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When configuring a plasma cutting system, persons oftentimes struggle with the decision of choosing amidst a water cutting table and an air down-draft cutting table. While both styles of table are effective, each has it is vantages and disadvantages. Before making your decision, you must take into considerateness and valuate the types of materials you will be cutting, size of parts, the specifics of your application, and the short- and long-term costs affiliated with each type of table.

PRICE: The firstborn thing that most humans look at when choosing their cutting table is the significant divergence in the up-front cost amid a water table and an air down-draft table. Water tables are plainly much less expensive. If price is the only consideration, then the decision is an easy one, choose the water table. The more primary and ofttimes overlooked factor when making this decision is the long-term cost of each system. Long-term costs include maintenance, waste disposal, operational efficiencies, and other elements that will be outlined later in this article.

There are likewise cost issues to consider within these two categories of cutting tables. Water tables are available in fixed water level and adaptable water level configurations. Evaluation of your routine will determine whether you need a fixed water level table or the capacity to adjust the water level of the table. Likewise, air down-draft tables are available as a regular down-draft that draws air from the entire area of the table or as zoned down-draft tables that have dampers so that you are only drawing air from the area in which you are cutting. A zoned down-draft table is more expensive, but allows you to use a smaller, less costly dust aggregator because the air volume requirements may be significantly less.

MATERIALS: The types of materials you will be cutting are necessary in this decision making process. If you are cutting primarily steel/stainless steel, either type of table will work well for you. However, if you are cutting aluminum, water tables may present a major safety hazard. When plasma cutting aluminum over a water table, the dross falling into the water invented by the cutting procedure will give rise to a chemical reaction with the water. This chemical reaction will extract Hydrogen out of the water that will cumulate in pockets underneath the plates or in the bladder of adaptable level water tables, creating an explosion hazard.

The pockets of Hydrogen that cumulate under the plate will ordinarily just fabricate “popping” sounds as they are ignited and are commonly not huge sufficient to cause a significant explosion. Some users have added water circulation schemes to prevent/minimize this condition. The dandier hazard is the accumulation of Hydrogen in the bladder of an adaptable water level cutting table. Adjustable level water tables basically have an inverted open-top box in them that is filled with air to raise the water level and emptied of air to lower the water level. If Hydrogen cumulates in the bladder and is ignited, it will invent a major explosion. These explosions have blown the gantries off of machines and gravely injured and/or killed persons in the vicinity of the machine. Manufacturers do not approve of and highly discourages any cutting of aluminum over a water table.

MAINTENANCE: The long-term cost of preserving water tables versus air down-draft tables is a substantial and often overlooked topic in the decision making process. All cutting tables pile up scrap and slag and need to be cleaned out on a regular basis. Most users will have to do this at least once or twice per year, and heavy users may have to do this four or more times per year. In addition, water tables have a tendency to construct unpleasing odors over time as bacteria grows. With the ever increasing regulatings and limitations of waste water disposal, this cost is increasing each year. When you consider that a typical 8′x12′ cutting table holds approximately 1,500 gallons of water, or a typical 10′x20′ cutting table holds approximately 3,000 gallons of water, the water disposition costs may add up quickly.

An air down-draft system will require periodic emptying of particulate from the dust collection system, remotion of slag/dross from the cutting table (slag pans may be added to make this routine even easier), and occasional substitute of filters. There are no special waste disposition costs related with this regular maintenance, and machine down-time is likewise specifically less.

OPERATIONAL EFFICIENCIES: There are a number of constituents to consider from an operational side when comparing water tables and air down-draft tables. These elements include the size and type of parts you are cutting, plasma performance, and cut quality.

The size and types of parts you are cutting may be a determining factor in this decision making process. Companies that cut a lot of little elements that would have a tendency to fall through the slats and into the table must strongly consider an air down-draft system. This will grant your operators to quickly retrieve constituents from inside the table, reducing the need to “fish around” for parts in murky water, and denigrate “lost” parts. If you are cutting very long elements where straightness is an issue, a water table may be better suitable for your application. By partially submersing or “floating” the plate you are cutting, the cooling effect of the water will help stabilize the temperature of the plate and denigrate camber and/or warping.

For a lot of years, the major plasma makers have discouraged cutting over water. They claimed that cutting over water reduces their plasma capacity by as much as 20%, and scaled down cut quality. In our customers’ experience, setting the water level just beneath the level of the plate or partially submerging the plate does not have a noticeable affect on performance, cut quality, or consumable life. Cutting with the plate under water may cause difficulties with consumable life as the cutting torches are not designed to be submerged and coolant coming into contact with the electrodes may cause them to fail prematurely and perhaps clog the air/gas nozzles creating difficulties with cut quality.

Cut quality amid constituents devised over either type of table has been reasonably comparable. The greatest divergence is that more dross adheres to the back of constituents cut over a water table because the dross cools quicker and sticks to the portion as opposed to being blown down into the table. The “dross-free” rating by the plasma makers is scaled down when cutting over water. This dross/slag is not difficult to remove, but does add time/labor to the processing of parts.

SUMMARY: In order to select the best table for your application, it is essential to take all of these constituents into consideration. Spending the time to evaluate your processes and long-term costs now, will ascertain that you select the best, most cost effective solution to your peculiar application for now as well as for the future. Your plasma cutting scheme manufacturer may support you evaluate all of these elements and support you in the decision making process.

Which Cutting Table is Right for Your CNC Plasma Cutting Application?

Water Table vs. Down-Draft Table

-by Oliver Osterhues

Table Pan Full Pic

Table Pan Full Picture

Table Pan Full Pic