How to Cut Laminated Glass

You might not be glass experts, but we’re here to help. Can laminated glass be cut? Laminated safety glass is made from two or more layers of glass bonded together with a plastic interlayer, and if the interlayer is PVB, which is relatively soft, the answer is yes. A more difficult question is how to cut laminated glass. In this article, our experts at Apex Tempered Glass tell you how.

The challenge of cutting PVB laminated glass lies in its construction. To achieve a clean cut, you need to score both sides of the glass individually. Once you’ve created the initial score lines, you have to separate the two glass pieces by breaking them along the score. But that’s not all – the plastic interlayer still needs to be cut to fully separate the glass pieces.

Ways to Cut PVB Laminated Glass

Here are three common methods to cut this glass type.

Hand-Cutting with a Glass Cutter

This is a traditional method ideal for smaller cuts or straight lines. A specialized glass cutter with a carbide scoring wheel creates a deep score line on both the top and bottom glass surfaces. Once scored, a breaking tool or gentle pressure applied along the score can separate the glass layers. However, achieving clean, precise cuts and handling larger pieces can be challenging with this method.

Waterjet Cutting

This method utilizes a high-pressure stream of water mixed with abrasive particles to cut through the laminated glass. It offers excellent precision and can handle intricate shapes. The waterjet can cut through all layers (glass and PVB) in one pass, minimizing chipping and creating clean edges. However, keep in mind that waterjet cutting requires specialized equipment and skilled operators so this option isn’t as accessible.

Laser Cutting

Laser cutting is another highly precise method for cutting laminated glass. A focused laser beam melts and vaporizes the material along the cutting path, allowing for intricate shapes and clean edges. This method can cut through all layers in one pass, similar to water jet cutting. However, laser cutters are even more expensive and require significant expertise to operate safely and effectively.

Choosing the Right Method

Which method is ideal?

The best method for cutting laminated glass depends on several factors, including:

• Complexity of the cut: Straight lines can be managed with a glass cutter, while intricate shapes require water jet or laser cutting.
• Project scale: For small projects, hand-cutting might be sufficient, while larger projects may benefit from the efficiency of waterjet or laser cutting.
• Budget and equipment access: Hand-cutting is the most affordable option, but waterjet and laser cutters are expensive and need specialized training.

For most home improvement projects, a glass cutter might suffice for simple cuts, while for professional applications or intricate designs, waterjet or laser cutting would be the preferred choice for their precision and efficiency.

How to Cut Curved Laminated Glass

Cutting curved laminated glass presents an additional challenge compared to straight cuts.

The three methods mentioned earlier can all be used for curved cuts on laminated glass but with some adaptations:

• Glass cutter: For gentle curves, a glass cutter can be used with some finesse. However, it can be difficult to maintain consistent pressure and precisely follow the curve. Masking tape on the glass surface can provide a better grip for the cutter.
• Waterjet & laser cutting: Both of these methods excel at curved cuts because of their computer-controlled precision. They can follow complex curved paths with minimal chipping or breakage.

When cutting this kind of glass, here are some considerations to keep in mind:

• Complexity of curve: Simple curves might be manageable with a glass cutter, while tight curves or intricate shapes are best suited for water jet or laser cutting.
• Breaking the glass: After scoring the laminated glass with a cutter (on both sides), even for curved cuts, you’ll need to separate the glass layers. This can be done by carefully applying gentle pressure along the score line, following the curve.

Cutting curved laminated glass, especially with a glass cutter, requires skill and practice. We recommend consulting a professional glass cutter for complex projects or if you lack experience. This approach ensures a clean cut and minimizes the risk of shattering or damaging the glass.

Tips for Hand-Cutting Laminated Glass

Even though hand-cutting laminated glass isn’t ideal for every project, our team at APEX has provided some tips to increase your chances of success for straight cuts.

Preparation

• Gather your tools: You’ll need a high-quality glass cutter with a sharp carbide wheel, a straightedge (metal ruler works well), a breaking tool (like glass pliers or a tapping bar), safety glasses, and gloves.
• Clean and mark the glass: Thoroughly clean the cutting surface with a glass cleaner to remove any dirt or debris. Use a felt-tip marker to mark your cutting line on both sides of the glass.

Scoring

• Score both sides: Laminated glass requires scoring a deep line on both the top and bottom glass surfaces for a clean break.
• Use consistent pressure: Hold the glass cutter perpendicular to the glass surface and apply firm, even pressure as you draw the cutter along the marked line. Ideally, you should hear a slight scratching sound.
• One clean stroke: Try to complete the score in one smooth, continuous motion. Avoid going back and forth over the same line, as this can weaken the score and make a clean break harder.

Breaking the Glass

• Align the score: Place the glass on a flat, stable surface with the score line directly over the edge.
• Breaking tool or gentle pressure: Use a glass breaking tool (like pliers) or carefully apply gentle pressure along the score line on the top surface, following the score for a straight break.
• Separate the layers: Once the glass breaks along the score, you’ll still need to separate the plastic interlayer. Some professionals recommend using a utility knife with a fresh blade to carefully cut through the exposed PVB layer along the score line. Always be very cautious while doing this to avoid damaging the glass or injuring yourself.

