Essential Knowledge of Glass Laser Cutting Technology

Glass is a critical industrial material that finds applications across numerous sectors of the national economy, including automotive, construction, healthcare, display, and electronics industries. Its uses range from tiny optical filters as small as a few microns and glass substrates for laptop and tablet displays to large-scale glass panels used in mass manufacturing fields like automotive and construction.

A prominent characteristic of glass is its hardness and brittleness, which pose significant challenges to processing. Traditional glass cutting methods rely on cemented carbide or diamond tools, which are widely used in many applications and consist of two main steps. First, a crack is created on the glass surface using a diamond tip or cemented carbide grinding wheel. Second, mechanical force is applied to split the glass along the crack line.

However, this scribing and cutting method has several drawbacks. Material removal leads to the generation of debris, fragments, and microcracks, which reduce the strength of the cut edge and require an additional cleaning process. Deep cracks caused by this process are usually not perpendicular to the glass surface, as the separation lines created by mechanical force are generally non-vertical. Furthermore, production losses resulting from mechanical force applied to thin glass are another negative factor.

These defects can be mitigated by using stress-free glass and further optimizing the fixtures used for separation. Nevertheless, it is impossible to completely avoid the systematic contradiction between achieving vertical cutting lines and preventing edge debris or cracks. The development of laser technology has provided a solution to these quality issues.

Laser Scribing and Separation

Unlike traditional mechanical cutting tools, laser beam energy cuts glass in a non-contact manner. This energy heats specific areas of the workpiece to a predefined temperature. The rapid heating process is immediately followed by rapid cooling, creating vertical stress zones inside the glass and forming a debris-free, crack-free fracture along this direction. Since the fracture is caused by heat rather than mechanical forces, no debris or microcracks are generated. As a result, the strength of laser-cut edges is higher than that of edges produced by traditional scribing and separation methods. The need for finishing is reduced or even eliminated entirely. Additionally, the occurrence of glass fragments can be completely avoided.

For laser scribing, under the action of laser beam heating and subsequent cooling, a line approximately 10mm deep (about 10% of the glass thickness) is scribed on the glass surface. The glass can then be split along the scribed direction. Because this technology does not produce any glass fragments, common burrs and low strength on cut edges are avoided, and subsequent polishing and grinding processes are no longer necessary. More importantly, glass processed using this method is up to three times more shatter-resistant than glass separated by traditional methods. For glass with a thickness between 1mm and 5mm, it is even possible to complete the entire cutting process in a single step, eliminating the need for separation and subsequent polishing, grinding, and rinsing steps. The strength of the cut edge can be measured using the standardized four-point bending test from DIN-EN 843-1. A piece of glass is fixed on two rollers, and two other rollers are used on the upper surface of the glass to generate the required bending force, under which the glass splits into two parts. This test is repeated approximately 100 times to obtain reliable statistical data on separation feasibility.

In most cases, laser scribing and cutting are the preferred choices for mass processing. Their advantages include high processing speed, high precision, and simple parameter settings. However, when cutting many different lines and processing time is sufficient, full-cutting is a more attractive method due to its dry cooling method and no additional cutting steps. High-quality cut edges are achieved in both cases. It is evident that using laser cutting for glass can significantly save time while improving processing quality.

Applications of Glass Laser Cutting Technology

Transplanting a new and mature technology into mass production lines for processing high-tech products is no easy task. From the customer's perspective, before implementation, the technology must be an automated, reliable solution that is not only fully proven but also economically viable. In practice, the application of innovative technology is only effective in two scenarios: when the launch of new products requires new production methods to achieve innovative features or reduce production costs by reducing processing steps, or when existing production faces economic pressure and requires significant improvements in production methods to alleviate it.

In the flat panel display industry, it took five years for laser cutting technology to establish its position in production lines, following thousands of hours of application verification across many processing lines. Today, it is commonly considered for the production of new products with a risk of glass breakage, such as glass-containing communication and mobile products in the electronics industry, or other products with fragile thin glass components like sensors, touchpads, or glass casings.

Processing is usually carried out in clean rooms, just like in the biochemical industry, as these fields are highly sensitive to particles generated by traditional cutting or grinding steps. For example, substrate materials covered with DNA codes (biochemical barcodes) or materials cut into pieces by lasers are used for product testing. The next most promising application industries for laser cutting technology will be the solar energy and automotive industries.

Just as laser technology has developed in the metal processing industry over the years, laser cutting technology for glass processing will continue to evolve; it will be widely used in the processing of various products, replacing traditional methods. However, traditional glass processing methods will still maintain their important position in the processing of most glass products, generally in applications where the quality requirements for cut edges are not very high.

Laser shape cutting is an innovative technology that will find its place in the electronics, automotive, or construction industries. In addition to laser cutting of glass, many other laser-based glass processing methods are in the further development and testing stage, such as drilling, chamfering, and coating removal. These processes require different types of lasers, such as green lasers.