AUTOMOTIVE TURNING

ADVANCED CUTTING MATERIALS FOR PERFORMANCE AND PRODUCTION EFFICIENCY

PCD

Technical Characteristics
The increasing use of aluminum and silicon based light alloy parts in the automotive, motorcycle and aerospace
industries, of exotic or composite materials made of carbon, glass, Kevlar fibers, mainly used in the aerospace industry,
has given a definite boost to the research and development of cutting materials; this has led to the increasing use of
Polycrystalline Diamond (PCD) cutting edges.
This cutting material is obtained by sintering blends of synthetic diamond powders and specially treated powders that
act as a binder.

Benefits
The use of Polycrystalline Diamond (PCD) cutting edges allows for remarkable durability of the cutting edges, which
retain their integrity up to operating temperatures of approximately 800°C.
This edge life justifies the use of PCD for machining light alloys and composites.

Cost-benefit relationships in manufacturing reality
In order to evaluate with suƯicient objectivity the cost-benefit ratio of the use of PCD cutting edges, particular attention
could be paid to the machining costs required to obtain surface finishes below Ra 0.5.
Roughness values that are lower and lower are essential to obtain the tolerances required to produce parts with
increasingly precise dimensions, for applications that require reliability guarantees, or to improve lubrication by reducing
wear between friction parts.
The use of PCD cutting edges allows a significant increase in cutting speed, with consequent savings in machining time,
and the achievement of extremely low surface finish values.

CBN

Technical Characteristics

Cubic Boron Nitride (CBN) is obtained by treating the main component of the mixture, hexagonal boron nitride crystals,
at high temperature and pressure.
The conversion of Hexagonal Boron Nitride to Cubic Boron Nitride takes place at pressures of about 18 Gpa and
temperatures between 1730° and 2000°.
By adding Boron Oxide to the original mixture, the required temperature and pressure can be lowered.
This process makes it possible to obtain a material, CBN, with Vickers Hv hardnesses of about 40/50 Gpa, in shapes and
sizes precise enough to be cut and shaped into cutting edges that are generally placed on carbide inserts.
The diƯerent “concentrations”, in terms of the percentage presence of cubic nitrides and the size of the grains that make
up the powder, help to determine the relationship between wear resistance and toughness of the cutting edge.

Benefits
Cubic Boron Nitride (CBN) is the cutting material solution with hardness characteristics second only to natural diamond,
but with greater chemical stability where higher operating temperatures are required due to the pressures and friction of
the material being removed from the cutting surfaces.

Cost-benefit relationships in manufacturing reality
Edge life as a function of cutting speed and reduction of machine time very often justifies higher edge costs for lower
cost per piece produced, while higher costs can be tolerated for higher productivity as long as they are within the context
of proper resource management.