Should the cutting tank be separate from the Gantry Motion System?

Some waterjet machines are built so the tank is separate from the gantry motion drive system, and some are attached. WARDJet builds both styles of machines. It is possible to order the Z-Series machines with the tank separate or attached to the motion system. All R-Series machines are automatically separate as the smallest R-Series unit starts at 12" x 13" cutting envelope, so we ship the tank separate.

Tank Attached

Gantry Seperate From Tank

Competitors of WARDJet will often incorrectly, and clearly unaware of the machines we build, accuse WARDJet of only building systems with the gantry motion system attached to the tank. Regardless of this error, let's talk about why we would offer the Z-Series machines with the tank attached. We clearly did not do this by mistake and have a very good reason for our actions.

Accusation

You do not want to purchase a WARDJet machine where they build the gantry system attached (not true as you can specify to have it separate) to the tank because you will have the following issues:

• Vibration and resonance generated in the cutting process will be transferred to the side beams, up through the risers into the cross beam, back down into the Z carriage and into the cutting head, reducing the quality of your cut.

Comment on WARDJet and other waterjet manufacturers

General response

So if you are told to be aware that vibration and resonance are an issue, what the person pointing this out is saying, is that this is an issue with their machine, and they have addressed it by separating the tank from the motion system. Right? Think about this one more time, vibration and resonance IS A PROBLEM with their machine and they sorted it out by separating the tank. So if they have this issue, we do need to look at the effect this has on quality cutting of parts on their vibrating, resonating tanks - even if they are separate! This is like telling you, hey, we have a problem and we have not solved it in the tank. We just separated the problem from the gantry. Our tank still has this issue and parts cut on the grates will still have this problem. Yup. This is a strong self inditement of a flawed design.

Other waterjet manufacturers

• All the comments above are certainly issues that could be true. In fact, there are machines being sold where this is of major concern. There are definitely waterjet manufacturers who have not addressed these points as we have. Make sure you identify them and remove them from your list of potential suppliers. Now let's see how WARDJet have solved these issues.

'Other Manufacturers' Point Loads	'Other Manufacturers' tanks may be OPEN
'Other Manufacturers' Point Loads	'Other Manufacturers' Point Loads
Typical WARDJet Tank sits flat with the load evenly spread across the floor. The tank is reinforced with 1/4" steel. The simple installation process of the tank will compensate for uneven floors or if your floor is not level.

WARDJet's RESOLUTION

• Vibration and Resonance: We are well aware of the occurrence of vibration and resonance especially when multiple cutting heads are used simultaneously and even more prevalent when the water level is below the grate support. The more air the waterjet stream passes through, the more the turbulence in the water tank. This translates into vibration and resonance. I have personally seen the front wall of a typical water tank shake so much that it was literally moving.

So with this knowledge in hand, WARDJet wanted to do everything possible to address this issue, rather than just avoid it by separating the tank. Clearly, if the tank vibrates, the grate or slats in the tank holding and supporting your material will shake around. Forget being attached to the gantry – you now have a major issue. Your part is shaking like crazy! This will result in slower cutting speeds, lower quality cuts and loss in tolerance.

WARDJet then proceeded to design a tank that was as resistant to all negative characteristics where possible.

• We started by using heavy ¼" steel plate throughout.


• We then shaped the front and back of the tank, formed to resist any lateral deflection. It is also comfortable to stand at and good for your back. It also takes a beating and a huge load if you are dragging material over it.


• We then beefed up the inside of the front and back walls with a 6" x 2" x ¼" channel box-welded on the lower section of the tank. The front and back channels are then connected to each other with a 6" x ½" plate.


• We then weld a 3" x 2" x ¼" angle on the bend - adding more stiffness.

• The side of the tank has two 6" x 2" x ¼" channels box-welded on each side. These are then tied together again with 6" x ½" beams spaced a maximum of 27" apart.


• Tubular column supports are welded onto the floor of the tank with a ¼" load bearing plate under each post. So we have ½" steel under each post.


• The floor of the tank is flat and will be supported directly onto the floor in your building. No spans with jacking points like others. Our load per square inch into your floor is minimal. When tanks are suspended your point load into your floor is extremely high. WARDJet tanks can take loads of 20,000 lbs standard. I don't think this is the case with many other tanks.


• The WARDJet support grate system then has leveling capacity to ensure the surface is level and parallel with the travel of the cutting head. Whether you are using the Job Shop Grates, Heavy Duty Grates, Pure Water Grates or Concrete Grates, they are all supported on a sturdy foundation provided by an incredible tank.

WARDJet addressed the issue head on. We did not try to avoid it. We invested time and resources and consider the tank as important as the entire motion system. We do not treat the tank as a "box" under the machine that holds the water. We solved the issue.

The CHALLENGE

• Ask for drawings and details of how the tank that will be under your gantry and supporting your material is built.


• Ask for proof that resonance and vibration has been addressed in the systems you are looking at.


• Ask for the point loads going into your floor, and what the maximum load capacity of the tank is.


• Finally, walk up to the machine and kick it! Then watch what happens to the side of the tank and the water. Enough said about vibration and resonance.