Magnesium is the lightest metal used in construction and therefore offers the greatest potential for weight reduction. The automotive
industry in particular has an upcoming interest in the use of magnesium alloys. To observe the interactions beiween woIkpiece material and
tool material and coating, respectively, turning experiments were carried out machining the alloy AZ91 HP. When machining magnesium
dry, flank build-up due to adhesion between cutting tool and workpiece can occur at cmting speeds of V~ = 900 m/min and more for
uncoated and TiN-coated cemented carbide 1001s. Tools with either polycrystalline diamond (PCD) insert or coating can be used to reduce
friction and adhesion in the tool-workpiece contact resulting in low machining forces as well as a superior surface quality even at high
cutting speeds of V, = 2400 mlmin. PCD coatings can also be applied to complex tool geometries. As tool wear can hardly be observed
when machining magnesium alloys, a magnesium-based metal matrix composite (MMC) is machined to combine the adhesive effects of
magnesium with the abrasive load caused by a reinforcement component. Excessive tool wear can bz observed for TiN-coated carbides
even at low cutting speeds of I’, = 100 nv’min. PCD coatings show better results but cannot compete with tools having a PCD insert if a low
film thickness is chosen.