Growth through automated grinding

The transition to being a member of a global group has seen Apex Cutting Tools expand its reach into the aerospace market, but with automotive tier one suppliers, as well as GM and Chrysler nearby, the automotive industry remains a core focus. The growth of the company located near Niagara Falls now sees it undertake the processing of over 1000 re-grinds a week for a single customer. With an output of more than 10,000 carbide and PCD tools a month, the company also manufactures hundreds of steel tool bodies with indexable inserts in the same timeframe.

Apex Cutting Tools produces more than 2000 new PCD and solid carbide tools each month, with more than 8000 tools on a repeat cycle of re-grind, re-coat and re-supply to clients. This total output has more than doubled in the past 10 years. Notably, each and every tool is a special, which makes production at Apex Cutting Tools far removed from the volume production market. The company operates two shifts, and if machines can be loaded with a batch of tools for overnight production at the end of the second shift, they will be. This strategy sees machines like the Vollmer Vgrind 160 running up to 24 hours a day.
CNC Grinding Department supervisor at Apex Cutting Tools, Stephan Rodrigue, says: “The breakdown of our production is relatively equal between PCD and indexable tools, with solid carbide being the majority of production. Our volumes are generally in the range of 5 to 50 tools, with some runs occasionally reaching a few hundred. We have one customer that comes in on a Friday with a 1000 tools that have to be re-ground by the following Monday.”
The company has a series of manually loaded CNC tool grinders, which are now reaching the end of their service life, something likely to be expedited by poor machine support and the arrival of automated machines like the Vollmer Vgrind 160.
Referring to the acquisition of the Vollmer Vgrind 160 just over two years ago, Rodrigue says: “The company invested heavily in DMG Mori and Mazak machine tools for producing tool bodies, Zoller Genius tool measuring machines and a range of CNC tool and cutter grinders. We were invited to look at the Vollmer Vgrind 160 machine but, as it was going to be our first Vollmer, we were somewhat apprehensive. Our opinion changed as soon as we looked closer. Now it’s here we’re thoroughly impressed and already looking at a Vollmer erosion machine.”

One of the key features that drew Apex Cutting Tools to the Vollmer Vgrind 160 was the CNC control platform, as Rodrigue explains: “The Vollmer has the Numroto Plus CNC software platform, which is a different control system to our older tool grinding machines. Numroto is now on most of our new machine acquisitions and the Numroto Plus platform is a must for us going forward. This is because it allows any program to be swapped between any of our new machines, regardless of brand.”
The thousands of solid carbide tools are produced or re-ground on four automated CNC grinding machines and three ageing manually loaded machines.
“As we produce tools with shank diameters from 3 up to 20 mm in 1 mm increments on the Vollmer, they were kind enough to give us the drawings to produce our own collection of auto-load pallets in our own machine shop,” says Rodrigue. “As standard, the HP160 pallet magazine can hold 272 tools with 3 mm shanks, while for larger tools with 20 mm shanks, we can hold 54 tools. We also have a special collet in the spindle for doing tool shanks up to 25 mm and the machine has a steady rest to support the production of drills over 200 mm long. The HP160 with its two-pallet system works fantastically well, and the tool capacity gives us long periods of automated production.”
Of critical importance to the prolonged periods of unmanned running is the auto-change six-wheel pack that is stored at the rear of the machine. Automatically, the wheels are measured in-cycle with a probe, dressed and/or changed depending upon the geometry of each tool. So, regardless of whether the HP160 is loaded with carbide blanks or tools for re-grinding, the Vgrind will undertake complete fluting, geometry generation or re-grinding to the exact program specifications.
Comparing tool production cycle times to alternate machines in operation at Apex Cutting Tools, Rodrigue says: “This is a tough question as all our machines have different capacities and power levels, but in most cases the Vollmer gives us cycle time gains over our other machines. This is largely due to the vertically aligned spindle configuration on the Vgrind. For example, we will rough grind the flutes on the lower spindle and then do the finishing cycle on the top spindle, which instantly removes the constant wheel changes that are common on our other machines.
“The finishing wheel will undertake micron precision grinding with outstanding surface finishes whereas the rough grinding can really rip the material off,” he continues. “We are doing a 24 mm diameter tool at present with a 12 mm core diameter and the Vgrind will grind the flutes in a single pass. Compared with most of our other machines, this stock removal is well above their rates. The Vgrind is at least 30% faster at roughing than some of our older machines. This is impressive considering the machine has belt driven spindles as opposed to the direct drive spindles on newer Vollmer machines.”

