Getting into gear with new mandrel

Hard work and first-class teamwork between gear manufacturer Hänel and Hainbuch has certainly paid-off. The new Mando G211 mandrel for gear manufacturers is particularly suitable for gear hobbing, cutting and grinding, and this has been demonstrated at Hänel. Now available as a standard mandrel from stock, this solution for gear cutting has optimised the manufacturing process, reduced set-up times and improved gear quality, largely credit to the stable clamping features that dampen vibration.

When a new product like the Mando G211 mandrel is launched, it must be tested thoroughly under real-world conditions. In this case, Hainbuch was looking for a reliable partner capable of testing a prototype, and the company approached Hänel GmbH & Co KG from Bad Friedrichshall, Germany.
Commenting on its willingness to participate, Jürgen Renner, the production manager at Hänel GmbH, says: “We already had positive experiences with Hainbuch clamping devices, so for us, the whole thing sounded promising from the very beginning. We saw the potential for improvements in our manufacturing and processes – that’s why we agreed. I must add, our management is very open to such partnerships and, if it results in rewarding optimisation and keeps investments manageable, nothing stands in the way of such a project.”
Hänel initially received two prototypes of the Mando G211 mandrel in sizes zero and two. The mandrels were tested on a Richardon R400 manual loading machine and a Gleason-Pfauter GP200 hobbing machine with automatic loading to see if they would be compatible.

“For our employees, this new clamping system was very strange, as for 20 years they worked with a clamping system from the machine manufacturer without radial clamping, which worked fine to date,“ admits Renner. “Initially, we had to make some adjustments to the machine and, in addition, we did not reach our zero-line on the Gleasen-Pfauter machine because the mandrel was too tall. As a result, adjustments to the machine and loading system were required. What followed were conversations with the responsible designers at Hainbuch. We have diligently tested and passed on all the information needed to further optimise the mandrel – all design changes were implemented by Hainbuch.”
The revised second prototypes were subsequently made available, undergoing field trials before a few minor adjustments to the machine were made. It was evident that the stiff and slender mandrel could go into series production and be produced for stock.

At Hänel, batch sizes are between 30 and 1000 pieces, which customers specify because of the precision. As a rule, the high-quality gears are hardened and ground, so reworking is not an option.
“With the current clamping system, we couldn‘t achieve good concentricity,” says Renner. “The workpiece was pressed axially downwards. Now it is clamped with the mandrel from the inside, radially outwards. Thus, we have higher clamping stability. This eliminates the reworking of certain components. For some of our orders, the old clamping system was good, because the concentricity was not so important. But basically, the better the concentricity, the easier it works later. With a normal hardened gear, the bore still needs to be reworked, but all the workpieces that are fully geared can now be reduced to one operation.”
Hänel has also improved set-up times with the new mandrel. This time reduction is because when using the Mando G211 mandrel, only the segmented clamping bushing and not the entire clamping system has to be changed. Use of the G211 also eliminates the need for alignment, which of course saves time. Even if the mandrel and segmented clamping bushing have to be changed to a different size, it is still faster. There are only three screws on the mandrel for the support and a screw on the segmented clamping bushing.
“If everything is prepared optimally, and the part family is in stock and can be processed one after the other, we will certainly save 50% of the set-up time,” says Renner. “Not only is the set up faster, but the process is more stable and safer.”
Andreas Hoffmann, head of toolmaking, sees even more benefits: “Thanks to better stability, we can drive higher feed rates. Even tool wear is reduced because we have less vibration.”
Hänel now has six Mando G211 mandrels, the two prototypes and four standard mandrels in sizes zero to four.

Hoffmann explains: “All new components have been manufactured with the mandrel ever since. Even with older components, we try to change over to the mandrel clamping because the segmented clamping bushings from Hainbuch can be delivered within one day. That’s a huge advantage for us.”
“For me, it is incomprehensible that we have not worked with Hainbuch before,” Renner concludes.
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Subcontractor progresses to five-axis machining

Craigavon-based subcontractor Boyce Precision Engineering primarily serves the commercial aerospace sector, which accounts for 70% of turnover. A majority of throughput involves producing aluminium parts for first-class and business-class seating, plus various aluminium structural components. Aerospace recognitions include AS9100 accreditation (the global quality management system for the aerospace industry), as well as supply chain recognition SC21 (Bronze Award) and ADS Group membership.

