Thread locking – For screw connections
that need to hold securely
A thread lock is the right solution if particularly high demands are made on the long-term durability of the screw connection. The lock prevents the screw from simply
wriggling loose and thereby weakening the connection.
The following basic thread locks types are available:
- Clamping lock
- Adhesive lock
- Sealing lock
It seals and is removable
Clamping locks are based on various types of plastic layers. The coating can cover the entire area of the screw thread, be limited to individual spots or take the form of
fine threads that are inserted into the existing thread.
Clamping locks can be applied to screws as well as nuts and other thread forms. They are dry to the touch and easy to use without further preparation.
In application, the clamping lock creates a positive connection between the screw thread and the nut thread. It stops the screw coming loose unintentionally and serves
as captive protection even when the screw is exposed to impact or vibration. The thread lock does not stop the screw being loosened intentionally so that the screw can
still be removed easily.
A spot coating often suffices to provide the clamping effect required. The lock also acts as a sealant when the whole thread is coated all around. A groove is milled in the
thread and a fine plastic thread pressed into it to apply the thread lock.
Almost all clamping thread locks for screws meet the requirements of DIN 267, Part 28. The products we use differ in function and temperature resistance; some of them
are recognizable by their colours:
- Poly Lok: Spot and round coating made of polyamide (green)
- TufLok: Spot and round coating (blue)
- Klemm-tight: Thread locking (red and others)
- Precote 19-2: Acrylic-based clamping coating (red)
- S-Lok: Spot and round coating (blue)
- Long-Lok: Spot or thread locking (green and others)
provides a permanent hold
The threads are coated with a micro-encapsulated adhesive with adhesive-locking screws. In an unused state, the screw is dry and not sticky and easy to handle during use.
Only when screwing in the screws do the micro-capsules burst due to the pressure and shear stress and release the adhesive together with hardener.
After curing, the adhesive forms a strong anti-rotation lock in the thread. The enormous advantage of this adhesive lock is provided by the maximum security against
unwanted loosening, even under dynamic loads and after a long service life. Since it can be applied to threads of all kinds, all screws can be furnished with an adhesive lock.
It has a good sealing effect in addition to its function as anti-loosening lock.
All stainless-steel screws we supplied with an adhesive seal meet the requirements for the functional properties of adhesive coatings on screws made of steel specified
in DIN 267, Part 27.
The micro-encapsulated adhesives recommended differ in their effect and temperature suitability. They can be recognized by their colours:
- precote 30 (yellow)
- precote 80 (red/green)
- precote 83 (red)
- precote 85 (turquoise)
- Scotch Grip 2353 (blue)
- Scotch Grip 2510 (orange)
Shut out liquids and gases
All thread locking procedures, whether clamping or adhesive, also have a sealing effect. Sealing screw connections is the priority for sealing locks. This can both be carried out
over the thread or in the form of a lower head seal. Sealing locks are dry, not sticky and seal immediately.
These seals must fulfil two functions. The first is to provide a maximum sealing effect for all thread sizes, screw materials and surface finishes.
The second important feature is high resistance to temperatures and various media. Sealing materials must be provide equal resistance in contact with gases, oils, greases and solvents.
We use the following products as sealing locks, which can be recognized by their colours:
- precote 4 (white)
- precote 5 (white/blue)
- precote 6 (white/green)
- Plastisol (underhead coating)