 pump, also helped the decision-making process.”
For further information www.heller.biz

Filtering out secondary operations

Headline Filters in Aylesford, Kent has taken a big step towards streamlining the manufacture of its components by adopting twin-spindle turning and five-axis machining to reduce set-ups and take advantage of lights-out operations.

New process routes for around half of the factory’s production of bonded microfibre filter housings involve four new CNC machines installed between September 2018 and July 2019: three turning centres with Y axes from Biglia, Italy, and a German-built Spinner machining centre with trunnion-mounted rotary table. All of the machines were supplied by UK agent Whitehouse Machine Tools.
A backlog in multi-operation turning and milling of a particular filter part, a complex stainless steel head designated ‘112’, prompted the manufacturer to look for a more productive solution. The obvious choice was a lathe with powerful driven tooling and twin-opposed spindles to enable in-cycle machining of the reverse end of the component.
Space is limited on the shop floor in Aylesford and the machine initially considered was too large to be conveniently installed. Whitehouse demonstrated how the more compact Biglia B565-YS lathe, which was also half the price, could do the job – provided it was fitted with double, triple and quad tool holders in its 12-station turret so that the requisite number of tools could be deployed.
Programs were written and time studies carried out at Whitehouse on this part, as well as two other components, and the feasibility of all processes was confirmed. The first Biglia B565-YS was installed in September last year and ran for several months to clear the ‘112’ component production backlog.

Rob Hibberd, director of Headline Filters says: “As soon as we saw the lathe producing the stainless steel components in one hit, we knew it was the way forward and quickly ordered a second identical model, which arrived at the end of last year. The previous production method involved turning on two separate single-spindle lathes and three set-ups on a three-axis vertical machining centre, so five ops in all. Total cycle time was 17 minutes, including three minutes for repositioning the part on the VMC.
“The new cycle time of 16 minutes on the Biglia is not much different, as its driven tooling cannot compete with the milling power of a machining centre,” he continues. “However, the big advantage now is that there is no inter-machine handling or work-in-progress, and production is minimally attended, so the operator can look after several machines. Even more importantly, we can take advantage of unmanned ghost shifts for extra production output. We gain up to eight hours overnight when machining aluminium and brass parts, and a couple of hours when running stainless steel before the tips become blunt and the lathes shut down automatically.”
He adds that a further advantage of single-hit production is the ability to better hold tolerance, as no cumulative errors are introduced by repeated re-clamping. Run-out is improved and ±0.05 mm tolerance is easily held on O-ring seal faces. Surface finish is also enhanced due to the stability of the Biglia lathes and the ability to run modern tooling at the recommended feeds and speeds, so less subsequent polishing is needed. It is also notable that tool life is prolonged on these lathes due to their rigidity.
In another before-and-after example, an aluminium ‘360’ filter head previously needed turning on a lathe and prismatic metal cutting on a machining centre, taking 12 minutes (including handling between the two machines). The part is now produced in one hit in an 11-minute cycle on a B656-YS bar auto. Again, the main benefits are a reduction in work-in-progress, better accuracy and the ability to automate production.
Whitehouse facilitated unattended running by fitting to each lathe a Hydrafeed MSV80 bar magazine for feeding 1 m stock through the spindle and providing a Rota-Rack rotary parts accumulator to collect finished components delivered via a parts catcher and conveyor. The B565-YS lathes were supplied with a bigger spindle bore than usual, 75 mm rather than 65 mm, to enable the production of Headline Filters’ larger parts in high volumes.