The contract machinist started operations in 2006 and in little more than a decade has made significant strides; the company now employs 34 staff. Earlier this year, Democratic Unionist Party MLA (Member of the Legislative Assembly) for the local Upper Bann constituency, Carla Lockhart, hosted a visit to the firm by party leader Arlene Foster and the chief executive of Invest Northern Ireland, Alistair Hamilton.
In recent years, there has been an increase in the complexity of the prismatic aerospace parts that Boyce Precision manufactures, making a progression from three-axis to five-axis machining necessary. For the new machining capacity, joint owners and brothers George and Brian Boyce decided to move away from the supplier of two-thirds of their three-axis machines. Instead, they opted for a 600 x 550 x 450 mm capacity, German-built Hermle C 250, which was supplied by sole UK and Ireland agent, Kingsbury.
The five-axis machine’s suitability was immediately apparent and a second, identical model has since been installed. The configuration of Hermle vertical machining centres places the three linear axes within a modified gantry above the working area, while the integrated trunnion provides a rigid, stable platform for the two rotary axes, which includes a ±115° swivel for production flexibility. The machines in Craigavon have integral Blum tool breakage detection to allow long periods of unattended running across the two shifts that Boyce Precision operates.
A further trend within the aircraft seating sector is towards larger components, which are even more complex to avoid the labour costs and delays associated with assembly. Once orders for such parts were promised, Boyce had no hesitation in placing an order for a larger Hermle C400 with a working volume of 850 x 700 x 500 mm.

The machine will be delivered in November 2018, directly to a new, 18,000 sq ft factory unit currently being built for the subcontractor in Portadown. Treble the size of the current premises, the building represents a £3m investment, taking into account the capital cost of the third Hermle five-axis machine and the imminent purchase of two further three-axis machining centres.
Boyce says: “As these are our first five-axis machines, ordering the initial one was a big decision. Our company policy is to buy the very best equipment we can afford, not only machines but also work holding, tooling and engineering software.
“We had extensively researched the five-axis vertical machining centre options, but before going ahead with Hermle I had a chance to see how the machines are manufactured at an open house at their factory in Gosheim, which gave me confidence in the build quality,” he adds. “Price and after sales support were also important considerations, and on both counts we felt confident in the Kingsbury offering. Their training of our skilled engineers on the shop floor was seamless, allowing them to pick up five-axis operation quickly.”
The benefits of five-axis machining to Boyce Precision are far-reaching. One-third of the time, the two Hermle C250s are executing programs requiring the interpolation of all five CNC axes simultaneously – work which formerly could not have been carried out.
To fulfil other contracts requiring only three-axis cycles, automatic positioning and clamping of the rotary axes reduces the number of separate operations needed to complete a job, in some cases dramatically. Aerospace parts that used to need two or three separate operations are now completed in one hit.
A pharmaceutical component that previously required eight separate set-ups now requires only two. This sector, together with medical engineering contracts, accounts for 20% of the subcontractor’s turnover, with the remaining 10% spread across automotive , motorsport, TT racing and general engineering. The latter work focuses on contracts for the construction industry, particularly bespoke jigs and fixtures, but also includes the manufacture of items for film sets, such as aluminium-bladed swords, daggers, shield parts and catapults used by actors in the television series, Game of Thrones.

