Laser Cutting Glass without Chipping: Guide

Laser Cutting Glass without Chipping: Guide

Laser Cutting Glass without Chipping: Guide

When you need to make complex cuts in glass, laser cutting can be a great choice.

Glass is both transparent and reflective in nature. How can a laser light cut such a material?

This article is all about laser cutting glasses. I discuss how to cut laser cut glass and the probable challenges that you may face when cutting glass on a laser.

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How to Laser Cut Glass

Laser cutting allows cutting out complex curved geometries in glass. High energy CO2 lasers of 30W and above are the best choice for cutting glass. As the thickness of glass increases, the power of the laser required also increases. A high power laser can cut through glass quicker.

The process of using a laser cutter to perform clean cuts in glass consists of a few basic steps.

Creating the Design

The first step is to make the necessary designs which would then be cut out from the glass.

You can use any CAD/CAM software of your choice that exports files in the format your laser control software supports.

If preparing the design is not one of your strengths, you can always use free laser cut design files provided by various websites online.

Following are some of the popular CAD software and their supported export file formats.

SoftwareFile Format
Adobe IllustratorAI, DXF, JPG, SVG, SVGZ, PDF, and EPS
InkscapeSVG, SVGZ, PDF, EPS/EPSi, LaTeX, and HPGL
Autodesk Fusion 360SVG, DXF, IPT, DWG, SKP, and DWG
Laser CADCDR, DXF, and PLT

Popular CAD software

Performing Test Cuts

To know the proper settings needed to cut a type of glass, you will have to perform some test cuts.

By testing different laser power, speed, and feed settings, you can find the proper settings for the type of material you cut.

Yes, it causes material wastage, but doing test cuts allows you to understand the material you are cutting. In addition, the correct cut setting saves you from making any expensive mistakes.

Making the Cut

Cuttting glass with laser
Cutting glass with laser (Source: Theo Yu - YouTube)

Once you determine the optimal settings, you can cut glass efficiently. It minimizes material wastage and helps you process more cutouts from a given glass sheet.

Cooling the laser-cut glass edge with an air assist minimizes microfractures that can develop in the cutting path. It also results in a smoother cut.

Laser Cutting Glass - Basics, Types of glass

Glass is a transparent solid non-crystalline material. They are made by melting quartz having silicon dioxide (SiO2) as its building block.

The molten liquid silicon dioxide does not recrystallize as it cools. Instead, it slowly becomes an amorphous solid which fills all its gaps at the microscopic level.

This helps achieve a smooth cut edge finish on glass.

Electromagnetic Spectrum
Electromagnetic Spectrum

Glass is transparent in the visible light range (380 -780nm) as it allows visible light to pass through without capturing any of its energy on the atomic level.

However, for ultraviolet light, glass is not transparent as the electrons of SiO2 capture its energy. This is why you don't get a tan if you

Laser cutting is a significant part of glass fabrication as only through an accurate and precise cut can the desired shape and size of glass be made.

The wavelength of the laser to use depends on the glass. However, most types of glass can be cut using a CO2 laser operating at a wavelength of 10,600nm.

Types of Glass for Laser Cutting

Laser cutting glass (Source: Alibaba)

The most widely used form of glass today is soda-lime glasses. It is the go-to glass for most consumer products.

It is so widely used that when someone refers to glass, they're most likely referring to soda-lime glasses.

75% of the currently manufactured glasses are also soda-lime glass.

Typical glasses that can be laser cut are borosilicate, silicate, lead, aluminosilicate, and fiberglass.

Stained glasses can also be cut using a laser, and they are doped with color additives for various decorative applications. Unfortunately, as a result, they are heavily prone to fractures.

Laser cutting is not only limited to these glasses. It can cut other processed glasses like toughened or tempered glasses, laminated, heat-strengthened, reflective, and frosted glasses.

You will need to use high-powered lasers with a small laser beam for cutting such hard glasses.

Following is a list of the various types of glass and the appropriate laser cutter for them.

GlassLaser TypeWavelength
Soda-lime glassesYAG laser1064 nm
Stained glassCO2 laser10,600 nm
Borosilicate glassUV laser355 nm
Silicate glassCO₂ laser10,600nm
FiberglassCO₂ laser9,300nm or 10,600nm
Quartz GlassCO₂ laser9,300nm or 10,600nm
Aluminosilicate glassCO₂ laser9,300nm or 10,600nm
Lead crystal glassCO₂ laser9,300nm or 10,600nm

Laser type and wavelength for different glasses

Optimal Settings for Laser Cutting Glass

Laser Power

When cutting glass, you need to use a laser with power ranging from 30W to 800W depending on the thickness and structural composition of the glass.

