A breakthrough solution to reclaiming rubber-metal bonded parts.

From the moment when rubber was first bonded to metal, a problem was born. When the need arises, how does one get the rubber back off, once the part has been molded? From rejected products to worn out parts in the field, a true dilemma is formed for the rubber-affiliated industries. The problem begins when a machined piece of metal is bonded with rubber. With today's ever growing metal prices, that machined metal may have a value of $5.00 or $50,000.00, depending on the part. From the drilling industry's stator pipes to the solid forklift tire, rubber eventually wears out; but the metal the rubber is bonded to remains perfectly usable.

This problem has been so perplexing over the years, and the solutions so scarce, that some huge oil companies, as well as rubber companies, have even resorted to having an employee take the parts home and burn them in a field at night. This practice does not occur much anymore, due to stringent EPA laws and fines, but with the price of metal, the problem of reclaiming is bigger than ever. These days, companies have turned to legal burn-off ovens and liquid nitrogen baths to get rid of the rubber. Burn-off ovens, however, can bring the metal to very high temperatures that often take the temper out of the steel; not to mention the environmental concerns with smoke and ash created by the ovens. It is also slow, as well as costly, to burn these parts. Liquid nitrogen can be very expensive and potentially dangerous, as employees are subjected to the sub-zero substance. Then you have the rubber to deal with for disposal. This method is also labor-intensive and time-consuming.

Another method of modern reclaim is the use of water jet systems. This is probably the worst of the solutions, because of its extremely slow approach and because of the fragments of rubber left on the part after the jets have cut off the majority of the rubber. A watery, rubber sludge (sometimes mixed with oil residue) is produced from this process that must then be dealt with. Because of the high pressures associated with the procedure, upkeep can be a problem with the equipment, also.

Finally, a breakthrough has been made in dealing with this monster of a problem. Advanced Reclaiming Technology, based in Georgetown, TX, has developed a patented procedure that slays the giant. The process attacks the bond, not the rubber. The bond is gently broken in a matter of seconds or minutes, compared to the hours that other methods take when they attack the rubber, and it is done at a fraction of the cost. When a part is reclaimed with this process, the rubber is basically left in its whole state, and the metal is completely unaltered. This means no more heat-treating metal after reclaiming. With this process, the rubber can be ground and used in a variety of ways, or landfilled in most areas. As far as cost is concerned, let us take for example an 18' long stator pipe (or mud motor) of average diameter. If one burned the rubber out of the pipe, it would take a cycle time of one to three hours, at a cost between $100 and $300, depending on the efficiency of the oven. With Advanced Reclaiming Technology's method, it could reclaim the same pipe for around $13.00 in about 14 minutes. The process also works for virtually any part, in any industry.

In 1999, a company was formed under the name Pro-Claim in Temple, TX. Its primary business was reclaiming rubber-to-metal bonded parts, and its main focus was serving the oil and rubber industry. Pro-Claim had a problem, however; it had a secret process for reclaiming these parts. This made getting new customers a challenge, because the customers were not allowed to know how the parts were being reclaimed. They could see the results, but could not see the workings of the system. Pro-Claim could reclaim any size part in existence, from parts as small as a button to inserts weighing in excess of 30,000 pounds. If it could be molded, it could be reclaimed. They reclaimed inserts made of copper, brass, aluminum and stainless steel, as well as cast and machined metal parts. A patent was applied for, but as long as the patent was pending, the process remained a secret. The company was in business for over five years in Temple and Brenham, TX, and many leading companies in the industry have tested the parts they reclaimed. Companies like Hydril, Oil States and Weatherford tested the parts for hardness and to be sure tolerances remained the same for the inserts. Pro-Claim passed every test by these companies.

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The U.S. patent for the process was approved in November of 2005. This turn of events has now allowed the process to be revealed. For example, we will take a stator pipe or mud motor, as they are called in the industry. Stator pipe can range in length from three to 25 feet and from two to 36 inches in diameter. The pipe has spiraled rubber bonded to the inside of the pipe almost the entire length of the pipe.

The process works in the following manner: To reclaim a stator pipe, several pieces of pipe are loaded onto one end of the machine (figure 1). The operator selects the size of the pipe on a computer touchscreen. A conveyor-type system feeds the stator into the machine. Doors close on both ends of the machine so that the stator is completely enclosed. The pipe then begins rotating. This rotation is fairly slow, around 10 to 12 rpm. This is key in the functionality of the process. A set of fuel and oxygen burners is automatically ignited, and heating begins in a uniform manner along the entire length of the pipe. This allows the heat, as the pipe is rotated, to dissipate into the thickness of the pipe wall. In the time it takes the pipe to rotate around to the heat source again, the heat is transferred inward. This allows the time necessary for an even transfer of heat throughout the insert. As the pipe rotates around again, the heat is continually applied to the entire surface area of the pipe. As the applied heat seeks to make the metal uniform in temperature, the inside wall of the pipe becomes heated also. Keep in mind that the heat ranges for this process are very low, which ensures that the metal properties never change. As the inside wall of the pipe reaches the temperature set point, the bond actually breaks. When the bond breaks, it breaks uniformly around the pipe and the whole length of the pipe. When the set point is reached, the burners automatically cut off, and the doors are opened on the machine. During the process, a vacuum-type filtration system is utilized to take care of the vapors that are formed. Keep in mind the goal is to never ignite or burn any rubber, so the exhaust is minimal.

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Once the pipe is conveyed out of the machine, two choices await. One can choose to pull the rubber out of the stator pipe while the pipe is still warm with a small winch-type system, or cap the ends and wait 24 hours (until the next day) and simply reach in and pull the rubber out. Rubber has a slight shrinking effect after the process, so removal is exceedingly easy after the waiting period.

A typical stator can be reclaimed in about eight to 14 minutes. This is extremely fast, considering the time it takes every other system to try to accomplish the same task. As soon as one pipe comes out of the machine, another can be immediately loaded. This allows the user to reclaim (depending on pipe size) 60 to 150 stators a day.

The cost of reclaiming is roughly a dollar a minute for stator pipe. Other industries with other parts can be very different; both cheaper, as well as more expensive. Small stators can be reclaimed in as quickly as four minutes, while some of the biggest pipes might take 45 minutes. This means the cost is a fraction of other systems and methods of reclaim. System upkeep is minimal, and is primarily the result of changing heating heads and filters. This process has been needed for a long time and is a welcome relief for the oil, rubber, heavy equipment, mining and scores of other industries.

The newly formed company, Advanced Reclaiming Technology, seeks to lease or to sell the intellectual property to companies so they can reclaim their own parts in their own facilities, versus performing the procedure as a service. This means that companies would not need to ship parts to a different city in order to get parts reclaimed. They could also reclaim rejects in a matter of minutes versus days. Rubber-to-metal bonding is used in the oil industry, railroad, mining, automotive, marine, heavy equipment and military, as well as many other industries.

A company, depending on the industry, could gain a huge advantage over the competition with this technology. Imagine being able to get parts from the field and refurbish them at a fraction of the cost of new parts. If a company could reclaim parts better, faster and cheaper than their competition, it naturally stands to reason one could cut overhead and increase profits, as well as having the option of offering their products to the consumer at a lower price. This process could be utilized over and over again with the same results. The reputation of companies is also at stake, with an ever growing eye on environmental issues. We all need to utilize the most environmentally sound processes in everything we do.

by Jay Tankersley,

Advanced Reclaiming Technology