The reduction in the number of set-ups also means that tight tolerances can be held more easily. On some aerospace parts, and even those for the pharmaceutical industry, such
as blister pack tooling, tolerances specified on the drawings are as tight as ± 20 µm.
Boyce says: “Hermle machines are inherently very accurate and able to hold this tolerance easily. The spindle in particular has no discernible run-out. Machine construction is very rigid, which not only ensures accuracy, but leads to longer tool life. The cachet of having Hermle equipment on your capacity list is not to be underestimated.”
He recounts an incident in January 2018 when the 18,000 rpm, HSK 63 spindle of the second Hermle C 250 was accidentally knocked out of alignment by an operator. Luckily, the machine has a patented safety feature in the spindle whereby six mounting bolts with collapsible sleeves crumple and absorb the energy just long enough for the shock to be detected, triggering automatic machine stoppage.
The spindle itself was undamaged and needed only to be remounted with six new bolts, which was done by one of Kingsbury’s local service engineers within a few hours the next working day. This process saved the expense of buying a new spindle cartridge and perhaps also the motor, as well as the costs of more major maintenance and extended machine downtime.
To ensure that there was no underlying spindle damage, vibration analysis files captured at different rotational speeds were sent by Kingsbury engineers to the Hermle factory for evaluation, where it was confirmed that the accident had not caused a spindle fault.
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Winning the tooling race at Tridan

In 2007, Tridan Engineering made a strategic decision to target prestigious aerospace contracts and steer away from commercial, agricultural and power-generation subcontract machining. In the past five years, the Clacton-based company has invested heavily in infrastructure, accreditations and machine tools, which has certainly paid dividends in achieving its goals.

Celebrating its 50th year in business, the subcontractor has spent more than £2.5m in the past two years on new acquisitions, including two Mazak Variaxis i500 machines (as well as an i600 and an i700), a Quick Turn 300 plus a Quick Turn 200MSY. Other recent investments include a six-station Palletech automation system and an additional three machines on order from XYZ.
The investment in high-specification four and five-axis machine tools, and the ever-expanding variety of materials being machined, has prompted a strategic overview of Tridan’s cutting tool strategy. In the two years since deciding to overhaul its tooling strategy, the AS9100-certified company has reduced its cutting tool suppliers from 14 to just two. From the 14 vendors, it is Industrial Tooling Corporation (ITC) that is driving innovation and cost reductions, and standardising cutting tools.
Discussing the logic behind consolidating its cutting tool vendors, Tridan Engineering’s senior production engineer Peter Townsend says: “When it came to cutting tools, our shop floor had no consistency or standardisation, and shop floor staff would order new tools from one of our suppliers as and when they needed them. To consolidate our suppliers, we firstly wanted to eliminate a few of the smaller vendors that couldn’t support our diverse demands. Once we did this, we started 18 months of trials with many of the internationally recognised tooling brands.
“During this process, we were going beyond trialling one vendor against another based on the usual parameters of tool life, performance and cost reductions,” he continues. “We were looking at the complete package: the service and technical support; the rapport between our engineers and the tooling representative; the diversity of the product portfolio; and of course, performance, consistency and cost were always key parameters. In fact, the arrival of a twin-pallet machine and a six-station pallet system means that reliable performance and longevity for lights-out running has become more prevalent than ever.”

