VW TL 591 Lamp Covers Made from Organic Glass - Material Requirements

The “VW TL 591 Lamp covers made of organic glass - Material requirements” standard, developed by the Volkswagen automotive company, describes the requirements for lamp covers made of organic glass, for example, for brake lights, turn signals, rear position lights, parking lights, and reverse lights.

This standard defines material requirements and test criteria for external lenses (covers) made from organic glass (plastics such as polycarbonate or polymethyl methacrylate) used in vehicle exterior lighting components.

The VW TL 591 standard applies to transparent or translucent outer lenses of the following types of lights:

• Stop lights (brake lights)
• Signal lights (indicators)
• Rear position lights
• parking lights
• Reverse lights (reverse lights)
• And similar outdoor lighting units

The aim of this standard is to ensure that these plastic lenses meet stringent performance, durability, and safety standards for automotive use. Organic glass is preferred over traditional mineral glass in modern vehicles due to its lighter weight, impact resistance, design flexibility, and ability to integrate complex shapes.

The basic requirements in this standard are described as follows:

• Material approval: Initial supplies and modifications are made in accordance with VW 01155 standard. Granular raw materials are approved according to VW 50026 standard.
• General characteristics: Including tests for mechanical strength, optical transparency, and resistance to environmental factors.
• Weather and aging resistance: Tests are conducted against UV rays, heat, humidity, and chemical resistance to maintain transparency and color stability throughout the vehicle's lifespan.
• Mechanical tests: Impact resistance, scratch resistance, and dimensional stability tests are performed.
• Optical requirements: Light transmission, light scattering, and color requirements are evaluated to ensure correct light distribution and visibility.
• Emissions and environment: Low emissions and compliance with relevant regulations are ensured.

Materials such as polycarbonate or polymethyl methacrylate must pass a series of standardized tests to be approved for use in Volkswagen Group vehicles.

In modern automobiles, headlights, taillights, and turn signals are critical safety features. Lenses protect the bulbs/LEDs while allowing light to pass through effectively. Poor quality materials can yellow, crack, fog up, or lose clarity over time due to exposure to sunlight, temperature changes, or road chemicals. This can lead to reduced visibility, failure of inspections, or safety risks. The VW TL 591 standard helps ensure consistently high quality among suppliers.

This standard is part of Volkswagen’s broader set of technical delivery terms (TL) specifications, covering thousands of components and materials.

In short, the VW TL 591 standard is a material specification that defines the requirements for organic glass (transparent plastics) used in automotive lighting systems. These materials are essential components in vehicle lights such as headlights, taillights, turn signals, and reflectors. This standard ensures that materials used in lighting units meet the stringent performance, durability, and safety criteria required in automotive applications.

The VW TL 591 standard applies primarily to the following thermoplastic optical materials:

• Polycarbonate (PC)
• Polymethyl methacrylate (PMMA)

These materials are used in the following areas:

• Headlight lenses
• taillights
• Signal lamp covers
• Reflectors and light guides

This standard covers material requirements for organic glass used in lighting units, as an alternative to traditional glass.

The VW TL 591 standard essentially defines three categories:

• Standard type
• Tip A
• Type B

These classifications reflect different performance levels, particularly in terms of mechanical strength and environmental resistance.

This standard specifies a wide range of material and performance requirements, including:

• Optical properties:
• High transparency and clarity.
• Controlled light transmission and propagation.
• Color stability over time.
• Mechanical properties:
• Impact resistance (e.g., Charpy impact resistance)
• Resistance to cracking and deformation.
• Structural integrity under vibration.
• Thermal properties:
• Heat resistance (e.g., Vicat softening temperature)
• Stability at high lamp operating temperatures.
• Chemical resistance: Resistance to the following is evaluated:
• Washing liquids
• Fuels and oils
• Cleaning agents
• Environmental resilience:
• UV resistance (no yellowing or deterioration)
• Resistance to weather conditions and aging.
• Environmental cycle test (temperature and humidity cycle)

Materials should generally undergo standardized tests that comply with ISO and DIN standards. For example,

• Impact testing (e.g., ISO 179 standard)
• Heat resistance test
• Tensile crack resistance test
• Weather and UV exposure tests

In addition, the materials must also comply with Volkswagen's broader standards. For example,

• Material approval and documentation systems
• Environmental compliance requirements

The VW TL 591 standard has evolved over the years and undergone numerous revisions. Recent updates include:

• Improved impact resistance requirements
• Improved environmental testing procedures
• Updated chemical resistance criteria

This standard is considered important for the following reasons:

• Safety: Protects the visibility and signal performance of vehicle lights.
• Durability: Prevents cracking, yellowing, or malfunction over time.
• Compliance with regulations: Complies with global automotive lighting regulations.
• Quality consistency: Ensures suppliers deliver uniform, approved materials.

Without this standard, lighting components can degrade rapidly, leading to reduced visibility and potential safety risks.

In conclusion, the VW TL 591 standard is a key Volkswagen material specification that regulates plastic optical materials for automotive lighting systems. By defining stringent requirements for performance, durability, and environmental resistance, it ensures that vehicle lighting components remain safe, reliable, and visually consistent throughout their service life.

For many years, our organization, with its competent and experienced team, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services compliant with the VW TL 591 standard.