Should you use a wet or dry deburring machine?

Each system has its advantages and disadvantages.

Wet deburring machines flood coolant into the work area. Gravity returns the coolant with dirt and grinding particles to a filter that catches the particles and recycles the coolant to the main tank. Some machines have a filtering system as a stand-alone unit, while others have a filtration unit under the machine to save space. Wet systems eliminate the need for a dust collector, offer long belt life, and minimize hazards when working with different metals.

Wet systems do require a strict maintenance regimen. Certain coolant mixtures work best with certain materials, and excessive corrosion occurs if proper water and lubricant mixtures are not maintained. A number of factors affect the water chemistry in a machine. For example, regular tap water has sodium, calcium, magnesium, and sulfur dissolved in it, and as water evaporates from the tank it leaves these harmful minerals behind.

Daily cleaning and monitoring the chemical makeup of the coolant are vital for optimal machine performance. Some wet machines have stainless steel in critical areas to prevent corrosion. A few machines are made entirely of stainless steel to suit even the most rigorous applications.

Bearing life is the most troublesome problem with wet machines. On some newer systems, pressurized bearings prevent moisture from entering, but this is a relatively new, somewhat untested technology. As always, proper maintenance is the most effective solution.

Dry machines can require less maintenance, provide a longer machine life, and can be less expensive to purchase and operate. However, it is very important to be aware of potential problems. Aluminum dust can accumulate in ducting, and all it takes is one spark to start a fire. Again, maintenance is critical, and cleaning the machine after changing from one material to another is essential.

Dry machines also can leave dust particles and grit on the part surface. If those flat parts are not cleaned, they can prematurely wear press brake tooling, which can be expensive, especially if you’re using hardened, precision-ground punches and dies.

Dry systems also require either dry or wet dust extractors. Dry extractors are adequate for collecting dust from various processes. They must be changed regularly and disposed of properly. However, they do pose some serious hazards if they aren’t maintained properly. Dry filters consist of cloth, paper, synthetic, and other materials. Various metals, abrasive grits, brush fibers, and oil residue can get into the filters, and a hot spark could cause a fire. Check with your fire department for local laws on dust collection.

This is why wet dust extractors have become some more popular. They eliminate the cost of regular filter changes and disposal. But more important, the filter medium—usually just tap water—saturates the particles and quenches any hot sparks. The dust is pulled into a water wash or scrubbing system, and particles settle to the bottom where they can be removed easily. Most wet filters are stainless steel, so rusting isn’t a problem.

Most heavy-duty grinding applications are done dry. When running both aluminum and steel in the same machine, a wet dust collector must be used to prevent fires caused by ignition of the dust. Regardless of what collector you use, though, it is imperative that you check and clean ductwork daily to eliminate any fire hazard.

Ultimately, the type of machine and options you choose will depend on the type of burr removal and finish you require. The decision between a wet or dry machine, and the options needed, should be made after samples have been run by the machine builder.