High-energy CO2 lasers are the industry standard for cutting glass. This is because their operational wavelength has a reasonable absorption rate on glass.

Cutting Speed

The thickness of glass influences the cutting speed you can achieve with a laser.

By increasing the laser power, you can cut glass at a higher speed.

Generally, a cutting speed of around 15 ipm is recommended for an 80W laser against a glass of 0.10" thickness.

Work Area

The work area of the laser cutter is an important aspect that you should consider.

You should choose a laser cutter depending on the size of the glass sheets you plan to use.

For a small business, a desktop laser cutter is a good choice. Desktop lasers are relatively affordable and use minimal space.

In case of large businesses or industries, the optimal choice would be industrial-grade laser cutters.

Work Holding

Since glass is heavy enough to stay stable when laser cut, in most cases you wouldn't need fixturing when laser-cutting glass.

When using low-density glass, it is better to stick it using double-sided tape or fixturing of some kind that does not leave scratches on the glass surface.

Air Assist

A high-pressure air assist with a small-size laser nozzle is recommended for laser processing glass.

Air assist cools the laser-cut edge and helps limit microcrack development along the cut path.

Lenses

When choosing lenses for working on glass, select those that have an ISO-10110 standards certification for use in crystals and glass materials.

A short focal laser lens with an extended depth of focus is what you need for laser-cutting glass. It ensures the laser beam is focused on a small focus spot throughout a thick glass piece.

Recommended lens settings for efficient cutting of glass is a lens with 2" focal length, 0.03" Depth of Focus (DoP), and a spot size of 0.001".

Exhaust System

When laser cutting glass, visible smoke or fumes are not generated because of the general absence of impurities.

Just because the fumes generated are not visible does not necessarily mean they are not harmful.

The toxicity of the generated fumes will depend on the additives added to the material. For example, some stained glass emits dark visible fumes when laser-cut.

It is always better to have a good ventilation setup for your laser cutter. It can quickly remove the fumes generated and prevents the machine parts from corrosion and being stained.

How to Improve Quality of Cut in Glass

To get a smooth cut on glass, cover the surface with a damp paper towel or an application tape. This limits the microfractures developed on the glass and helps in giving a clean cut.

A stable focal distance has to be maintained throughout the cut. Do not change the laser height once you start cutting. Changing the laser height can sometimes cause uneven cuts on the glass plane.

After long hours of operation, the laser lens will be clouded with fume and residue which reduces laser density and causes uneven cuts.

Cleaning the lense regularly is important for your lense to last long.

The best method for cleaning lenses is using alcohol solutions with at least 90% alcohol content. You can also use acetone.

Laser wavelength, glass thickness, spot size, absorption coefficient, power, speed, and glass structure are some of the main parameters that affect the quality of cut.

To get a good quality cut, you will have to optimize these parameters.

Advantages of Laser Cutting Glass

While there are other traditional methods for glass cutting, they have several disadvantages.

A tungsten carbide wheel cutter used for cutting glass
A tungsten carbide wheel cutter used for cutting glass

Sharp cutters like a wheel cutter use a cutting wheel with a V-shaped profile made of tungsten carbide or polycrystalline diamond to score glasses.

It creates a fracture line and weakens the glass along the score path. When pressure is applied, the glass will break into two as it has weakened along the path.

While scribing and breaking the glass in such a way, micro-cracks will develop, and the cut will not be perfectly perpendicular to the glass surface.

Fractures along the wrong path will cause material wastage as you will have to redo the whole process again. It will also waste your time, money, and other resources.

Cutting glasses with cutting wheels is only limited to cutting in straight lines. What if you want to create curves and cut out a shape from the inside of the glass?

This is when laser cutting comes in handy. Lasers can cut almost any complex shape with ease.

Laser cutting has found application in glass processing for many decades now, and it has come a long way.

A computer generated illustration of laser cutting glass
A computer-generated illustration of laser cutting glass (Source: Lehigh University)

In most industrial settings, the laser cuts glass by heating and melting up the incidence line and cooling the cut with a cold jet of air or air-liquid mixture.

This results in precise and controlled fissuring in the glass. It also avoids microcracks from developing, and does not need further processing (grinding/polishing).

Though laser cutting is more expensive compared to conventional glass cutting, it has several benefits.

Laser cutting is a clean contactless process that gives a high-quality surface finish with chip-free cut edges.

Among the three main types of lasers (CO2, crystal, and fiber lasers), CO2 is the best choice for cutting glass.

