The basis of our success: the best products on the market
precote® coatings offer solutions for locking, sealing, assembly and disassembly
The precote® products, specially developed as a pre-coating, offer advantages in terms of operational reliability, processing and efficiency in series production.
Best known are the reactive precote® threadlockers. These (coatings) have the advantage that there can be up to four years between coating and installation of the screw, thus simplifying logistics and storage, for example. This is made possible by the micro-encapsulated components, which remain inactive until they are used. Only when the screw is screwed in is the system activated, hardening and providing reliable locking and sealing of the thread. Consequently, handling of the screws during installation is simplified because they are dry and solvent-free.
- Automotive and supplier industry
- Aeronautical engineering
- Rail vehicle construction
- Plant and mechanical engineering
- Household appliances and electrical engineering
- and other customer-oriented solutions
precote® solutions for fastener
Advantages of a precote® coating
- Reliable
- Inexpensive
- Machine pre-coated by qualified and certified coating partners
- Reproducible, defined assembly conditions
- Corrosion-inhibiting
- No additional mechanical sealing and securing elements required
- Simple, problem-free storage
We would be happy to advise you on your applications in person and offer training courses on precote® products at our premises, at your premises or at your customers' premises.
Sample coatings to test our products in your company under original conditions can be requested from us at any time.
Microencapsulation at omniTECHNIK
The secret of reactive precote® thread locking lies in our own microcapsules. The combination of microcapsules and a coordinated binder system to create a locking pre-coating is our core competence.
The microcapsules ensure that the reactive part of the coating remains inactive until the
component is screwed in.
If you look closely, you can see the microcapsules in the coating.
The positioning of locking precote® coatings
In order for the pre-coating to function properly, the position and length of the coating must be adapted to the final position in the mating component after installation.
In order to achieve the securing effect in accordance with DIN 267-27, a minimum overlap length of 0.8 × nominal diameter must be maintained.
Optimal conditions for the use of precote®
Thread mating thread
- A tolerance of 6g / 6H, even after galvanic treatments, is strongly recommended. If the tolerances are too low, there is a risk that the pre-coating will be scraped off during the assembly process and will not safely enter the thread gap.
- The threaded inlets should be manufactured in accordance with DIN 76-1 and have a counterbore of at least 1.05 × nominal diameter.
- A suitability test of the material combinations used is generally recommended. The surfaces of the parts to be secured should have been positively tested with the precote® coating. Additional lubricants, oils or other influencing factors may affect the function.
- Material combinations to be secured must match each other, e.g. coefficient of linear expansion.
Coating
- The position and length of the precote® coatings must be adapted to the respective screw connection.
- The filling level should be optimized for the thread geometries. A filling level of 60 - 80 % is sufficient for most applications with standard threads. A higher filling level does not increase the strength, but leads to scraping of the product. For threads ≤ M6, a filling level of ≥ 80 % must be selected. For special threads, e.g. fine threads, a lower filling level is often sufficient. Only a functional test is decisive for assessing the coating quality. Please contact us or your coating partner.
- Contamination of the coating, e.g. by oil, must be avoided.
- The required top coat approved by omniTECHNIK should be applied after the precote® coating, e.g. precote Top 100.
- For sealing applications, at least 4 threads should be coated and installed overlapping to achieve a reliable sealing effect.
- The omniTECHNIK "Packaging and storage information" must be observed
Assembly
- Screws with precote® coating should be installed in one movement without axial feed.
- During pre-assembly, the speed should be controlled and a low speed selected for final tightening. low speed should be selected for final tightening.
- The curing times must be observed.
More information
- precote® is a microencapsulated 2-component adhesive.
- precote® coatings can also be used in conjunction with plastic screws.en.
- All precote® coatings are tested for their temperature application range. The values stated in the data sheets are continuous use temperatures.
- All precote® coating materials have been positively tested for resistance after bolting in accordance with automotive specifications. The standard test media are petrol, diesel, cooling water, brake fluid, engine oil and mineral and synthetic oil-based gear oil.
- Locking and sealing thread coatings are designed for single use. Reuse is not reliable and the locking or sealing effect is not defined.
