about 750 u03bcm e g 300 350 400 450 500 550 600 650 700 or 750 u03bcm is produced in the matrix alloy the exact values of the layer thickness depend on different influencing factors such as process parameters positioning accuracy of the device and dimensional tolerances of the casting therefore when thicknesses are given below reference is always made to a u201c mean u201d layer thickness and the tolerance range can be kept very narrow because the device can be centred at the component the alloyed on zone may be applied in strips wherein the strip width is about 2 mm or more e g 2 3 4 5 6 7 8 9 10 11 or 12 mm or more preferably about 2 mm to about 4 mm in a further machining stage the starting layer thickness of about 300 to about 750 u03bcm is then reduced by precision machining such as honing to the required end layer thickness by removing up to about 150 u03bcm the alloyed on zone may be honed directly without an intermediate machining operation preferably the uppermost layer of alloyed on zone which is removed does not exceed about 30 of total layer thickness e g 5 10 15 20 25 or 30 the end layer thickness achieved by the.