A proven means of making production processes more effective is to combine several machining operations in one tool. However, this creates a very high volume of chips that have to be reliably controlled and efficiently discharged.
The new spiral-fluted PCD step drill from Mapal ensures optimum chip transport so that extreme reductions in machining time for drilling and boring processes in aluminium parts are possible. Where previously three tools were necessary for piloting, deep hole drilling and boring, these three operations can now be performed with just one tool in a single shot.
Optimum chip removal and reduced heat input into the part
Several features are crucial for the exceptional performance of the new PCD step drill, and these have to be perfectly matched. The spiral-fluted chip spaces, in particular, contribute to a very good chip transport out of the bore and ensure that there is no congestion of chips even at the transition from the solid drilling to the boring step. The right flute geometry and pitch is crucial for this, and the chip flutes are also polished over the whole length of the drill to minimise the friction of the chips. The PCD blades embedded perfectly into the spiral of the solid drilling and boring step result in a good cutting behaviour of the drill. This reduces the heat input into the part compared with conventional drills with straight flutes. And finally the correct position of the coolant outlets for MQL machining is crucial for the performance of the drill so that the aerosol reaches the points where lubrication is necessary. This reduces the risk of build-up edges and naturally also helps to prolong the tool life of the drill.
Producing spark plug bores 75% faster
One application example is the spark plug bore in a cylinder head of AlSi6Cu4. The bore is produced on a machining centre with minimum quantity lubrication, making the controlled removal of the chips from the bore particularly important. At a spindle speed of n = 5,600 rpm and a feed rate of vf = 2,500 mm/min, the one-shot solution from Mapal reduces the cycle time by 75%. That corresponds to a time saving of 42 seconds for a cylinder head for a 4-cylinder engine, offering a significant boost in profitability and productivity.
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