Above this diameter batch sizes are lower, but recently the manufacturer’s US distributor started to request bigger products in higher quantities, which put pressure on the company’s single large-capacity turning machine. Positive experience with the first two Biglias again pointed Hibberd in the direction of Whitehouse, which in April 2019 supplied the largest capacity version of a twin-spindle Biglia 750-YS with Y axis and C axis.
The Biglia 750-YS is capable of turning components up to 552 mm diameter by 765 mm long, far larger than needed. More pertinently for Headline Filters, it is possible to use a bar puller in the turret or, alternatively, the counter spindle to feed stock up to 100 mm diameter through the bore of the main spindle into the working area to simulate the advantages of having a bar feeder. A 38 kW main motor, 17.5 kW driven tools in the 16-station turret, rotational speeds up to 10,000 rpm, plus the availability of high-pressure coolant, promote productive machining.
An early example of time advantage using this machine involved the production of a ‘380’ aluminium filter head in one operation in a cycle time of 15 minutes 50 seconds. Previously, using the other large lathe, which is of single-spindle design without driven tools, the part had to undergo two operations and then be transferred to a machining centre for milling and drilling. The three operations took 21 minutes 15 seconds, plus handling between machines.
As 15,000 of these parts are needed annually, the production cost saving is considerable. Work-in-progress is eliminated, avoiding the need to have batches of typically 400 part-finished components in storage. Moreover, as Hibberd points out, each part can be assembled into a filter for delivery and invoicing straight away, not days or weeks after machining operations have been completed.
A previous difficulty in the factory was that six lathes with limited or no live tooling were feeding components to a pair of overloaded, entry-level VMCs with 7000 rpm spindles for milling and drilling. That problem was alleviated by the arrival of the three Biglia lathes with their driven cutters, so the machining centres were able to cope. However, with an eye to the future, Headline Filters decided to invest in its first five-axis machining centre to boost prismatic metal-cutting capability.
The Spinner U5-630 five-axis VMC supplied by Whitehouse in July this year with 12,000 rpm BT40 spindle, provides more productive machining as higher rotational speeds increase metal removal rates and enable the use of more capable, contemporary tooling. A large magazine for 32 cutters, high-pressure coolant and Blum probing for setting tools and workpiece datums, form part of the production package. The extra power and rigidity will help when producing filter parts from tough materials, not only stainless steel, but nickel and titanium alloys.

Jason Rose, engineering and workshop manager, says: “We use the Spinner mainly in 3+2 axis mode for automatic workpiece positioning to reduce the number of manual set-ups. Nevertheless, we have a certain amount of contour milling to do and, when I design new products in future, I’ll have greater flexibility to incorporate features that would be uneconomic or impossible to complete on a three-axis, or even a four-axis VMC.”
He also advises that the U5-630 is significantly faster at cutting metal than the other machining centres on site. In one example, a 12-minute cycle was reduced to seven, and in another, 45 minutes was reduced to 20. There is potential to improve on these times further as Headline Filters’ operators become more familiar with the new cutters they can now use, as well as the Siemens control system, which is the first on site.
For further information www.wmtcnc.com

Gearbox casings produced up to 66% faster

Replacement of an ageing, single-table, horizontal-spindle machining centre with a new, German-built Burkhardt + Weber (BW) twin-pallet model supplied by UK agent, Kingsbury, has revolutionised the machining of industrial gearbox casings at Rochdale-based Renold Gears. The gearbox casings are produced mainly from iron castings and fabrications, but also from steel and aluminium.

The resulting savings in floor-to-floor times of between one-half and two-thirds are due to increased metal removal rates during cutter engagement, significantly reduced non-cutting times through faster axis movements, fewer operations due to better fixturing methods and faster component changeover through offline set-up on the second pallet.
Furthermore, with the twin-pallet configuration, if there is an issue during the machining of a component it can be brought out of the working area for inspection, allowing production of the next part to commence. Such troubleshooting would have resulted in a lot of unproductive time on the previous machine.
Renold’s gearboxes are large prismatic components that can measure more than 2 m in height and weigh up to 3 tonne. Around 20% of the products manufactured are standard, with the remainder being customer-specific designs that are produced in quantities of between one-off and 30-off per month. Fast, flexible machine tools are needed to produce such relatively low batch sizes in a cost-effective manner and allow the manufacturer to compete in world markets.
When the company’s CEO was appointed in 2013, he instigated modernisation initiatives that started with the factory infrastructure. A programme followed of drive and control retrofits and mechanical upgrades to what are fairly specialised machine tools, such as worm screw and wheel production centres.

