Machining Fundamentals 610
Direct Shell Production Casting (DSPC): A
variation of the Fused Deposition Modeling
process that prints a three-dimensional model
using sand or ceramics instead of plastic.
The fi nished model can be used as a mold or
mold core for casting. (Ch. 26)
divider: A layout tool with pointed legs of
equal length used to draw circles and arcs.
(Ch. 6)
drill gage: An instrument used to measure the
diameter of a drill of various series. (Ch. 12)
drilling machine: A power-driven machine
that holds the material and cutting tool and
brings them together to cut or enlarge a hole.
(Ch. 12)
drill point gage: An instrument used to ensure
a drill is correctly sharpened. (Ch. 12)
drill press: A machine that rotates a drill
against stationary material with suffi cient
pressure to cause the drill to penetrate the
material. It is primarily used for cutting
round holes. (Ch. 1)
dry cycle: Cycling through all programs of a
CNC machine once during setup without a
part in place to check for potential problems.
(Ch. 22)
dual dimensioning: A system that uses both
the U.S. Conventional system of fraction
or decimal dimensions and SI Metric
dimensions on the same drawing. (Ch. 4)
ductility: A property of metal that permits
permanent deformation by hammering, rolling,
and drawing without breaking or fracturing.
(Ch. 28)
dwell: To leave the cutting tool in place for a
period of time after it has reached the fi nal
cutting depth. This helps to relieve pressure
on the cutting tool and improves fi nish.
(Ch. 20)
dye penetrant inspection: A
nondestructive testing method in which
a dye is applied to a part’s surface and
drawn into flaws by capillary action. The
excess dye is removed and a developer
is applied. The developer draws the dye
back to the surface, marking the location
of any flaw. (Ch. 27)
E
eddy-current inspection: A nondestructive
testing method that detects fl aws by
measuring changes in impedance in a test
coil placed near the test sample. A material
without fl aws will generate a different
impedance than a material with fl aws.
(Ch. 27)
electrical discharge machining (EDM): A
process in which material is eroded from
workpiece by an electric arc between the
electrode and workpiece. (Ch. 31)
electrical discharge wire cutting (EDWC):
A machining process that removes material
from the workpiece by creating an arc
between a wire electrode and the workpiece.
It is similar in function to band machining.
(Ch. 31)
electrochemical machining (ECM): A process
that removes material from the workpiece
through electrolysis. In this process, an
electrolyte surrounds the electrode and
workpiece, which are electrically charged.
(Ch. 31)
electrode: In electrical discharge machining,
an negatively charged tool. When voltage
builds to suffi cient strength, an arc jumps
from the electrode to the workpiece, eroding
a small amount of metal from the workpiece.
(Ch. 31)