Surface finishing for plastic parts
tool-dropping method
The tool-free method for surface finishing of plastic parts makes it possible to integrate the desired surface structure directly during the manufacturing process. This technique introduces the texture and design of the surface directly into the mold, giving the finished part the desired surface finish without the need for additional post-processing steps such as painting or milling.
The targeted alternation between structured and polished areas creates high-contrast and aesthetically pleasing design surfaces. Furthermore, a surface texture also conceals irregularities such as flow lines, weld lines, and sink marks that can occur during plastic injection molding. VDI 3400 and SPI are two established standards for the surface classification of injection molding tools. Both systems provide guidelines for determining and describing the surface finish, but with different approaches and focuses.
- The VDI 3400 is defined by the Society of German Engineers and includes 45 different texture levels with varying degrees of roughness. The classes are numbered (e.g. VDI 12), with lower numbers representing a smoother surface and higher numbers representing a coarser texture.
- The SPI standards divide surfaces into four main categories (A, B, C, D), which are in turn divided into specific subcategories (eg SPI A-1, A-2, A-3). This classification is based on the surface quality achieved by different polishing processes. A-grade surfaces are high gloss, while D-grade surfaces are textured, matte.
Painting of plastic parts
Painting not only enhances the appearance of plastic parts, but also increases their durability and resistance. By applying layers of paint in a targeted manner, the parts are given a uniform, smooth surface that is both visually appealing and pleasant to the touch. Modern painting techniques offer a wide range of colors and effects, from high-gloss and metallic finishes to matte and textured surfaces, allowing for enormous design flexibility.
A painted plastic part is better protected against environmental influences. The paint layer acts as a barrier against UV radiation, moisture and chemical corrosion. This significantly extends the service life of the plastic parts. A painted surface is harder and more resistant to abrasion and scratches. This is particularly advantageous for components that are used in demanding environments and are exposed to high mechanical stress.
Soft touch finish
The Soft touch finish gives the plastic parts a pleasant, velvety surface that is not only visually appealing, but also provides a high-quality, soft feel. Soft-touch coating is often used in areas where the feel of the product plays an important role, such as automotive interior panels, electronic housings and consumer goods.
Conductive inks
A conductive paint coating gives the plastic parts conductive properties that make them ideal for protection against electromagnetic interference and electrostatic discharge. Conductive paint contains conductive particles such as carbon, silver or copper. This coating is particularly suitable for applications that require high electromagnetic compatibility (EMC) and ESD protection, such as electronic housings.
Oppression
Plastic molded parts are printed using various printing techniques such as pad printing, screen printing and digital printing. Printing enables the components to be individually designed with logos, patterns or technical information. With pad printing, the desired print motif is incorporated into a steel cliché and transferred to the surface to be printed using a silicone stamp. Compared to other printing techniques, the soft printing stamp adapts very well to the surface contour. It is also possible to print on convex and concave surfaces. Possible color specifications: NCS, RAL, Pantone or color samples.
laser marking
Laser inscription opens up a multitude of possibilities for providing plastic covers and buttons with an attractive nighttime design. By using precise laser beams, lettering, engravings and other graphic elements can be incorporated into the workpieces with the greatest accuracy. With laser marking, plastic parts can be personalized in an elegant and professional way to create unique designs that meet your unique needs.
laser texturing
The laser beam can also be used to create textures by selectively removing material or altering surface properties. This process allows for the creation of complex patterns, microtextures, and surface modifications that can improve grip, reduce friction, or provide unique visual and tactile effects.
IMD (In-Mould Decoration)
In-mould decoration (IMD) allows decorative surfaces to be integrated directly into the plastic component. The designs are clear, detailed, and resistant to wear and fading, as well as mechanical stress and environmental influences. Furthermore, the use of different films allows for special visual effects such as brushed textures or so-called [missing information - likely "textured" or "smooth" finishes]. Dead Front-Effects – the latter allow displays or symbols to be made visible only when activated.
The prepared design film is precisely inserted into the injection mold. The pressure and heat applied during injection molding bond the film to the plastic, permanently integrating the design into the component. The film fuses with the plastic to form a robust surface.
After cooling, the finished plastic part is removed from the mold. The decorative design is now an integral part of the component. Integrating the decoration into the injection molding process eliminates additional steps and costs for subsequent surface finishing. This can lead to more efficient and cost-effective production.
PVD coating
PVD (Physical Vapor Deposition) coating gives plastic parts a metallic surface that is both visually appealing and functional. This coating offers excellent hardness and wear resistance, as well as high resistance to corrosion and chemical influences. It is frequently used in applications where both aesthetics and product durability are crucial. Typical applications include automotive interior and exterior components, electronic devices, and consumer goods where a high-quality, metallic appearance is desired.
Design Guide Plastic Molded Parts & Free Sample Card
Our Design Guide for Plastic Molded Parts and the pioneering free sample card with plastic erosion structures are aimed specifically at developers, designers and buyers who are intensively involved in the development and production of plastic molded parts.
The construction guide offers a comprehensive and detailed Overview of engineering plastics and their diverse applications in practice. Furthermore, a special focus is placed on important topics such as Material selection and construction. This guide will help you make your projects more efficient while achieving better results.
Our high quality N&H plastic sample card Made of robust, black ABS plastic, it offers you a compact and clear overview of 12 different SPI surface treatments – from highly polished to rough textured versions. The menu is complemented by the 12 most common VDI 3400 surface textureswhich are established as industry standards in plastics processing.
The sample card serves as an effective planning tool, helping you select the optimal surface structure for your plastic molded parts early and accurately. This not only simplifies the development process but also significantly contributes to increasing product quality and design precision.
This clear sample card makes it easier for you to coordinate technical requirements with the look and feel of your plastic parts. It helps you make the right decisions at every stage of your project—from planning and development to series production.