During the trial period, ITC was fast emerging as the front runner to win the solid-carbide round tooling business from Tridan. This preference emerged from the relationship between ITC’s technical sales engineer Gary Bambrick and the Tridan engineers and shop-floor machinists. However, with tooling manufactured in Tamworth, it was the rapid turnaround on standard and special tools that also impressed Tridan.
Says Townsend: “We manufacture families of aluminium frame racks for the aerospace industry in batches of 10-off every couple of weeks. With a significant amount of material removal, we applied the ITC 49G9 series of ripper end mills with through-coolant and a trochoidal strategy that was recommended by Gary. This immediately reduced the cycle time from 6 hours to less than 5 hours, a 20% reduction.
“With these racks there are a number of thin walls that needed machining and the tools were pushing against the wall, generating different wall thicknesses and wavy surface finishes,” he adds. “Gary worked closely with us and ITC’s Tamworth headquarters to change tool geometries, edge preparation and corner radii on a 10 mm diameter 3081 series end mill that was used for finishing the thin wall profiles. This not only resolved our technical issue, it demonstrated the expertise and the level of support from ITC.”
With the arrival of the six-station Palletech system, Tridan is achieving upwards of 140 hours of production every week on its latest Mazak machining centre. Manufacturing titanium alloy enclosures for the aerospace sector, the cell has been producing 50 parts per week with a cycle time close
to 3 hours each.
The philosophy of this cell is to maximise machine utilisation and, using ITC’s solid-carbide VariMill end mill tools, Tridan was attaining four days of tool life from each end mill. To extend tool life further, Bambrick suggested a diamond-coated end mill. The result extended tool life from four days to seven, a 40% improvement. With 90% of tools in the cell being supplied by ITC, Bambrick is currently investigating additional opportunities.
Another special application that was causing tremendous difficulty was a nose cone for the defence industry. The titanium cone had a roughing cycle time of 45 minutes that ITC reduced to 25 minutes with a five-fluted ripper, a significant saving on a batch of 100 parts.
Following internal rough machining, the cone requires a series of slots and features, and the limited reach inside the cone caused tool vibration that was impacting upon tool life. The previous end mills were wearing out rapidly through vibration, typically after machining just three parts.
“With the combination of the challenging aluminium alloy material and extended reach requirement, the vibration being created was ruining cutters,” says Townsend. “Added to this, the slots have a 0.03 mm tolerance that we struggled to hit because of the vibration. ITC developed a 2.8 mm diameter extra-long end mill on a 12 mm shank that instantly eradicated the vibration, and improved surface finish and tool life. The new tool ensured we were easily within tolerance, while tool life went from one tool for every three parts, to five tools for the full batch of 100 parts. This gave us consistency, reliability, conformity and it meant we didn’t have to keep changing tools and checking parts. We have a number of ITC tools that have been running for weeks on this family of parts.

“Following the benefits of ITC tools in our production cell and the proven success of the VariMill 4777 series, we trialled the same VariMill roughing tool on a chassis part for the defence sector manufactured from S154 hardened steel (321HB),” he continues. “We were using a high-feed indexable end mill from another supplier and were burning out 2-3 insert edges on each part. Although this sounds like a high burn-out rate, the cycle time was 12 hours per part for each of the 30 components. Gary once again recommended the 4777 series and it slashed the cycle time from 12 hours to 3, and we managed to complete a full batch of 30 parts with just two end mills. This was a 70% cycle time reduction and a 90% tool life extension. We cannot credit Gary and ITC highly enough for the quality of their service and products.”
The tooling strategy at Tridan is continually evolving to suit the ever increasing material diversity and lights-out production requirements. Tridan has selected its two primary vendors based upon indexable and solid-carbide tooling solutions with a number of small vendors still being a necessity for special applications.
Concluding on this point, Townsend says: “ITC has proven that its solid-carbide end mill and drilling lines can outperform everything we have trialled. But most importantly, the support from Gary Bambrick has been exemplary. Gary has not only instigated the introduction of new products, but also new strategies to enhance productivity.”
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Leaving nothing to chance

Specialist tooling solutions supplier Cogsdill-Nuneaton has recently invested in a new Doosan vertical machining centre from Mills CNC. The machine, a DNM 6700, has been installed at the company’s 27,000 sq ft facility, where it is being used, primarily at this moment in time, to produce precision components for Cogsdill’s range of ZX facing and contouring-head tooling systems. These components include different sized front-mounted cross slides, with slide ranges from 200 to 900 mm, which are machined from nitrided and carbon steel.

The decision to invest in the new Doosan DNM 6700 machine followed an internal review undertaken by Cogsdill into its existing CNC machine tool capabilities and, in particular, whether current milling capabilities were adequate to meet growing demand from customers worldwide for its large-capacity tooling solutions.
Says Lee Donaldson, executive director, Cogsdill UK: “We invest regularly in advanced CNC machine tool technologies, and the audit and review highlighted a potential improvement opportunity within our existing CNC milling capabilities.”
With global demand for its larger tooling solutions on the increase it became clear to management and production staff at Cogsdill that investment in a new, reliable and large-capacity vertical machining centre was required.
“To ensure we acquired a vertical machining centre that matched our needs and expectations we did our homework and created a ‘key criteria’ checklist before investigating the market,” says Donaldson.
In addition to the working capacity of the new machine, other requirements included the machine’s cutting performance, its availability and price, as well as the scope and scale of the technical back-up and aftersales support services provided by the machine tool supplier.
“Although we hadn’t invested in a Doosan machine tool previously, we knew that Doosan machine tools have a good reputation in the market, and that Mills CNC, the exclusive distributor of Doosan machines in the UK and Ireland, is a successful company with a significant market presence,” says Donaldson.

