Section 13. qxd

machining centers.
This is
a machine equipped with as many as 200 tools and with an automatic
tool changer (Fig. 13.4.9). It is designed to perform various operations
on different surfaces of the workpiece, which is placed on a pallet capa-
ble of as much as five-axis movement (three linear and two rotational).
Machining centers, which may be vertical or horizontal spindle, have
flexibility and versatility that other machine tools do not have, and thus
they have become the first choice in machine selection in modern man-
ufacturing plants and shops. They have the capability of tool and part
checking, tool-condition monitoring, in-process and postprocess gag-
ing, and inspection of machined surfaces. 
Universal machining centers
are the latest development, and they have both vertical and horizontal
spindles. 
Turning centers
are a further development of computer-
controlled lathes and have great flexibility. Many centers are now con-
structed on a 
modular
basis, so that various accessories and peripheral
equipment can be installed and modified depending on the type of prod-
uct to be machined.
MACHINE TOOLS
13-55
Fig. 13.4.9
Schematic of a horizontal spindle machining center, equipped with
an automatic tool changer. Tool magazines can store 200 different cutting tools.
An approach to optimize machining operations is 
adaptive control.
While the material is being machined, the system senses operating con-
ditions such as forces, tool-tip temperature, rate of tool wear, and sur-
face finish, and converts these data into feed and speed control that
enables the machine to cut under optimum conditions for maximum
productivity. Combined with numerical controls and computers, adap-
tive controls are expected to result in increased efficiency of metal-
working operations.
With the advent of sophisticated computers and various software, mod-
ern manufacturing has evolved into