Waterjet Tips

Hopefully you will find that reading through these tips provides you with more insight into the process. Some of the tips are obvious, while others are only seen through experience.

1. Cutting Thick Material

When cutting under 0.100 inch thick material little is gained by using medium (50 HP) or large (60 to 80 HP) cutting heads. Use a small parameter combination (25HP) and consider multiple head to increase production if needed.

2. Cutting Through Air Gaps
Avoid cutting through air gaps greater than 0.020″. The jet tends to open up in the gap and cut the lower layer roughly. When stack cutting, keep the sheets together.

3. Smaller Abrasive Grains
Smaller abrasive grains (120 mesh or smaller) will produce a slightly slower speed but slightly smoother surface (as compared to 80 or 50 mesh).

4. Productivity Is Cost Per Inch
Productivity is cost per inch, not cost per hour. It matters very little how much it costs per hour to run an abrasive waterjet. What matters is how many parts you get off in a given length of time. Some users make the mistake of trying to reduce operating cost by minimizing the abrasive flow rate. Even though abrasive is 2/3 of the abrasive waterjet operating cost, you must produce parts quickly to consume your overhead (labor, facilities, lease payment). Cut as fast as possible, using all available horsepower and the peak abrasive flow rate.

5. Water Pressure Lowered And Raised By The Controller
If you intend to pierce composites, glass, and stone on a regular basis, ensure the system has the ability to have the water pressure lowered and raised by the controller. Also, you should investigate vacuum assist or other techniques to improve probability of successfully piercing these brittle or laminated materials.

6. Control Systems Specifically Designed For A Process
Control systems specifically designed for a process are typically more efficient and easier to use than generic multi-process controls.

7. Material Handling Automation
Most machines do not employ material handling automation, such as shuttles. Only when material handling constitutes a significant portion of part production cost should automation be considered. 90% of all Abrasive waterjet machines are loaded and unloaded either by hand or with the aid of simple overhead cranes, jib cranes, or fork lifts.

8. Ordinary Tap Water
Ordinary tap water is used to feed the waterjet systems. 90% of all waterjet and abrasive waterjet users require only water softening prior to sending that water through the pump’s inlet water filters and then to the intensifier. Reverse Osmosis (RO) and De- Ionizers tend to make the water so pure that it becomes “ion starved.” This aggressive water seeks to satisfy its’ ion starvation by taking ions from surrounding materials, such as the metals in the pump and high-pressure plumbing lines. RO and De-I can greatly extend orifice life, while simultaneously performing very expensive damage to the intensifier and plumbing. Orifices are rather inexpensive. High-pressure cylinders, check valves, and end cap damage will far outweigh orifice life improvements.

9. Cutting Underwater
Cutting underwater reduces surface frosting or ‘hazing’ found on the top edge of an abrasive waterjet cut. Cutting underwater also greatly reduces jet noise and workplace mess. The only negative is that operators cannot see the jet clearly during cutting. If the operator objects to underwater cutting, consider electronic performance monitoring. These monitors will detect deviation from peak cutting performance and stop the system prior to part damage.

10. Different Abrasive Mesh Sizes
If you plan on using different abrasive mesh sizes for different jobs, consider adding a small (100 pound) or large (500 to 2,000 pound) bulk transfer. Without having a bulk transfer hopper for each mesh size you regularly run, you may produce downtime and nuisance along with your production.

11. Break Out Tabs
Break out tabs can prove effective for cutting of materials under 0.3 inch thick. Although break out tabs generally guarantee you’ll need a secondary operation of grinding off the tabs, their usage allows material handling to be performed faster – simply unload a cut sheet with the cut parts still in tact. The harder the material, the smaller the break out tab should be. Consult your manufacturer for detailed suggestions.