Creating A Hole – The Various Techniques

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Creating A Hole The Various Techniques
Home-making takes up most part of the machining
operations, wherein a perfect hole is required
to be cut into a workpiece. While the most basic
process used to cut a hole within a metal is
drilling, there are many other processes
involved too, in order to make for a perfect
finished hole. These include reaming, tapping,
and boring. Each process if different, and unique
in its own way. Well learn more on that later
in the blog. Creating a hole In machining, a hole
is cut from the workpiece by a rotating cutting
tool that enters the workpiece axially. The
diameter and geometry of this cutting tool will
create a hole with the same diameter and
geometry. While all machined holes have the same
basic form, they can still differ in many ways to
best suit a given applications. A machined hole
can be characterized by several features or
parameters that determine the hole-making
operation and tool required. The diameter The
cutting tools used for hole-making are available
in standard sizes, ranging from 0.0019 inches to
3 inches. Fractional sizes, letter sizes, number
sizes, and metric sizes are available. The
closest standard sized tool should be used,
because the diameter of the hole can be
determined only by the tool selected. The depth
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The depth of a hole can be determined by the
depth to the point, or the depth to the end of
the full diameter portion of the hole. The total
depth of the hole can be determined by, and is
limited to the length of the cutting tool. The
tolerance This depicts the precision of the hole,
which can be affected by a number of factors
like the tools sharpness, the vibration, and the
build-up of chips of material. With some methods
being suited for only tight-tolerance holes, the
specified tolerance of a hole will determine the
method of hole-making used. The recessed
top Machined holes are generally recessed at the
top to accommodate the head of a fastener,
allowing it to sit flush with the surface of the
workpiece. There are two types of recessed holes
counterbore with a cylindrical recess, and
countersink with a cone-shaped recess. The
threads This is considered when the hole is a
threaded one. Such holes are machined with the
help of taps and dies, to accommodate a threaded
fastener. The pitch is of considerable
importance here, which is the measure of spacing
between two consecutive threads, which can be
expressed as the number of threads per inch
(TPI) or the distance in millimeters (mm) between
the threads. Techniques for making holes As
mentioned above, drilling is the most basic
procedure for making a hole, but other
procedures like reaming, tapping, and boring also
exist, to create different types of holes. Lets
learn about each one of these processes in
detail. Drilling A drill bit is used here to
enter the workpiece axially and cut a hole
within. The four basic types of drill bits used
include twist drill, center drill, spot drill,
and tap drill, each beginning a hole, which can
be completed further by any other operation
mentioned below. Reaming A reamer is used to
enlarge an existing hole, by removing minimal
amount of material, to obtain a more accurate
diameter and a smooth internal finish. The
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flute of a reamer can be straight or in helix, as
required by the operation and application. Tappin
g A tap is used here to cut internal threads into
an existing hole, which is selected based on the
major diameter and pitch of the threaded hole.
Threads here may be cut through the entire
length of the hole, or only till a specified
depth and pitch. Boring A boring tool cuts along
the internal surface of an existing hole, to
enlarge the diameter, or obtain more precise
dimensions. This single-point cutting tool can
be set to cut the desired diameter, by using an
adjustable boring head. Whether a boring bar, or
a boring head, or any other boring tool, whatever
you need to bore a hole, you can get it all at
Finetech Toolings, your one-stop solution for
precision boring tools in Bangalore. Counterboring
/countersinking Counterbore tools or countersink
tools are used to enlarge only the top portion
of an existing hole to provide space for the head
of a fastener, such as a bolt or screw, to sit
flush with the surface of the workpiece. The only
difference that lies in both the tools is that
the counterboring tool has a pilot on the end to
guide it straight into the existing hole, and the
countersink tool comes with angles of 60, 82,
90, 100, 118, or 120 degrees, as required.