Most frequently asked questions for waterjet cutting.

Water jet cutting is the most effective way to cut shapes in metal for the majority of jobs. I guess I’m bias as a water jet cutting provider. Though the water jet cutting machine industry is becoming ever refined, the acceptance of water jet cutting is still growing. We have new customers all the time. They usually have a bundle of questions. Here are just the first five questions we usually get when a customer starts cutting with us.

1). How does water cut metal?

The water is really just the vehicle for the cutting media. Abrasive garnet is mixed with the high pressure water to make the cut.

2). How many pounds of pressure will the machine generate?

The early water jet machines would pump at 30,000 psi. The most common is 60,000 psi but 90K and 120k models are coming out now.

3). How thick can you cut?

The great thing about water jet cutting is that you can cut any thickness. However, the thicker you cut, the slower the machine travels. While it may take one minute to cut a part out in 1/4″ steel, it may take an hour to cut the same part in 3″ steel. For each part, there is a thickness that hits diminishing returns. Often times parts thicker than 1.5″ can be flame cut and machined for the same cost as water jetting.

4). What materials can you cut?

About any material can be cut with water jet cutting. The harder the material is, the better, as long as it’s not brittle. Plastics can do well but if the material is laminated, I don not recommend waterjet cutting. The stream of water will break through the first layer but then while entering the second, the blast will rip the layers apart, delaminating the material. It will end up looking like bad plywood left out in the rain for a year. Sometimes, a trick to eliminate this is to add a long “lead-in”. The lead-in is the cut between the initial pierce of the waterjet and the start of the actual cutting of the feature. A lead-in is used to eliminate any distortion from the pierce and enhance the tolerance of the cut feature. The lead-in is always left in the scrap drop, or the parent plate, not in the part.
Any metal, stone or solid plastic arterial is a fine candidate for waterjet cutting.

5). How fast will the machine travel?

This is a function of three things; the material being cut, the thickness of that material and the quality of kerf quality desired.
The less dense the material, the faster the travel speed is. Aluminum is about 2-3 times faster cutting than steel. Stainless is about 5%-10% slower than steel in the same thickness. If the part will be machined to size and final shape later, then a faster cutting speed can be used, reducing cost. Many times the final part finish remains the waterjet cut shape, so a slower travel speed is used to enhance the cut surface.

I will update with the next set of FAQs’ regarding waterjet cutting soon. I hope this is helpful and I really hope I can bring waterjet cutting into your workflow. Contact me any time for more info or a quote.