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Paul Cobb

Physics graduate drives subcontract success

1024 576 Paul Cobb

A big thank you to Dave Tudor from Production Engineering Solutions for writing a great article about our MD Paul Cobb and the growing sucess of HPC Services.

Read the original article here at pesmedia.com.

When physics graduate Paul Cobb asked his father Reg in 1997 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. However, as PES discovers, it was a risk that paid handsome dividends.

In 1997 Paul and Reg Cobb were partners in the family’s subcontracting firm in Stapleford, Hemlock Engineering, which specialised in producing mainly prismatic parts and continues to do so.

Paul Cobb, owner of HPC Services

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. A small factory unit was rented in nearby Ilkeston and a Japanese-built Citizen Cincom L25 sliding-head, bar-fed, turn-mill centre was installed. 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 very latest, most highly productive CNC equipment available on the market, designed to slash production times, reduce costs and improve component quality. Under Paul’s influence, it has become Hemlock’s maxim as well.

Over the intervening 24 years, he has invested in around 20 CNC sliding-head, twin-spindle lathes of nominally 12, 20 or 32mm bar capacity for HPC, all exclusively from the same supplier. Ten Cincoms are in operation, the others having been systematically replaced with newer models. There are also seven fixed-head, twin-spindle CNC lathes on the shopfloor of the current premises, where around 30 staff are employed.

When Paul launched HPC, he took one production job from Hemlock with him 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. The 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 time of seven minutes. On the Citizen L25, the same job was completed in one hit in a one-minute cycle. The parts are machined today on a different slider at a rate of 1,000 per month.

Due to complete machining in one set-up, the components produced by HPC were of better quality, 5µm concentricity and 10µm dimensional tolerance being held reliably. 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.

Paul comments: “Over the years, turned parts subcontractors from around the world have quoted for this work. However, by harnessing the efficiency and accuracy of machines like the Cincom sliders we are globally competitive on price as well as 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. And of course, our delivery times are much better than Far Eastern competition can offer, added to which control over projects is easier. As a result, we are seeing a strong trend towards reshoring of work.”

Today, HPC has some 5,000 different part numbers on its books. Components are produced from 38mm diameter bar or smaller on the Cincoms. Quantities range from 100- to 40,000-off 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 £3 million annual turnover, the remainder being fixed-head turning. 10% of revenue is reinvested every year in new plant and equipment, a proportion that also applies to Hemlock’s £7 million turnover.

Fifth generation productivity gains

One of the latest components produced at HPC in one hit on a sliding-head lathe requires only milling, there being no turning content at all. The parts are being machined on one of a pair of recently delivered Cincom M32-VIIIs of a radically different design compared with the earlier M32s on site. The first of the new machines was delivered in November 2020 and Paul was so impressed with its performance that a second arrived a month later.

The prismatic component looks as though it has being 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. Part of a date-coding machine, it is produced in one operation in a cycle time of four minutes 53 seconds on the lathe, whereas it would require four operations totalling seven minutes on a vertical machining centre.

A year or so before the arrival of the two new M32s, which have been supplied with kits to allow bar up to 38mm diameter to be accommodated, the chief designer from Citizen’s Japanese factory visited HPC to ask Paul 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.

Paul explains: “The difference is amazing. It is possible to machine exotic alloys at double the speed compared with on 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 10mm 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.”

Paul Cobb, managing director
The Citizen Cincom L20-VIIILFV sliding-head lathe on the shopfloor at HPC

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. It is useful for producing angled features on components and additionally is able to carry out front working so that the turret can be freed up earlier to perform operations on the reverse end.

Cycles for many jobs are significantly quicker. For example, when producing a particular 303 stainless steel flange from 38mm 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 to save remnant wastage when producing relatively short components like the flanges. In this case, 262 parts can be produced from a 3m bar compared with 225 if the guide bush is in place, delivering 37 extra parts, an increase of 16.4%. With 5,000 of the flanges produced annually, the saving is significant.

Programmable chip breaking software is ideal for turning plastic

Citizen’s advanced technology 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, as copious quantities of long, stringy swarf is produced, 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, where it is integrated into the operating system rather than being a macro, the facility can be switched in and out of a programmed cycle by G-code command.