Three years later, the company’s production workers were asked which machine on the shop floor they would most like to replace, and the large horizontal machining centre was almost unanimously chosen. By then, this machine’s unreliability was resulting in sometimes having to outsource machining to meet production deadlines. After several twin-pallet HMC options had been considered, the decision was taken to purchase a BW MCX 1400 with a 3200 by 2200 by 2000 mm working volume and B-axis NC table.
A senior manufacturing engineer at Renold Gears says: “During trials, the BW machine proved capable of more than halving the cycle times on the old HMC, and was also more productive than the other four-axis machines with pallet changers that we considered. We gave two test parts to each potential supplier: a gearbox casing for a heat exchanger and another for an escalator drive. On average, they were machined around 15% quicker on the MCX1400.”
Key elements of the machine specification that deliver this high productivity are acceleration of up to 5 m/s² to rapid traverse speeds of 60 m/min, and a 60 kW/3500 Nm/5000 rpm spindle with HSK-A100 interface.
The engineer at Renold Gears adds that other factors favouring the chosen machine were its availability on short delivery, as well as its ergonomic design, which promotes safety when personnel approach to access the working area or carry out servicing while it is running. Additionally, the 180-pocket tool magazine (extendable to 330) is helpful, as a large number of cutters are needed to cope with Renold’s wide range of gearbox casing sizes and materials. A majority of these tools can be permanently resident in the magazine.
Drawing tolerances are tight for such large components, down to 20 µm in total for certain machined features like gear centres and shaft bores, some of which are produced by interpolation milling. The reliability and repeatability with which this level of accuracy is achieved on the MCX 1400 means that downstream benefits are experienced in the metrology department. CNC inspection is faster, as it requires less comprehensive routines and fewer components need to be checked.

Kingsbury prides itself on providing a production solution rather than a machine tool. While the BW installation at Rochdale was not what the supplier would class as a full turnkey project with tooling and fixtures, which Renold provided itself, it nevertheless entailed significant early support.
Initial test programs were converted directly into cycles for production parts covering two families of casing, while further programming support was provided along with on-site operator training. Service is carried out by Kingsbury’s own engineers via the company’s divisional LPM (Large Prismatic Machines) offices in Warwick.
The engineer at Renold Gears concludes: “We’ve also been migrating the machining of our custom gearboxes and some standard product across to the BW machine to take advantage of its high productivity. It already does the work of the old horizontal machining centre and another machine, and we’re looking to consolidate jobs on the BW that we currently put on a third machine. Once a process is in place on the MCX 1400, it eats the work.”
For further information www.kingsburyuk.com

Takumi takes off with hyperMILL

A name established from the Japanese term for craftsman or artisan, ‘Takumi’ Precision Engineering has been delivering both craft and artisanship to the shores of Ireland for over 20 years.

The Limerick-based company has invested heavily in recent years with a new factory expansion that has taken floor space to 50,000 sq ft, and over €5m invested in new machine tools and CAM software to further extend its market position on the Emerald Isle.
Takumi Precision is a prominent figure in the medical device, pharmaceutical, aerospace and precision engineering sectors in Ireland. The company manufactures orthopaedic implants and instruments, cardiovascular assembly aids, medical grade rasps, balloon moulds, and delivery system components, as well as aluminium wing and fuselage components for the aero industry, and electrical, electronic, mechanical and optical engineering parts for the precision machining sector.
Down the years, Takumi has invested in turning centres from Tornos, Doosan and Miyano with three- and five-axis machining centres from Doosan, Spinner and, most recently, Matsuura adding to the plant list. One of the company’s core investments has been hyperMILL CAM software from Open Mind Technologies, which was driven by the onset of barrel tool technology, an influx of five-axis machines and challenges with previous CAM systems.
Commenting on the changes at Takumi, managing director Gerry Reynolds says: “Only five years ago, 90% of our work was in the medical industry, with the remaining work being across a number of sectors, including the aerospace market. We had an opportunity to enter the aerospace segment in a more positive way, increasing volumes from 1 to 3-offs, to continuous batches of 10-15-off, on the Airbus A220, previously known as the Bombardier C-Series. We had to invest in five-axis technology to accommodate the ramping-up of this complex aerospace work, so we bought 13 five-axis machines in the past five years.”

