In this article, we would like to introduce the water jet cutting machine process, from the fundamental principles to the step-by-step operation.

The Core Principle: Erosion, Powered by Pressure

At its simplest, a waterjet cutter is a tool that uses the power of extreme pressure to erode a narrow line in a material. Think of it as a super-powered, ultra-precise version of using a garden hose to cut a groove in soft sand—but on an industrial scale.

This process is achieved in two main ways, leading to the two primary types of waterjet cutting:

1. Pure Waterjet Cutting: Uses only a stream of pure water. Ideal for soft materials like foam, rubber, food, and gaskets.

2. Abrasive Waterjet Cutting: Mixes an abrasive garnet sand into the water stream. This turns the water into a “liquid saw” capable of cutting hard materials like metal, stone, glass, and ceramics.

The following flowchart illustrates the complete journey of water through an abrasive waterjet system, which is the most common type for industrial applications.

 

Step-by-Step Breakdown of the Abrasive Waterjet Cutting Process

Let’s walk through the journey of water and abrasive, corresponding to the flowchart above.

Step 1: Pressurization (The Heart of the System)

• Input: Ordinary tap water is fed into the system through a filter to remove impurities.

• The Pump: This is the most critical component. The water is pressurized by either an Intensifier Pump or a Direct Drive (Crankshaft) Pump.

  • An Intensifier Pump (the most common type for high-power applications) uses hydraulic power to push a piston, amplifying water pressure to extreme levels, typically 60,000 to 90,000 PSI (4,000 to 6,200 Bar).

  • The ultra-high-pressure water is then delivered to the cutting head through specially designed high-pressure tubing.

Step 2: Stream Formation (Transforming Pressure into Speed)

• The Orifice: At the cutting head, the high-pressure water is forced through a tiny gemstone nozzle, usually made of sapphire or ruby. This orifice, typically between 0.004″ to 0.015″ (0.10 to 0.38 mm) in diameter, transforms the high-pressure water into a coherent, supersonic stream traveling at up to Mach 3 (over 2,000 mph / 3,200 km/h).

Step 3: Abrasive Mixing (Creating the “Liquid Saw”)

• Abrasive Introduction: In the mixing chamber (located just below the orifice), the ultra-fast water stream creates a powerful vacuum. This vacuum draws in a precisely measured flow of hard, granular abrasive (typically garnet) from the abrasive hopper via a feed line.

• Momentum Transfer: The water stream accelerates the abrasive particles, transferring its kinetic energy to them. The abrasive particles become the actual “teeth” of the cutting tool, while the water primarily serves as the accelerating vehicle.

Step 4: Focused Cutting (The Point of Erosion)

• The Focusing Tube: The mixture of water and abrasive then travels through a narrow, elongated tube called a focusing tube or kerf. This tube, made of a very hard material like tungsten carbide, collimates the stream, keeping it coherent and focused for a precise cut.

• The Cutting Action: This focused stream of abrasive particles is directed onto the material. The cutting occurs through microscopic erosion. Each tiny abrasive particle chips away a minuscule piece of the material. The stream moves along a CNC-guided path, “eroding” the desired shape with exceptional accuracy. The cutting head is typically mounted on a gantry system that allows for movement along the X and Y axes, while an automated Z-axis controls the height for optimal cut quality.

Step 5: Material Removal and Waste Management

• The Cut Path (Kerf): The stream cuts a narrow path called a kerf. The width of the kerf is determined by the focusing tube diameter, typically ranging from 0.020″ to 0.050″ (0.5 to 1.3 mm).

• Slurry: The spent water, used abrasive, and microscopic particles of the cut material (called “slag”) exit the bottom of the workpiece as waste slurry. This slurry falls into a catch tank or water basin below the cutting table.

• Slurry Management: The slurry is usually pumped into a settling tank or a separation system where the water is filtered and can often be recycled, and the solid waste is collected for disposal.

 

Key Advantages of Waterjet Cutting Process

• Cold Cutting: No heat is generated, so there is no Heat-Affected Zone (HAZ), preventing warping, hardening, or altering the material’s intrinsic properties.

• Omni-Capable: Can cut virtually any material by simply adjusting pressure and abrasive feed rate.

• High Precision: CNC control allows for intricate shapes and tight tolerances (±0.003″ / 0.08 mm is common).

• No Tool Changes: The “tool” is a stream of water and abrasive, so it never gets dull. You can switch from cutting titanium to foam by stopping the abrasive flow, without any physical tool change.

• Environmentally Friendly: The process produces no hazardous fumes or gases.  The primary waste (garnet and material dust) is inert and can be responsibly disposed of.