A watermist fire suppression nozzle whose component parts are made by HPC exclusively on Citizen Cincom sliding-head lathes

Paul concludes: “LFV on the Cincom L20 we bought in 2017 is absolutely brilliant for turning plastic. 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 also allows us to run the lathe unattended for long periods, which normally would be impossible when machining this type of material. The software will also be a big advantage if we receive contracts for producing components from ductile, long-chipping metals such as copper.”

Citizen Machinery UK
www.citizenmachinery.co.uk

Author
Dave Tudor
Editorial Director

Swarf and Chips: Invest+Automate=Profit

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Our MD Paul Cobb, talks to Colin Griffiths of MTDCNC about the BROTHER machines.

It was great to welcome Colin Griffiths from MTDCNC’s weekly show Swarf and Chips to Hemlock Ltd, to speak about all things machining, including the reliability, precision and speed of our BROTHER machines that makes us one of the most competitive companies to place work with.

70% reduction in cycle time on these parts turned our business around!

150 150 Paul Cobb
Our MD Paul Cobb, talks to Colin Griffiths of MTDCNC about the BROTHER machines.

We’d like to say a big thank you to Colin Griffiths from MTDCNC for coming down to HPC to speak to our Managing Director Paul Cobb about the amazing BROTHER Machines.

In the video, Paul explains how the introduction of BROTHER Machining Centres helped turn around the Hemlock Ltd business and helped keep our customers.

Kingsbury UK Case Study

1024 682 Paul Cobb

Background

A third 5-axis, vertical-spindle machining centre has been installed by subcontractor Hemlock Engineering, Nottingham, in response to a steady increase in work from a variety of sources. Aircraft seat parts, medical prostheses, components for laser equipment used in dentistry and printing, fire suppression nozzles and parts for camera tripods and beer pumps are typical of the diverse range of contracts regularly received from more than 200 customers.

The Challenge

Even though 95 per cent of jobs undertaken by Hemlock are in aluminium, high power and torque are still needed when taking deep cuts to prevent the cutter stalling.

The Solution

The latest Hermle C 22 U, supplied through UK agent Kingsbury, is a robust, 5-axis model capable of highly productive metal removal using the 25 kW / 80 Nm / 20,000 rpm spindle and 45 m/min rapids. Working envelope is 450 x 600 x 330 mm.

The Outcome

Two factors distinguish the C 22 U, in the view of Hemlock’s managing director, Paul Cobb. First is the machine’s reliability, as it has operated faultlessly since it was installed in March 2013. Second is its ability to hold extremely high tolerances, down to a few microns on some optical parts used in dental laser equipment.

He also commented that there were less expensive machines on the market than the Hermle, but it was by no means the costliest. In any case, the price of a machine tool is of secondary importance. It is uptime that is crucial to maintain output and profitability.

“I thought it was going to be a good machine when I saw them being made at the German factory and it has not disappointed. The build quality is awesome and the clever design ensures that vibration is minimised, resulting in lower tooling costs, higher accuracy and less wear and tear on the machine. I know it will still be good in 10 years and more, so now I could not imagine buying any other make of 5-axis machine.”

Paul Cobb, Managing Director.

Read the original story at Kingsbury UK

Production times slashed by between a half and two-thirds on new Brother SPEEDIO machines

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Subcontractor’s highly productive VMCs will give any competitor a run for their money, from Budapest to Beijing.

A seminal moment has arrived in British manufacturing, it appears. Using the latest ultra-highspeed machine tools, UK subcontractors can rival their competitors in low-wage countries and still make a profit.

Paul Cobb, managing director of Nottingham contract machinists, Hemlock Engineering, describes how this is possible using 30-taper Brother Speedio machines from Whitehouse Machine Tools.

He has calculated that the average 8-second chip-to-chip time on his 40-taper vertical machining centres (VMCs), of which he has 20, costs his company £400,000 per year in idle time for tool changes alone. The 1.4-second chip-to-chip time of the Brother Speedio would save Hemlock nearly a third of a million pounds annually if he operated 20 of them.

The received wisdom in UK manufacturing is that lower volume, higher complexity work has tended to stay on these shores while higher volume production of simpler components has largely disappeared abroad, notably to the Far East and more recently to former Eastern bloc countries.

Mr Cobb said, “Half of the parts we make are exported and most of the remainder end up abroad via our UK customers.

OEMs are global and can have their components made anywhere in the world.

“Two or three of our contracts for annual quantities of 10,000 or more are under attack every year on internet auctions from competitors outside Europe.

