Increasing demands for lower costs of ownership is the reason why half the European car market is now diesel powered. The resulting development of common rail pump technology has transformed the image of the diesel engine from being noisy and dirty to one that is a highly efficient state of the art motive power source - and, in turn it has spurred new levels of production expertise in machine tool technology and applications.

But as diesel engines gain an ever-growing number of supporters from the motoring public, the development and production engineering currently also being applied to direct injection gasoline engines, which are now able to provide up to a 20% improvement in economy over conventional engines, means consumers have an even greater and more cost-effective number of alternatives.

As Markus Schnyder, managing director of Mikron Machining Technology based in Agno, Switzerland maintained: 'Fuel injection for both diesel and petrol engines is a very demanding technology sector with its associated design and development, as well as machining, constantly pushing the boundaries of production engineering knowledge to meet the ever-tightening legislation.' And he should know - because he heads up the Mikron operation that has become the world leader in the supply of machining technology to the fuel injection business.

Market forces, too, constantly change with consumers dictating economy, performance and lower cost of ownership with ever lengthening service intervals.

Hand in glove with higher performance, greater pumping pressures and more precise fuel flow comes increasingly sophisticated and smaller mechanical parts, and ever more precise dimensional size and geometric tolerances to complement the constant development of software and controlling electronics in vehicle management systems.

To meet such specifications, changing material requirements mean greater difficulty in machining, and more precise surface requirements, and while the number of parts in an assembly are often reduced, they tend to be more complex.

This therefore demands a greater consistency of production where there is little or no room for error or deviation.

Machining processes are also having to be combined into single operational cycles employing different process technologies in the shortest cycle times, and this adds further to the equation of complexity.

Mikron Machining Technology, with a third of its machine tool sales in fuel injection, and more than 350 production units installed around the world, is at the forefront of these rapidly developing levels of sophistication but, unlike other machine tool suppliers, it is able to combine both machine tool and tooling expertise.

Adds Markus Schnyder: 'With the 'micron' being the reference point for measurement, machine tool building has progressed to such a level that it satisfies the daily talk of production people that involves tolerances that were purely in the dreams of designers and quality engineers' just a decade or so ago.' Over the last 40 years, Mikron Machining Technology has taken its world-leading position as a manufacturer of production machine tools to the fuel injection industry and today it lists as customers most of the international companies involved in pumps, filter and injector manufacture.

The fuel injection industry formerly demanded dedicated machine tools, largely volume hungry rotary and in-line transfer machines and special purpose equipment tooled for the life of the product.

Today the market has changed.

Flexibility is so important; what's needed is the ability to ramp production up and down according to market demands, to provide in-built capability for re-tooling for new developments and being able to modify processes to achieve even greater levels of productivity to thus meet cost-down and performance improvement demands.

With its burgeoning role as a solutions provider, Mikron Machining Technology has progressively built a knowledge bank of machining requirements, often working with customers on simultaneous engineering projects, where development and production techniques are run together to shorten lead times.

As a result, the company has created a core machine range able to be creatively and practically tooled for production according to the volume, productivity and levels of flexibility required.

The Mikron machine range covers the CNC in-line, but modular and highly flexible Multistep expandable linear transfer machine, which is able to incorporate into a single cycle five-axis simultaneous operations enabling 5.1/2 face production of small and medium batch runs of parts up to 150mm cube without reclamping.

Such parts include housing and injector bodies, for instance, that have to be produced and process methods include changeover to different components.

This can be carried out exceptionally quickly, in around 20 to 40 min.

The Multistep provides totally new levels of flexibility by incorporating automatic fixture transportation.

Due to its modular construction the machine can be expanded and will perform all the processes typically applied to a machining centre but with the advantage of up to 22 tools for use in each module.

With rotation of B- and C-axes, the Multistep can machine a component from both sides and with the workpiece and fixturing able to revolve at up to 400 rev/min, turning and profiling under CNC control can be performed.

This facility is in addition to normal milling, drilling, threading and even gundrilling processes that can be incorporated into the cycle.

Chip to chip times for toolchanging is fast at less than one second.

The Multistar rotary indexing machine with 24 stations can incorporate up to 44 spindle units and is able to produce parts such as nozzles from a solid blank at a rate of up to 600 per hour.

Then there's the mechanically driven Multifactor, typically used for nozzle bodies, spacers, sleeves, barrels and pistons and able to be fitted with up to 3-axis CNC stations for added flexibility.

Meanwhile, the Mikron NRG-50 is a 12-station rotary transfer machine able to carry up to 66 tools that, at its launch in 2005, set a new benchmark for accuracy due to the incorporation of the Mikron development advanced thermal stabilisation technology.