General Tips

• Practice on scrap glass: Before attempting your actual cut, we recommend practicing scoring and breaking on a piece of scrap laminated glass to get the feel for it.
• Work in a well-ventilated area: Glass dust can be irritating, so wear a dust mask if needed.
• Safety first: Always wear safety glasses and gloves when cutting glass to protect yourself from flying shards or cuts.
• Consider complexity: Hand-cutting is best for straight lines on smaller pieces. For intricate cuts or larger projects, consider using a professional glass cutter or opting for water jet or laser cutting methods for better precision and safety.

Tips for Waterjet Cutting

Here are some tips to optimize your waterjet cutting process.

Pre-Cutting Preparations

• Material selection: Ensure your laminated glass is compatible with waterjet cutting. It can handle various materials, but consult your machine manual or a waterjet specialist for specific recommendations.
• Design optimization: Waterjet cutting excels at intricate shapes, but consider simplifying your design if possible to minimize cutting time and garnet usage (abrasive used with waterjet). Sharp corners can be a challenge, so explore using rounded edges where you can.
• Nesting: When cutting multiple pieces from a single sheet of glass, utilize nesting software to maximize material usage and minimize scrap.

Cutting Parameters

• Water pressure & flow rate: These settings determine the cutting speed and edge quality. A qualified technician or the machine manual will guide you on the optimal settings for laminated glass. Higher pressure generally translates to faster cutting speeds but can affect edge quality.
• Garnet selection & feed rate: The size and type of garnet (abrasive) used can impact the cutting speed and edge finish. A finer garnet creates a smoother edge but might cut slower. The feed rate controls how quickly the garnet is introduced into the water stream. Experimenting with these settings under expert guidance can help you achieve your desired results.

Factors to Optimize the Process and Minimize Cracking

• Fine mesh abrasive: For laminated glass, using a fine mesh abrasive is crucial. This minimizes chipping along the cut edges and allows for a smoother finish.
• Proper fixturing: The laminated glass needs proper support beneath it during cutting. This helps prevent cracking. The ideal support should be flat, uniform, and slightly soft to absorb the waterjet impact and avoid bouncing back onto the glass. Waterjet bricks are a good option, but clamps, weights, or tape can also be used depending on the situation. Cutting underwater can further minimize frosting on the underside of the glass.
• Orifice size and pressure: Cutting laminated glass requires high pressure for precise cuts. A qualified technician can help determine the optimal orifice size and water pressure for your specific project.
• Minimize sagging in the abrasive line: A sagging abrasive line can disrupt the abrasive flow and cause uneven cutting or sudden bursts that could crack the glass. If your abrasive line is prone to sagging, consider using a shorter line length.
• Piercing pressure: Similar to the high pressure for cutting, start with a high piercing pressure to ensure the water jet penetrates the material before the abrasive flow begins.
• Gradual temperature changes: Laminated glass is sensitive to rapid temperature fluctuations. When transitioning between the hot water tank and cold air or cold water during cutting, ensure a gradual shift to minimize stress on the glass and reduce the risk of shattering.

Safety and Maintenance

• Machine familiarization: Before operating the waterjet, make sure you thoroughly understand the safety protocols, emergency procedures, and proper operation techniques.
• Personal Protective Equipment (PPE): Always wear safety glasses, gloves, and ear protection while operating the waterjet. Depending on the application, additional PPE like respirators or face shields might be necessary.
• Regular maintenance: Regularly inspect and replace water filters, garnet catchers, and intensifier pump components as per the manufacturer’s recommendations. Proper maintenance results in optimal performance and extends the life of your waterjet machine.

Additional Tips

• Test cuts: Before running your final cuts, perform test cuts on scrap laminated glass to dial in your water pressure, flow rate, and garnet settings to achieve the desired cut quality.
• Water quality: Monitor your water quality. High levels of minerals or impurities can affect cutting performance and damage machine components. If necessary, you can also consider water treatment systems.
• Clamp securely: Ensure the laminated glass is securely clamped to the cutting table to avoid vibrations or movement during the cutting process, which can affect cut quality.

Tips for Laser Cutting

The main tips here concern laser settings and machine parameters.

Laser Power and Speed

These settings determine the cutting speed and edge quality. A qualified technician or the machine manual will guide you on the optimal settings for laminated glass. Higher power can cut faster but might affect edge quality or even cause heat cracks.

Focus and Assist Gas

The laser beam focus and assist gas (often compressed air) play a crucial role. Proper focus ensures a clean cut, while the assist gas helps remove debris and prevent burning or charring on the glass surface. You must consult a specialist for these settings.

Generally speaking, we don’t recommend a DIY approach for laser-cutting laminated glass. The process requires significant expertise and can lead to cracking or heat damage in the glass if it’s not done correctly.