“OEMs are always looking for lower prices. Subcontractors in the UK and presumably other Western European countries as well often do not get an opportunity to pitch, as Mr Cobb inspecting platestheir rates are expected to be too high.

“It is true that we would lose money doing this type of work using our 40-taper machining centres, even at the lowest hourly rate feasible.

Paul Cobb, managing director

“However, Brother Speedios are so incredibly fast that they give us an edge. They typically halve production times, knocking one-quarter off the cost of manufacturing a part.”

He also explained that, with a 4th axis indexer fitted, one operation can frequently be saved compared with using a 3-axis machine, which can reduce floor-to-floor time further, by up to a factor of three overall, cutting costs even more.

Instead of being 10 or 15 per cent too expensive, Hemlock can be a similar margin under the competition when quoting, or even more, so can realistically take on high-volume work and still make a profit.

Production rates two to three times higher Mr Cobb is optimistic about the possibility of winning such contracts. He cites the initial job put on his first Brother Speedio S500X1 4-axis machine, which is equipped with a Kitagawa high-speed CNC indexer.

Whitehouse Machine Tools had demonstrated a turnkey manufacturing solution on the machine at its Kenilworth technical centre to show that the Japanese-built machines are a viable route to high profitability. The application involved producing a pair of left- and right-hand plates for a printer, 380 mm square by 12 mm thick, from solid aluminium.

For many years, Hemlock had been machining the plates two pairs at a time in two operations per plate on a 3-axis, 40-taper VMC in a cycle time of just over 48 minutes, or 24 minutes for two components. This included five minutes to refixture them all to drill holes in two opposing sides of each plate. Manual deburring of sharp edges took extra time, so in practice only four plates per hour were produced. On the 4-axis, 30-taper S500X1, which has a working volume of 500 x 400 x 300mm, a single pair of plates is machined in one hit over twice as quickly, in a 12-minute cycle. It includes deburring with a milling cutter, so the parts are ready for delivery immediately they leave the machine. The production rate is therefore 10 plates per hour, ie 2.5 times higher.

Mr Cobb using Brother Speedio

If the through-spindle coolant option on the Speedio had been chosen, the cycle time would have been even faster at just 8 minutes, equating to 15 plates per hour, or nearly four times the original production rate.

The productivity hike from the first machine, installed in August 2014, was so great that Mr Cobb decided to replace three additional 40-taper machines straight away with Brother Speedios.

Two further identical models were installed, as well as an S700X1 with 700 mm travel in the X-axis. All four were delivered within the space of one month. The larger machine is fitted with through-spindle coolant and a faster Yukiwa CNC indexer, which rotates at 200 rpm, double the speed of the Kitagawa indexers.

Mr Cobb continued, “All of the indexers fitted by Whitehouse are not only fast but also very rigid during machining. It is because they are clamped hydraulically at both ends, rather than being held by the servo motor. “It allows us to take heavy milling cuts without vibration, maximising productivity and prolonging the life of the cutters.

“In addition, their speed of rotation enables us to spin swarf off the components and fixtures after each cycle, so we save a few more seconds by not having to blow the chips away with an air gun.”

Fast when cutting – and between cuts

Rather than having a standard 10,000 rpm spindle or the 27,000 rpm option, all of Hemlock’s Speedio VMCs are fitted with a 7.4kW / 16,000 rpm spindle. Mr Cobb considers

it optimal for machining the various grades of aluminium that account for around 95 per cent of production at the Nottingham factory. He believes that higher speed spindles lack torque and require unnecessarily costly, balanced tooling, while lower speeds are not enough for productive removal of light alloy.

Rapid spindle deceleration to zero for tool exchange and acceleration to full rpm as well as quick indexing of the 21-station turret combine to bring the chip-to-chip time down to 1.4 seconds, cutting out a lot of idle time. Tapping at 6,000 rpm also promotes high productivity, as do 50 m/min rapids in the linear axes, up to 30 m/min cutting feed rate and axis accelerations of up to 2.2g.

A comparative analysis of the cutting data from the standard VMCs and the new Speedios at Hemlock reveals that, on average, the former are in-cut for 45 per cent of a cycle whereas the Brother machines are cutting for 66 per cent of the time. It results in a massive potential increase in metal removal of nearly 50 per cent.

Another facet of the machines that Mr Cobb appreciates is the power of the latest Brother CNC system. It has faster processing and 200-block look-ahead, enabling higher accuracy machining, especially in 3D.