The machine is highly flexible with up to 140 programmable axes and has the ability to cut with 30 tools simultaneously on all surfaces and at any angle of approach on a component within a single cycle.

The Mikron NRG-50 is indeed a machine tool development that is right at the forefront of production technology.

Another major advantage Mikron Machining Technology can offer the fuel injection industry is input from its sister company, Mikron Tool, itself a highly specialised operation located nearby the headquarters in Agno.

Mikron Tool has the ability to develop cutting tools such as drills, endmills and form tools in conjunction with the application engineering and machine tool build teams.

As a result, not only can high levels of productivity and tool life be tuned into production, but also the development of precise tooling geometry, ensures that precision, tool life and process security is perfectly transposed from the machine tool platform into the workplace.

For instance, hole intersection and breakout points are critical in fuel injection pumping and injector systems.

And with the tendency to specify difficult to machine materials and very deep small holes with extended length to diameter ratios, the tool and machine characteristics must match.

Failure to do so leads to tool point wander, swarf problems and tool breakage, resulting in process interruptions and short, poor productivity and low machine utilisation.

Typical applications include extremely tough 50 MnCrV4 forged steel truck injector, and such is the application engineering and machine build quality that a 3.56mm diameter hole with a tolerance of +0.05mm was drilled 78mm deep, (a 22:1 depth to diameter ratio) using a Mikron CrazyDrill in 20s.

Starting with a pilot drill to enable bushless drilling at 6,000 rev/min and 0.04mm/rev feed rate, penetration was 254mm/min over a depth of 6.3mm.

The tool was then changed to a Mikron CrazyDrill of the same size to finally drill to depth at 9,094 rev/min at 0.025mm/rev feed rate (227mm/min penetration rate).

In fuel injection applications, holes as small as 1.7mm diameter are drilled with high pressure 120 bar fully programmable through the tool coolant.

All Mikron Machining Technology's production systems can be tailored to suit material characteristics whether hard or soft, and here the 24 or optional 18-station Multistar, the fastest transfer machine in the world of which over 1,000 have been installed, is prime example.

On fuel injection nozzle production, in addition to drilling and recessing the Multistar machines are even used for final grinding and honing.

Explained Giovanni Zanot, chief of Quotation Department, the Multistar machine - which has an indexing accuracy of +/-2.5 micron - is very flexible to application engineer for short cycling volume production due to the number of stations.

For instance, to produce 1.3mm diameter holes in an injector nozzle 14mm deep, the process can be split into three drilling stations and a final reaming to size which enables the machine to produce 10 parts/min.

When this is compared to gundrilling the same hole, the production rate would be far slower, achieving at best, only four parts/minute with the additional downside of higher tooling costs.

An advantage of the Multistar is that a part such as a nozzle can be rotated in the collet improving concentricity and squareness between the guide bore, the outside diameter and seat of the component.

The outside diameter of the head can also be turned and faced in-cycle and inspection carried out during the machining process to check that the depth of the seat is within tolerance.

The machine can also be used to incorporate inspection and even assembly processes in-cycle as well as performing very specialist processes including grinding, bending, measurement and test.

The mechanically driven Mikron Multifactor suitable for pieces up to 100mm cube combines very precise table indexing of +/-0.004mm with perfectly synchronised clamping and unit head positioning while maintaining cycle times up to 30 parts/minute with minimal lost time.

With eight, 10, 12 or 15 stations according to the application, either mechanical or fully programmable CNC heads can be incorporated as well as programmable indexing of the workpiece at each station.

As a result, complex features required by the fuel injection industry can be incorporated into a single highly repetitive automated cycle including the generation under CNC of profiles and internal recesses such as chambers used to accommodate hole breakthroughs.

In addition, a most important advantage of having up to three CNC axes available per station is the ability to interpolate and program the machining of a feature via different axes.

This capability can prove invaluable to enable precise and consistent machining cycles to mechanically remove any burrs or sharp edges within the automated production cycle.

While having the ability to produce components at up to 30 parts/min, the Mikron fully CNC-controlled 140-axis NRG-50 is ideal for family part production while commanding new levels of flexibility for re-tooling when ramping production requirements up and down.

It can even be switched from a vertical to a horizontal component fixturing configuration and produce parts from either bar or be robot loaded with blanks, castings or forgings.

And with in-built ATS, Mikron's Advanced Thermal Stabilisation technology designed into the original concept, any possible influence of ambient temperature to accuracy is accounted for giving production management the confidence that component accuracy is ensured.
This sets a new order of machining capability in critical component manufacture.