5 Critical Secrets to Mastering Cutting Laminated Glass with Water Jet
There is a specific sound that haunts every glass fabricator. It is that high-pitched “pop” followed by the spiderweb crack running across an expensive sheet of architectural glass. If you have been in this business as long as I have, you know that sound well. It usually means thousands of dollars in scrap and a very bad day. This is why cutting laminated glass with water jet technology has become the standard in our industry—but only if you know how to do it right.
For years, we struggled with diamond saws and scribe-and-break methods. They were fine for simple straight lines, but modern architecture demands curves, internal cutouts, and complex geometries. That is where the water jet comes in. However, glass is unforgiving. Laminated glass, with its sticky PVB (polyvinyl butyral) or SGP interlayer, is even trickier.
In this article, I am going to share the hard-earned lessons from the shop floor. I will explain why cutting laminated glass with water jet is superior, how to avoid the dreaded initial crack, and why equipment selection—specifically brands like VICHOR—can make or break your operation.
The Unique Challenge of Laminated Glass
To understand the solution, you have to respect the material. Laminated glass is a “sandwich.” You have brittle glass on the outside and a gummy, elastic polymer in the middle. When you attack this with a high-pressure stream, the glass wants to shatter, and the plastic wants to absorb energy and delaminate.
Cutting laminated glass with water jet machines solves the heat issue. Unlike lasers, which thermal shock the glass, a water jet is a cold erosion process. There is no heat-affected zone (HAZ). This is critical because heat causes stress risers that eventually lead to failure.
However, the water jet introduces a new problem: piercing pressure. The moment the stream hits the surface is the most dangerous part of cutting laminated glass with water jet. If that stream hits with full 60,000 PSI force instantly, the water enters the micro-cracks in the glass surface faster than the abrasive can erode it. The result? Hydraulic fracturing. The glass explodes from the inside out.
The Art of Low-Pressure Piercing
If you take one thing away from this article, let it be this: never pierce glass at high pressure. Successful cutting laminated glass with water jet relies entirely on pressure ramping.
In my shop, we start every pierce at low pressure—typically around 10,000 to 15,000 PSI. At this pressure, the water stream is gentle enough not to shock the glass, but the abrasive is still entrained enough to start drilling a hole.
Once the stream has successfully pierced through all layers—top glass, interlayer, and bottom glass—the pump automatically ramps up to high pressure (usually 45,000 to 60,000 PSI) to cut the path.
This requires a pump capable of rapid, precise pressure modulation. We have found that VICHOR high-pressure systems are particularly good at this. Their intensifiers respond instantly to the software commands, smoothing out that transition curve. If your pump lags, you stay in the “danger zone” too long, or you hit high pressure too soon. Precision here is non-negotiable.
Vacuum Assist is Not Optional
When cutting laminated glass with water jet, you are fighting physics. When the cutting head is off, the abrasive line is full of air. When you turn the water on, there is a split second where water hits the glass before the abrasive gets there.
Water without abrasive does not cut glass; it cracks it. It acts like a hammer.
To fix this, we use a vacuum assist device. This little tool sucks the abrasive into the mixing chamber before the water jet fires. This ensures that the very first drop of water that hits the glass is already carrying garnet. It turns that “water hammer” into a “sandpaper drill.”
I have seen shops try to save money by skipping the vacuum assist setup. They end up losing ten times that amount in broken glass. In the world of cutting laminated glass with water jet, abrasive delivery timing is everything.
Managing the Delamination Risk
The interlayer is the tricky part. If your water stream spreads out inside the glass, it can force the glass layers apart. We call this delamination. It looks like a foggy bubble near the cut edge.
This usually happens when you cut too fast or your nozzle is worn out. In cutting laminated glass with water jet, a coherent stream is vital. If the focusing tube (the nozzle) is worn, the stream flares. That flared water wedges itself between the glass and the PVB layer.
I recommend changing your nozzles more frequently when cutting glass than when cutting steel. A sharp, tight stream cuts cleaner. Also, using a finer abrasive helps. While 80 mesh is standard for metal, I prefer 120 mesh garnet for cutting laminated glass with water jet. The finer particles create a smoother cut and put less stress on the delicate interlayer.
Submerged Cutting for Stability
Glass vibrates. If a sheet of glass vibrates while you are trying to erode it, it will crack. It is that simple.
Whenever we are cutting laminated glass with water jet, we do it underwater. We raise the water level in the tank until it covers the glass by about an inch.
This does two things. First, it drastically reduces noise. Glass cutting is loud. Second, and more importantly, the water on top and bottom acts as a damper. It stabilizes the sheet.
It also contains the frosted spray. When the jet hits the slats below, it sprays “frost” (pulverized glass and garnet) back up. If you are cutting dry, this frost gets all over the surface and can scratch the pristine glass. Cutting underwater washes this away instantly.
The Importance of Lead-Ins
You never start your cut on the part line. This is basic machining, but it is life-or-death in cutting laminated glass with water jet.