Our new Speedios will give any of our competitors a run for their money, whether they are in Budapest, Beijing or anywhere else in the world.

Paul Cobb, managing director

It also has many standard features that are costly extras on other controls. He pointed to the Brother CNC C00 specification at the URL: www.brother.com/europe/machine/sx1/spec/ index.htm#spec-nc and noted that 58 features are standard in the proprietary control and only five are options.

Two more Speedios every year

In conclusion, Mr Cobb said, “Our new Speedios will give any of our competitors a run for their money, whether they are in Budapest, Beijing or anywhere else in the world.

“We plan to replace two of our standard 40-taper VMCs with two Speedios every year for the foreseeable future in a bid to halve production times right across our shop floor.

“We have around 2,000 job numbers here. It takes time to swap jobs from our existing machines to the new platform because we rewrite each program, rather than just edit and transfer it.

“Only in that way do we gain maximum productivity advantage from the Speedios and Whitehouse helps with that.”

Most cycles, invariably involving interpolation in up to three axes plus indexer positioning, are created off-line using seats of hyperMILL and Mastercam. Occasional data input is required on the shop floor for programming simple jobs or to edit cycles.

Further advantages of the new Brother machines are their low power consumption, which reduces electricity bills, and their superior accuracy, with 10 microns positional tolerance routinely held by Hemlock at its Nottingham factory.

The proximity of Whitehouse Machine Tools’ HQ has also been a benefit. The Brother agent’s applications engineers frequently visit the Nottingham subcontractor to assist with setting up jobs and to give advice.

Read the original story at Whitehouse

Dualmist nozzles set to revolutionise fire control

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COMPANY SYNERGY BETWEEN HEMLOCK HPC AND PREMIER MIST

About three years ago a couple of guys from Wakefield walked into Hemlock. Their search for a company with both sliding head lathes and five-axis milling machines had brought them to our door – and the company’s name was Premier Mist.
The company MD, Peter Duval, had in his hand a strange aluminium nozzle which looked similar to a
fire sprinkler, but was, as he put it, “far, far superior”.

This nozzle was designed not to spray water, but mist – which made it far more effective at extinguishing fires. Mist hangs in the air rather than dropping to the floor, which helps stop the transmission of heat, uses far less water, and reduces water damage.

The nozzle featured lots of small, complex components so our engineers were instantly interested in producing them on our sliding head machines. We began making small production runs on the nozzles, but very quickly found them expensive to produce and difficult to assemble, so we set about helping Premier Mist develop new designs which would be easier to manufacture.

We brought in angled powered tooling to remove the need for second operations on the 5 axis, and also combined numerous simple components into fewer complex parts. With production increasing, we designated part of the factory as a dedicated assembly area so we could supply Premier Mist with completed nozzles.

Not much later, we received a call from Peter asking if we were interested in buying into the company. There was obvious synergy between HPC and Premier Mist, and seeing the potential for growth, we agreed. HPC eventually took on development of a new range of brass nozzles and together with Premier Mist, we launched the DualMIST brand for this new range.

The DualMIST nozzle features lots of small, complex components so our engineers were instantly interested in producing them.

Nozzles are currently being put through rigorous fire and component testing at BRE (Building Research Establishment). If they are successful, DualMIST will be the only company in Europe to have a fully BSI-approved Watermist system that complies with the latest standards.

We are now actively looking for partners and installers in the UK and Europe to use this system.

Premier Mist have been doubling in size every year using this technology and with their new range of nozzles they are set to take a significant chunk of the UK market. Volumes are currently at 25,000 nozzles per year – HPC have the capacity to manufacture at least 100,000 per year without buying any additional machines.

Because HPC were now developing nozzles in house, we had free rein on their design and since we could now machine, build, test, and repeat all under one roof, they began evolving at a much more rapid pace.

Years of development took place in just a few months and within a short space of time, we had completed designs for a whole range of nozzles for different applications. We also came up with totally original designs for a metal-to-metal seal that may be set to revolutionise the sprinkler industry, along with a totally unique brass filter that screws into the back of the nozzles to prevent the small misting holes from clogging.

Company synergy between Hemlock HPC and Premier Mist.

