Thread Whirling on
CNC Turning Machines
Thread Whirling of I.D.
Technology and Benefits of Thread Whirling
and O.D. threads is
Many different types of threads, with almost any form,
mostly used on parts for
whether single or multiple start, LH or RH can be pro-
the medical industry
duced with thread whirling. With the same tool, different
with the machining of
thread profiles can be produced, since the thread lead is
surgical implant parts,
produced by the feed rate. Also, metric threads can be
for example on bone
blended into special threads and threads behind a shoulder
screws with self-locking
can be produced. The whirled thread is completely burr-
special threads (picture
free, which is an important requirement for medical
2). The main benefits of
threads and has a high quality finish and form accuracy.
thread whirling lies in
The thread tolerance is in the range of a few hundredth
the relatively simple
of a millimeter, respectively app. one thousandth of an
machining of tough
inch, and can be controlled by optimizing speed and
external thread whirling is shown on examples produced
steels such as stainless
feed rate.
on the Traub TNL12 machine model.
and titanium alloys. If
Compared to other threading processes such as thread-
thread whirling opera-
milling, rolling, or single pointing, the thread whirling
External Thread Whirling
tions were done on
process is simpler since the part does not have to be
The tool for external thread whirling consists of a whirling
separate machines in
supported even on long threads, and the thread can be
head with several carbide cutting inserts. To produce a
the past, it is common
cut into the solid material without pre-turning. The tool
certain thread profile, a tool form is calculated and speci-
practice today to inte-
life of the carbide tools is much better compared to other
ally made for the particular thread. The whirling head is
grate thread whirling
processes, which results in a better process reliability.
positioned directly at the guide bushing, which is a prere-
into the machining pro-
Relative to the part diameter, extremely long threads can
quisite for high accuracy, and is tilted according to the lead
cess on CNC turning
be produced even on very small diameters. Thread depth
angle of the thread.
machines.
and length is only limited by the machine equipment.
Then the cutting inserts are mounted into the head
Thread whirling produces fine chips and the chip form is
(picture 3). When cutting, only one cutting edge is enga-
comma-shaped. With the Traub sliding headstock auto-
ged at one time. The thread whirling head is running at a
matics, highly accurate threads from M0.6 to M8 can be
high RPM, determined by the cutting speed. The spindle,
produced with thread whirling. Subsequently, internal and
operating in C-axis mode, determines the feed rate,
Picture 2: Self-tapping
bone screws with
special whirled threads,
6 mm / .236 resp.
5 mm / .197 DIA
Picture 1: holder for CMM with whirled I.D. thread M2
Picture 3: whirling head with 3 cutting inserts
Picture 5: I.D. whirling tool for M1.4
Picture 4: 3 whirling heads on the turret of the TNL 12
Picture 6: I.D. whirling
respectively the thread lead. The thread is cut in a short
produced in one pass. The tool is made based on the thre-
amount of time into the solid material in one pass, which
ad requirements and achieves a high tool life com-pared
assures a high accuracy. Coolant is supplied through the
to other threading processes. The whirling unit can be
whirling head. At the end of the thread, the whirling head
mounted in the backworking station or (picture 6) in the
is lifted off and retracted. The whirling head can be moun-
turret, for cross threading.
ted in the turret or in the end-working tool carrier. With
the turret tool carrier concept of the TNL12, it is possible
Thread Whirling Summary
to mount up to 3 whirling heads at one time (picture 4).
The significant benefit of thread whirling is the capability to
This allows automatic engagement of a new head when
produce a wide range of thread-forms and lengths in
the cutting edges are worn (redundant tooling).
tough steels and titanium, particularly for the medical
industry. High thread quality and favorable chip form offer
Internal Thread Whirling
important advantages compared to other processes.
Internal thread whirling can be done on sliding headstock
Traub offers the whirling technology on turning machines
and fixed headstock machines. With the high frequency
as an economically and technically attractive process, and
spindle, the necessary RPM of up to 60000 is achieved.
the only builder capable of offering 3 whirling heads in one
The part turns slowly; in one revolution the tool moves by
set-up.
the amount of the thread lead. The tool is positioned
parallel to the work piece axis. After drilling, the thread is
TRAUB
Drehmaschinen GmbH
73262 Reichenbach, Germany
Tel. +49 (7153) 502-0
Fax +49 (7153) 502-694
www.traub.de
Sales and Service in North America:
INDEX Corporation
829 Bridgeport Avenue
Shelton, CT 06484, USA
Tel. +1 (203) 926-0323
Fax +1 (203) 926-0476
www.index-usa.com
04.01 - 789/1 ME Printed in Germany Subject to change without prior notice
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