Mechanical Scratch Tester

The Mechanical Scratch Tester is a mechanically driven instrument designed for evaluating coating hardness based on scratch resistance performance. During testing, the coated panel is clamped and moved at a controlled constant speed while a spherical stylus or alternative scratching tool is pressed against the surface under a defined load. By applying either fixed or variable loads, the system can generate different levels of coating damage ranging from visible marks to complete film failure. An integrated voltmeter detects electrical contact between the stylus and the metallic substrate, enabling clear determination of coating breakthrough. The tester is suitable for standard metal panels up to 100 × 150 × 1.6 mm with a coating thickness of up to 0.3 mm.

Application

Primary test purposes

Coating scratch resistance evaluation

Coating hardness assessment based on mechanical damage behavior

Determination of coating failure load

Detection of coating breakthrough on conductive substrates

Typical tested materials

Painted metal panels

Industrial coatings

Automotive coatings

Protective and functional coatings on metal substrates

Laboratory standard test panels

Standards

(1) GB/T 23989-2009 – Determination of scratch resistance of coatings

(2) GB/T 5210-2006 – Paints and varnishes – Pull-off adhesion test

(3) GB/T 1768-2006 – Determination of abrasion resistance of paint films

(4) ISO 1518-1 – Paints and varnishes – Scratch test – Part 1: Determination of scratch resistance

(5) ISO 20502 – Coating materials – Scratch test

(6) ASTM C1624 – Standard test method for adhesion and scratch resistance of ceramic and hard coatings

(7) DIN EN 1071-3 – Advanced technical ceramics – Mechanical properties of ceramic coatings – Part 3: Scratch testing

Parameters

Features

Mechanical drive system enclosed by a protective cover for stable and safe operation.

Constant sliding speed of approximately 3–4 cm/s.

Rigid, well-balanced stylus arm that minimizes vibration and instability during scratching.

Equipped with a 1 mm tungsten carbide ball stylus fixed at 90° to the test panel.

Stylus can be easily removed for inspection or replacement.

Tungsten carbide tip provides long service life without frequent replacement.

Adjustable loading system with selectable weights from 100 g to 2 kg (0–20 N).

Optional additional weight up to 10 kg available for testing harder coatings.

Compatible with standard metal panels up to 150 × 100 mm and thickness up to 1.65 mm.

Optional transparent plastic safety cover to prevent accidental contact during operation.

Accessories

(1) 1 mm tungsten carbide ball stylus

(2) Standard weight set (100 g to 2 kg)

(3) Optional additional weight kit (up to 10 kg)

(4) Optional transparent protective cover

Test Procedures

Specimen preparation

Mount a standard coated metal panel (up to 100 × 150 × 1.6 mm) into the clamping fixture.

Ensure the panel is flat, clean, and firmly secured.

Load setting

Select the required weight according to the test standard or evaluation objective.

Place the weight above the stylus to apply the desired normal force.

Scratch execution

Start the instrument to move the panel at a constant speed of 35 mm/s.

The tungsten carbide stylus scratches the coating along a straight path.

Breakthrough detection

Monitor the voltmeter: when electrical contact is detected between stylus and metal substrate, coating failure is confirmed.

Result evaluation

Record the applied load at which visible damage or breakthrough occurs.

Compare results with standard requirements or reference panels.

Maintenance Information

Clean the tungsten carbide stylus after each test.

Inspect the stylus tip regularly; replace if worn or damaged.

Keep moving rails and mechanical parts free from dust and debris.

Ensure protective cover is installed during operation.

Avoid exceeding the maximum recommended load for routine testing.

FAQ

1. What types of coatings can be tested?

You can test painted metal panels, industrial coatings, automotive coatings, and protective or functional coatings on conductive substrates.

2. How is coating breakthrough detected?

The integrated voltmeter detects electrical contact between the stylus and metallic substrate, indicating coating failure.

3. What is the maximum panel size supported?

The instrument supports panels up to 100 × 150 × 1.6 mm with coating thicknesses up to 0.3 mm.

4. Can the test load be adjusted?

Yes, standard weights provide 0–20 N load, with an optional additional weight kit up to 10 kg for harder coatings.

5. What is the stylus material and geometry?

The standard stylus is a 1 mm tungsten carbide ball with a 90° angle, durable and replaceable.

6. How is scratch consistency ensured?

The rigid stylus arm and constant mechanical sliding speed minimize vibration and maintain uniform scratches.

7. Is operator protection included?

Yes, an optional transparent protective cover prevents accidental contact during testing.