Corrosion protection for thread-rolling screws with solutions from DÖRKEN

Thread-rolling screws have a characteristic property: during assembly, they automatically produce their suitable nut thread by forming the material in the counterpart. This has several significant advantages: direct bolting eliminates the process steps of drilling, threading and chip removal, saving both time and money. At the same time, the material consolidation in the thread ensures a higher load capacity. Thread-rolling screws therefore represent a very economical solution and are therefore preferred for building constructions.

In order to benefit from the practical screws in the long term, optimum corrosion protection must be planned in advance. DÖRKEN offers effective solutions here. With our thin coating systems and specific relubrication, you prevent contact corrosion and protect your components from damage.

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screws without DÖRKEN-coating
After salt spray test according to ISO 9227 for thread-rolling screws: Here screws without DÖRKEN-coating compared to...
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screws with DÖRKEN-coating
screws with Dörken-coating that show no red rust after at least 1,000 hours

The smart coating for thread-rolling screws: Zinc flake systems provide active corrosion protection

Thread-rolling screws are generally more expensive than metric standard screws, but are gaining in importance due to their advantages. Since they can be screwed into all plastic deformable materials, they are not only used in the automotive industry and in mechanical engineering, but also in building constructions of all kinds. Without suitable protection, there is a risk of corrosion due to the screwing into components made of various materials and the daily stresses (temperatures, humidity, chemical substances). A zinc flake coating from DÖRKEN offers efficient protection.

How does zinc flake corrosion protection for thread-rolling screws work?

  • Basecoat: A zinc-containing basecoat is applied to the screws to provide cathodic protection. That means: The coating provides a barrier for the thread-rolling screws. If the surface is damaged, the less noble zinc ‘sacrifices’ itself in favour of the nobler basecoat – this is also called the sacrificial anode.
  • Topcoat: Thread-rolling screws can then be coated with a topcoat. This not only extends the corrosion protection, but can also be used for the precise adjustment of desired properties (coefficients of friction, chemical resistance, colour, etc.).   
  • Lubrication: In addition (or instead of the topcoat), a lubrication layer can be applied which - like the topcoat - increases the corrosion protection and additionally influences the coefficients of friction as well as the thread forming torque.    



Some advantages of coating thread-rolling screws

  • Extremely thin coating for highest fitting accuracy
  • Long-lasting corrosion protection
  • Reduces the risk of hydrogen embrittlement  
  • Chromium (VI)-free
  • Lubrication

More than corrosion protection: Low screw-in torque for thread-rolling screws due to DELTA-LUBE® 50 lubrication

For efficient use, thread-rolling screws must be easy to assemble and easy to undo without undue force. The colourless DELTA-LUBE® 50 lubrication not only guarantees defined coefficients of friction and a low thread-rolling torque, but also protects the underlying basecoat and thus improves corrosion protection.

The coating is carried out in a non-electrolytic process according to the standards DIN EN ISO 10683 and DIN EN 13858. The dip spin process is the suitable application technique for small components such as thread-rolling screws.

The special properties of DELTA-LUBE® 50  

  • Organic
  • water-based
  • Integrated lubricant
  • Trueness to gauge
  • Chromium (VI)-free in accordance with EU End of Life Vehicle Directive 2000/53/EG
  • REACH requirements
  • RoHS 2 Directive (EU Directive - Waste Electrical and Electronic Equipment 2002/95/EG)

DELTA-LUBE® 50 achieves a defined coefficient of friction window of 0.06 – 0.09 µges as well as a low thread forming torque.

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A construction srew without DÖRKEN lubrication
A construction srew without DÖRKEN lubrication heats up to 120°C due to high clamping pressure and high thread forming torque.
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A construction screw with DÖRKEN lubrication
A construction screw with DÖRKEN lubrication heats up to only 80°C due to the low clamping pressure and low thread forming torque

DÖRKEN: We are your partner for reliable coatings for thread-rolling screws

DÖRKEN Coatings has been successful in the field of microlayer corrosion protection systems for over 30 years – thanks to continuous innovation, close cooperation along the entire value chain and consistent quality assurance, we offer flexible coating solutions for thread-rolling screws and all other components that need to be reliably protected against corrosion. Whether you are a manufacturer or a coater, the experts at DÖRKEN Coatings are always on hand with advice and assistance and provide comprehensive support. 

The advantages of thread-rolling screws for the manufacturer

  • Access to a worldwide network of licensed coaters
  • Consistent high quality
  • Expert advice to find the optimal solution for the project
  • Customised solutions to individual specifications

Do you have any questions about our coating systems for thread-rolling screws or other components? Would you like to inform about other Dörken MKS coating solutions such as electroplatingcoil coating or KTL?

Then contact our specialists and let us talk about your requirements – we will gladly help you!

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