Recycling tires is a must for protecting the environment. There are many different ways to recycle tires and shredding tires is an option provided you have a market for your end product.

Tire shredders are not inexpensive machines and doing your research on both the markets and machines is a necessity. Markets for tire shred can include landfill alternative daily cover, civil engineering projects for aggregate replacement and tire-derived fuel (TDF), which is used mainly in cement plant kilns, pulp and paper factory kilns, and by energy companies. Tire shredding also can be the first step in making a crumb rubber product.

Mike Hinsey, director of operations at Granutech-Saturn Systems, said, "The first thing a person needs to do before getting into the tire recycling market is to establish what their market is. That will determine if you need shredders, granulators, or cryogenic machines."

Mark Diemunsch, owner of Barclay Roto-shred, agrees. "I believe if you can't shred one million tires a year, you can't afford the entry fee for this business. If you are doing 5,000 tires a year you'll never recover your investment."

Once the market is determined, it is time investigate equipment needs.

Mr. Hinsey said, "Look for a manufacturer who has had time in the tire recycling market and is catering to the market. It is different than any other market and the machines have to be built to handle the market.

Mr. Hinsey added, "We found that what was needed for tire shredding was more torque and less shaft speed. By slowing down the shaft, torque is increased. We also increased the size of the shafts, gears, bearings, just about everything had to be made larger. You can't cut corners anywhere in a tire shredder."

Charles Astafan, Columbus McKinnon general manager, Sarasota operations, said, "You need a shredder that is specifically made for tires. Shredders that 'also do tires' rip and pull at the rubber and tear it apart, exposing the steel. Depending on the market, lots of exposed steel makes an unmarketable product, especially for TDF."

He continued, "We really make a tire chipper rather than a shredder. Our machine cuts the tires so that the chips do not have 'whiskers' or 'spider legs'- steel that is exposed past the edge of the cut. Cement plants and others who use tire chips for TDF want the steel in the chips but they do not want it sticking out of the pieces. It causes the tire pieces to catch on each other and clump together."

Choosing the Right Shredder

David Fleming, manager rubber and tire division, SSI Shredding Systems, Inc., said, "You need to know if you are going to be processing passenger tires, light truck tires, semi-trailer and truck tires, agricultural tires or off-the-road tires such as mining machine tires. Each one of these tires processes a little differently. Each type of tire requires a different configuration."

Mr. Diemunsch said, "Most people don't realized that they can't get away from collecting semi-truck tires. These are some of the hardest tires to shred on an ongoing basis. People will make a mistake if they buy something just to handle passenger tires."

Barclay Roto-Shred focuses on a primary shredder. "We developed the primary shredder in 1992. It is used in front of existing shredders. The primary shredder takes tires and makes them into 6" strips on the first pass. Our primary shredder can handle truck tires and it has 50-horse power. This makes it available for plants that may not have the ability to run larger shredders that take 1,000 or more horsepower. The primary tire shredder can also help reduce wear and tear on the secondary shredders as well. The shredder also can make 2" chips to be sold," Mr. Diemunsch said.

There are mobile tire shredders and shredders that are set up at a plant or site.

Mr. Fleming said, "With mobile machines you go to customers and shred at their site. There is less production with this type of machine. Those who have a trucking service to bring the tires to a central processing facility will actually do more processing of tires.

Mr. Diemunsch said, "I believe the guys who will be successful at starting a tire shredding business are the ones who are in transportation and have trailers they are able to drop off and leave at a business, such as a tire retailer, and pick up and haul back to a processing site."

Hydraulic and electric units are available for tire shredders. A tire shredder needs to have automatic reversal. Tire shredders with auto reverse will stop automatically, reverse, and then start forward again. The tires are then repositioned. Most shredders have a pressure switch of some sort that senses the incoming load. A predetermined safe maximum load is set on the sensor, which will activate the auto reverse if it senses an overload.

Mr. Fleming said their electric-driven machines have an auto reverse and also have a programmable reverse available. "This allows the operator to make long strips, reserve the strips and then send them back through again for a smaller product. This is useful in some situations, but also cuts down on production."

