Dry Scratch Resistance Test Performed Using BMW AA 0134 Crockmeter

The “BMW AA 0134 Dry Scratch Resistance Test Using Crockmeter” standard, developed by BMW, a multinational vehicle manufacturer, describes an internal testing method for evaluating the dry scratch resistance of surfaces used in vehicles, particularly coatings, paints, and interior and exterior materials. This testing method uses a Crockmeter (a standardized friction or abrasion testing device) to simulate mechanical wear from dry friction, ensuring that automotive coatings can withstand everyday scratches without significant damage.

A Crockmeter is a linear abrasion testing device that rubs a standardized abrasive material (typically dry wool felt or special abrasive paper) back and forth over a test surface under controlled pressure and cycles. The BMW AA 0134 standard specifies the following parameters:

• Applied load/pressure (e.g., 9 N or specific weights).
• Number of friction cycles.
• Abrasive finger or head type (typically a round punch with a defined radius of r=22 mm, such as the CR22).
• Evaluation criteria include visible scratches, changes in gloss, color transfer, or material deterioration.

This method complies with broader industry standards such as DIN 55654 or ISO 105-X12 for color fastness to friction, but has been adapted to BMW's automotive durability requirements.

These tests utilize a Crockmeter (friction resistance testing device) to simulate dry abrasion from everyday contact (e.g., fingers, clothing, or dust). This testing is unique to BMW and is carried out by accredited testing laboratories or suppliers.

The necessary equipment used in the tests is as follows.

• Crockmeter: Manual or motorized linear wear testing device.
• Test head: Specific to this standard, conforming to the requirements of DIN 55654. Typically includes a friction shaft/pendulum with a friction surface 25 mm wide.
• Abrasive: Dry wool felt (usually 15 mm x 15 mm pieces, white) or fine abrasive paper (e.g., 9 micron polishing paper, in sheets such as 215,9 mm x 279 mm).
• Weights: For applying a standard load (typically 9 N or as specified).
• Gray scales: Used to assess color transfer or damage (e.g., ISO gray scale for staining/assessment).

Flat test specimens (e.g., coated panels or material samples) are conditioned for at least 24 hours in a standard climate (at a temperature of 23 degrees plus/minus 2 degrees Celsius and a relative humidity of 50 percent plus/minus 10 percent). The specimen is securely fixed to the Crockmeter base without damage. A fresh, dry wool felt pad or the specified abrasive paper is attached to the test head/finger. It is essential to ensure the contact surface is clean and smooth. The test head is mounted with the required weight (usually approximately 9-10 N downward force). Linear reciprocating cycles are performed (stroke length is usually 100–120 mm). The number of cycles is specified by BMW (usually 10-100 dry cycles depending on the material; the exact number is part of the proprietary specification). The speed is approximately 1 cycle per second.

The eroded area is visually evaluated from the following perspectives:

• Visible scratches, wear, or changes in shine.
• Color transfer to abrasive (using a grayscale for staining, 1-5 rating).
• Material degradation (e.g., blistering or substrate exposure).

Gloss retention is measured (e.g., before/after with a reflectometer) or, if necessary, cross-hatching is used. It is then graded according to BMW acceptance criteria (pass/fail depending on the absence of significant damage).

This method, unlike wet etching methods, is a dry test (does not involve any liquid). For precise parameters (total number of cycles, load, abrasive type, acceptance limits), the BMW AA 0134 standard is followed.

This standard is often used in conjunction with BMW GS 97034 (surface test) or VW PV 3987 or VW PV 3991 standards for similar friction tests.

This standard is considered important for the following reasons:

• Ensures surface durability: Automotive interiors (instrument panels, upholstery, leather, plastics) and exteriors (paint, clear coatings) are constantly subjected to abrasion from fingers, clothing, keys, or dust. This test confirms resistance to dry scratches and prevents unsightly marks that could affect perceived quality.
• It is part of BMW’s rigorous quality assurance: like other AA standards (e.g., BMW AA 0129 standard for corrosion), the BMW AA 0134 standard is mandatory for supplier parts and materials. This testing helps BMW maintain its superior standards for long-term aesthetics and customer satisfaction.
• Simulates real-world use: Unlike wet wear or stone chip tests, this test focuses on dry friction, common in everyday vehicle interaction, and provides a reliable estimate of wear over time.
• It complements other tests: It is often used in conjunction with standards such as BMW GS 97034 (scratch and abrasion resistance) or BMW AA 0471 (Abrex wear) for comprehensive surface assessment.

In conclusion, BMW AA 0134 and similar standards contribute to BMW vehicles' reputation for having high-quality, durable, and wear-resistant surfaces, reducing warranty issues and increasing resale value. This test is widely referenced in BMW supplier manuals.

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 in accordance with the BMW AA 0134 standard.