What is Metal Swarf and Chips?
In metalworking, metal swarf is the metallic chips that are leftover when machining the metal to shape. The history of the term “swarf” is interesting. In Middle English geswearf means “iron filings” or “rust”. In terms of scandinavian origin, Old Norse svarf means “metallic dust.” In Proto-Germanic, it can mean “that which is rubbed off–i.e shavings” and “to mop, wipe, or rub off.”
There are various kinds of swarf based on the manufacturing process that made the swarf.
Fines and Filings are the tiniest flecks of material that most often come from grinding tools.
Shavings range in size from the powder up to larger chips your cutting tool slices from a piece of metal.
Turnings are the result of a turning process. Depending on the material, they can be long curly-cue shaped strips of metal.
Typically, swarf is regarded as a waste material. So, it is something you need to figure out how to dispose of.
Hazards of Coolant and Swarf
Health and Safety Risks
If we’re talking about swarf, and the manufacturing processes that produced the swarf involved coolant, than by definition that swarf will be soaked in the coolant. Therefore when considering hazards, we have to consider hazards associated with both coolant and swarf.
Starting with the coolant, we know that contact with many metalworking fluids can cause irritation to the skin, eyes, nose, lungs and throat.
The dangers of swarf are a little more direct since the metal shavings can consist of razor sharp shards of metal. Whether we’re talking about needle-like swarf causing puncture wounds, thrown swarf (material removed and thrown by the machine tool) causing shrapnel injuries, or ribbon swarf just straight up cutting into flesh, these are all hazards found when handling swarf.
In some cases, we may be dealing with fire hazards. In the case of coolant, straight oil-based coolants are the most combustible. Swarf can also be highly flammable because of its high surface area. Be especially cautious of metal chips consisting of iron, titanium, calcium, magnesium or other reactive metals. Worse, swarf stored in bins may even spontaneously combust, particularly if covered with metalworking coolants.
If you’re working with radioactive metal waste, you’ll need to consult with appropriate resources to find the best safety measures to use there.
To start, always be informed of proper operating and maintenance procedures for your machinery.
Personal Protective Equipment (PPE)
You may want to use appropriate protective equipment depending on the nature of the Sward and Coolant you’ll be dealing with. PPE includes protective sleeves, protective goggles, chemical resistant clothing or aprons, gloves and safety shoes.
Keep in mind that you may only wear some of that PPE when directly dealing with the swarf, but not while using the machinery. Gloves are generally a bad idea around rotating machinery, for example.
Make sure your facility is set up for fire prevention and that you have proper fire extinguishers on hand that are designed to handle metal fires.
Air Cleaning Systems
Air Cleaning Systems can be helpful for keeping mist out of the shop air.
Cleaning Swarf from the Workpiece
Once the machining cycle has finished, it is important to clean the swarf from the workpiece. This is most commonly done using an air gun. But another more automated approach is to use a chip fan.
Cleaning Swarf from the CNC Machine
Periodically, it’s important to clean the swarf from the CNC Machine as well. Depending on your CNC Machine, methods for doing this will range from manual brushing and air nozzle work, to coolant washdown, to automated mechanisms like chip augers and conveyors.
Many types of swarf can be recycled if proper care is taken. The benefits to recycling swarf are that it adds cash back to your operation, it reduces negative impact on the environment, and it can keep your workspace clean and more efficient.
At the very least, it can be helpful to recycling if you segregate your chips by material type.
At the most, your firm may be ready to invest in equipment that can convert your swarf into briquettes. Other equipment may be used to help remove the coolant from the swarf so that it can be recycled or reused as well.
Extra Credit: What is Swarf Milling?
The term “Swarf Milling” refers to a type of 5-Axis milling toolpath. With Swarf Milling, the tool is positioned so milling is being done by keep the tool so its side is always tangent to the surface being machined. Another term for Swarf Milling is Flank Milling.
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