1024 576 Paul Cobb

Dualmist nozzles set to Revolutionise fire control synergy between hemlock

About three years ago a couple of guys from Wakefield walked into Hemlock. Their search for a company with both sliding head lathes and five-axis milling machines had brought them to our door – and the company’s name was Premier Mist.
The company MD, Peter Duval, had in his hand a strange aluminium nozzle which looked similar to a
fire sprinkler, but was, as he put it, “far, far superior”.

This nozzle was designed not to spray water, but mist – which made it far more effective at extinguishing fires. Mist hangs in the air rather than dropping to the floor, which helps stop the transmission of heat, uses far less water, and reduces water damage.

The nozzle featured lots of small, complex components so our engineers were instantly interested in producing them on our sliding head machines. We began making small production runs on the nozzles, but very quickly found them expensive to produce and difficult to assemble, so we set about helping Premier Mist develop new designs which would be easier to manufacture.

We brought in angled powered tooling to remove the need for second operations on the 5 axis, and also combined numerous simple components into fewer complex parts. With production increasing, we designated part of the factory as a dedicated assembly area so we could supply Premier Mist with completed nozzles.

Not much later, we received a call from Peter asking if we were interested in buying into the company. There was obvious synergy between HPC and Premier Mist, and seeing the potential for growth, we agreed. HPC eventually took on development of a new range of brass nozzles and together with Premier Mist, we launched the DualMIST brand for this new range.

The DualMIST nozzle features lots of small, complex components so our engineers were instantly interested in producing them.

Nozzles are currently being put through rigorous fire and component testing at BRE (Building Research Establishment). If they are successful, DualMIST will be the only company in Europe to have a fully BSI-approved Watermist system that complies with the latest standards.

We are now actively looking for partners and installers in the UK and Europe to use this system.

Premier Mist have been doubling in size every year using this technology and with their new range of nozzles they are set to take a significant chunk of the UK market. Volumes are currently at 25,000 nozzles per year – HPC have the capacity to manufacture at least 100,000 per year without buying any additional machines.

Because HPC were now developing nozzles in house, we had free rein on their design and since we could now machine, build, test, and repeat all under one roof, they began evolving at a much more rapid pace.

Years of development took place in just a few months and within a short space of time, we had completed designs for a whole range of nozzles for different applications. We also came up with totally original designs for a metal-to-metal seal that may be set to revolutionise the sprinkler industry, along with a totally unique brass filter that screws into the back of the nozzles to prevent the small misting holes from clogging.

British Manufacturing at its best (with a little help from Japan)

British Manufacturing at its best (with a little help from Japan)

1024 682 Paul Cobb

A seminal moment has arrived in British manufacturing, it appears. Using the latest ultra-high-speed machine tools, UK subcontractors can rival their competitors in low-wage countries and still make a profit. Paul Cobb, Managing Director of Nottingham subcontract machinists, Hemlock Engineering Ltd, describes how this is possible using 30-taper Brother Speedio machines.

He has calculated that the average 8-second chip-to-chip time on his 40-taper vertical machining centres (VMCs), of which he has 20, costs his company £400,000 per year in idle time for tool changes alone. The 1.4-second chip-to-chip time of the Brother Speedios would save Hemlock nearly a third of a million pounds annually if he operated 20 of them.

The received wisdom in UK manufacturing is that lower volume, higher complexity work has tended to stay on these shores while higher volume production of simpler components has largely disappeared abroad, notably to the Far East and more recently to former Eastern bloc countries. Mr Cobb said, “Half of the parts we make are exported and most of the remainder end up abroad via our UK customers. OEMs are global and can have their components made anywhere in the world. “Two or three of our contracts for annual quantities of 10,000 or more are under attack every year on internet auctions from competitors outside Europe. “OEMs are always looking for lower prices. Subcontractors in the UK and presumably other Western European countries as well often do not get an opportunity to pitch, as their rates are expected to be too high. “It is true that we would lose money doing this type of work using our 40-taper machining centres, even at the lowest hourly rate feasible. “However, Brother Speedios are so incredibly fast that they give us an edge. They typically halve production times, knocking one-quarter off the cost of manufacturing a part.” He also explained that, with a 4th axis indexer fitted, one operation can frequently be saved compared with using a 3-axis machine, which can reduce floor-to-floor time further, by up to a factor of three overall, cutting costs even more.

“Brother Speedios are so incredibly fast that they give us an edge. They typically halve production times, knocking one-quarter off the cost of manufacturing a part.”

Instead of being 10 or 15 per cent too expensive, Hemlock can be a similar margin under the competition when quoting, or even more, so can realistically take on high-volume work and still make a profit.