Despite the Vollmer Vgrind 160 being significantly faster than alternate machines, Rodrigue says it is difficult to draw parallels between the various grinding centres at Apex Cutting Tools.
“We have manually loaded grinding machines, machines dedicated to small tools and others dedicated to hob grinding, so like-for-like comparisons are difficult. What we have noted is the kinematic advantages of the vertically aligned twin spindles that pivot around the C axis. Firstly, having two wheels in the work envelope reduces wheel changes to improve processing speed. Secondly, the extremely robust grinding wheel column maximises rigidity and vibration damping. It is this rigidity that contributes to massively reducing flute roughing times. The closest comparative machine would be a very high-end machine that cost hundreds of thousands of dollars more than the Vgrind.
“An extra rail at the top of the C axis gives the axis support from the top and bottom and the whole thing can swing around and grind from two positions,” he adds. “The solidity of that whole system and the spindles Vollmer uses, that’s just the biggest factor. There is no comparing that. Some of our machines have a suspended spindle, so you lose precision, surface finish and the rigidity depends fully on the spindle. Here, you have a massive structure that comes in and really takes out the material.”
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Turn-mill centres ideal for hydraulic components

A second pair of Miyano BNE-51MSY turn-mill centres from Citizen Machinery UK has been installed at contract machinist Unicut Precision of Welwyn Garden City. Joining two identical twin-spindle, twin-turret lathes with live tooling and a Y axis supplied at the end of 2017, the latest arrivals form the mainstay of efficient production for complex components used in the hydraulics industry, which accounts for a large proportion of Unicut’s business.

Unicut was established in 1990 by 24-year-old Jason Nicholson and a partner, who has since left the company, in a double garage in Barnet. Back then, the company had just £5000 to spend on second-hand manual and cam-controlled machines, but progressed to CNC turning in 1993. In 2017 the company diversified into prismatic machining with the purchase of a multi-pallet machining cell, followed quickly by a second. A third cell is now on order for delivery later in 2019, which will be a record year for capital investment at £2.3m.
Over the years, Nicholson has bought 104 CNC lathes, 93 of which were either Citizen Cincom sliding-head models or fixed-head lathes from Miyano, which merged with Citizen in 2011. Today, Unicut operates 22 Cincom lathes with up to 13 CNC axes, 80 cutting tools and 138 bar coolant pressure, as well as eight Miyano machines deploying up to 72 cutters. The machines are usually replaced every five-to-seven years, to take advantage of the high residual value of the lathes at that age.
While turning machines have been sourced mainly from this supplier, each purchase is rigorously analysed by Nicholson with respect to machine cost and achievable cycle times to ensure lowest cost per part and the most rapid return on investment. Ease of machine integration and use, and the desired quality of component, are also paramount considerations. Additionally, prompt provision of service is an important deciding factor.

