|Nickel plating||Serves both decorative purposes and corrosion protection. Because of the hard layer, application in the construction of electrical apparatus, as well as in the telephone industry. Especially for screws no abrasion of the coating. Nickel-plated iron parts are not recommended for outdoor use. Improvement of corrosion protection by impregnation.|
|Veralize||Special hard nickel plating|
|Chrome plating||Mostly after nickel plating, layer thickness approx. 4 µm Chrome has a decorative effect, increases the tarnish resistance of nickel-plated workpieces and improves corrosion protection.
Bright chrome plating: high gloss.
Matte chrome plating: matt gloss (silk gloss).
Barrel chrome plating is not possible.
|Brass plating||Brass plating is mainly used for decorative purposes. Steel parts are often brass plated to improve the adhesion of rubber to steel.|
|Copper plating||Often used as an intermediate layer before nickel, chrome and silver plating. As a top coat for decorative purposes.|
|Silver plating||Silver orders are used for decorative and technical purposes.|
|Tin plating||Tin plating is mainly used to achieve or improve the solderability (soft solder). Also serves as corrosion protection. Thermal post-treatment is not possible.|
|Anodizing||Anodic oxidation creates a protective layer on aluminum that acts as a corrosion inhibitor and prevents staining. For decorative purposes, virtually any color shade can be achieved.|
|Hot dip galvanizing||Dipping in zinc bath, the temperature of which is approx. 440° - 470°C. Layer thickness min. 40 µm. Surface matt and rough, staining possible after a short time. Very good corrosion protection.
Applicable for threaded parts from M8. Ensure thread runnability by suitable measures.
|Excellent high zinc coating (silver-gray color) for parts with tensile strength Rm ≥ 1,000 N/mm² (strength classes ≥10.9, hardness ≥ 300 HV).
In this coating process, hydrogen-induced embrittlement is excluded by process engineering. Temperature resistant up to approx. 300 °C. Applicable for threads ≥ M4
|Chemo-mechanical plating process. Degreased parts are placed in a plating drum together with a special mixture of glass beads and zinc powder. The glass beads act as a carrier for the zinc powder grains and bring them to the workpiece surface, where they adhere by cold welding.|
|Chemical process for sharpening stainless steels for decorative purposes|
|Burnishing||Chemical process, bath temperature approx. 140 °C with subsequent oiling. For decorative purposes only light corrosion protection.|
|Phosphating||Only light corrosion protection. Good adhesion for paints. Appearance gray to gray-black. Subsequent oiling improves corrosion protection.|
|Impregnate||Especially for nickel-plated parts, post-treatment in dewatering fluid with wax additive can seal the micropores with wax. Significant improvement in corrosion resistance. The wax film is dry and invisible.|
|Tempering||In the case of electroplated fasteners made of steels with tensile strengths Rm ≥ 1,000 N/mm² or hardness ≥ 320 HV which are under tensile stress, there is a risk of failure due to hydrogen embrittlement. Hydrogen can be partially eliminated by tempering at approx. 180°C to 230°C (below the tempering temperature). However, according to the current state of the art, this process does not offer a 100% guarantee. Tempering must be carried out immediately after the galvanic treatment.|
|Form friction-reducing and wear-inhibiting layers. Protection against high friction (galling).|
|Waxing||Sliding layer to reduce the insertion torque of thread-forming screws.|
|Table 1: Coating metals|
|Ni b Cr r*||Nickel-Chrome||F|
|CuNi b Cr r*||Copper-Nickel-Chrome||H|
The use of cadmium is restricted in certain countries
*The ISO classification code is in ISO 1456
|Table 2: Layer thickness|
|Layer thickness (µm)||
|One coating metal||Two coating metals*|
|no layer thickness specified||-||0|
|5||2 + 3||2|
|8||3 + 5||3|
|10||4 + 6||9|
|12||4 + 8||4|
|15||5 + 10||5|
|20||8 + 12||6|
|25||10 + 15||7|
|30||12 + 18||8|
|*The thicknesses specified for the first and second coating metals apply to all combinations of coatings with the exception that chromium is the top layer, which always has a thickness of 0.3 µm.|
|Table 3: Post-treatment and passivation by chromating|
|Gloss level||Passivation by chromating*
|bluish to bluish iridescent²||B|
|yellowish shimmering to yellow-brown, iridescent||C|
|olive green to olive brown||D|
|bluish to bluish iridescent²||F|
|yellowish shimmering to yellow-brown, iridescent||G|
|olive green to olive brown||H|
|bluish to bluish iridescent²||K|
|yellowish shimmering to yellow-brown, iridescent||L|
|olive green to olive brown||M|
|high gloss||No color||N|
|arbitrary||Like B, C or D||P|
|matt||brown black to black||R|
|plain||brown black to black||S|
|shiny||brown black to black||T|
|all gloss levels||without chromating³||U|
*Passivation is only possible for zinc or cadmium coatings.
²Applies only to zinc coatings
Example of such a coating: A5U
If the component hardness exceeds 320 HV or the tensile strength Rm exceeds 1,000 MPa, the manufacturing process must be checked using a hydrogen embrittlement detection test. In general, galvanic coating should not be applied at all in order to exclude the risk of hydrogen embrittlement fracture.
If an electroplated coating is nevertheless to be applied, the parts must be annealed at approx. 200°C for approx. 6 hours at the latest 4 hours after the electroplating treatment. Subsequent heat treatment reduces the risk of hydrogen embrittlement, but complete elimination cannot be guaranteed.
DIN EN ISO 4042 - Fasteners - Electroplated coatings
DIN EN ISO 15330 - Fasteners - Tension test for detection of hydrogen embrittlement - Method with parallel bearing surfaces
DIN EN ISO 1456 - Metallic and other inorganic coatings - Electroplated coatings of nickel, nickel plus chromium, copper plus nickel and copper plus nickel plus chromium