Cutting Glass with CO2 Lasers

CO2 lasers are the popular choice for many consumer and industrial level applications for cutting glasses.

Using a CO2 laser you can minimize material wastage and reduce work time by cutting glass faster and more accurately compared to other lasers.

The CO2 laser's infrared wavelength of 10,600nm is perfect for laser-cutting glass as the energy absorption rate is 80% at this operational wavelength.

Most CO2 lasers use a single-stage controlled fracture technique (laser scribing) to cut through glass.

It does so by melting glass below its transition temperature and cooling it with a coolant nozzle.

This technique cuts the glass surface in conjunction with surface cooling. It is a good technique for cutting thick glasses.

Laser cutting glass using controlled fracture technique (Source: Coherent)

The controlled fracture technique requires less power and can cut with a much higher speed. This technique also gives a good edge strength because of the lack of microcracks.

When glass is cut under a high-temperature environment, the microcracks developed in the process cannot sustain. Instead, they will reform to fill the gaps to give a solid cut surface.

You can cut a 0.14" thick glass at a speed ranging from 43 ipm to 67 ipm using a CO2 laser with power varying from 700 - 1300W.

A 0.02" thick, stained glass can be cut with a 400W CO2 laser at a speed of ~50 ipm by utilizing 100% of the laser power. For an effective cut, you can also use an air assist.

Cutting Glass with UV Lasers

Holes made in soda lime glass with a UV laser
Holes made in soda-lime glass with a UV laser (Source: Spectra-Physics)

The 355nm operational wavelength of a UV laser can be focused at a tight spot (<10 micrometers) to create high intensities required for cutting glass.

With a UV laser, it is possible to cut 0.007" thick borosilicate glass at a speed of ~47.2 ipm. By reducing the thickness further down, you can cut at much higher speeds.

In such lasers, the heat accumulation on glass can be minimized by using a small laser spot size and highspeed beam scanning galvanometer.

UV lasers are primarily used for industrial glass cutting applications, and such glasses are used in many different consumer electronics such as television, smartphones, and more.

Cutting Glass with Short-Pulse Lasers

Comparison of short pulse and long pulse laser cutting (Source: IPG Photonics)

Pulsed lasers operate by sending laser beams at a repetitive pulse rate. As the repetitive rate reduces, more energy can be built between each pulse.

A shot-pulse laser is a good choice for cutting thin glasses. Their operational range is from nanoseconds to femtoseconds.

Such lasers use variations of pulse duration, pulse energy, and pulse frequency to cut different glasses.

It works by creating channels of microcracks from the surface to the back that are developed by the propagated laser beam.

Short pulse laser does not have the problem of creating a recast layer of molten glass and keeps the surface of glass clean from such debris.

They also reduce the thermal shockwave acting on the glass as the cut material vaporizes before even spreading the heat.

So it does not create melt zones along the laser path and prevents the glass from developing microcracks.

By increasing the pulse energy, you can create longer cracks in the glass. However, controlling the depth by adjusting the pulse will be a challenge. In most cases, a rough cut is formed, sometimes requiring polishing.

Challenges in Laser Cutting Glass

High Initial Cost

Though laser cutters provide good cut results, they are comparatively costlier than traditional glass cutting equipment.

The initial investment needed for laser cutters can be limiting.

Need for Expertise

Laser cutters themselves are a piece of precision equipment. It needs a trained operator and good maintenance.

The software programs used to control lasers also have a bit of a learning curve.

Limitations of Lasers

There are a few limitations that you need to be aware of when cutting glass with lasers.

Limitations of continuous-wave lasers in cutting glass

In continuous-wave lasers, the laser beam generates a wide melt zone. As a result, it increases the thermal shockwave acting on the glass and generates microcracks along the cut path.

Due to the thermal shockwave, the heat readily transfers to the surrounding area and forms a recast layer of glass debris.

Continuous-wave lasers also cause damage to the glass surface and leave behind lots of surface debris. Again, this requires post-processing of glass and adds to your expense.

Limitations of CO2 lasers in cutting glass

CO2 lasers with power in the kilowatt range are used for a process called two-stage laser melting and evaporation process. In this process, the laser increases the glass temperature above the transformation temperature of the glass.

This type of glass cutting is viable only for an industrial environment as it requires the glass to be heated and kept in its annealing temperature range of 510 °C - 600 °C.

Limitations of fiber lasers in cutting glass

A fiber laser(Source: Precitec)

A fiber laser will not be able to cut glass as effectively as a CO2 laser does. A Fiber Laser's wavelength is outside the absorption range of glass. Their wavelength ranges from 780 nm to 2200 nm.