The investment has paid dividends, with aerospace work increasing from 5% of turnover to almost 60% in less than five years. However, this success is not to the detriment of the medical business, as Reynolds continues: “Our business has doubled in size over the past three years due to the increased aerospace work, but the medical sector remains crucial to Takumi. Medical components are now 40% of our business; the volume of work has not reduced, it just hasn’t grown at the level of the aerospace work. We now have 87 staff and are targeting a monthly turnover of €1m.
“Around 10 years ago, I didn’t understand CAM and would have argued against it,” he adds. “However, there was a necessity for CAM to run our machines and at the time I called it ‘finger CAM‘, as we were programming at the machine. We progressed to a more comprehensive CAM system and eventually installed eight seats. However, a visit to the AMRC in Sheffield introduced us to Ceratizit’s barrel tools and Open Mind’s hyperMILL CAM system, which changed the game.”
After investing heavily in CAM software, Reynolds was naturally apprehensive at the prospect of changing software again.
“Over the past 5-6 years, we’d spent a lot on CAM packages and what we had, worked relatively well, but there were a few issues with processing speed, occasional crashes and some feature limitations,” he says. “It was the barrel-tool machining features within the hyperMILL MAXX High Performance Strategy that appealed to me, but I wanted my team to take the lead, as they would be the ones using the software.
“The team did their due diligence, taking in hyperMILL demos and then asking our existing CAM vendor if the barrel-tool feature and the mirroring package were available,” adds Reynolds. “Our CAM supplier and other vendors all said ‘it’s on its way’ or ‘it’s in development’ regarding more than just these two features in hyperMILL. That told us all we needed to know about the various vendors in the market, but it told us a lot more about hyperMILL. They are clearly streets ahead of the other CAM developers. We have rapidly moved to hyperMILL; we bought our first seat 18 months ago and now have six seats. Our previous CAM system is currently being phased out.”
Primarily, the reason Takumi Precision invested in hyperMILL was the potential of barrel tools to significantly improve productivity.
Commenting on this capability, Reynolds says: “The hyperMILL MAXX Machining High Performance Package and the respective barrel tools with their innovative geometry allow us to step-down 5 to 10 mm, as opposed to 0.4 to 0.8 mm, when finishing pockets, walls or profiling features. This has instantly reduced finishing cycles by at least 70%, giving us a minimum overall cycle time improvement of 30% on every component.”
However, the benefit is not just the cycle time improvement.

“We’ve historically had a number of staff undertaking finish-polishing of parts to ensure our surface finishes exceed customer expectations,” he says. “Despite the increased speed and step-over rate with hyperMILL MAXX High Performance Machining, the surface finishes are much better than before. This is because the barrel tool has a higher engagement rate that keeps the tool in constant contact with the workpiece.”
Another feature that persuaded Takumi Precision to invest in Open Mind CAM software was the mirroring function, as Reynolds explains: “In the aerospace industry, almost everything is manufactured with a left- and right-hand component. The mirroring feature in hyperMILL is remarkably comprehensive and, with the touch of a button, we’re reducing our programming times on most components by 50%. We have eight programming staff and the mirroring feature in hyperMILL is effectively doubling the productivity of this team.”
Although hyperMILL has reduced cycle times on the shop floor by over 20% and reduced programming times by upwards of 50% in the office, the benefits reach much further.
“Open Mind’s hyperMILL is much faster than previous CAM systems and it handles ‘big data’ much better than we’ve previously witnessed,” states Reynolds. “This has eliminated unforeseen PC crashes and massively improved the reliability, processing and delivery of our data to the
shop floor. Furthermore, Open Mind’s hyperCAD, which is integrated into hyperMILL, is an excellent platform that has eliminated our reliance on CAD packages such as Inventor. We can now expedite jobs through hyperCAD to hyperMILL with ease.”
For further information www.openmind-tech.com