 

Practical Considerations of Waterjet Cutting Process

• Cutting Speed: Thicker and harder materials require slower cutting speeds. Waterjet is generally slower than laser cutting on thin metals but faster than wire EDM and unmatched in extreme thicknesses.

• Taper: A slight V-shaped taper can occur on the cut edge, with the top of the cut being slightly wider than the bottom. Modern CNC systems can use “Taper Compensation” software to tilt the head slightly and produce perfectly straight edges.

• Noise: Waterjet cutting is a loud process, often requiring operators to wear hearing protection.

This detailed process is what makes waterjet one of the most versatile and valuable tools in modern manufacturing.

 

 

 

 

Many manufacturers are increasingly adopting CNC waterjet cutting technology because it solves specific challenges posed by other cutting methods.

• Versatility and Flexibility: A single waterjet machine can process an enormous range of materials, from titanium and tool steel to delicate stone, glass, and foam. This eliminates the need for multiple dedicated machines for different materials.

• Preserves Material Integrity: As a cold-cutting process, waterjet produces no heat-affected zone (HAZ). This is critical for materials that would warp, melt, or have their structural properties weakened by heat, ensuring the original strength and quality of the material are maintained.

• Reduces Post-Processing and Waste: Waterjet cutting typically delivers a satin-smooth edge quality that requires little to no secondary finishing, saving time and labor costs. The narrow kerf (width of the cut) also minimizes material waste, which is both cost-effective and environmentally friendly.

• Capability with Extreme Thicknesses: While lasers are limited to relatively thin materials, waterjets can easily cut through very thick plates (exceeding 10 inches in some cases) that other thermal processes cannot handle.

 

Blow table introduce so different features of waterjett cutting machine, laser cutting and mechanical cutting process:

 

💎 How to Choose the Right Cutting Manufacturing Process

The best CNC cutting method depends entirely on your project’s specific needs. Here is a simple guide:

• Choose Waterjet Cutting if: You are working with a wide variety of materials, especially thick metals, stone, glass, or composites. It is essential when you cannot compromise the material’s structure with heat and need high accuracy on thick parts.

• Choose Laser Cutting if: Your primary work is with thinner metals and plastics, and speed is a critical factor. It is ideal for high-volume production of parts where extreme precision on intricate designs is required.

• Choose Mechanical Cutting if: Your operations involve more traditional machining (drilling, milling) or you are working with materials and budgets where CNC machining or die-cutting is the most cost-effective solution.

💎 How to Pick the Right Waterjet Cutting Machines According to Your Applications

Waterjet cutting is an incredibly versatile technology that can handle a vast range of materials, from the hardest metals to the most delicate food products. Its ability to cut without heat or mechanical stress makes it the preferred choice for applications where material integrity is critical.

The table below summarizes the common applications of waterjet cutting across different material categories.

 

 

💡 Why These Applications Benefit from Waterjet Cutting Process

The widespread use of waterjet cutting across these diverse fields is due to several key advantages that address the limitations of traditional cutting methods:

• No Heat-Affected Zone (HAZ): Unlike laser or plasma cutting, waterjet is a cold-cutting process. This means it does not generate heat that can alter the material’s properties, cause hardening, or lead to warping and distortion. This is crucial for metals where structural integrity is paramount and for materials like plastics that can melt.

• Exceptional Versatility: A single waterjet machine can cut almost any material. A workshop can switch from cutting a 6-inch thick titanium plate to a delicate granite mosaic or a soft foam gasket without needing to change the tooling, dramatically increasing operational flexibility.

• High Precision and Complex Designs: With CNC control, waterjets can produce highly intricate and complex shapes with great accuracy. The narrow stream of water (or abrasive slurry) allows for tight tolerances and minimal material waste, which is essential for detailed architectural features and precision engine components.

• Minimal Mechanical Stress: Waterjet cutting exerts very little force on the material. This is particularly important for brittle materials like glass, granite, and ceramics, which are prone to cracking under the pressure exerted by traditional blade cutters.

 

🔍 How to Choose the Right Cutting Process Application for Your Needs

When considering waterjet cutting for a specific project, the decision often comes down to the unique requirements of the material and the final part.

• For metals and hard materials: The primary advantage is the elimination of heat distortion. If you are working with heat-treated aluminum, stainless steel, or titanium where the material properties must not be compromised, waterjet is an excellent choice.

• For brittle materials like glass and stone: The key benefit is preventing cracks and chips. If you need intricate designs in glass or precise cuts in expensive stone slabs with no secondary finishing, waterjet technology is ideal.

• For soft or delicate materials: The ability to cut without crushing or fraying is critical. For materials like foam, rubber, food, and textiles, the pure waterjet method (without abrasive) provides a clean, sanitized cut that other methods cannot match.

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