Bumotec

A Bumotec s191H is enabling SMTP Technology to machine surgical cutting tips – including titanium types - in a single set-up and to very high accuracies, allowing the company to extend the reach of its innovative ultrasonic therapeutic products to compete on the world stage in orthopaedic, neuro and joint surgery. 

The precision-engineered cutting tips – the critical ‘working end’ of the company’s XD series power tools that use ultrasonic vibration to cut bone and with no risk of damage to soft tissues – feature ‘teeth’ with helical tips (of varying number) that must be machined accurately to within 10 microns. Below-quality teeth will affect the flow of ultrasonic energy and could cause loss of control or even breakages during use.

The Bumotec s191H with 65 mm bar capacity, bar feed system and high-pressure (HP3) coolant was selected to produce the cutting tips, it says, “because of its high rigidity and its ability to consistently multi-task machine in a single set-up”. Indeed, in a 40-minute cycle, the Bumotec enables the production of a perfect helical tip head using mainly turning/milling functions (but also drilling and tapping, plus deep hole drilling).

SMTP also reveals that since installation (at the end of 2015), the machine “has operated perfectly non-stop every day since”, manned by two operators working in shifts each day to allow the machine to run non-stop from 6.00 hrs through to 23.00 hrs.
 

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In another example, the machining of aero engine fuel injectors, the Bumotec s191 produces the tool steel workpieces complete from 15 mm diameter bar, utilising 18 tools in a single set-up and completing the sequence of turning, milling, grinding, drilling, deburring and engraving on the six-sided complex component.

In particular, the machining demands flawless surface finishes – of inner and outer surfaces with both conical and cylindrical profiles; inner surfaces must be accurate to ensure perfect fuel flow and outer profiles must ensure perfect assembly.

The Bumotec s191 can achieve highly accurate (to +/- 2.5 microns) machining solutions within an X, Y and Z axes range of 410 mm, 200 mm and 400 mm, respectively, courtesy of its linear drives and high-level thermal stability. In addition, its main spindle is complemented by a sub-spindle that can turn in both horizontal and vertical planes, for multi-process/tasking routines, and tool magazine options extend to up to 90 pockets on a machine that has rapid traverse rates of 50 m/min and a 30,000 (or 40,000) revs/min spindle speed that also contribute to its ultra-fast cycle times.

A Bumotec s181 is enabling one producer of ‘traditional’ turned parts to not only finish-machine a multi-operation component with interconnecting holes to a burr-free state and with superb levels of roundness and surface finish, but the new machine is also allowing the company to welcome new business where effective and efficient single set-up, multi-operation workpieces are required.

The s181 was installed to produce a distributor for a respiratory protective device; the component that connects an oxygen bottle to a respirator mask (as used by the fire service).

Produced from a special aluminium alloy with silicon (AlSi05) forged blank, the workpiece presents a number of machining demands before it is anodised – in particular the production of a hole (H7) that is drilled to a tolerance of 14 microns and must not have burrs on the interconnecting channels. The Bumotec inserts the blank automatically then processes all six sides of the workpiece.

One critical aspect of producing the distributor is the fact that the initial blank is forged to a high tolerance, so a specially-designed clamping system – one that will hold the part rigidly but without damage or deflection - has been developed and adapted to the machine.

In another instance, the production of a stainless steel workpiece from 14 mm bar, the cycle time on a modern machining centre was 389 seconds but on the Bumotec s181 it took just 254 seconds to complete the part – a 38 per cent productivity increase!

With HSK-40 (30,000 revs/min) spindle, the Bumotec s181 can produce very small components with high accuracy and stable process repeatability.