Using self-locking taps
The mounting rings delivered by Kongsberg Maritime are fitted with self-locking threads. Normal screws are designed to be loosened. It is however important to avoid accidental loosening, especially when the installation is subjected to dynamic stress. For this reason, additional locking devices are required. These are often expensive, they can only be used once, or react critically to temperature changes.
Introduction to Emuge self-locking threads
Emuge self-lock is a tap design with an integrated locking feature. Standard metric bolts are used. The internal thread provides a self-locking connection, which can be used repeatedly. It is not necessary to involve a secondary locking device (for example chemical, nylon or mechanical). The Emuge self-lock bolts withstand the vibrations better than standard (metric) threads, because the thread contact stops the sideway movement. The special design of the internal thread profile also provides a more even distribution of the tightening stress over the whole thread length. The assembly is just as easy as with a normal (metric) thread. There is no general applicable standard (e.g. DIN standard) for the Emuge self-lock thread.
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A Emuge’s saw-tooth profile up to pitch P ≤ 0.7 mm
B Emuge’s saw-tooth profile up to pitch P >0.7 mm
C Standard thread
D External thread
E Internal thread
The advantages of using Emuge self-lock thread include:
•  The thread locking feature if integrated in the internal thread
•  Modified profile with ramp surface in the direction of stress
•  30° ramp surface provides self-locking effect
•  Easy assembly
•  No assembly errors (forgetting the locking device) possible
•  Use the standard external threads (screws) with tolerance class "medium"
•  Even distribution of stress over the whole tread length
•  No stripping of threads
•  Economically efficient locking system, no additional components are necessary
•  Undiminished holding power even under dynamic stress
•  Repeated loosening and re-tightening without loss of function
•  Internal threads can be produced with Emuge taps, cold forming taps or thread milling cutters
•  Larger thread hole diameters, i.e. increased tool life for threading tools
•  Larger tolerance for thread hole diameters
Drawing standard
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Whenever self-locking threads are required, this is shown on the technical drawing. In the case of tapping through holes, the arrow at the end of the center line illustrates the screw-in direction of the bolt.
The drawing is normally provided with the following - or similar - text: Drill diameters for threads differ from standard. Self-lock taps can be supplied by Kongsberg Maritime.
Note
Refer to manufacturer’s website for the latest drawings and information about the self-locking taps. The illustrations and information provided here is for reference only.
Taps
The pretension locking thread self-lock (taps) from manufacturer Emuge must be used.
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Note
In case of tapping through holes it is important that the profile of the Emuge self-lock threads is in the correct direction compared with the entering direction of the bolt.
Gauge
Use Emuge self-lock gauges. Note that the gauge must be used in the correct direction.
Self-lock taps provided by Kongsberg Maritime
Several self-lock taps are on stock at Kongsberg Maritime, and can be ordered from us.
Threads Drill diameter for threads Part number
M6 ø5.2 mm 700–078838
M8 ø7.0 mm 700–078531
M10 ø8.8 mm 700–078408
M12 ø10.7 mm 700–078409
M16 ø14.5 mm 700–078410
Manufacturer
•  ManufacturerEMUGE-Werk Richard Glimpel
•  Manufacturer’s addressNurnberger Strasse 96–100, D-90607 Lauf, Germany
•  Manufacturer’s website: http://www.emuge.de