This means a fiber laser can etch or engrave on glass surfaces but cannot cut.

Although a ytterbium-doped fiber laser is better at glass cutting compared to the traditional titanium-sapphire fiber laser, a CO2 laser can outperform both.

HyperRapid NXT- Glass Laser Cutter

HyperRapid NXT laser cutter (Source: Coherent)

HyperRapid NXT is an ultrashort pulse laser from Coherent that is available in 1064nm, 532nm, and 355nm. It pulses in the picosecond range with a pulse energy of 250 microjoules.

Its SmartCleave laser cutting technology allows processing glass at high-speed with good quality.

The 100W version of HyperRapid NXT easily cuts brittle materials. For example, it can cut strengthened and unstrengthened glass, sapphire, and ceramics.

HyperRapid NXT can also cut metals, semiconductors, plastics, and organics.

OMTech AF2028-60

OMTech AF2028-60

OMTech AF2028-60 uses a 60W CO2 laser and gives a 20" x 28" work area.

It is a good option for consumer-level applications and small businesses.

OMTech AF2028-60 easily cuts thin glass sheets of 0.05" thickness. On glasses with a thickness of 0.2" and above, this machine marks a fracture line which can then be snapped with a little pressure.

The maximum speed at which the machine can mark is ~1416 ipm. It works on wood, paper, plastics, leather, fabric, stone, and a wide range of other nonmetallic materials.

OMTech AF2028-60
60W CO2 laser with a work area of 20'' x 28''.
Maximum speed of ~1416ipm.

Laser Cutting Services

If you do not have enough expertise with laser cutters and their software or cannot afford a laser machine, it is better to outsource your work to a custom laser cutting service.

Several online and offline laser cutting businesses offer glass cutting and etching. You can search them online or visit some makers workshop near you.

Some of the popular online glass cutting services in the US are:

Final Thoughts

Microscopic view of mechanically cut (left) and laser-cut (right) glass samples (Source: Wiley)

The bottom line is that laser cutters excel in providing a consistent cut quality on glass that a mechanical cut technique fails to provide.

Even though the mechanical technique may look cheap initially, you will have to do extensive post-processing once you cut, which may get expensive.

Laser cutting allows you to precisely cut glass by reducing material wastage and boosting productivity by enabling you to cut shapes of various geometry.

It also reduces the number of processes a sheet of glass undergoes before getting it to the desired final shape. As a result, post-processing and cleaning are required only in some cases.

Though a superior technique, laser cutting could not replace manual cutting completely. This is mainly attributed to the substantial initial investment laser cutters need.

Residual laser light when cutting glass
Residual laser light escaping from the glass that was being cut (Source: Savvas Papasavva - YouTube)

When using a laser for cutting glass, you will have to be extra vigilant as there is a high chance for the laser light to refract and bounce off in different directions.

You must be aware of the laser safety risks, hazards, and control measures before you start working with any laser equipment.

Make sure you only work with lasers by wearing safety glasses and full sleeve dresses. Also, glass pieces can be sharp so handle them with extra care.

Laser cutting has already gone mainstream in cutting curved glass shapes. Such glasses are widely used in many modern gadgets.

Now is an excellent time to catch up with laser cutting glasses as it is an innovative and continuously developing field. A lot of industries currently processing glass are using lasers because of the flexibility it brings.

Laser Cutting and Engraving Other Materials

Following are some detailed guides on laser cutting different materials.

MaterialLink to Guide
PaperLaser Cutting Paper
AcrylicLaser Cutting and Engraving Acrylic
AluminumLaser Cutting and Engraving Aluminum
LeatherLaser Cutting and Engraving Leather
PlasticLaser Cutting and Engraving Plastic
PolypropyleneLaser cutting polypropylene
BrassLaser Engraving Brass
FabricLaser Cutting Fabric
FoamLaser Cutting Foam
PlywoodLaser Cutting Plywood
VinylLaser Cutting Vinyl

Laser Cutting Guides for other Materials

Frequently Asked Questions

Can a laser cut glass?

A laser can cut glass with great precision and minimal material wastage. In addition, lasers can cut glass in many complex shapes without microfractures which otherwise would not be possible.

Can a CO2 laser cut glass?

A CO2 laser can cut glass with great effectiveness. CO2 laser's infrared wavelength of 10,600nm is perfect for cutting glass as it absorbs more laser energy at this wavelength.

Can a fiber laser cut glass?

A fiber laser can cut glass, but it cannot do as good a job as a CO2 laser. This is because the fiber laser's wavelength (780 nm - 2200 nm) is outside the absorption range of glass.

About John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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