Page 431 - DC_SWISS(Catalogue_TM_ES-EN)

INTERESTING HINTS FOR TAPPING

Cold welding What are the causes of cold welding?
Cutting speed too high or too low
Unsuitable tap selection
Tap with non-adapted cutting geometry
Coolant unsuitable for material
Insufficient coolant
Axial pressure (pull or push) on the tap
Core hole too small
Torn core hole walls
Drill chips in the hole
Centering error
Concentricity error

Effects of cold welding:
torn threads
short tap life
rejected threads
tool breakage
scrap workpieces

Tap fitting The tap must be clamped axially to the core hole.
On non-synchronized machines (feed/speed), we recommend the use of a
tapping spindle.

Tapping heads With non-synchronized machine spindles (feed/speed) the feed rate should,
as a rule, be programmed approx. 5 - 10 % lower than the thread pitch. In
these cases a tapping chuck must be used which will compensate the diffe-
rence between the feed rate and the thread pitch.

It is important that the tension spring in the axial compensation is set to a light
rate to avoid axially loading the tap.

The compression spring, on the other hand, should be tensioned so that the
tap starts to cut by compressing the spring at the most up to one half pitch.

Important hints:
A good stability of machine and equipment is a prerequisite for optimum
quality and performance.
Ensure that the correct cutting speed is selected.
Make sure that ample lubricating coolant is used when tapping.

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