I’m starting my journey with aluminum and as I usually do, I hit multiple discussion boards prior to getting started. One thing I kept reading over and over again, some of which is repeated here, is to not use your dust collection when working on metals. The biggest concern appears to be starting a fire. Several folks have pointed out that a good cleaning of the dust collection system before shifting from wood to metal can mitigate the risk.
I’ve done two aluminum runs with no dust collection and the cleanup is extensive.
I took a look at the instruction manual for my Vacmaster Wet Dry VWM510 and it has no warnings about metal and I do not see any warning for the Dustopper Cyclonic Dust Separator.
Building a fort to protect the shop from the evil chip monster was somewhat effective but not ideal.
So, does dust collection for metals fall under shop folklore or is there a real reason it should not be used?
I can’t comment on the possibility of a fire hazard inside the dust bin (which seems remote for aluminium chips, but I tend to not take any chances myself), but my reason for not having dust collection installed when I mill aluminium, is “just” to be able to install the air jet locline to blow the chips away (which does make a mess, but I’d rather clean-up than risk chip recutting, melting, poor cut quality, etc…). The dust shoe is in the way, so it needs to go.
Shop vacs and dust collectors use an impeller to generate the vacuum. The impeller is connected to a motor. The motor is supposed to be sealed from the impeller to prevent what ever is being vacuumed up from contaminating the motor. The motor still have a fan on it that cools the impeller motor. Most motors consist of a stator and rotor. The stator is electrically charged to cause the rotor to rotate. There is a magnetic field which is not important to aluminum for its magnetic properties but is important due to its conduction properties. You do not want aluminum chips inside your dust collector motor. As Julien said the heat from an aluminum chip has long been cooled on its journey from the source to the bin so fire from a hot chip is not likely. However there is still a chance of static starting a fire if the metal chips are mixed with saw dust. So be sure to clean out your dc system before starting a metal project and also when it is completed before you start back with wood. Other materials like carbon fiber are bad to breath in and even the best dust collection leaks dust into the air.
It is ok to vacuum up aluminum metal chips if you take precautions. If you have a good quality dust collection system and it is kept clean. Be sure you keep a type ABC Fire Extengisher close buy for all CNC operations. Check your dust bin for smoke before leaving your shop for the night. Have a smoke detector in your shop area.
I have done all my Aluminium machining with my dust collection active. It’s not as good as a compressed air jet for cooling the cutter and clearing chips out of the cut, but I get very little hot shrapnel from the cut on the machine.
I have a cheap cyclone separator (a proper conical one which creates a vortex, not the dodgy side entry cylindrical) and then the shop vac has it’s dust filter installed upstream. I’ve not found any aluminium in the filter or collector bucket of the shop vac.
I have been using dust collection with aluminum for a long time. I have a 100 foot Peachtree hose going to my dust separator. I don’t think the chips would stay that hot by the time they reach the sawdust. My separator is on my back porch so thats a plus. I will take this warning
serious though, from now on I will empty the bucket before I get started on Aluminum.
I switch from a dust boot to air blast when I am cutting any deep channels or holes in Aluminum. As soon as it starts running over its own chips they start to melt and start coating the bit. Not so much a problem with a powerfull shop vac and dust boot for shallow light cutting but as soon as you start going deep…
Do you see any wear in the hose or separator from the metal chips? I suppose if you have a setup with mild bends it would minimize impact.
At work, I’ve seen glass filled plastic pellets wear holes in the heavier duty hoses from conveying material, but it had a lot to do with the aggressive bends that sometimes just happen when temporary configurations are quickly put in place.
A quick follow-up after processing everything that was shared.
I used my dust collection system to vacuum up all the aluminum chips and did a quick inspection afterward. I could not find any chips in the shop vac filter or bin. The Dustopper Cyclonic Dust Separator appears to have done a great job. Next, I checked all the hose from one end to another and could not find much in the way of aluminum which is a good sign that I’ve got enough suck to get things from the work to the dust separator.
I went down a rabbit hole researching what it takes for combustion to occur with sawdust and it’s a DEEP hole. The moral of it is a common one. Preventative maintenance and being prepared go a long way. Clean things out when switching material and on a regular basis. Ensure you have a smoke detector that is operational and tested. Finally, have a good fire extinguisher appropriate for what you are doing. All of which was mentioned in one form or another already.
For now, I’m going to give this dust collection a try when working with aluminum and I’m actually inspired to create an attachment that allows for air assistance and dust collection to work together in an efficient manner.
I’d like to see what you come up with.
I’m about to start looking into air blast on one side and vacuum on the other…just as soon as I reach the bottom of these first two rabbit holes.
