CNC machining is a process suitable for
producing high accuracy, high tolerance parts in prototype, one-off, and small
to medium production runs. While parts are typically produced with tolerances
ranging between +/- 0.001 in. to +/- 0.005 in., some machining machines can
achieve tolerances of up to and greater than +/- 0.0005 in. The versatility of
the machining process allows it to be used in a wide range of industries and
for a variety of part features and designs, including slots, chamfers, threads,
and pockets. The most common CNC machining operations include:
• Face
machining
• Plain
machining
• Angular
machining
• Form
machining
Face Machining
Face machining refers to machining
operations in which the cutting tool’s axis of rotation is perpendicular to the
surface of the workpiece. The process employs face machining cutters which have
teeth both on the periphery and tool face, with the peripheral teeth primarily
being used for cutting and the face teeth being used for finishing
applications. Generally, face machining is used to create flat surfaces and
contours on the finished piece and is capable of producing higher quality
finishes than other machining processes. Both vertical and horizontal machining
machines support this process.
Types of face machining include end machining
and side machining, which use end machining cutters and side machining cutters,
respectively.
Plain Machining
Plain machining, also known as surface or
slab machining, refers to machining operations in which the cutting tool’s axis
of rotation is parallel to the surface of the workpiece. The process employs
plain machining cutters which have teeth on the periphery that perform the
cutting operation. Depending on the specifications of the machining
application, such as the depth of the cut and the size of the workpiece, both
narrow and wide cutters are used. Narrow cutters allow for deeper cuts, while
wider cutters are used for cutting larger surface areas. If a plain machining
application requires the removal of a large amount of material from the
workpiece, the operator first employs a coarse-toothed cutter, slow cutting
speeds, and fast feed rates to produce the custom-designed part’s approximate
geometry. Then, the operator introduces a finer toothed cutter, faster cutting
speeds, and slower feed rates to produce the details of the finished part.
Angular Machining
Angular machining, also known as angle machining,
refers to machining operations in which the cutting tool’s axis of rotation is
at an angle relative to the surface of the workpiece. The process employs
single-angle machining cutters—angled based on the particular design being
machined—to produce angular features, such as chamfers, serrations, and
grooves. One common application of angular machining is the production of
dovetails, which employs 45°, 50°, 55°, or 60° dovetail cutters based on the
design of the dovetail.
Form Machining
Form machining refers to machining
operations involving irregular surfaces, contours, and outlines, such as parts
with curved and flat surfaces, or completely curved surfaces. The process
employs formed machining cutters or fly cutters specialized for the particular
application, such as convex, concave, and corner rounding cutters. Some of the
common applications of form machining include producing hemispherical and
semi-circular cavities, beads, and contours, as well as intricate designs and
complex parts with a single machine setup.