Mr. Hinsey said, "If a recycler is using a shredder to make landfill cover, just about any well-built shredder will do. Once someone moves into TDF you start narrowing the field. The shredded material may be feed stock for a granulator.

Granulation removes the wire from the tire chips and brings the chips down to a size that is 3/8" or less. Removing the steel requires a machine that rips the steel out of the chips. Then the rubber and steel go through screens and magnetic separators. Any material still containing steel would be sent back through.

Mr. Astafan said, "You can't remove the steel with a shredder. You need another machine. "Our 'Liberator' cuts, screens and liberates the steel."

In rare cases, the steel is marketable. "Some people are very good at removing the rubber on the steel. Those that do, have sold it or at least can get rid of it for free. The steel with rubber is cross-contamination and is waste," Mr. Astafan added.

Granulation Machines Can be a Fire Hazard

Mr. Hinsey said, "With systems that require the removal of steel there is always a chance of fire. Tire shredding and granulation is an inherently dangerous process. The medium speed grinder that pulls out the wire equals iron against iron. This can create a spark."

Machines for this purpose should have heat and fire detectors and a system included that will prevent fire. Some machines have water misters and temperature detectors that will shut down the machine if it gets too hot.

"We added these sensors," said Mr. Astafan, "because of fires that have happened in the past. This industry is moving forward in technology and the technology is getting better and better."

Mr. Hinsey added, "Every plant that deals with rubber can have a fire. The fibers in the rubber are a petroleum product, mostly nylon. A catastrophe can happen if these machines are not watched and managed properly. Our machine has temperature and fire detectors and we train our clients to deal with these situations, if they come up."

Maintenance of the Tire Shredders is Expensive

Knife replacement is the single largest maintenance expense. The cost for the knives will be more than all other maintenance on the machines.

Mr. Hinsey said, "Shredders are built strong, so there is not a tremendous amount of maintenance on the rest of the machine. You want to buy a shredder you know will be up well over 90 percent of the time."

Different shredders have different types of knives systems. Mr. Hinsey said, "Some are configured on a upturn one-piece knife. Others have segmented knifes. Our knives will last from four weeks to several months, depending on the use and type of tire. We are always working to develop knives that will last longer."

Mr. Astafan said, "Our patented knife system has one of the longest life spans in the industry. We are working to reduce the costs involved with the knives. Our knives are regrindable and movable. Our knives were developed for tires and are never sold for anything other than tire shredders. "

"Our blades are designed so that they can be easily resharpened," said Mr Diemunsch. "This is a must for a primary pass shredder. You can get 10,000 tons through on one sharpening of our blades. The tool steel is heat-treated and hard all the way through allowing for multiple sharpening and then shimming of the blades to continue."

Another important part of shredder maintenance is making sure the cutter stacks are tight.

Mr. Fleming said, "The cutter configuration between the rotors needs to be kept tight. If it starts to wobble, things become loose and material can build up inside. Then you end up with more tearing than shearing. Keeping the cutter tight also is a better use of energy, it shears faster, and there is more compression of the threads in the end of the shaft."

The real expense of shredding is in the machine that cuts the rubber still containing metal. Once the metal is taken out, the other machines for making crumb rubber and even rubber powder do not have as much maintenance expense.

Used Machines are on the Market

Mr. Fleming suggests if buying a used machine, it should be one that was made for the tire market and type of tire you are going to process.

"Everyone wants the cheapest used machine they can find," he said. "It is hard to take a used machine that was made for a different application and try to make it work for you. You may, in a short time, end up spending more on a used machine than on a new machine purchased for your application.

Mr. Hinsey gave this piece of advice. "The tire market is fairly complex. You cannot do enough research in this market. Even after you spend the money and get things up and running, you will still be learning things you didn't know, whether it's a month later or a year later. Get multiple opinions. You will be spending between a few hundred-thousand dollars to a few million dollars on a system."

Mr. Diemunsch added, "The tire recycling business is a stable business. Even in bad economic times, people still have to drive their cars. If you are big enough and have the high volume of tires you need to negotiate contracts, you should succeed."