VW TL 52451 Painting Decorative Metal Exterior Components - Requirements

The standard “VW TL 52451 Painting of decorative metal exterior components – Requirements”, developed by the Volkswagen automobile company, applies to the painting of exterior add-on parts with a metallic substrate that are located in the visible area and therefore must meet primarily decorative and functional requirements, e.g. roof rails, wiper arms, steps, styling bars, pillar covers and chrome-plated and subsequently painted trim parts.

The basic requirements in this standard are determined as follows:

• Confirmation of the initial delivery and changes must be ensured according to the VW 01155 standard.
• The prevention of harmful substances must be ensured in accordance with the VW 91101 standard.
• The cutting burr on the components must at least meet the “medium” manufacturing accuracy according to the VW 01088 standard.
• A minimum of 10 components are required for a complete review.
• The supplier must include the information specified in this standard and the initial sample or development sample inspection report on all components to be inspected.
• Areas where the requirements described in this standard do not apply should be marked on the drawing. Different requirements should be specified.
• Proper installation should prevent damage to the coating.

The appearance requirements are determined as follows:

• Components must have a uniform appearance across their entire surface and conform to the drawing requirements, color standard, and optical properties specified in the table.
• Pores, cracks, and other defects that detract from the specified appearance must not be permitted. Deviations from these specifications must be noted on the drawing.
• The degree of gloss, color, and texture must be documented on the initial sample or in the development sample test report (including any tested components or test panels).

All painted components are tested for outdoor durability according to VW standard 50185. Any complaints arising from this testing process obligate the supplier to rectify the complaint and improve the paint system.

The paint requirements are determined as follows:

• The painting process must be coordinated between the painter and the paint manufacturer.
• The paint manufacturer provides information on compliance with the requirements of the German technical test standards (TL), provides processing instructions and offers application-technical support.
• The painter provides information about the substrate and pretreatment steps, checks requirements as early as possible, confirms compliance with the paint manufacturer's processing instructions, and requests application-technical support.
• The blank manufacturer must provide information about the substrate (substrate, pretreatment, previously applied paint layers) and guarantee its suitability for further painting.
• If the VW 13750 standard is used in the drawing entry, the layer thicknesses required in the relevant specifications must be adhered to. For different layers, the layer thicknesses specified in the table apply.
• The paint structure is given in the standard.
• Deviations from the paint structure must be identified in the drawing entry.
• The total coating thickness is determined according to DIN EN ISO 2178 (magnetic induction method), DIN EN ISO 2360 (eddy current method) or DIN EN ISO 1463 (microscopic method).
• The microscopic method is also suitable for determining individual coating thicknesses.
• In a pure wet coating system, the total coating thickness should not exceed 110 μm.
• In a system that includes powder coating, the total coating thickness should not exceed 150 μm.
• Recoating is only permitted when using the same color. The total coating thickness for recoating is limited to a maximum of 160 μm for a pure wet coating system and 200 μm for a powder coating system. The requirements of the TL 52451 standard must also be reliably met for recoating.

For technological tests, the components to be tested should be one week old. Alternatively, they can be stored at 60°C for 24 hours before testing, followed by 2 hours of conditioning at room temperature according to VW 50554-2.

In short, the VW TL 52451 standard specifies requirements for the painting of decorative metallic add-on parts on the exterior of vehicles. These include components such as roof rails, wiper arms, styling bars, pillar covers, and chrome-plated parts that are subsequently painted. These parts are typically in visible areas and must meet both decorative and functional criteria.

The main features of the VW TL 52451 standard can be summarized as follows:

• Paint structure: This standard outlines acceptable paint structures, which may include a primer coat followed by a single or double coat of topcoat. Specific materials and thicknesses of these coatings are defined to ensure durability and aesthetic quality.
• Performance requirements: Painted parts must withstand various environmental tests, including outdoor weathering, to ensure long-term performance. Coatings must maintain uniform appearance, gloss level, color, and texture over time.
• Supplier responsibility: Suppliers are responsible for ensuring their products meet specified requirements. Any issues identified during testing are the supplier's responsibility to address.

This standard was developed in cooperation with Porsche and replaces the previous Porsche technical supply specification PTL 7520. It reflects a comprehensive approach to ensuring the quality and durability of exterior decorative paintwork on metallic vehicle components.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the "VW TL 52451 Painting of Decorative Exterior Metal Components - Requirements" standard.