How to Design a Water jet Cutter

It is VERY simple:

you rise the water pressure to 2000 bar and let the jet flow via a nozzle.

Basically it is all.

You might want to add a CNC gantry similar to the open source mechmate.com design and significant pump control, a 'water basin' to shoot 'into' below your material.

Some water jet systems also do significant filtration before re-pumping/pressurizing of the water then add 'grit' to it to help the 'beam' be more abrasive.

"who to design a water jet for cutting operations"? A water jet system designer.

If you meant, HOW to design a water jet for cutting operations, get a really big pump and some really hard orifices. And, use abrasive materials to enhance the cutting effectiveness.

The best water-jet cutting machine designers work in the Pacific Northwest in smaller city called Woodinville Washington for DSI a division of John Bean Technologies.

Water-jet cutting is simple only in concept; like most specialties, wjc employs advanced technologies, fairly sophisticated machinery, and very specific techniques relative to the materials processed and desired work output. I worked along-side the design team at DSI in Redmond, Washington for many years (at their parent company FMC FoodTech) and believe DSI's engineering team is unsurpassed in most every metric in the "water-jet cutting / vission-scanning" wjc sector. Their DSI portioner line incorporates visual technologies with "medium-pressure" water jet technologies to cut all types of food products according to user-defined criteria to acheive extremely precise weight portions, product profiles and combinations of both. Most of the major quick-serve-industries have DSI portioners on both their ready to eat and ready to cook production lines. Even if your interest is other than the food processing industries, you might consider calling them directly as, second to equipment designers, they are great at R&D and extremely knowledgeable about the global wjc industries. Fascinating equipment with broad applications. Good luck with your research.

They must be easy to make. My old boss made one for cutting fabric. It was a 4ft x 8ft table. The system worked like a giant plotter. It used cad *.plt command files and cut out the shapes need. It had a high pressure pump with a plastic flex line which looped high above the table and back down to ruby tipped discharge nozzle that moved on a 2 axis gantry about 6 inches above the table. Table was made with tall thin criss-cross pattern metal weave. Worked very well for a lot of years. If you want to cut something serious like steel you need a serious pump and some dangerous pressures. Be Careful.