In 1999, the first Cincom sliding-head lathe was delivered to Unicut, a 12 mm bar auto, and within a year three more were installed, followed three months later by a 32 mm model. The first Miyano appeared on the shop floor in 2002. The CNC lathes replaced cam-controlled turning machines, which had all gone by 2003. CNC equipment was by then achieving similar cycle times to cam-type lathes, with the added advantages of higher quality and unattended running, including overnight, leading to much higher profitability.
To distinguish Unicut from other subcontractors, Nicholson decided early on to adopt a different business model by approaching OEMs, analysing their main cost drivers, investigating the possibility of re-engineering components for more efficient production, establishing desired cycle times, identifying machine tools needed to produce parts within those times, and then proposing to make the required capital investments, subject to the manufacturer’s commitment to a fixed-term contract. Strategic supplier status is what Unicut seeks in its business relationships with customers, and 80% of throughput at the Welwyn Garden City factory is produced on this basis.
For machining larger diameter parts, a 51 mm capacity Miyano costs about the same as a top-end 32 mm Cincom sliding-head model. Unless a high component length-to-diameter ratio dictates otherwise, Nicholson prefers the fixed-head option based on a number of factors, including rigidity, thermal stability, value for money and speed. Bar capacity is greater, offering more flexibility; spindle power is higher, leading to increased productivity; cycle times are comparable; access is easy for setting up, despite the compact machining area; and the Mitsubishi control supports superimposed machining whereby three tools can be in cut at the same time, a facility regularly used at the Welwyn Garden City facility for elevated levels of productivity.

Once a BNE-51MSY is set, Nicolson says that it will produce a run of say 1000 components to very high accuracy without having to touch the machine by the simple expedient of including macros in the program to offset tools automatically after a predetermined number of parts have been produced. Tolerances down to ±2 µm can be held and surface finish is described as impeccable. He favours the Mitsubishi CNC system fitted to Miyano and Cincom lathes due to its flexibility and ease of operation using the drop-down menus and comprehensive graphical support. Citizen’s
off-line Alkart Wizard software helps to ensure jobs quickly enter production. However,
for larger production runs, time can generally be cut from a cycle by tweaking the program at the control.
Citizen’s operating system in the CNC system fitted to one of Unicut’s Cincom sliders features patented LFV (low frequency vibration) software that operates in two CNC axes simultaneously, allowing stringy swarf to be broken into shorter chips of a length to suit the material being cut and the swarf conveyor. The feature is popular with operators, as it enables uninterrupted production without having to stop the lathe due to ‘bird nests’ clogging the workpiece and tools.
Citing a 320 stainless steel part that was previously impossible to run unattended, even during the day yet is now routinely left to run lights-out with LFV, Nicholson says: “The feature is easy to use and does not require any special skill set. The software can be switched on and off, either manually or within a program, and parameters can be adjusted. It is especially good for processing plastics unattended, as well as other difficult-to-machine metals such as Duplex and titanium. It just works.”
In conclusion, he shares his thoughts on the current buoyancy of the subcontract machining sector due to the weakness of the pound against overseas currencies. This factor has cut 20% from the price of components that Unicut exports and boosted turnover, despite raw material, and indeed the equipment on which to machine it being more expensive. The firm’s first order from China
was delivered in August this year and exports overall currently account for 40% of turnover, up from 10 to 30%
in previous years.
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First Brother R650X2 arrives in Europe

At the beginning of November 2019, Whitehouse Machine Tools delivered to the Andover facility of MRT Castings (an aluminium diecasting and machining specialist), the first Brother Speedio R650X2 machining centre to be installed in Europe. The 30-taper machine is equipped with twin pallets carrying 4th-axis trunnions, as well as Blum workpiece and tool probing to ensure the accuracy of machined parts.

Replacing a 20-year-old Brother model with a standard table that was still producing parts within tolerance, the new machine has reduced cycle times by 30% when running identical programs due to the speed and power of the manufacturer’s CNC C00 control system. Additionally, automatic pallet change cuts loading times, presenting parts to the spindle faster and increasing productivity still further.
A sequel to Brother’s flagship TC-32B QT, the latest 16,000 rpm spindle machine has the largest number of tools available in the Speedio range, 40 as opposed to the former machine’s 21, as well as a larger X-axis stroke, up from 550 to 650 mm, and an 800 mm long table instead of 600 mm. Z-axis travel is also slightly more. That the R650X2 has these characteristics is partly down to the closeness of Phil Rawnson, managing director of MRT Castings, to the Japanese machine builder.

