Efficiency in a machine shop is the goal of every precision manufacturer. Each aspect from design and cutting patterns, to the speed of processing, to just-in-time delivery of raw materials, are some of the measurable or scalable improvements CNC machine shops will gravitate to with Lean Manufacturing. Since the very nature of machining is subtractive manufacturing or removing materials in a controlled manner to form a final size and shape, scrap is a big part of the process. Reducing waste and recycling have always been areas of focus of the industry. Scrap, in the past, was trucked off the landfill to rust and contaminate the soil. With rising costs for raw materials and innovations in recycling trends for machine shops, there are many benefits for everyone, including new business for recyclers, lower cost for the consumer, and fewer materials in landfills for everyone.
Metal scrap is known by many names including chaff, swarf, turnings, filings, and shavings. In varying sizes and compositions, scrap is a danger on the machine shop floor. Fine particles can damage eyes and lungs, and larger chips could remove a finger. Scrap is also often mixed with coolants and other cutting chemicals that create a fire hazard. Handling and storage are important safety measures for dealing with scrap in any machine shop. Moving it out for recycling is your best option.
Modern recycling centres contract with the industry to pay for scrap metal collection when they were once paid to haul it away. Scrap goes through a purification process employing heat, called smelting, and a drossing system to separate the various metals to reforge them into usable ingots and bars for machining and other industries.
Since steel maintains its metallurgical properties through recycling, some estimates quote between 85 to 98 percent of the content of the steel bars used in machining are recycled steel. Brass, copper, and aluminum also see around 75% recycled materials used in machining. Most aluminum, as a point of fact, from its first raw production, is still in use today in North America, having been recycled many times over.
Many machine shops clean their scrap before it is sent off for recycling. This means separating the oils and fluids to create a clean metal scrap. This costs the manufacturer time but earns them a higher value for their scrap material. Once the oil is separated, smart manufacturers considered how this could also be recycled.
The cost-saving of using a hydrogen machine to separate the oils and coolants provides a clean, clear coolant that can provide a second life. Unlike metals, coolant will degrade over time, but the rising costs of coolant have far exceeded the cost to recycle it. Many companies believe the cost-savings in recycled coolant far outweigh the cost of the service contractor or the equipment purchased to produce it.
Coolant can further be recycled during processing. Removal of the tramp oil, or the dirty layer containing particles and bacteria, in a simplistic sense, with separators and gravity, keeps the returned coolant clean and pure. Keeping coolant clean can improve tool life by 15% to 20%.
New Ideas in Recycling
As energy needs increase and robotics become more commonplace, perhaps new technologies like robots that feed on metal for power will find a place in machine shops. This will resolve some of the scrap problems from processing while producing power for robotic functions in the shop that won’t need battery backup.
The recycling focus in municipalities across North America has become its own worst enemy. It is so easy to throw material in a blue bin and assume it receives a second life, that the demand for recycled materials (aside from aluminum) has lost its demand. But there is still a need to recycle plastic. The sheer volume is overtaking landfills, oceans, and waterways and it’s worth a look to see if a plastic recycling business could fit into a corner of your shop. One or two machines dedicated to breaking down polymers can bring your “green” rating up, and provide a separate income stream. Be sure you begin with some good research. Mechanics are playing an interesting role in recycling plastic, like the new technology used with double screw extruders to separate air and liquid in recycling foam.
While some of these processes may be more difficult for smaller shops, as an industry, machine shops should be proud that steel is the most recycled material on the planet, by weight. It is recycled more than all other materials combined. Smaller shops may find the recycling of other materials easier to accommodate with specialized polymer processing equipment if their metal and coolant scrap load isn’t high enough to attract a contract with a recycler. Recycling trends in machine shops will only continue to advance. The machining industry has been a leader in recycling and will continue to innovate. Generally, if machine shops look at something as a resource, rather than waste, it will become one.
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