Introduction:

Waterjet cutting is an extremely versatile and precise cutting method that utilizes a high-pressure stream of water mixed with abrasive particles to cut through virtually any material. Waterjet machines provide many advantages over traditional cutting methods like laser or plasma cutting, making them popular for industries like manufacturing, aerospace, military, automotive, and more. This article will provide a comprehensive overview of waterjet cutting technology, how waterjet machines work, their capabilities and limitations, as well as tips for choosing the right waterjet cutting machine for your needs.

How Waterjet Cutting Works:

Waterjet cutting utilizes the power of water to slice through materials. The process starts by pumping water at an extremely high pressure, usually over 50,000 psi, through a series of small diameter tubes and water preparation equipment. The high-pressure water is then forced through a tiny hole in the cutting head, creating a thin, supersonic stream. As this water jet exits the orifice, abrasive particles like garnet or silicon carbide are introduced and mixed into the stream. This abrasive-laced water jet is then directed toward the material being cut. The high-velocity stream quickly erodes the material, essentially grinding it away via abrasion from the particulate. The water jet can cut rapidly and precisely, all while producing no heat affected zone (HAZ) on the material.

Benefits and Advantages of Waterjet Cutting:

- Cuts virtually any material - metals, stone, glass, composites, rubber, foam, food, etc.

- No heat affected zone means no structural damage or warping

- Extremely precise, clean cuts with tight tolerances

- Rapid cutting speeds, especially for softer materials

- Minimal waste and scrap material

- Versatile - can produce straight cuts, bevels, perforations, 3D shapes

- Environmentally clean process with no toxic fumes

Waterjet Machine Components:

Waterjet cutting systems consist of several main components:

- High pressure pump - generates the required water pressure for cutting

- Abrasive hopper and metering system - stores and regulates abrasive flow

- Mixing tube - mixes water and abrasive into continuous jet stream

- Cutting head with orifice - directs jet stream toward work material

- Multi-axis machine motion system - moves jet stream along cutting path

- Catcher tank - collects used water and abrasive material

- Water recycling system - filters and reuses water

Water flows through an intricate high pressure circuit before being forced through the tiny cutting nozzle at pressures from 30,000 to over 90,000 psi. The abrasive is metered into the jet stream via a precisely regulated system. The mixed water and abrasive jet accelerates to over twice the speed of sound as it exits the cutting head. This supersonic jet stream can cut rapidly and accurately along a programmed path.

Waterjet Machine Capabilities:

Waterjets can cut material thicknesses ranging from delicate paper to 12+ inches of stainless steel. Ideal applications include:

- Metal fabrications - steel, aluminum, copper, brass

- Stone and tile

- Glass, composites, laminates

- Gaskets, seals, insulation, foam

- Food products - fruits, vegetables, meat

- Automotive and aerospace components

- Military and prototype parts

- Arts, crafts, jewelry

- Signs, displays

Waterjet machines can produce straight cuts, beveled edges, polished finished, perforations, etching, and shaped profiles. Complex 3D shapes can be cut out of solid blocks of material or sheet stock. Tolerances down to 0.005 inches are possible. Cutting speeds vary based on material, thickness, and desired edge quality. Softer materials like gaskets can be cut at over 100 inches per minute while harder metals like stainless steel require slower feed rates around 10 ipm.

Cutting Head Configurations:

Waterjet machines come with several different cutting head configurations:

- Standard single cutting head - can only cut one material type and thickness at a time

- Dual cutting heads - allows for fast switching between two materials or thicknesses

- Dynamic Waterjet - special cutting head with two adjustable orifices that can dynamically vary the waterjet stream during cutting without needing to stop. This allows cutting of mixed material stacks.

- Multiple cutting heads - some larger systems have multiple cutting heads for production cutting of higher volumes

Waterjet Abrasives:

The most common abrasives used for waterjet cutting include:

- Garnet - hard almandine mineral, high cutting speed but more expensive

- Silicon carbide - sharp, hard synthetic material, lower cost

- Olivine - natural sand abrasive, higher density for better cutting power

- Aluminum oxide - synthetic mineral, moderately priced

- Glass beads - rounded softer abrasive for delicate cutting

The type of abrasive, its size, flow rate, and mixing ratio with the water all significantly impact the cutting effectiveness and edge quality. Garnet and silicon carbide tend to provide the best all around performance.

Water Quality Requirements:  

Because the high pressure water is the driving force behind waterjet cutting, maintaining proper water quality is crucial. Most waterjet machines require water filtration down to 5 microns to protect the pump and prevent nozzle clogging. Deionized water is ideal since it prevents scale buildup and corrosion inside the pump. Chlorinated tap water can damage components over time. A reverse osmosis filtration system is commonly used to purify water for waterjet cutting systems.

Positioning Accuracy and Precision:

Waterjet machines can maintain positioning accuracy to within 0.005 inch thanks to rigid frames, high precision linear motion guides, and software calibration. Precision ball screws, servo motors, and glass scale encoders enable both high speed and very fine controlled motion. Cutting tolerances down to +/- 0.001 inches are possible on thinner materials. The software controls and motion compensation algorithms also account for abrasive taper and lag for improved precision.

Conclusion:

Waterjet cutting provides fast, extremely precise, versatile cutting and machining capabilities for virtually any material while introducing no heat or structural damage. Waterjet machines are a highly effective yet economical solution for manufacturing, fabrication, art, prototyping, and other applications where flexibility, precision, and speed are paramount. This guide covers the key aspects of waterjet technology and components to consider when choosing a waterjet cutting system for your needs.