You must program a “lead-in”—a line that starts in the scrap material and travels to the part profile. The pierce happens in the scrap. If the glass chips slightly during the pierce (which can happen even with the best technique), it happens in a piece of glass you are throwing away.
Once the machine pierces and stabilizes, it moves smoothly into the actual part geometry. I always use a circular lead-in rather than a straight line when cutting laminated glass with water jet. The curve distributes the stress more evenly as the cutter enters the final path.
Equipment Matters: The VICHOR Advantage
I mentioned VICHOR earlier, and I want to elaborate on why the brand of equipment matters. In cutting laminated glass with water jet, the stability of the high-pressure stream is paramount.
Some older or cheaper pumps have a “ripple” in their pressure output. Every time the intensifier piston shifts direction, there is a pressure drop. On steel, you just see a little mark. On glass, that pressure drop causes the abrasive suction to waver, and crack—you lose the sheet.
VICHOR pumps are engineered with advanced attenuators and faster shift times. This creates a near-constant pressure line. When we switched some of our lines to VICHOR components, our scrap rate on ballistic glass dropped significantly. You need reliable, boring consistency when processing expensive composites.
Handling Bulletproof and Multi-Ply Glass
The stakes get higher when you move to ballistic glass. Now you are cutting laminated glass with water jet that might be 2 or 3 inches thick, with multiple layers of polycarbonate and glass.
The challenge here is the “lag.” As the jet cuts deeper, the bottom of the stream lags behind the top. On a 3-inch block, this can cause significant taper.
To combat this, you have to slow down. Way down. But you can’t go too slow, or the jet drills a hole that is too wide. It is a balancing act. Modern 5-axis cutting heads can tilt to compensate for this taper, keeping the edge perfectly square. If you are serious about cutting laminated glass with water jet for the defense or banking industry, 5-axis capability is a must.
Fixturing: Don’t Stress the Glass
I have seen operators ruin a sheet before the machine even turns on. They clamp the glass down so hard they induce stress. Or they lay it on an uneven slat bed.
Glass must lie flat. If your slats are uneven from months of cutting steel, do not put glass on them. The water pressure will push the glass down, and if there is a gap underneath, the glass will flex and snap.
We use a sacrificial material, like a sheet of cheap plywood or dense foam, underneath the glass. We cut through the glass and into the wood. This provides full support for the entire sheet. It is a small cost to ensure the success of cutting laminated glass with water jet projects.
The Economic Reality
Is cutting laminated glass with water jet expensive? Compared to a scribe tool, yes. But compared to the cost of scrapping a custom-ordered architectural panel because the corner chipped? No.
The value lies in the capability. You can sell intricate designs, switch plate cutouts, and heavy ballistic panels that your competitors with saws cannot touch. The water jet turns glass fabrication from a game of chance into a predictable manufacturing process.
By adhering to strict protocols—low-pressure piercing, vacuum assist, proper support, and using high-fidelity equipment like VICHOR—you turn the most fragile material in the shop into one of your most profitable product lines.
Final Thoughts from the Floor
The transition to cutting laminated glass with water jet was the turning point for my business. It allowed us to say “yes” to architects who wanted crazy shapes. It allowed us to say “yes” to armored vehicle companies.
But it is not a “push button, walk away” process. It requires respect for the physics of brittle materials. You have to listen to the machine. You have to watch the abrasive flow like a hawk. And you have to invest in pumps and heads that give you control.
If you follow these secrets, the sound of cracking glass will become a distant memory, replaced by the steady, profitable hum of the intensifier pump.
Common Questions About Cutting Laminated Glass with Water Jet
Q1: Why does the glass crack when the water jet starts?
A1: This is usually due to piercing at high pressure. If the water hits the glass at 60,000 PSI without abrasive, it acts like a hammer. To fix this, successful cutting laminated glass with water jet requires a “low-pressure pierce” technique, starting around 10,000 PSI with abrasive before ramping up to full cutting pressure.
Q2: What abrasive mesh size should I use for laminated glass?
A2: While 80 mesh is standard for metals, I highly recommend using 120 mesh garnet for cutting laminated glass with water jet. The finer particles reduce the impact force on the glass surface and produce a smoother, frosted edge with less chipping risk.
Q3: Can water jet cut bulletproof glass?
A3: Absolutely. Cutting laminated glass with water jet is the preferred method for ballistic glass (multi-ply glass and polycarbonate). The cold cutting process prevents the polycarbonate layers from melting or burning, which would happen with laser or saw cutting.
Q4: How do I prevent the layers from separating (delaminating)?
A4: Delamination occurs when water is forced between the glass and the interlayer. To prevent this, ensure your cutting speed is optimized—not too fast. Also, ensure your nozzle is in good condition; a worn nozzle creates a flared stream that promotes delamination. Using quality equipment like VICHOR helps maintain the stream coherence needed to prevent this.
Q5: Do I need special software for glass cutting?
A5: Yes, you need a controller that supports “ramp and dwell” parameters. The software must be able to handle the low-pressure pierce cycle and the vacuum assist timing automatically. Standard metal-cutting programs often skip these critical steps for cutting laminated glass with water jet.