Regular meetings serve to advise the manufacturer about the UK manufacturing sector and what the market requires. For example, increased X-axis capacity is a standard request from MRT, as evidenced by the company’s involvement in the development and introduction of the Brother Speedio S1000X1 with 1000 mm X axis. A pair of these machines was installed at Andover four years ago, the first models to be sold by Brother’s sole UK and Ireland agent Whitehouse Machine Tools.
Similarly, in April 2019, MRT was the first in the UK to receive a Brother cell with Feedio robotic component handling to automate a five-axis M140X2 machining centre that was purchased at the same time.
Rawnson says: “Brother’s willingness to consult with its customers is a good sign, as it means it is listening to what the market wants. We made it clear to them that we prefer a large machining envelope to give us more flexibility in the methods we use to fixture parts. There are several ways we exploit the additional working volume, especially extra X-axis travel.
“If we need to hit several faces of a component, we can carry out a second machining operation sequentially by fixturing parts side by side on a single fixture,” he adds. “Or we can clamp a larger number of small parts to fill the table. By putting more castings under the spindle at the same time, fewer tool changes are needed per component and productivity is increased.
“Alternatively, we can use the three or four CNC axes to machine longer castings at the highly productive rates possible using a 30-taper machine.”

Pallet-change Brothers are generally employed at the Andover facility if cycle times are short, say less than five minutes, to minimise spindle idle time during sequential Op 1 and Op 2 machining on six sides of a casting. Fixed-table machines are more economical if cycles are longer, as one operator is able to load and unload a pair of machines to complete the two operations in tandem.
The accuracies achieved are impressive, down to a couple of microns for bearing bores. Some electrical assemblies comprise up to 20 individual castings and tolerance build-up can become a problem if such tight limits are not held. Other work for the electronics, defence and high-end lighting sectors also stipulates tolerances that are sometimes very tight. Parts coming off the Brothers are not only dimensionally accurate, but highly repeatable, according to Rawnson.
He says: “MRT Castings has been a family run business since its formation in 1947 and has always worked in partnership with its customers, constantly evolving to meet their demands. Brother has adopted a similar partnership approach by listening to what we and other subcontractors want, and developing new machines that fit our changing requirements.”

Early 2020 will see the opening on the Andover site of a new foundry that is some 60% larger than the existing facility, which will close to provide extra space for an additional machine shop to cope with the ever-increasing amount of new contracts being won by MRT, from both existing and new customers. More and more these orders are arriving from overseas, the firm having won the ‘Queen’s Award for Enterprise: International Trade’ in 2016 after increasing overseas sales by 330% in the previous three years to a point where exports now account for half of annual turnover.
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Soaring ambitions at Birds Precision

Mills CNC, the exclusive distributor of Doosan machine tools in the UK and Ireland, has supplied family-owned precision subcontract specialist Birds Precision Engineering Ltd with a new, large-capacity Fanuc-controlled Doosan DNM 6700XL vertical machining centre.

The machine, which incidentally was one of the first (if not the first) of its type to be sold by Mills in the UK, was installed at Birds Precision’s 3000 sq ft facility in Nuneaton in September 2019. The DNM 6700XL is being used, predominantly at this moment in time, to machine high-precision, complex prismatic parts for one of the company’s many long-established UK customers.
Essentially comprising base castings and guideways for state-of-the-art, special purpose machines, the components being produced on the Doosan are made from cast iron and steel. The castings are large (1.2 m long x 640 mm wide) and often weigh up to 500 kg. Machining typically takes place in small batches (one-off through to five- or six-off) to tight dimensional tolerances (0.01 mm) and exacting surface finishes (Ra 1.6).
Birds Precision supplies the parts direct to its customer and, according to owner and managing director, Chris Bird, “they have to be right first time…every time”.
The quality, lead-time fulfilment and cost demands of this customer, and others like it, were among the main reasons why Birds Precision invested in the Doosan DNM 6700XL.
Says Bird: “To maintain our preferred partner relationship with existing customers and win new business contracts with new and existing customers, we made the strategic decision to upgrade our machine-tool capacity and capabilities.”

