What is tapping process?
Tapping on a nut
Fig. 1 Tapping done on a nut

The operation in which internal threads are formed to the workpiece is known as tapping process.

What is a tap?
Terminologies of a tap
Fig. 2 Terminologies of a tap

A tap is a equipment which produces chips by removing material with the help of multiple cutting teeths.
Taps have two, three, or four flutes.
The most common production tap is the
two-flute spiral-point tap.
In two-flute tap, the chips are forced into the hole to remove the tap when it reached the end of cut.
The strength of three-fluted taps are more as the availability of material is more in the flute.
Tap sizes range up to 100 mm.

Also read

Grinding process
Milling process
What are the different types of taps?

Tapered taps serve the main purpose to reduce the torque required for the tapping of
through holes.
Bottoming taps help in tapping blind holes to their entire depth.
Collapsible taps are used in large-diameter holes, after tapping has been completed,
the tap is removed from the hole without rotation as it is collapsed mechanically.

What happens when chips are not removed properly?

Chip removal is a major problem during tapping as very small clearances are present.
The excessive torque can damage the tap if the chips are not removed properly.
When a cutting fluid is used and periodic reversal of the tap is done, the chip removal takes place and hence improves the quality of the tap.
For higher tapping productivity, drilling and tapping can be combined in a single operation with a single tool.
First a drilling section is present at the tip if the tool, followed by a tapping section.

How is the tapping process done?

Tapping can be done by hand or with machines such as
(a) drilling machines,
(b) lathes,
(c) automatic screw machines, and
(d) vertical CNC milling machines.
There are special tapping machines which can carry out multiple tapping operations.
Multiple spindle tapping heads are used extensively, particularly in the automotive industry,
where 30 to 40% of machining operations involve the tapping of holes.

What is tap life?

With proper lubrication, the life of the tool is as high as 10,000 holes.
The technique used to measure drill life is also used to determine the tap life.
Taps usually are made of high-speed steels (M1, M2, M7, and M10).

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