- If the threaded part needs to be reassembled, the following options are available:
- Use of new, unused precote® coated screws according to thorough removal of adhesive residue from the mating thread.
- Clean the threads and reassemble using anaerobic adhesives. Threaded parts that have been damaged during initial assembly and use must not be reused under any circumstances.
- The coefficient of friction is crucial for series assembly in order to achieve uniform preload on all assembled parts. precote® coatings are available with different coefficients of friction. The friction coefficients of the coatings can be found on the corresponding product pages.
- Transportation locks are temporarily effective, clamping coatings. To select the right product, the torque required for the application must be defined.
Implementation with a chemical threadlocker:
The effectiveness of precote® is calculated in three steps.
- When tightening a screw, three torques are added to the final tightening torque:
Torque under the head + torque in the thread + torque of the thread pitch = tightening torque - When the breakaway torque is measured, the thread-climbing torque acts in the opposite direction, so the breakaway torque may be lower than the tightening torque:
Torque under the head + torque in the thread - thread rising torque = breakaway torque - The strength of a fully cured threadlocker achieved in the test without preload could theoretically be added to the reference value (2.) achieved without precoating.
Due to geometric, surface and other influences, this value may deviate from the theoretical value.
Transportation & storage
omniTECHNIK recommendations for transportation and storage of coated parts
All properties of reactive and non-reactive pre-coatings are only guaranteed if the parts are stored and treated in accordance with the manufacturer's recommendations.
Transportation
Parts that are transported and stored under conditions that deviate from the omniTECHNIK recommendations must be tested for functionality in accordance with the applicable standards.
Temperature
Max. Storage temperature 30°C (85°F). Temperature peaks of up to max. 40°C (104°F) are permissible during transportation.
Temperature shocks during transportation and storage should be avoided.
Low temperatures have no effect on correctly dried coating materials if the parts are brought back to RT and no condensation occurs.
Humidity
Max. Storage humidity 65%RH. During transportation, humidity peaks of up to max. 75% RH are permissible.
The storage conditions of the coating manufacturer must be observed for all pre-coating materials. Parts stored under conditions that deviate from the manufacturer's recommendations must be checked after sufficient drying to ensure that function and appearance have not been impaired.
NB: Moisture is always detrimental to reactive systems as it slows down reactivity and softens the coating, altering its properties, both for assembly and functionality.
Mechanical damage to the coating
Rough handling of the coated parts should be avoided.
As most parts are handled as bulk material, certain cavities in the pre-coating are unavoidable.
However, the recommended thread filling of >/=60% ensures the necessary amount of material in the thread gap.
Capsules that break mechanically during transportation, storage and handling can lead to sticky surfaces.
In general, these small quantities of destroyed capsules do not impair functionality.
UV, direct sunlight and outdoor storage
The storage of coated parts outdoors and thus any exposure to the weather should be strictly avoided.
Significant amounts of UV radiation and direct sunlight have a negative impact on the properties and functionality of precote® materials.
Color and other visible changes during storage
Parts that have a brittle appearance, slight color stains, discoloration or color changes must be checked for proper functioning (e.g. installation torque).
Such changes do not necessarily impair functionality.
Packaging and storage
Coated parts must be allowed to dry at room temperature for at least 6 hours (preferably 24 hours) before packaging. The coatings must be dry and free of solvents.
Airtight or vacuum-tight packaging is a suitable means of preventing condensation and mechanical damage or deterioration of the pre-coating material.
Silica gel or other drying aids in packaging for the transportation of coated parts are recommended.
Chemicals that come into contact with the pre-coated parts
Chemicals other than those validated by OmniTECHNIK (e.g. anti-corrosion oils or top coats) must not be applied to the screws before the pre-coating or as a second coating on top of the pre-coating.
Applicable standards for the storage of coated parts
- ISO 7730 Definition of RT
- DIN 267-27 Functionality
- DIN 267-28 Functionality
- VDA 19-2 Cleanliness of parts
- DIN EN ISO 3269 Cavities on bulk material
- Guideline of the screw association for component cleanliness.