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Surface Treatment
From durable coatings to perfect finishing. For the best quality and durability.
Surface coating: protection, function and finishing
Whether corrosion protection, appearance or resistance – the right coating makes the difference. On request, we finish surfaces to your requirements: precise, durable and reliable.
Surface treatment is a crucial step in metal processing. It protects workpieces from corrosion, increases wear resistance and improves appearance. Depending on the application, mechanical, chemical or thermal processes are used. Whether in the automotive industry, mechanical engineering or medical technology – the right surface finish has a decisive influence on the quality and longevity of components.
Key surface treatment processes (externally processed)
1. Pickling – a clean base for further processes
Pickling removes oxides, scale and contaminants from metal surfaces. Particularly with stainless steel or aluminium, this process is essential to ensure a clean surface for subsequent coatings.
2. E-coating (KTL) – effective corrosion protection
Cathodic dip coating (KTL / e-coating) is a coating process that produces a uniform, resistant protective film on metal parts. It is widely used in the automotive industry and offers high resistance to weathering and chemicals.
3. Anodising – protection and finishing of aluminium
Anodising is an electrochemical process that gives aluminium a hard, corrosion-resistant oxide layer. This layer can be clear or coloured and improves resistance to environmental influences.
4. Phosphating – adhesion promotion and protection
This chemical process forms a phosphate layer on metal parts that serves as a primer for coatings while also providing a degree of corrosion protection.
5. Chromating – protection for aluminium and zinc
Chromating is a chemical process that gives aluminium or zinc a thin protective layer. This improves corrosion resistance and acts as an adhesion promoter for further coatings.
6. Nickel plating – durable, corrosion-resistant surface
In electrolytic nickel plating, a thin layer of nickel is applied to the metal. It protects against corrosion and wear and is often used in technical applications or for decorative purposes.
7. Milling – precise mechanical machining
Milling is a machining process used to create complex shapes and fits in metal parts. External processors can use high-precision CNC milling machines to produce demanding geometries.
8. Drilling – precisely fitting openings for assembly purposes
Drilling is an essential mechanical machining step required for many components. External processors use high-precision machines to produce holes in various sizes and depths.
9. Hardening – increasing wear resistance
Targeted heat treatment increases the hardness of metal parts. Processes such as induction hardening or gas nitrocarburising make components particularly resistant to mechanical stress and abrasion.
10. Foam gasketing – perfect sealing through precise foam application
In the Formed-In-Place Foam Gasket (FIPFG) process, a liquid sealant is applied directly to the component, where it cures into an elastic foam. This creates a seamless, flexible and durable seal that provides reliable protection against water, dust and chemicals. This technique is used primarily in the automotive industry, electrical engineering, air-conditioning technology and mechanical engineering for enclosures, door seals and protective covers.
External processing
Which operations are most frequently outsourced – from coatings to mechanical finishing.
Surface coating (pickling, e-coating, anodising, phosphating, chromating, nickel plating)
Machining (milling, drilling)
Heat treatment (hardening)
Gasket foaming (FIPFG)
- Surface coating40 %
- Mechanical processing25 %
- Heat treatment15 %
- Foam gasketing15 %
- Special processing5 %
Frequently asked questions
Surface treatment and mechanical finishing of metal parts covers a wide range of processes – from coatings and seals to precision machining. Here we answer the most frequently asked questions on topics such as corrosion protection, mechanical processing, foam gasketing (FIPFG), hardening and coatings. If you have any further questions, we will be happy to help.
Why are some surface treatments carried out externally?
Specialised processes such as e-coating (KTL), anodising or hardening require special equipment and expertise. External processing ensures the highest quality and efficiency.
How long does external processing of metal parts take?
Processing time varies depending on the process. While mechanical operations (milling, drilling) are often completed within a very short time, coatings such as anodising or nickel plating can take several working days.
Which surface treatment offers the best corrosion protection?
For steel, e-coating (KTL) and nickel plating are particularly effective, while aluminium is protected by anodising or chromating. The choice depends on the environment and the stresses the component is exposed to.
Can externally processed parts be modified afterwards?
Yes, although an existing coating may need to be removed or adjusted. Mechanical operations such as drilling are often possible afterwards, whereas coatings usually have to be renewed.
Which factors influence the choice of surface treatment?
The most important criteria are material, area of application, desired properties (corrosion protection, appearance, hardness) and environmental conditions. In many cases, a combination of several processes makes sense.
What does foaming mean in metal processing?
Foaming is a process in which metal is foamed by adding gases or through chemical reactions. This produces lightweight yet stable metal structures with a porous or honeycomb-like structure.
What is Formed-In-Place Foam Gasket (FIPFG) seal foaming?
FIPFG is a process for producing seals directly on components. A special foam
(e.g. PU or silicone foam) is applied automatically and cures. This creates a seamless, elastic seal with a high sealing effect.
What are the advantages of the FIPFG process?
- Perfect fit – The seal is applied directly to the component.
- Excellent sealing performance – protection against water, dust and chemicals (IP67/IP68).
- Automated manufacturing – consistent quality and high repeatability.
- Cost and material savings – less waste than with inserted gaskets.
- Good adhesion – Firm bond with the substrate, no additional adhesives required.
Which materials are used for FIPFG seals?
- PU foam (polyurethane) – soft, elastic, weather-resistant.
- Silicone foam – resistant to high temperatures and chemicals.
- Hybrid sealants – specially developed materials for particular requirements.
How resistant are the foamed gaskets?
FIPFG gaskets are extremely durable and resist water, dust, chemicals and temperatures from -40 °C to +200 °C (depending on the material). They meet high protection ratings such as IP67/IP68.
Can an FIPFG seal be modified or removed afterwards?
No, a foamed gasket is firmly bonded to the component. If it needs to be removed, this can be done by mechanical processing before a new gasket is applied.
Are there alternatives to the FIPFG process?
Yes, alternatives include:
- Inserted foam or rubber gaskets – easy to replace, but less precise.
- Formed-In-Place Gasket (FIPG) – Liquid sealants, but without foaming.
- Injection-moulded gaskets – manufactured separately and then fitted
How long does an FIPFG seal last?
Depending on the material and ambient conditions, the seals can last more than 10 years. PU foam seals are elastic and durable, while silicone seals even withstand extreme temperatures and aggressive chemicals.
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