Cogsdill also had direct experience of working in collaboration with both Doosan and Mills CNC as a technical partner; supplying advanced tooling solutions to both. A recent example involved Cogsdill working in partnership with Doosan and Mills CNC to deliver a turnkey process for auto-loading facing heads, boring tools and splining tools, into a Doosan horizontal boring machine (a DBC 130) for a US-based oil and gas customer.
Following extensive research into the market, Cogsdill ultimately decided on investing in a new DNM 6700 vertical machining centre.
The DNM 6700 is a large-capacity vertical machining centre equipped with a work table measuring 1500 x 670 mm and axis travels of 1300 x 670 x 625 mm in X, Y and Z. A high-torque (118 Nm) direct-drive spindle (18.7 kW/12,000 rpm) also features.
Says Donaldson: “The working envelope of the machine was of critical importance, and the DNM 6700 large-capacity working envelope enables us to machine larger components [as well as smaller components] in a single set-up. This means faster production and reduced part cycle times.
“Similarly, the cutting performance of the machine was important,” he adds. “The DNM 6700’s direct-drive spindle technology gives us ability to achieve high volumetric removal rates when required, as well as fine finishes. It is a very versatile machine.”
To increase the machine’s flexibility further still, Cogsdill, as part of its investment in the DNM 6700, also ordered a 4th/5th axis unit to be supplied with the machining centre.
In terms of availability, Mills CNC has at least 70 new Doosan machines, at any given time, in stock at its technology campus in Leamington. A significant proportion of these machines comprises its best-selling DNM vertical machining centres.
“The quick availability of the new machine was important,” says Donaldson. “We attended MACH 2018 where we visited Mills CNC’s stand and supplied them with a ‘letter of intent’ to purchase a DNM 6700. Just a few weeks after the event, once we had acquired external grant-based funding, the machine was delivered, installed and commissioned.
“I have to say that we were presently surprised with the machine’s price,” he continues. “There is a lot of technology and functionality packed into the DNM 6700 and, while price isn’t everything, it clearly is an important factor when making any capital investment.”


With regard to support, all Doosan machines supplied by Mills CNC are backed by the company’s aftersales service and support.
“Mills CNC’s reputation in the market for its aftersales support is second to none, and we have direct experience of this having worked in partnership with Mills delivering a number of turnkey and process improvement projects for customers,” says Donaldson. “Just knowing that you have Mills’ technical, applications and service back-up at your disposal inspires confidence.”
Since being installed at Cogsdill’s facility in Nuneaton, the DNM 6700 has been used to machine front-mounted cross slides housed in the company’s ZX facing and contouring head tooling systems. These cross slides are rough machined from solid on the machine prior to stress relieving, and are then semi-finished, heat treated and ground before final finishing operations take place.
On average, machining times for roughing, semi-finishing and finishing are 60 minutes, 90 minutes and 30 minutes respectively.
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Doubling-up on die-sink machines

Following a recent move to a facility more than twice the size of its previous premises, RST Engineering has invested in another Sodick AG60L die-sink EDM to help keep pace with a growing order book. Installed in February 2018 by Sodi-Tech EDM, the machine joins an existing AG60L that has performed impressively since 2012. The two machines are now working side-by-side producing a host of complex parts such as titanium internal gears and splines for the motorsport industry.

