Section 13. qxd

diamond turning,
typically using a single-crystal
diamond cutting tool and rigid machine tools. Applications for such
parts and components are in the computer, electronic, nuclear, and
defense industries.
Turret Lathes
Turret lathes are used for the production of parts in moderate quantities
and produce interchangeable parts at low production cost. Turret lathes
may be chucking, screw machine, or universal. The universal machine
may be set up to machine bar stock as a screw machine or have the work
held in a chuck. These machines may be semiautomatic, i.e., so
arranged that after a piece is chucked and the machine started, it will
complete the machining cycle automatically and come to a stop. They
may be horizontal or vertical and single- or multiple-spindle; many of
these lathes are now computer-controlled and have a variety of features.
The basic principle of the turret lathe is that, with standard tools, setups
can be made quickly so that combined, multiple, and successive cuts can
be made on a part. By 
combined
cuts, tools on the cross slide operate
simultaneously with those on the turret, e.g., facing from the cross slide
and boring from the turret. 
Multiple
cuts permit two or more tools to oper-
ate from either or both the cross slide or turret. By 
successive
cuts, one tool
may follow another to rough or finish a surface; e.g., a hole may be
drilled, bored, and reamed at one chucking. In the tool-slide machine only
roughing cuts, such as turn and face, can be made in one machine.
Ram-type turret lathes
have the turret mounted on a ram which slides
in a separate base. The base is clamped at a position along the bed to
suit a long or short workpiece. A cross slide can be used so that com-
bined cuts can be taken from the turret and the cross slide at the same
time. Turret and cross slide can be equipped with manual or power
feed. The short stroke of the turret slide limits this machine to com-
paratively short light work, in both small and quantity-lot production.