Edge Chamfering Knowledge in Cover Glass Industry

In the cover glass industry, edge chamfering is a critical post-processing procedure affecting product safety, durability, aesthetics, and assembly compatibility. It grinds and polishes sharp cut edges into specific shapes to eliminate sharpness, reduce stress concentration, and meet application needs. Below is a concise overview of common chamfering types, processing principles, and quality control points based on practical experience.

1. Common Types of Edge Chamfering for Cover Glass

Cover glass chamfering is classified by shape, precision, and application, with six mainstream types tailored to specific product requirements.

1.1 Seamed Edge

The most basic and cost-effective type, mainly for safety by grinding sharp edges smooth with a coarse-grit diamond wheel. It is used in industrial control screens, as pre-processing for high-precision chamfers, and for mass-produced, low-aesthetic-demand products.

1.2 Flat Edge

Ground into a straight, horizontal shape with more refined grinding than seamed edges, ensuring smoother surfaces and uniform thickness for better assembly. Suitable for industrial displays, surveillance screens, and low-end consumer electronics, often paired with simple scratch-resistant coatings.

1.3 Pencil Edge

Named for its pencil-like rounded arc, balancing safety and basic decoration. Processed with emery-embedded tools, it is used in retail touch screens, furniture glass, and mid-range electronics, with a radius of 0.5-2.0mm for comfort and stability.

1.4 Beveled Edge

A high-aesthetic type with a 30°-60° diagonal V-shape (1-5mm width), requiring high-precision grinding and polishing. Used in high-end electronics and commercial displays, processed by CNC machines and polished to a mirror finish with cerium oxide.

1.5 2.5D Edge

Mainstream in consumer electronics, with subtle curved edges (R0.3-R1.5mm) and a flat center. It improves touch experience and aesthetics, used in smartphones and wearables, processed by CNC grinding, polishing, and anti-fingerprint coating.

1.6 Step Edge

A special layered, stair-like chamfer, customized for lighting, special-shaped displays, and high-end decorative glass. It requires high-precision equipment to ensure uniform steps and smooth transitions, avoiding chipping.

2. Core Processing Principles

Chamfering involves three linked stages: grinding, polishing, and cleaning, with deviations affecting quality.

2.1 Grinding Stage

Uses diamond wheels (80#-800# grit for rough to precision grinding) to shape edges. CNC machines ensure dimensional consistency, with multi-axis machines for special-shaped chamfers.

2.2 Polishing Stage

Removes grinding scratches using polishing agents (cerium oxide, aluminum oxide) and soft tools. Multi-stage polishing is used for beveled/2.5D edges, while seamed/flat edges may need minimal or no polishing.

2.3 Cleaning Stage

Removes residues via ultrasonic cleaning, deionized water rinsing, and drying. Plasma cleaning is used for high-precision applications to enhance surface cleanliness and adhesion.

3. Key Quality Control Points

Strict control ensures consistent quality, focusing on two core aspects:

3.1 Dimensional Accuracy

Controls chamfer angle, width, radius, and thickness uniformity (e.g., ±1° for bevel angle, ±0.05mm for radius). CMM inspects regularly to adjust machine parameters.