As a consequence, the company’s machine tools that were being used to produce the large guideway parts, were soon in the spotlight.
“We had been using Herbert DeVlieg horizontal jig mill borers to machine these types of parts,” explains Bird. “Although these machines, despite their age, were still capable of delivering the accuracies required, it was becoming increasingly difficult to source spare and replacement parts. We realised that this situation would only become more acute over time, and so we decided to search the market for an alternative.”
The machine decision-making process was designed and implemented by consensus, with a number of the company’s younger members of staff playing the lead role in contacting machine-tool suppliers and drawing up a shortlist of potential machines that could meet the company’s immediate and future requirements.
“The future of the company lies, to a large extent, in our ability to recruit and retain top young talent,” states Bird. “Our recently-introduced apprentice programme, which enables our apprentices to gain valuable skills, relevant work experience and nationally recognised qualifications, is helping us meet this objective.
“Another angle to our commitment to investing in young people is involving them, where possible, in the future direction of the company and trusting them with important decisions, such as future machine tool acquisitions,” he adds.
Although not a Doosan machine-tool user at the time, staff members from Birds Precision had visited Mills CNC’s stand at MACH 2018, where they had seen a number of Doosan vertical machining centres being put through their paces.
One of these members of staff was machine shop manager, Tom Bird, who says: “Mills CNC has a good reputation in the market, and we liked the Doosan machines on their stand. So much so in fact that we invited sales staff from Mills to visit us at our facility to discuss our future requirements.”
It was during these discussions that Birds Precision was alerted to the imminent introduction of the new Doosan DNM 6700XL machine, a three-axis vertical machining centre with a 2.1 m X-axis stroke.

Explains Tom Bird: “The technical specifications of the DNM 6700XL, including its size, rigidity and power, ticked all the right boxes for us. We also liked the machine’s competitive price, quick availability and the fact that it was backed by Mills CNC’s aftersales service and support. Furthermore, because the DNM 6700XL is a new machine, we were convinced that it would help differentiate us in the market and provide a distinct competitive advantage.”
Since being installed, the DNM 6700XL has not missed a beat, and employees at Birds Precision have been impressed with the machine’s cutting performance, especially its high stock-removal capabilities and its ability to maintain high volumetric accuracy over long machining runs.
Concludes Chris Bird: “Such is the accuracy and surface finish of the parts being produced on the DNM 6700XL that they no longer need to be ground and hand scraped. The DNM 6700XL represents a significant investment, but armed with this technology we are confident about our future growth and prosperity.”
In addition to its large capacity, the DNM 6700XL is equipped with a 18.5 kW/15,000 rpm spindle with 20 bar through-spindle coolant capability, a large work table (2200 mm x 570 mm) and an integrated thermal compensation system. The latter minimises the effects of heat generation and regulates thermal expansion, ensuring high component accuracies and process optimisation.
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Transforming the machine shop

When a customer of subcontractor Apsley Precision Engineering suddenly stopped manufacturing components in-house, one of the redundant machine tools, a Miyano fixed-head, twin-spindle, single-turret lathe, was purchased by the contract machinist’s managing director, Peter Aymes.
Its arrival in 2012 on the shop floor at the company’s 12,000 sq ft facility in High Post, near Salisbury, heralded the start of a big improvement in CNC turning capability. Following the purchase of two more second-hand Miyanos, July 2019 saw the arrival from Citizen Machinery UK of the first new model, a BNJ-51SY twin-spindle, twin-turret lathe with a Y axis.

Aymes says: “We were aware of this make of bar auto and knew they rarely come on to the second-hand market, so we were lucky to be able to buy the first machine, a BND-51S twin-spindle lathe with live tooling in the turret. Compared with our single-spindle, bar-fed lathes without driven tools, it approximately halved cycle times for machining parts up to 51 mm diameter. Generally we were able to start producing components in one hit rather than two or three operations, reducing handling and work-in-progress. That in turn improved accuracy and allowed us to manufacture more cost-effectively, so we became more profitable. It is difficult to overstate the improvement the machine made.”

