Back in the dark ages of injection mold making, nobody seemed to care much about having a mist collection system for their surface grinder or milling machine. Most of the coolant was more or less sprayed onto the workpiece by a hose and nozzle, with the mist simply dissipating into the atmosphere of the room.
This actually was not that bad because most shops were not making huge molds with a lot of coolant mist being sprayed everywhere. This was a bit like the nasty graphite dust generated by grinding EDM electrodes; you just tried to minimize the exposure and damage.
Now that plastic injection mold making has become a global phenomena with production-like qualities, it is essential to confront the problem of mist that is generated from the machining operations. The industrial approach requires appropriate industrial supplies.
Reasons to use a mist collection system
- The best reason is that is makes sense in every possible way. Worker health is of utmost importance and air quality is enforceable by law, through OSHA. Besides the penalties of non-conformance, there is simply the fact that it is detrimental to the health of workers to be continually exposed to coolant mist.
The last thing any mold making company wants is to deal with a Federal government bureaucracy such as OSHA, or to have valuable employees suffering from dermatological or breathing problems. These two reasons alone are enough to warrant taking action. Here is a link to the official OSHA guidelines for metalworking cutting fluids.
- Coolant mist, if left unfiltered will accumulate on the walls, ceiling and floors, making for a slippery and dirty environment. Both water and oil soluble coolants become extremely dangerous if left to evaporate on the floor, with a very good possibility that someone will slip and fall. CNC tooling, such as shrink fit toolholders become grimy and attract airborne debris such as dust and chips.
Retrofitting older machines with a mist collector
New CNC milling machines, CNC lathes, EDMs and WEDMs come with the option to have a mist collector mounted at the factory. This is obviously the best choice, as the mounting and installation will have likely been tried and tested successfully in other shops.
But when an older machine needs to be outfitted with a collector, there are several options available. You can have the mist collector mounted directly on the machine, use existing or new ductwork to join a centralized vacuum system, or use the work cell approach.
Machine mounting mist collectors
This is the most popular option, for several reasons. It takes no floor space, can often be easily mounted, and can be customized for nearly any machine tool. The collector should be directly connected to the cutting area, but hoses and ductwork and be used to connect a system on the rear of the machine.
Ducted mist collectors
When a machine mounted system is not possible, the next most popular option is a ducted mist collector. This type of application typically requires that the ductwork is no more than 10 ft. from the working area of the machine tool.
Some high speed milling machines, for example may react to the vibration of the collector, thus making the ducted option advantageous.
Work cell collection systems
When work cells became popular, this option was also common. However, there are numerous disadvantages for a typical mold making operation. Mold making is a very flexible business, with constant interruptions and changes in scheduling. If, for example, only one machine in the cell required use, the large capacity mist collector would have to be used, wasting energy. Also, when the collector requires maintenance, and they all do because of the filters, the entire cell must be shut-down.
Mist collection is a necessity
Keeping a modern injection mold making shop safe, clean and productive is essential, if a company intends to compete and be successful. A properly installed and functioning mist collection system is necessary to help achieve this goal.