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Technical Information

Tapping Speeds

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Factors when trying to determine the best tapping speeds:

• Material to be tapped

• Length of chamfer on tap

• Percentage of full thread to be cut

• Length of hole (depth of thread)

• Pitch of thread

• Cutting fluids

• Machine equipment

• Horizontal or vertical tapping

The best and most efficient operating speeds for taps cannot be

calculated with the same certainty, as for many other metalcutting

tools.

With other tools, the feed per revolution can be set at any desired

point and can be varied as conditions demand. Taps, on the other

hand, must always be advanced at a rate equal to one pitch for

every revolution. The style of tap may vary the conditions.

For example, with a bottoming tap, the first thread on each land

cuts the full height of thread, while, with a taper or starting tap, a

number of threads do their share of the cutting before the full height

of thread is reached.

The depth of thread also varies, depending on the pitch. The

coarser the thread, the greater the advance of the tap per revolution

and the greater the amount of material removed.

The method of feeding the tap, and the type of equipment

for driving, also influences the permissible speeds. If taps are

mechanically fed at the proper rate of advance, they can be

operated at higher speeds than if they are required to feed

themselves and pull some part of the machine along with them.

Speeds may be modied to take into account any or all of

these factors:

• Speeds must be lowered as length of thread increases

because, in deep thread holes, the accumulated chips

increase friction and interfere with lubrication.

• Bottoming taps must be run slower than plug taps.

• Tapping full height of thread calls for slower speed than if

the commercial 75% height only is required.

• Coarse-thread taps in the larger diameters should be run

more slowly than fine-thread taps of the same diameters.

• The quantity and quality of cutting fluid may affect the

permissible speeds as much as 100%.

• Taper threaded taps, such as pipe taps, should be

operated from 1/2–3/4 the speed of a straight thread tap

of comparable major diameter.

RPM Formulas

SFM = Surface Feet per Minute

RPM = Revolutions per Minute

IPM = Inches per Minute

TPI = Threads per Inch

S m/m = Surface Metres per Minute

/ = 3.1416

mm/min = millimetres per minute

P = Pitch (1/number of threads per inch)

Inch Sizes

SFM

RPM

IPM

Metric Sizes

S m/m

RPM

mm/min

= RPM x tool diameter

3.82

= 3.82 x SFM

tool diameter

= RPM

TPI*

= / x tool diameter x RPM

1000

= mm/m x 1000

/ x tool diameter

= mm P x RPM

0.26 x RPM x tool diameter

span id="f1" style="font-size:7px;vertical-align:baseline;color:#221e1f;">*P x RPM

Y104

zakaz@widiahanita.ru

WIDIA - Полный каталог инструмента - 2017