So when a machine is referred to as a “2 ft by 4 ft (0.6 x 1.2 m)” machine, that is not the total size of the machine, but the size of the bed. Typically, machines are made to accommodate standard material sizes to simplify loading.
Waterjets are machine shop tools and even a “small” machine requires industrial levels of power and water supply not found in a home workshop.
For “off-the-shelf” machines, there are basically three sizes:
Some machine shops will have a single small machine to supplement the other machine tools they use. Other shops, with more waterjet work, will have several medium machines, while a dedicated waterjet shop might have several small machines, one medium sized one, and one large waterjet running multiple nozzles.
Custom machines are built and designed for specific purposes. In some cases, they are built into a production line, so that the material is constantly moving past them as they cut.
Custom machines are used for diaper cutting, food cutting, cutting automotive carpet, mining applications, eye surgery, and cardboard box making (if the material moves quickly enough it doesn’t have time to get wet).
Are big waterjets faster than small waterjets?
It seems like a large waterjet machine should be faster than a small waterjet, since that’s the case in many other areas. But just as a sports car can be faster than a dump truck, that’s not always the case with waterjets.
With larger machines, you can run multiple nozzles at one time. Since the nozzles need to move together, this is typically used for larger production runs, but it will be much faster than a smaller machine with a single nozzle making the same part.
You can also load larger pieces of material into big waterjets. Time spent loading and unloading material is time not spent making parts. If you can reduce the amount of time (per part) spent loading and unloading material, you can make each part more quickly.
On the other hand, with larger machines, the plumbing between the pump and the nozzle tends to be longer and more complex, resulting in pressure loss. While the pressure might be 60,000 PSI (4,100 bar) at the pump, it may only be 55,000 PSI (3,800 bar) at the nozzle. This pressure loss means that the pump must either work harder to produce more pressure at the nozzle (and use more energy and increase maintenance), or the cutting must be slowed down to compensate.
Small machines have shorter plumbing runs and lose less pressure.
Small waterjet machines are smaller than 2 x 4 feet (0.6 x 1.2 m) in size and are typically they are used in general machine shops. They are also popular in EDM shops, schools, and other places where a multipurpose machining tool is handy.
If you are looking at a first machine to purchase, these are great choices because they don’t cost much and there is little risk in purchasing one. The waterjet can pay for itself if you keep it busy as little as a half day per week.
- The initial payment on machine is low, so the machine doesn’t have to spend as much time working to pay for itself. There is a low risk to purchase.
- For price of some of the big machines, you may be able to buy two small machines, and double your productivity.
- The small size makes them convenient for secondary machining. Ergonomically, they are simply more fun to use.
- Small footprint does not take up a lot of shop space.
- Easy to move around as your shop flooring arrangement changes.
- Easier than larger machines to setup and install.
- Generally offer higher precision than their larger cousins.
- In some cases, smaller machines can offer faster cutting, because shorter plumbing lengths reduce pressure loss between the nozzle and the pump.
- Small cutting area, although on some machines you can feed larger stock into the machine.
Complete systems can be had for less than $80,000. A complete system is everything you need to get a new machine and have it running including the pump, XY table, nozzles, abrasive delivery system, controller, software, installation, and training.
While at first this may seem like a lot of money for a machine tool, keep in mind that small machines can quickly pay for themselves. Waterjets bring in more revenue per hour than traditional tools and can pay for themselves quickly.
Medium-sized waterjet systems range from 4 x 4 feet to 4 x 8 feet (1.2 x 1.2 m to 1.2 x 2.4 m) in size. Sometimes they are used with multiple cutting heads, although multiple heads usually work better with larger machines. These are typically purchased by machine shops who do larger work, or simply want a machine that is large enough that they can fit big sheets of material to reduce the time spent loading and unloading material.
- Fit larger sized sheets of material into the machine. Not only does this allow for larger pieces, it also lets the operator cut more pieces before having to change the material.
- Smaller footprint relative to a larger machine means less space used.
- Easier than the giants to setup and install.
- More expensive than smaller machines. Sometimes you may be better off with multiple smaller machines.
- More difficult to load and unload materials, because material sheets can be larger.
- Awkward to use for secondary operations due to their large size.
Complete systems are available for around $100,000 to $200,000, depending on options. A complete system is everything you need to get a new machine and have it running including the pump, XY table, nozzles, abrasive delivery system, controller, software, installation, and training.
Large machines can fit material that is 8 x 16 feet (2 x 4 meters), or larger in their beds. They typically run multiple cutting heads, and are used in high production environments. Large waterjet-only job shops and laser shops are typical buyers of such machines.
A large waterjet machine (shown on the manufacturing floor)
- Fit huge sheets of material into the machine
- Run multiple cutting heads at once
- Large material size means more parts per sheet, which translates into less time changing material per part
- Large initial cost
- More difficult to load and unload materials because of their size
- Awkward to use “as a machine tool” for secondary operations
- Large enough to require specialized shipping and installation in most cases
- Need to have a lot of work to pay for the machine.
- The tolerances on such big machines can be lower than other waterjet machines low (but this is not always the case)
- More expensive to own and operate
- Pressure loss in long length of plumbing between pump and nozzle can result in less efficient cutting (higher costs for lower cutting speeds.)
Complete systems are available for around $200,000 to $400,000, depending on options. A complete system is everything you need to get a new machine and have it running including the pump, XY table, nozzles, abrasive delivery system, controller, software, installation, and training.
Choosing a pump
Tank and table size