Page 391 - THREADING CATALOG

USER GUIDE
TAPS

For Optimum Tapping Conditions, Reduced Chip Explusion
Machining Times and Increased Tap Life Tap selection is also influenced by the type of hole
being threaded. Through hole tapping usually requires
Selection of the Most Suitable Tap a tap that pushes the chips out in front of the cutting
As a general rule, materials with deformation edge and through the other end of the hole. A bottom
capability of at least 10% can be cold-formed. To hole tap must pull chips up and out of the hole.
decide on the most suitable tap, please refer to the
tap recommendation table on pages 374-377.

Pre-Tapping Holes
Check that the holes are within the prescribed
size range depending on the application
(see table on pages 379-381).
The holes should be clean and swarf-free.

Lubrication
Frequently the lubricant content of the coolant used
for general machining is too low for tapping.
• If it is not possible to increase the lubricant
content, following are some possible solutions:
• A separate Iubricating unit can be connected
to the machine control, to deliver the required
quantity of concentrated emulsion into the core
hole or onto the tap.Tapping in separate operations
allows the use of the ideal tapping lubricant.

Tapping Speeds
The tapping speed has a great influence on chip flow
and the life of the tap. It is worthwhile to establish the
ideal speed by tapping trials. For recommended initial
values, see table on page 377. In addition, the following
should be taken into consideration: characteristics
of the material, machine and clamping method.
Effects of Unsuitable Tapping Speed
• Forced tapping.
• Tap lead chipping caused by overloaded cutting tooth.
• Torn threads.
• Unsatisfactory tap life.
• Rejected threads.

Tap Jamming
Some possible causes of tap jamming are:
• Unsuitable tap.
• Tap with incorrect cutting geometry.
• Unsuitable coolant for material.
• Insufficient coolant.
• Axial pressure (pull or push) on the tap.
• Core hole too small.
• Breaks in walls of core hole.
• Speed too high or too low.
• Swarf trapped in the hole.
• Incorrect alignment of tap and core hole.
• Tap eccentricity.

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