GMW 14688 Scratch and Abrasion Resistance

Developed by General Motors Worldwide (GMW), the “GMW 14688 Scratch and Abrasion Resistance” standard is a test standard used to evaluate the scratch and abrasion resistance of plastic materials and components. It is particularly applicable to automotive interior and exterior plastic parts where surface appearance, durability, and perceived quality are important.

This standard applies to uncoated interior and exterior plastic parts and defines two different evaluation approaches:

• Method A Scratch Resistance: This method is the standard method. It can be used with molded components as well as sample plates. The basic concept is to apply a controlled scratching action to the plastic surface and then evaluate the resulting visible damage. A typical scratch test involves a defined scratching tool, controlled force, and controlled movement on the sample. The resulting scratch is then evaluated in terms of its visibility or change in surface appearance.

In practical automotive testing, cross-scratch equipment associated with the GMW 14688 standard can use controlled loads and scratch paths to produce repeatable surface damage. The key principle is repeatability: the two materials must be subjected to essentially the same mechanical stress for their scratch resistances to be objectively compared.

• Method B: Abrasion Resistance: This method evaluates abrasion resistance instead of traditional scratch resistance. An abrasion is a change in surface appearance that typically occurs with relatively light mechanical contact. Unlike a deep scratch, an abrasion may primarily manifest as a change in gloss, color, texture, or surface reflectivity.

The GMW 14688 standard defines this method as a development method and restricts it to sample plates with the correct color and texture. This distinction is important because a material may have good resistance to relatively deep scratches but still show noticeable surface marks from light contact.

During vehicle use, plastic surfaces can be damaged by fingernails, tools, clothing accessories, luggage, cleaning equipment, and other objects. Even if the plastic remains structurally intact, visible scratches or changes in gloss can significantly reduce the perceived quality of the vehicle. The GMW 14688 standard provides a controlled laboratory method to determine how susceptible a plastic surface is to such damage. Therefore, this standard helps manufacturers in the following areas:

• Comparing different plastic materials and formulations.
• Evaluating surface durability during material development.
• Selecting suitable materials for both internal and external components.
• Establishing consistent supplier quality requirements.
• To reduce visible surface defects on production equipment.
• Checking the cosmetic quality of automotive plastics.

The GMW 14688 standard applies primarily to uncoated plastic components, including automotive interior and exterior parts. Examples may include:

• instrument panels
• Door trim panels
• Center consoles
• Pole coverings
• Glove box components
• Armrests
• Key frames
• Decorative plastic components
• Exterior plastic flooring

Test laboratories also list plastics, elastomers, and foils among the materials that can be evaluated according to the GMW 14688 standard.

Scratch resistance and abrasion resistance are different things:

Scratch Resistance, Abrasion Resistance

• The main concern:
  • Scratch resistance: Physical scratch/damage
  • Abrasion resistance: Change in surface appearance.
• Typical assessment:
  • Scratch resistance: Visibility of the scratch
  • Abrasion resistance: Change in appearance/gloss.
• The standard situation:
  • Scratch resistance: Standard method
  • Wear resistance: Development method
• Example applicability:
  • Scratch resistance: Molded parts and sample plates.
  • Wear resistance: Accurate color/grain sample plates.
• Main application:
  • Scratch resistance: Material/component durability.
  • Abrasion resistance: Cosmetic surface durability.

Therefore, scratches and wear should not be considered exactly the same characteristic.

After mechanical processing, the tested area is examined to determine the degree of visible surface alteration. Depending on the applicable procedure and material, the assessment may include visual evaluation or instrumental measurement of changes in surface appearance. This is particularly important for automotive plastics, as two scratches of similar physical dimensions can have very different visual effects depending on the material's color, texture, grain structure, gloss, and pigmentation. For example, a scratch on a glossy black part may be much more noticeable than a similar scratch on a textured gray part.

The GMW 14688 standard is important because surface appearance is a crucial component of perceived automotive quality. A plastic part may meet dimensional and mechanical requirements, but if its surface shows visible damage during normal use, it may be rejected by the customer. Therefore, testing supports various stages of the automotive supply chain: material selection, formulation development, part development, supplier qualification, production quality control, and vehicle durability. It can help identify materials that are more resistant to daily contact and thus retain their appearance for longer.

Automotive components can encounter many sources of surface damage, including:

• quotes
• Keys and other personal belongings
• Tools used during assembly
• Clips and fasteners
• Baggage and cargo
• Cleaning equipment
• Scrolling objects
• Repeated contact between responsive components
• Assembly and service operations

Especially for internal components, even if a single incident doesn't cause serious damage, repeated small contacts can gradually lead to visible deterioration.

The GMW 14688 standard is particularly valuable for automotive interiors because many components are constantly exposed to human contact. For example, a center console can be touched hundreds or thousands of times over the life of the vehicle. Door panels and instrument panel surfaces are also touched during normal entry, exit, cleaning, loading, and maintenance. Therefore, a suitable material must possess not only sufficient strength and dimensional stability but also good cosmetic durability.

In conclusion, the GMW 14688 standard contributes to long-term vehicle appearance, perceived quality, supplier competence, material selection, and customer satisfaction by specifying materials and surface designs resistant to visible damage.

For many years, our organization, with its competent and experienced staff, 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 in accordance with the GMW 14688 standard.