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Gantry robot gives Nutberry unmanned mill-turning

Gantry robot gives Nutberry unmanned mill-turning

Added to MTDCNC by CMZ UK Ltd on 03 September 2012

A CMZ mill-turning centre with a gantry loading robot is running 24 hours a day at East Sussex manufacturer Nutberry machining components for high technology pumps.

Nutberry specialises in the manufacture of gas springs for high-temperature applications and also makes its own range of metal bellows that are used in a variety of applications. Customers include steelworks around the world, global medical equipment manufacturers and companies making high-technology scientific equipment.
 
Many of the metal bellows it manufactures are welded to machined metal flanges and end-pieces and these are turned on CNC machines, including two CMZ turning centres.
 
The most recently installed of these is a TC 20 Y S lathe supplied with a gantry loading robot. The TC 20 Y S has a large, 140mm-stroke Y-axis, a sixteen-station tooling turret with 12kW driven tooling, 12' chuck and sub-spindle. The machine runs unmanned, producing fully-machined end-fittings from laser-cut rings and fabrications.
 
As Nutberry's Antony Montebello explains, the company bought its first CMZ machine, a TL20S turning centre, after he visited the CMZ factory and was impressed with what he saw.
 
'We had heard of CMZ, but we didn't know much about them and were looking at buying a high-end Japanese machine similar to ones we already run. What convinced us was a trip to CMZ's factory in Spain. We had the chance to see how they were made and we were really impressed with the way they manufactured all the parts and the process controls they had in place.
 
'And there wasn't any skimping on the bought-in components either. They also used the latest Fanuc controls and motors, which we know well from using them on our own special-purpose bellows forming machines.'
 
He says the decision to go with CMZ was a good one. He has been very pleased with the way the machine has performed and the service provided by CMZ.
 
'That made us look to CMZ again when we needed to cope with increasing demand from one of our customers, a vacuum pump manufacturer,' he adds.
 
The requirement wasn't simply to increase capacity. Mr Montebello says that they just could not have done the volume of work required doing it the way they had been. This involved turning the parts and then machining them in a number of separate operations.
 
'With the TC 20 Y S we could get the parts off in one,' he says.
 
The machine is used for a family of similar end flanges, all of which require milling, drilling and tapping operations as well as turning. They are all fairly thin disk-like components, with the laser-cut blanks typically 4mm thick. Some have a profiled shape round the circumference and all require various forms and tapped holes to be machined. The largest parts run on the machine at the moment are 188mm in diameter, but Mr Montebello plans to go up to about 230mm. All are produced running unmanned for up to 24 hours a day.
 
He says: 'The objective was to limit the amount of handling on a job and we use all the different aspects of the machine's capabilities.
 
'The 16-station turret gives a lot of flexibility, and we will have maybe five driven tools on there at a time. The long Y-axis is important, as is the power of the driven tooling – I'm really impressed with that.
 
He has found that the CMZ TC 20 Y S with the gantry loading robot lends itself very well to making these parts in volume.
 
'When we bought the machine, we hadn't expected to be able to run it 24 hours unmanned because of the tolerances we are working to – generally plus or minus 0.02mm,' he says.
 
'Based on the machine we had been using, we thought that we would have to tweak it every twenty or thirty components. But we can do 300-off without having to touch an offset and the cutters are still fine. It has a nice deep drop so the swarf falls away nicely and we don't have any problems with swarf build-up or jamming. It is a well-designed machine.'
 
What is critical though is the machine's reliable accuracy.
 
'In terms of accuracy, it just doesn't move. It is a very stable machine and that is why we can run it overnight quite confidently. We don't have to alter the offsets at all. It is very good in terms of repeatable accuracy.'
 
He says that this level of confidence is important because when you are starting from laser-cut rings and welded fabrications there is already a lot of added value in the component.
 
'We have to be sure we have a stable process and machine. We can stack up maybe 300 components on the loader and run them overnight knowing that there won't be any problems.'
 
Each of the 14 stations on the gantry robot can hold about 80 blanks, so it can be loaded up in advance for several production runs. Indeed, when cut blanks are delivered from the laser subcontractor they are often loaded straight onto the machine, rather than taking up storage space elsewhere in the shop.
 
Antony Montebello adds that the gantry is easy to program too. 'It works using macros, so once you have taught in the important positions and got those variables in the system it is very straightforward,' he says.
 
'And certainly, in comparison with our bar feeder machines, the TC20 YS with the gantry loader gives us a lot of capacity and capability on a pretty small footprint.'
 
Another benefit of the CMZ machine that Nutberry has found is that tool life is greatly improved.
 
Mr Montebello says: 'We used to do the turning part of this job on another machine and the tools just weren't lasting. On this machine we have hardly had to change the cutters at all. I would say that this was down to CMZ's quality of build, rigidity and the quality of the bearings.
 
'I am definitely very pleased with the accuracy and reliability of the CMZ machine. I can't fault it in any way. In the past we have invested in high-end Japanese machines and both our CMZ machines stand up very well against them, and there is a significant price advantage. We are very pleased with what CMZ have provided and certainly on the strength of that we would buy another.'

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