Another notable benefit was that an operator could set the Miyano and walk away for long periods to carry out other tasks, as changing offsets is unusual owing to the consistency of machining. This attribute is not evident with the subcontractor’s other bar autos, which tend to occupy an experienced setter for much of the time, raising the labour cost content of manufacture.
Based on all these advantages, a second Miyano BND arrived one year later. Purchased at auction, it produces parts from bar up to 42 mm in diameter, but is otherwise similarly specified to the first machine. Despite being 12 years old at the time, it was and still is capable of holding tolerances down to ±5 µm, which Aymes describes as “amazing”.
He continues: “By that time it was abundantly clear just how good these machines are. They are heavy, compact and very robust, which leads to high accuracy, repeatability and reliability. They need very little money spent on them for repair, so the cost of ownership is low. It is rare to operate a machine that is almost completely trouble-free. With the Miyanos, this applies to the electronics and electrics, as well as the mechanics.”
The third Miyano to be installed at the High Post factory, in 2015, was a second 42 mm machine of similar age acquired from another subcontractor, this time a BNJ model with two turrets. It was bought to cope with the increasing amount of work these machines were generating and to exploit the higher productivity possible due to the presence of a second turret to serve the sub-spindle, while the other turret operates at the main spindle. It resulted in higher production output, better prices for customers and shorter lead times.
With a view to increasing production output still further, as well as access the latest technology and provide back-up for the 51 mm capacity lathe, the subcontractor’s first new Miyano, a BNJ-51SY, was delivered in July 2019 by Citizen Machinery UK. As its designation implies, the machine has additional Y-axis movement on the main turret that is proving invaluable for machining off-centreline, and providing flexibility and accuracy of milled features.

Aymes cites one component that is produced far more efficiently with this feature: a tubular, thin-wall aerospace part machined from solid 304 stainless steel bar of 38 mm diameter. The component requires a blind, longitudinal hole to be drilled and bored and the outside diameter (OD) to be turned to leave two lugs. Not only does the Y axis allow the lugs to be drilled in-cycle, instead of the component having to visit a machining centre for completion, but by being able to program both Y-and C-axis movements into the OD turning, cutter deflection is minimised and accuracy is improved. As the part is required in batch sizes ranging from 200 to 800, the benefit is considerable.
Even more advantageous with the new machine, however, is the ability to take advantage of ghost-shift running, which is theoretically possible with the other Miyanos, but practically not feasible due to the absence of load monitoring to detect worn or broken tools and automatically stop the machine.
The latest lathe, with its fail-safe features and reliability, is regularly left to operate unattended overnight. So also is a multi-pallet, five-axis machining centre added to Apsley’s prismatic machining department in April 2018. Aymes predicts that these two machines will pay for themselves faster than all the others on the shop floor. He asserts that if a production centre is capable of running lights-out and is of the right quality, rapid amortisation renders the initial purchase price much less important.
When Citizen installed the latest lathe, it also supplied the subcontractor with the latest version of its Alkart CNC wizard programming software. Alkart assists and simplifies the creation of even complex cycles using a built-in G-code and M-code library, plus reference material and diagrams. Inexperienced users in particular benefit, such as Apsley’s Jay Pritchard, who is halfway through a four-year mechanical engineering apprenticeship. Pritchard finds the wizard useful when operating the new Miyano if his mentor is not available and the relevant manuals are not to hand. Alkart also helps with understanding how to use the machine.

Founded in 1984 by Aymes’ father Graham, the subcontract engineering firm has always split its machining approximately half and half between turning and milling. Key sectors supplied with high tolerance, complex parts and assemblies include aerospace, defence, medical and pharmaceutical. Non-kanban batch size is typically in the range of 20 to the low hundreds, and the company also operates a tool-room facility for smaller batch runs, prototype production and the manufacture of tooling and fixtures.
However, one-third of the company’s business derives from supply of components and assemblies just-in-time, providing price stability through the potential of the subcontractor to produce much larger quantities for consignment stock, with customer call-off typically at a rate of 1000 pieces per week.
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