There are always options when it becomes essential for machine shops to uncover ways of improving throughput. However, with the testing economic climate, traditional solutions, such as hiring more operators or buying more machines, can sometimes be viewed as cost-prohibitive and a somewhat risky exercise.
Of course, every situation has its own set of incidentals, but retrofitting a machine tool with new technology, such as a faster spindle, a better pallet loader or a high-pressure coolant system, can offer tremendous gains in productivity, at a fraction of the cost of machine replacement.
One company bearing testimony to this fact is the Birmingham Mint, where core business centres on the manufacture of medals. Until recently, stamping dies for medals were produced on a machining centre fitted with a spindle limited to 10,000 rpm maximum speed. However, due to problems with heat dissipation, the Birmingham Mint could only run the spindle at 6,000 rpm.
"We couldn't continue with the situation, as it was slowing production down," says managing director Angus Law. "Trying to run faster caused quality problems and we would lose surface definition."Having searched the Internet, Mr Law came across ITC, the UK distributor for Air Turbine high speed spindles.
"Other spindles needed an air compressor or a cooler, whereas the Air Turbine unit from ITC fitted straight on to our machine. The unit automatically blasts cool air at 70 psi directly at the cutting tool, which eradicated our problem."
Image: An air turbine in action at Birmingham Mint
The Air Turbine unit has increased spindle speed at the Birmingham Mint to 40,000 rpm and cut cycle times by 50 per cent. Furthermore, its versatility enables it to be fitted to virtually any machine tool, which means the company also uses the spindle for finishing and engraving operations.
At another OEM located less than 12 miles south, a similar success story is being experienced, following the retrofit of automation equipment to two 5-axis machining centres.
In order to further the production of its range of Jetstream high pressure, through-coolant turning tools, Seco Tools' Alcester facility in Warwickshire has recently upgraded its two Hermle 5-axis C30U VMCs to include 12-station Erowa pallet loaders. UK agent, Geo Kingsbury Machine Tools, undertook the turnkey project.
The aim was to achieve faster set-ups, and, thanks to the retrofit programme, up to 24 jobs can now be fixtured at any given time across the two cells. As average machining time per toolholder is 15 minutes – and because four tools are fixtured per pallet – approximately 12 hours unattended running is now possible on each machine.
A 157-position tool magazine was specified for the second Hermle, while the magazine on the first machine was extended to the same number of pockets, allowing space for sister tools during a ghost from 23:00 to 06:00.
Image: Seco Tools upgraded its Hermle machining centres
Turning machines can also benefit from retrofit projects. A case in point was witnessed recently at Birmingham turned parts sub-contractor MSP, which was experiencing a problem when machining components from Hastelloy bar on a CNC sliding-headstock lathe. The material's toughness was causing unpredictable and early failure of drills, taps and thread mills, which was slowing production and proving expensive. So the company called in Emmaco to install automated tool monitoring.
Fitted with an acoustic sensor to the sliding-head lathe's tool platen, the Argotech PA-2 checks automatically the sound frequencies produced during a critical machining operation, stopping the machine instantly in the event of tool wear or failure. During a full year of operating this system, MSP has not lost a single thread mill prematurely, whereas before the system was fitted, the sub-contractor was losing ￡400 worth of the cutters per week, based on 24-hour running. Therefore, within the first 10 weeks of installing the process monitor, there was a saving of ￡4,000: equal to the cost of installing the PA-2 and both sensors.
Mills CNC says that strong sales of its Doosan range of machine tools defies the assumption that in recession, manufacturers consider retrofit and refurbishment projects, rather than invest in new machines. That said, the company admits that customers can and do improve the performance of their existing Doosan and Daewoo machines via Mills '360' after-sales services, of which the retrofit of ancillary equipment is a core part.
Everything from rotary tables, bar feeds, steadies, extraction units, probing systems and high pressure coolant systems can be ordered, supplied and project managed by Mills. "Many customers who have had to cancel or postpone their investment in new machine tools have opted to investigate ways of improving the performance of existing machine tools," says the company's managing director, Nick Frampton. "There are a number of different reasons why customers retrofit ancillary equipment. Probably the most common is to increase productivity and versatility by integrating [for example] a 4/5-axis indexer or rotary table to a milling machine, or by investing in bar feed lathes or turning centres."
Other reasons cited by Mr Frampton include: in-process measurement and detection of tool breaks (by retrofitting probes); the need to improve machining capacity and capability by being able to machine larger and longer workpieces (using steadies); and the need to remove hazardous vapours and dust from machining areas (by fitting oil/mist extraction units).
Following on from the latter point, a sub-contract machine shop serving the aerospace sector has recently reduced its concentration of oil and dust in the working environment, thanks to the retrofit of extraction units from Air Cleaning Systems.
In 2006, Portsmouth-based VRS Precision Engineering procured Matsuura 800VG11 and Matsuura 1000VG vertical machining centres. The acquisitions enabled VRS to produce aluminium and stainless steel fuel filtration and air conditioning components for aerospace manufacturers such as Boeing and Airbus. Moving to technology such as through-coolant and high speed machining that generates high levels of swarf, smoke and coolant mist – the ISO: 9001 company was advised by Matsuura to invest in filtration systems for the machines, suggesting units from ACS.
ACS fitted colour-coded OMF1000 filtration systems to the Matsuura centres, as VRS production manager Rod Bradley explains: "As any machinist working on a modern CNC will find, with ever increasing speeds and feeds, combined with through or high pressure coolant, the machine has to be left for up to five minutes for the fumes to settle, before removing the part from the work envelope. This break is now a thing of the past with the ACS systems."
The company has since embarked on a mission to install filtration systems on all its machine tools, including Mori Seiki, Doosan Puma and Lynx models.
Pleased as punch
RPA , UK agent for Nisshinbo punching machines, has developed a retrofit PC-run CNC for older punching machines, originally aimed at the Nisshinbo machines, but now available for punching machines of any origin, including Amada, Trumpf, Strippit and LVD.
The facilities and functions of iMotion include: remote servicing, using an in-built modem; re-starting the job from any cut or punch; processing speeds unavailable in the normal CNC world; production management and batch control; two programs and displays held at any moment in time; and stations and tool types programmed individually for feeds, accelerations, hold-downs and delays.
First published in Machinery, October 2009