Pre-treatment is one of the key steps to
ensure the quality and adhesion of the final coating.
Pre-treatment is one of the key steps in the powder coating process to ensure the quality and adhesion of the final coating. Two common pre-treatment methods are sand blasting and pickling, each of which has its own advantages and disadvantages and is suitable for different application scenarios.
In this article, we will take a closer look at the
characteristics of these two pre-treatment methods to help you make an informed
choice for your application.
1. High surface cleanliness: Sandblasting
effectively removes dirt, oxidation and old coatings from the surface of the
workpiece, making the surface very clean. This helps to improve the adhesion of
the powder coating.
2. Adjustable Surface Roughness: The
sandblasting process can be used to control the surface roughness of the
workpiece by adjusting the grit size and pressure of the blast media. This is
useful for applications where a specific roughness is required. 3.
3. High environmental friendliness:
Sandblasting does not usually involve the use of hazardous chemicals and is
therefore highly sustainable in terms of environmental friendliness.
1. Possible damage to the surface of the
workpiece: The sandblasting process may damage the surface of the workpiece to
some extent, especially for some thin and delicate materials. This may require
additional surface repair work.
2. Generation of dust and waste:
Sandblasting generates a large amount of dust and waste, which requires
specialised handling and cleaning, increasing production costs.
3. Higher energy consumption: Sandblasting
equipment usually requires a high compressed air supply, which increases energy
consumption.
Sandblasting is suitable where a high
degree of surface cleanliness and adjustable roughness is required, for
example:
- Large metal workpieces such as steel
structures, ships and bridges.
- Automotive and motorbike parts to provide
good adhesion and surface quality.
- Preparation of film coatings, such as
spray paints or rubber.
1. Highly effective cleaning process: Acid
pickling thoroughly removes dirt, oxidised layers and harmful substances from
the surface of the workpiece and ensures a clean surface.
2. Suitable for a wide range of materials:
Acid washing is suitable for a wide range of metals, including steel,
aluminium, copper and magnesium.
3. Suitable for complex geometries: Acid
washing can handle complex workpiece shapes, ensuring that every part is
properly treated.
1. Use of hazardous chemicals: Acid washing
involves the use of strong acids, which can pose a threat to the environment
and the health of the operator. Strict safety measures must be taken.
2. Neutralisation and waste disposal
required: Waste acid needs to be neutralised and disposed of to ensure
compliance with environmental regulations.
Pickling is suitable where a high degree of
cleaning and degreasing of the surface is required, e.g.:
- Stainless steel products to remove oxides
from weld heat affected areas.
- Surface preparation of metal parts to
enhance adhesion.
- Aluminium alloy parts to remove oxidation
and improve paint adhesion.
Sandblasting and pickling are two common
methods used in the powder coating pretreatment process, and they each have
their own advantages, disadvantages and areas of application. The choice
depends on your specific application requirements, workpiece material and
environmental considerations. In practice, the right pre-treatment will ensure
the quality of the final coating and the performance of the workpiece.