Though Amerityre Corp. is a tire company, making tires is only part of its business. The company’s biggest efforts focus on making the manufacturing process more efficient. To this end, it develops and licenses top-secret processes, manufacturing equipment, chemical formulations and technology to other manufacturers that want to improve productivity.
As a result, few are privy to the inner workings of Amerityre’s manufacturing operations. When Gary Benninger, president and CEO, recently invited Material Handling Management to take an exclusive, private tour of Amerityre’s headquarters and manufacturing facility in Boulder City, Nev., we jumped at the opportunity.
Amerityre was founded in 1995 as the American Tire Corp., and in 1999, it became Amerityre. The company originally produced polyurethane foam-based tires that are still used today on bicycles, wheelchairs, lawn and garden vehicles, golf carts and commercial dollies.
In 2003, the company started working on a new technology called elastothane elastomer, which led to the development of a new line of polyurethane that could potentially replace rubber.
The resulting family of elastomer materials complemented the company’s existing foam-based lines. The company began producing tire fill, solid tires, composite tires and pneumatic passenger tires with these new formulations.
Today, the foam-based technology is used to produce low-duty cycle tires for low- to medium-load applications, while the elastomer-based material is used for medium- to high-load applications.
The 50,000-square foot Amerityre manufacturing plant in Boulder City opened in 2002. It produces highdensity foam tires for low-duty cycle commercial applications; tire fill for flat-proofing tires; polyurethane retreads designed to fit on rubber casings; automotive tires; and solid, flatproof tires.
To understand what makes Amerityre’s processes unique, one must first have a basic understanding of traditional tire manufacturing.
Assembly of a rubber radial tire requires at least two stages. The first stage involves manually building the tire on a steel drum. An operator positions the drum and then winds rubber and other materials around it, using hand tools along the way. The worker pulls strips of rubber from supply racks, aligns them with the edge of the drum, cuts the strips and then presses the ends together to form a continuous band on the drum. He or she brushes adhesive chemicals onto the rubber and then affixes more rubber layers. The employee then applies a liner and steel beads that will eventually hold the tire onto the rim of a wheel. The worker next applies steel and nylon belts and then treaded rubber. The result is an uncured product called a “green tire.”
The operator moves the green tire to a curing machine, which applies extreme heat and pressure to start the vulcanizing process. Curing usually takes 45 to 60 minutes per tire. Once the tire is cured and cooled, it’s ready for storage or shipment.
| Using a multi-station rotary machine, Amerityre can produce one prototype lift truck tire per minute. |
Although some of the larger tire manufacturers have reduced manual handling and improved productivity by using robots and other automated equipment, the process still requires multiple assembly points. And, smaller manufacturers often cannot afford to invest in automation, especially in today’s difficult economy.
Prices for natural rubber, carbon black, petroleum and steel—all materials needed to produce a tire—have exploded in recent years, and nearly every tiremaker has hiked prices to pass the cost along to distributors, dealers and customers. In addition, many U.S. tire manufacturers have closed plants or drastically cut domestic production.
Because of those cuts, U.S. tire shipments are currently at levels unseen since 1991, according to the Washington-based Rubber Manufacturers Association (RMA). The tire trade association reports that shipments will continue to decline by nearly 4% this year compared to 2007. “The decline in tire shipments reflects the worsening economic pressures predicted for both the consumer and commercial sectors,” according to RMA. “Overall, the combined OE and replacement tire shipments for 2008 light vehicle and truck categories are anticipated to decrease by more than 12 million units to approximately 298 million total shipments. Shipments totaled 310 million units in 2007.”
While U.S. tire shipments decline, those from Asian countries, particularly China, are rising. China is exporting tires to the U.S. at unprecedented rates. A recent report from the Ireland-based research firm Research and Markets shows that China’s tire exports have grown more than 30% per year and are set to exceed $7 billion in 2008. The analysis, “China Sourcing Reports: Tires,” indicates that the U.S. is the single-largest importer of China-made tires. Last year, the U.S. imported 38% of China’s total tire exports. These lowpriced tires from China are tightening the vice on U.S. manufacturers, forcing them to cut costs even more to stay afloat.
Road Less Traveled
Amerityre has a different way of coping with rising costs and competitive pressures. Though it faces similar challenges as its industry peers, the company has managed to boost production speed, reduce labor costs and enhance its competitive position through innovative material handling. The company continually investigates processes and technologies that reduce multiple process steps and manual handling as much as possible.
For example, Amerityre is using a unique manufacturing process to produce prototypes of non-marking, polyurethane elastomer lift truck tires. The prototype lift truck tire is a press-on, 16 x 5 x 10.6 tire with an internal steel band.
Benninger says the company can produce one prototype tire per minute. The secret: Amerityre has replaced the traditional assembly line with a multiple-station, rotary machine. This single machine can handle all the raw material input, curing and finishing. There is no need for separate curing equipment, so Amerityre saves floor space. And, materials don’t have to be transported from one area of the plant to another for separate process steps. Only four employees operate the 12-station rotary machine. One worker pours the polyurethane material into the mold using a high-pressure pour machine. The measured shot of polyurethane is poured into each mold in succession as the rotating equipment moves.
Each mold is automatically positioned under the pour head, so the operator does not need to move from station to station. In fact, all operators remain in place as the machine brings the work to the worker. And, workstations are positioned at ergonomic heights so employees don’t have to reach or bend down.
Once poured into the mold, the polyurethane automatically cures as it rotates. Because the
| One of the four employees who operate the rotary production machine trims excess material from the finished tire. |
|Tires cure automatically in the rotary machine, thus eliminating the need to add additional energy for curing. |
proprietary mixture undergoes a chemical reaction that cures it, adding extra heat or pressure is unnecessary. “At station one, a worker pours the polyurethane into the mold,” explains Benninger. “By the time the mold reaches station number nine, the amount of time it’s in the mold is nine times the dwell time at the station.”
The next worker on the circular path removes the mold from the machine, opens it and lifts the finished, solid tire out of the mold. After the tire is removed, a third employee trims off excess material, and the last worker reloads the machine with another mold. Then, the process starts over.
Along with being efficient, the manufacturing method is also safe for plant personnel and environmentally friendly, according to Benninger. Employees don’t use harsh chemicals to clean the molds. And, while most lift truck tires today are made of a TDI-based polyurethane material, Amerityre decided to use a more eco-friendly MDI-based polyurethane material. A closely guarded trade secret, the material is formulated in house. “MDI is a stable, inert, environmentally friendly material, while TDI is hazardous to employees and the environment,” says Benninger. The company created four polyurethane molds using the MDI formulation to demonstrate this process.
Benninger explains how the company’s unique material handling strategy offsets the high cost of raw materials. “Polyurethane material is even more expensive than rubber, but our processing method allows us to save money over rubber processing,” says Benninger. “Because we use less energy, less floor space and less labor, it costs less to make a million polyurethane tires than it costs to make a million rubber tires. Cost comes out because of the production process.”
In fact, Amerityre estimates that the capital investment required to produce one polyurethane passenger tire per minute is significantly less than the cost associated with a traditional rubber tire manufacturing line.
“We estimate that a manufacturer’s capital costs to go into production using our equipment to produce polyurethane tires will be approximately 10% of the capital equipment cost to produce an equivalent number of rubber tires,” says Benninger. “More importantly, our equipment will require approximately 20% of the square footage currently required. We are also projecting substantial savings potential in energy costs and a significant reduction in material waste. The whole process will revolutionize tire manufacturing technology.”