Threadlocker and seals

Precote thread coating

Threadlocker prevents self loosening and loss of clamping force due to vibration and shock loads. A well-known example is the application of a locking agent from a bottle for attachment.

For mass and serial mounting without mess and stunt work, we also offer the option of providing fasteners with precote® in addition to this option. Precote® is a pre-applied two-component adhesive for threadlocking and sealing. This dry and non-sticky coating is permanent once applied.

When mounting the precote® coated fasteners, the microcapsules break in the precote® layer. This releases the liquid components, after which they mix and harden. After curing, the fixing is vibration-free and reliably sealed.

Precote® is the advanced solution for all application areas where high safety standards, ease of use and efficiency in mass and series production are required.

Advantages of precote® prepainted threaded parts:

• Can't get loose
• Reliable
• Cost efficient
• Reproducible, defined assembly values
• anti-corrosive
• No additional mechanical sealing and fastening tools required
• The coated products can be stored for several years

Sealing performance of precote® coated threaded parts

The precote® coating is always a homogeneous, all-round coating. By polymerizing the adhesive, the threads are closed over the entire thread circumference, so that a reliable seal is obtained. For sealing functions, a coating length of at least 4 wires is required. Precote® can absorb very high pressures after curing. This sealing effect also prevents corrosion in the threaded connections.

Optimal requirements for using precote®

Thread and counter thread

• A tolerance of 6 g / 6 H, even after galvanic treatments, is absolutely necessary. At lower tolerances, the precoat cannot enter the thread opening and is scraped off.
• The threaded inlets must be manufactured in accordance with DIN 76 and have a countersink of at least 1.05 x nominal diameter.
• The surfaces of the parts to be fixed must be tested positivewiththe precote®coating. Lubricants or other influencing factors on the surface can impair function.
• The material combinations to be attached must fit together, e.g. linear expansion coefficient.

Coating

• The position and length of the precote® coatings must be adapted to the application.
• The fill level should be optimized for the wire geometry. A fill level of 60-80% is sufficient for most applications. A higher fill level does not increase the strength, but leads to scraping of the product.
• Contamination of the coating, eg by oil, should be avoided.
• The required top coat must be applied after the precote® coating.
• For sealing applications, a minimum of 4 wires must be coated and overlapped to achieve a reliable sealing effect.
• Please note the information "Packing recommendations for precote® coatings".

Assembly

• Precote® coated screws and bolts must be installed in one pass without axial feed.
• A controlled speed must be maintained during pre-assembly. The final tightening action should be done slowly.
• The curing times must be observed.
   

Other useful information

• Precote® is a 2-component adhesive and requires no air seal or metal ions for curing.
• Precote® coatings can also be used in combination with plastic screws. However, the breakaway moments that can be achieved with plastic screws are lower than with steel screws.
• All precote® coating materials are tested for chemical resistance after assembly according to automotive specifications. These are tested as standard on petrol, diesel, antifreeze, brake fluid, engine oil and transmission oil, both mineral and synthetic.
• All precote® coating materials tested positive for durability after screwing to vehicle specifications. The standard test media are petrol, diesel, cooling water, brake fluid, motor oil and transmission oil based on mineral and synthetic oils.
• Locking and sealing wire coatings are designed for single use. Re-use is not reliable and the fixing or sealing effect is not defined.

If it is necessary to reassemble the threaded part, the following options are available:

• Use of new, unused precote® coated screws after thorough removal of adhesive residue from the counter thread.
• Clean the wires and reassemble them with an anaerobic glue. Parts damaged by initial assembly and use must never be reused.
• In series mounting, the coefficient of friction is decisive to ensure uniform preload for all assembled parts. Precote® coatings are available with different coefficients of friction. The coefficient of friction of the coatings can be found in the product selection table below.
• Transport locks are temporarily effective, clamping coatings. In order to find the right product, the moment required for the application must be defined.

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