Production rates two to three times higher

Mr Cobb is optimistic about the possibility of winning such contracts. He cites the initial job put on his first Brother Speedio S500X1 4-axis machine, which is equipped with a Kitagawa high-speed CNC indexer.

Whitehouse Machine Tools had demonstrated a turnkey manufacturing solution on the machine at its Kenilworth technical centre to show that the Japanese-built machines are a viable route to high profitability. The application involved producing a pair of left- and right-hand plates for a printer, 380 mm square by 12 mm thick, from solid aluminium.

For many years, Hemlock had been machining the plates two pairs at a time in two operations per plate on a 3-axis, 40-taper VMC in a cycle time of just over 48 minutes, or 24 minutes for two components. This included five minutes to refixture them all to drill holes in two opposing sides of each plate. Manual deburring of sharp edges took extra time, so in practice only four plates per hour were produced.

On the 4-axis, 30-taper S500X1, which has a working volume of 500 x 400 x 300 mm, a single pair of plates is machined in one hit over twice as quickly, in a 12-minute cycle. It includes deburring with a milling cutter, so the parts are ready for delivery immediately they leave the machine. The production rate is therefore 10 plates per hour, ie 2.5 times higher.

If the through-spindle coolant option on the Speedio had been chosen, the cycle time would have been even faster at just 8 minutes, equating to 15 plates per hour, or nearly four times the original production rate.

The productivity hike from the first machine, installed in August 2014, was so great that Mr Cobb decided to replace three additional 40-taper machines straight away with Brother Speedios. Two further identical models were installed, as well as an S700X1 with 700 mm travel in the X-axis. All four were delivered within the space of one month. The larger machine is fitted with through-spindle coolant and a faster Yukiwa CNC indexer, which rotates at 200 rpm, double the speed of the Kitagawa indexers.

“All of the indexers fitted by Whitehouse are not only fast but also very rigid during machining. It is because they are clamped hydraulically at both ends, rather than being held by the servo motor. “It allows us to take heavy milling cuts without vibration, maximising productivity and prolonging the life of the cutters. “In addition, their speed of rotation enables us to spin swarf off the components and fixtures after each cycle, so we save a few more seconds by not having to blow the chips away with an air gun.”

Paul Cobb, Managing Director

Fast when cutting – and between cuts

Rather than having a standard 10,000 rpm spindle or the 27,000 rpm option, all of Hemlock’s Speedio VMCs are fitted with a 7.4 kW / 16,000 rpm spindle. Mr Cobb considers it optimal for machining the various grades of aluminium that account for around 95 per cent of production at the Nottingham factory. He believes that higher speed spindles lack torque and require unnecessarily costly, balanced tooling, while lower speeds are not enough for productive removal of light alloy.

Rapid spindle deceleration to zero for tool exchange and acceleration to full rpm as well as quick indexing of the 21-station turret combine to bring the chip-to-chip time down to 1.4 seconds, cutting out a lot of idle time. Tapping at 6,000 rpm also promotes high productivity, as do 50 m/min rapids in the linear axes, up to 30 m/min cutting feed rate and axis accelerations of up to 2.2g.

A comparative analysis of the cutting data from the standard VMCs and the new Speedios at Hemlock reveals that, on average, the former are in-cut for 45 per cent of a cycle whereas the Brother machines are cutting for 66 per cent of the time. It results in a massive potential increase in metal removal of nearly 50 per cent.

Another facet of the machines that Mr Cobb appreciates is the power of the latest Brother CNC system. It has faster processing and 200-block look-ahead, enabling higher accuracy machining, especially in 3D. It also has many standard features that are costly extras on other controls. He pointed to the Brother CNC C00 specification at the URL: www.brother.com/europe/machine/sx1/spec/index.htm#spec-nc

and noted that 58 features are standard in the proprietary control and only five are options.

Two more Speedios every year

In conclusion, Mr Cobb said, “Our new Speedios will give any of our competitors a run for their money, whether they are in Budapest, Beijing or anywhere else in the world.

“We plan to replace two of our standard 40-taper VMCs with two Speedios every year for the foreseeable future in a bid to halve production times right across our shop floor.

“We have around 2,000 job numbers here. It takes time to swap jobs from our existing machines to the new platform because we rewrite each program, rather than just edit and transfer it. Only in that way do we gain maximum productivity advantage from the Speedios and Whitehouse helps with that.”

