Cover Glass Quality Inspection
Cover glass quality inspection checks each stage, from incoming sheet to packed part, against the dimensions, strength, optics and coatings on your drawing. We test strengthening, impact, fragmentation, coating adhesion, chemical and thermal resistance, transmittance, haze, gloss and AF contact angle, and record the results for every lot.
Capabilities
Dimensions
2D measuring system · Surface roughness tester
Strength
Stress analyzer, ball drop · Four-point bending
Optics
Transmittance, haze · Gloss and color difference
Coatings
Water contact angle · Abrasion tester
Hardness and adhesion
Pencil hardness · Cross-hatch with 3M 610 tape
Environment
−40 °C cold, 200 °C thermal shock · Acid, alkali and water immersion
Gallery
Ask about testing for your part
Send your drawing and the tests and standards it calls for, and we will confirm which we run in-house, how they are sampled and what the report includes.
Inspection at Every Stage
Defects are cheapest to catch before more work is added, so each stage has its own checks.
- 01
Incoming glass
Sheet dimensions, optical quality, visible defects and material certificates.
- 02
After cutting and machining
Outline, hole positions and edge chips.
- 03
After strengthening
Surface stress on chemically strengthened glass; fragmentation, ball drop and thermal shock samples on tempered glass.
- 04
After printing
Color difference, print alignment, adhesion and alcohol resistance.
- 05
After coating
Transmittance, haze, gloss and water contact angle.
- 06
Final inspection
Every panel is checked for dimensions and visible defects before packing.
Test Methods and Pass Criteria
| Test | Method | Pass criterion |
|---|---|---|
| Ink and coating adhesion | 100-square grid at 1 mm; 3M 610 tape pressed 1 min, then pulled | ≤5% removed (4B) |
| Pencil hardness | H or 2H pencil at 45°, 500 g, 3 mm stroke | No scratch |
| Ball drop | 500 g steel ball from 1.5 m, or 250 g from 2 m, onto the center; 6 samples | No more than 1 broken |
| Fragmentation, tempered | Impact 20 mm from the edge; count in a 50 × 50 mm area | 3 mm: ≥45 pieces; 4 mm: ≥40; no splinter over 75 mm |
| Thermal shock | 300 × 300 mm sample at 200 ±2 °C for 4 h, then into 0 °C water to 1/3 depth | Not broken after 5 min |
| Cold resistance | −40 ±2 °C for 24 h | No coating loss |
| Acid and alkali | 5% H₂SO₄ and 5% NaOH for 24 h, then adhesion test | No peeling, ≤5% removed |
| Water resistance | 2 h boiling or 24 h cold immersion, then adhesion test | No peeling, ≤5% removed |
| Alcohol rub | 1 kg, 30 cycles | No peeling |
Tests for Each Treatment
Chemical strengthening
Surface compression and layer depth on a stress analyzer, with four-point bending for flexural strength.
Thermal tempering
Fragmentation count, ball drop and thermal shock on samples from each furnace load.
Printing
Color difference against the approved sample, cross-hatch adhesion and alcohol rub.
AF coating
Water contact angle at 5 points, before and after steel-wool abrasion.
AG etching
Gloss and haze against the specified level.
AR coating
Transmittance across the specified band.
Specify the Test, Not Just the Result
A pass means little until the test behind it is fixed. A 500 g ball dropped from 1.5 m hits with about 7.4 J; a 250 g ball from 2 m hits with about 4.9 J. Both are quoted in the industry as “the ball drop test,” yet one is half again as severe as the other. Name the ball, the height and the support on your drawing.
The same applies elsewhere. A tape adhesion test changes with the pull angle and the number of pulls, and water contact angle targets for AF glass range from 95° to 110° depending on the grade. State the method, the grade and whether the figure applies before or after abrasion.
For cosmetic defects, define zones, such as the display area and the printed border, with the allowed scratch and dot size in each, and the viewing distance and lighting used to judge them.