Established by Robert and Maureen Taylor in 1986, and now run by their sons Sean, Jason and Paul Taylor, RST Engineering has proven itself to be a progressive and ambitious precision engineering business based in Leighton Buzzard.
The recent move to 7100 sq ft premises has allowed the company to grow and improve its services with investment in machinery, staff, training and inspection equipment. Today, RST has 15 employees and is currently in the process of taking on two apprentices. The company specialises in EDM (wire and die sink) and milling (including five-axis machining) to help it produce complex parts for sectors such as motorsport, which is presently proving particularly strong.
“We’ve had Sodick wire EDMs in the business since 1998, after which we standardised on Sodick machines,” explains company director Jason Taylor. “However, we’ve only had Sodick die-sink machines since 2012, when we bought our first AG60L. The machine has proven so reliable in terms of performance and quality that, when we needed more capacity, there was only ever going to be one choice. We didn’t even look elsewhere.”
The new die-sink machine, another Sodick AG60L, now helps RST manufacture a myriad of complex motorsport parts from challenging materials, such as titanium, as well as tungsten carbide components for other industries.
“There are some peaks and troughs with motorsport, but generally the work is fairly continuous,” says Taylor. “We spark a lot of internal gears and splines for Formula One and other racing disciplines. It’s all low-batch, high-precision work. Tolerances of 10 µm on form are normal when it comes to internal splines and gears, but the Sodick machines hold that very consistently.”

A 24-tooth motorsport spline might take around 4½ hours in cycle time and RST prefers to produce many of its long-running jobs unmanned overnight. With this thought in mind, the sole upgrade requested by RST for its new AG60L was the option of a 12-station tool changer, rather than the standard six-station version.
“Due to the inherent challenges associated with machining titanium we tend to burn through a larger number of electrodes,” says Taylor. “As a result, we needed a tool changer with greater capacity for when we run lights-out. In fact, we also opted to upgrade the tool changer on our existing AG60L, which was retrofitted by Sodi-Tech EDM.”
According to Taylor, programming is a stand-out feature of the Sodick machines, a function that offers a high degree of flexibility.
“The control is so easy to use,” he says. “There’s the ability to do conversational programming, which is very comprehensive, or you can write an entire program yourself from scratch – and even bounce between the two methods. Three of us are trained to program the Sodick machines.”
RST also has four Sodick wire EDMs equipped with linear drive technology, two AQ325L models, an AG600L and an AQ750L with 500 mm capacity in the Z axis.
Linear motor technology, which is based on electronic drives, offers several advantages, including improvement in accuracy, repeatability, speed and acceleration. Since linear motors are a direct electronic drive (no mechanical parts), they eliminate problems with backlash and wear.
Data transmission to linear motors is instantaneous with the use of Sodick’s proprietary motion controller technology, while overshoot and undershoot do not occur thanks to absolute glass scales attached directly to the axes. These high-resolution scales measure the location of the drive at all times, so the exact position is always known. Moreover, because the magnetic drive eliminates unnecessary mechanical movement, rigid linear motors also produce zero vibration and zero backlash.
The precision and stability achieved with a no-contact drive makes linear motors a good option, even for applications that do not need their speed but require their accuracy. Importantly, Sodick offers a 10-year positioning accuracy guarantee, which helps companies such as RST provide quality parts to customers on a repeatable and reliable basis.

“Our biggest selling points are quality, delivery and flexibility,” says Taylor. “We work closely with our customers on complex components made from difficult-to-machine materials; always looking to find the best manufacturing solutions to produce the finished part to the required accuracy and within budget.”
RST clearly prides itself on quality, providing a professional service, loyalty and flexibility towards customers with whom it has built strong relationships over the past 30 years. The company currently holds AS9100D & BS EN ISO 9001:2015 quality certifications, while all of RST’s inspection equipment is externally calibrated and operates in a temperature-controlled environment.
A final word is reserved for the professionalism of the support team at Sodi-Tech EDM, which has become an important business partner for RST.
“Both of our Sodick AG60L die-sink machines are utilised all of the time with a fast turnover of work,” says Taylor. “Like the wire EDMs, they have become an integral part of our business. If we ever need to ask something of Sodi-Tech EDM they are always very responsive – they have highly knowledgeable people. This is very reassuring, not just for our motorsport customers, but those in other sectors we serve, such as metrology, satellite, aerospace, scientific and medical.”
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