Paul Cobb, Managing Director

Most cycles, invariably involving interpolation in up to three axes plus indexer positioning, are created off-line using seats of hyperMILL and Mastercam. Occasional data input is required on the shop floor for programming simple jobs or to edit cycles.

Further advantages of the new Brother machines are their low power consumption, which reduces electricity bills, and their superior accuracy, with 10 microns positional tolerance routinely held by Hemlock.

The proximity of Whitehouse Machine Tools’ HQ has also been a benefit. The Brother agent’s applications engineers frequently visit the Nottingham subcontractor to assist with setting up jobs and to give advice.

Distinguishing factors

1024 682 Paul Cobb

A third 5-axis, vertical-spindle machining centre has been installed by subcontractor Hemlock Engineering, Nottingham, in response to a steady increase in work from a variety of sources.

Aircraft seat parts, medical prostheses, components for laser equipment used in dentistry and printing, fire suppression nozzles and parts for camera tripods and beer pumps are typical of the diverse range of contracts regularly received from more than 200 customers.

A long-time user of over twenty 3-axis and 4-axis VMCs, the company later invested in two 5-axis machines with 36,000rpm spindles and 90m/minute rapids for high-speed finishing. In contrast, the latest Hermle C 22 U, supplied through UK agent Geo Kingsbury, is a more robust 5-axis model capable of highly productive metal removal.

Even though 95% of jobs undertaken by Hemlock are in aluminium, high power and torque are still needed when taking deep cuts to prevent the cutter stalling. The Hermle’s 25kW/80Nm/20,000rpm spindle, 45m/minute rapids and 450 x 600 x 330mm working envelope are ideal for the subcontractor’s needs.

Two factors distinguish the C 22 U in the view of Hemlock’s managing director, Paul Cobb. First is the machine’s reliability, as it has operated faultlessly since it was installed in March 2013. Second is its ability to hold extremely high tolerances, down to a few microns on some optical parts used in dental laser equipment.

Mr Cobb comments: “There were less expensive machines on the market than the Hermle, but it was by no means the costliest. We also prefer the Heidenhain control option rather than the Fanuc CNC system which comes as standard on many other machines.

“The price of a machine tool is of secondary importance, particularly at the moment with interest rates as low as they are. It is uptime that is crucial in order to maintain output and profitability and also the cost of repairs, which tends to be high when a 5-axis machine goes down.

Hemlock’s managing director, Paul Cobb

“Repair bills have been a problem with some of the machines we have installed over the years, but the C 22 U has performed well. It has not missed a beat working 20 hours a day for the time that we have owned it.

“I thought it was going to be a good machine when I saw them being made at the German factory and it has not disappointed. The build quality is awesome and the clever design ensures that vibration is minimised, resulting in lower tooling costs, higher accuracy and less wear and tear on the machine.

“I know it will still be good in 10 years and more, so now I could not imagine buying any other make of 5-axis machine.”

Hemlock’s managing director, Paul Cobb

It is rare for the Hermle C 22 U at Hemlock to be used in full 5-axis mode. Most jobs require one or two operations involving 3-axis machining with the two rotary axes fixed. Cycles are created offline using seats of hyperMILL and Mastercam.

Typical of components produced are aluminium blocks that direct a laser beam through a multi-axis articulating arm used for hardening dental fillings. A couple of microns has to be held to achieve the required angular tolerance either side of 45°, which is only possible in a shopfloor environment by machining it on three sides in one set-up on the C 22 U. Brackets for military night vision goggles are another example of tightly toleranced parts produced on the machine, requiring ±10µm to be held.

Production of large aluminium heat sinks for electronic equipment is a regular job to be found on the machine. Their dimensions preclude extrusion and castings do not have the correct thermal diffusion characteristics, so they have to be machined from solid. Deep, closely spaced fins complicate their manufacture, but again the combination of high metal removal rate on the Hermle using small cutters at 20,000rpm together with rotary axis positioning allows the parts to be produced in two hits in much faster cycle times than previously.

Hemlock Engineering has a sister company, HPC services, specialising in sliding head turn/milling from up to 32mm bar and fixed head turning to 65mm diameter. The group was established in 1986, employs 70 people, has a turnover of £7 million and in addition to production runs, regularly undertakes prototyping and sub assembly.

Read the original story at Kingsbury UK

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