FabShop Magazine - March 2012 - 20

››› dEBuRRing
Most filters use a paper media to separate the debris from the coolant. As the paper becomes clogged with debris, the coolant will begin to float on top of the media. Many filters have sensors for this and will automatically advance the paper, depositing the contaminated filter media in a waste bin. Some inexpensive machines have a hand crank to manually advance the filter paper. With either wet or dry machines, cleaning is important. Dry machines can be cleaned with a vacuum cleaner; the dust is usually light and easy to pick up. Most of the dust created by a dry machine is extracted by the dust collector, so they only need to be cleaned as often as the dust accumulates (how often will depend on how well the dust collector works). Wet machines must be cleaned regularly. PUMA Infeed a wet deburring machine. Most machines have a hose connected to the filter with a “garden hose sprayer” on the end, which is used to wash the machine out at the end of each shift. There will be a combination of debris and coolant resting in some areas of the machine, and if this coolant evaporates, the debris will dry and cake up. If this debris is allowed to accumulate, it will become even more difficult to wash away later. Also, accumulated debris will promote corrosion and may eventually require a significant tear-down and repair. One concern with dry machines is that the dust created in the deburring operation could become fuel for a fire or explosion, especially in the piping for the dust collection system. Such events are rare, mainly because there is normally no ignition source in the system.

A dry deburring machine. Dust collection is sometimes done with a centralized system that extracts the dust from several different machines in a factory, or a smaller dust collector can be used that is dedicated to the deburring machine. A wet-dust collector forces the air and airborne debris into a tank of water to immediately cool the debris and reduce the risk of fire or explosion. It’s recommended that dry-dust collectors are only used in situations that don’t create flammable dust. Wet deburring machines use a similar conveyor and a similar head or combination of heads as with dry machines. Wet machines add a system that sprays coolant on the parts, typically before and after each head. Because the coolant washes debris off the parts, no dust collector is necessary for wet deburring. Wet machines include a pan that directs the coolant to a filter (often located underneath the machine), and the filter separates the deburring debris from the coolant. The filter typically includes a pump that recirculates the coolant back to the spray nozzles. Wet deburring machines Wet deburring machines have a drying unit to remove the coolant from the part. Drying units typically include squeegee rolls to push the coolant off the part and an air-knife drier that blows the remaining coolant off the parts. While the parts leave the drying unit mostly dry, they might have some coolant residue, but this is typically not a problem, because the coolant includes rust inhibitors that could protect the parts as they sit on inventory shelves.

FabShop Magazine - March 2012

Table of Contents for the Digital Edition of FabShop Magazine - March 2012