With a water table your using a contained bed of water to capture the heat, smoke and dust. Most water tables are 4 to 6 inches deep across the entire cutting area. Some have sumps where the water can be drained off when not in use to allow for retrieval of small parts, table cleaning and to decrease evaporation rates. You can vary the water level in the table with a hose for low end tables or using air pressure in high end air bladder tables such as the Westcott Pro Series Plasma Table. Water level is critical to the effectiveness of the table. For certain applications like cutting Armor plate I will raise the water level and cut the plate underwater.
Because you have the water as a cooling media the material your cutting stays cooler so you have less warping and less Heat affected zone HAZ and discoloring around the edge of the cuts. Maintaining proper cut height is critical for getting the best quality cut, if your material stays flat and does not warp its easier for your machine to maintain the proper cut height across the sheet.
A plasma water table will help reduce the amount of noise from cutting as well, except when it cuts around open areas or edges where there is a lot of air and splashing noise. But you do not have the added noise of a fan or that added energy consumption that you would have with a downdraft system.
With a water table, it will be a bit messier and a bit more wet than a downdraft system. I like having a hose or a garden sprayer to wash off the parts when they are finished cutting. I also keep a small work table next to the cutting table with a towel so that I can dry and wipe off the parts after cutting. This is a step that you would not have with a downdraft, but parts are cooler and can be handled much quicker with a water table.
Advantages
- Water traps dust & smoke
- Less heat affected zone
- Less metal warping
- Does not require extra equipment or energy to operate
- Does not pull heat or AC out of the shop
- Parts can usually be picked up and handled quickly
- Captures 80-90% of dust and smoke
Disadvantages
- Can be messier and require rinsing of parts
- Requires water treatment chemicals to prevent corrosion
- Dropped parts need to be retrieved from the water and can be hard to find
- Water treatment chemicals can be expensive
- Needs to be kept from freezing in winter
The water in your water table needs to be maintained and monitored to be effective. Check our or page on water treatment here: Water Treatment Page
In conclusion, although the Water Tables are a bit messier than downdraft tables, most people prefer them due to ease of use. Others prefer a downdraft plasma table system, which is one of the less common types of cnc plasma tables. To learn more about the difference between the two, check out our Water Table vs. Downdraft Article.
