Many professional woodworking companies spend significant capital on production machinery but don’t address dust collection issues. Proper dust collection has many advantages, well beyond the obvious health benefits. An inadequate dust collection system can result in a poor quality finished product, reduced tooling life, and damaged woodworking machinery.
Health Issues
Wood dust can be very hazardous to workers’ health. Inhaling dust can lead to allergies, respiratory issues such as asthma, and worse yet, has been known to cause nasal cancer. Some wood species contain toxins that can cause severe respiratory problems when inhaled. Inhaling wood dust can reduce your lung capacity, which can be either temporary or permanent in some cases. By properly collecting dust and minimizing the amount of airborne dust in a shop, you will significantly reduce these health risks. Employee health risks can also affect your bottom line due to lost workdays and increased health care coverage.
Product Quality Issues
Wood dust that is not properly extracted can cause havoc on your finished product. The dust can build up on sanding belts that load up the belt in sanding applications. This can lead to friction between the belt and the workpiece, causing heat or a broken belt. It can also cause chatter as you ask the belt to remove more material than it can handle; thus, it will skip because it is overloaded.
On edgebanders, it is critical as well. Laminate and PVC chips can fall onto the panel; tracing wheels will roll over these chips causing a poor banded edge finish. Also, these chips can get into the glue pot and can contaminate the glue. On moulders and planers, inadequate airflow from the collector or poorly designed ducting will result in excess wood chips deflecting back onto the finished work surface, coating feed rolls, and being pressed into the wood surface, causing small dents in the workpiece. This will force the manufacturer to sand his product to remove the marks or discard the piece.
Reduced Tool Life
As described earlier, improperly extracted sawdust can lead to more friction which causes heat. This heat can prematurely wear down tooling, significantly increasing your sharpening costs and resulting in dull tools and ultimately a poor finish quality.
As a wood chip is machined, it carries the heat from the cutting action. You want to extract this chip to keep this damaging heat from the recalculating cutter.
Sanding belts can clog and, in fact, not sand after the grit is plugged, which causes friction. This friction is head which will wear down the sanding belt quickly.
Increased Maintenace Costs
Inadequate dust removal can lead to more frequent and serious machinery breakdowns. Excess dust can clog drives, gears, and worm/ball screws, causing premature wear and breakage. In addition, many CNC machines rely on airflow from the dust collector to cool the spindle. Poor airflow can cause early bearing failures in these situations.
What Size Dust Collector Do You Need
Several formulas go into sizing a dust system. Each diameter of the dust port requires a certain amount of Cubic Feet per Minute (CFM). Add up all of your ports, and you will then get a rough idea of the CFM needed. If some machines are only running periodically, you can reduce this figure by installing blast gates to restrict the airflow from that particular machine.
| Port Diameter | 3″ | 4″ | 5″ | 6″ | 7″ | 8″ | 9″ | 10″ | 12″ |
CFM/Port | 225 | 400 | 600 | 900 | 1200 | 1600 | 2000 | 2450 | 3500 |
What other factors should you consider?
Other factors to consider when sizing a dust collection system are:
- Type of dust you are collecting: Rough or fine. Fine dust requires more filtration than wood chips. Wood chips require more storage capacity than fine sawdust.
- Are you installing the system indoors or outdoors? You need to be aware of heat loss for outdoor installations as the dust collector collects dust and pulls the warm air out of your shop. A return air system can combat this issue. You need to be concerned with noise and local safety/fire codes for indoor installations. Also, in indoor systems, some codes specify that you cannot have dust collection systems indoors that are greater than 1500 CFM. Other regulations state that for larger systems, they are required to be 15′ from the nearest machine operator, and some require the system to be put in a separate room behind fire-rated drywall.
Importance of Proper Ducting
Improper ducting can undo any improvements you have made to your dust collection system. Improper ducting material, poor ducting layout, and improper duct diameter are only a few of the potential pitfalls you can face.
PVC ducting should not be used in wood applications. PVC is non-conductive and can build up static electricity. An operator could be struck with a static electrical charge, and it can be an extreme fire and explosion hazard. A term that is well known now is ComDust (combustible dust). These fine dust particles can become explosive when in contact with static electricity.
A poor ducting layout can significantly reduce the airflow, nullifying the dust collector’s CFM. You should not install sharp elbows when installing ducting, as this restricts airflow. Elbows should be gradual. Also, if you start with an undersized main duct, it will not allow enough airflow through the dust collector.
Also, when attaching ducting to a piece of equipment, it is in some cases necessary to have a length of flexible ducting as it may have a moving head or a cover that opens. Flexible ducting should be minimized in size because it dramatically reduces airflow compared to steel ducting.
Ryan Akhurst is the Co-owner and Vice President of Akhurst Machinery, leading the fourth-generation family-owned company.