From Timber Processing
New technology enhances endurance of Debarker Shafts: A technology developed by the former Soviet Union’s Military Industrial Complex is alive and well, and has immigrated to the U.S. Now, this cutting edge technology is making in-roads into an age-old industry in the South.
Lumber Industry and Ultrasonic Treatment
A Mobile, Alabama lumber company has turned to Birmingham, Alabama based Applied Ultrasonics and their patented Esonix Technology to solve plant maintenance problems in the debarker. When Birmingham, AL.-based Applied Ultrasonics asked the lumber company for a chance to prove that the technology works, Applied Ultrasonics’ new client pointed them toward the drive shafts in their Cambio debarker. When these shafts fail, the pineapple falls into the trough below, requiring two to four hours of downtime to retrieve the pineapple, replace the broken shaft, and get the debarker back up and running. As with any equipment shutdown, the resulting labor costs, loss of production, and repair costs are considerable and a major headache for Jack Few, Maintenance Manager at the Mobile operation.
“I was first introduced to the technology by one of our Board members who is also the President and Board Chairman for Applied Ultrasonics” stated Mr. Few. “At first I didn’t know what to expect, and I was very skeptical that there would be anything new under the sun that could help with this problem, but I was wrong.”
Applied Ultrasonics took two debarker shafts and treated them with their patented Esonix UIT process using their PLC 05 unit. This process uses ultrasonic energy to improve the useful life of metals. Many in the forest products industry are familiar with using ultrasound to detect cracks in machinery or to scan lumber for moisture; however, Esonix UIT is using ultrasound for a very different purpose than imaging. Mr. Horace Ward, Vice President of Operations for Applied Ultrasonics describes the technology as follows: “In the medical field, ultrasound is commonly used to destroy kidney stones and to treat pulled muscles; Esonix UIT uses ultrasound to improve the grain structure of the metal and impart residual compressive stress.”
The technology was first developed back in the 1970’s by Dr. Efim Statnikov who is currently the Vice President of Technology and Research for Applied Ultrasonics. When the technology was brought to the USA under a technology transfer program funded by the US Government and administered by the University of Virginia, it was sponsored by a group of Birmingham, Alabama businessmen. The technology has been thoroughly vetted by a number of leading research institutions, including Lehigh University, the University of Texas, the Federal Highway Administration, the US Navy, Coast Guard, and many others domestically and internationally.
The results of UIT ultrasonic treatment include:
- Ability to survive a much higher number of load cycles, or fatigue life (think repeatedly bending a coat hangar to break it)
- Enhanced resistance to corrosion
- Increased hardness
In the lumber industry test, the life expectancy of the debarker shafts was increased by over 300% resulting in a significant reduction in downtime and cost. This kind of life extension is delivered using a handheld, portable tool that sends ultrasonic energy deep into the treated material which strain hardens the material while also introducing residual compressive stress. The result is improved grain structure, increased localized hardness, improved geometry, and most important, longer life.
“I was truly surprised by the results from our initial testing and am now looking at all of our equipment problems to find other areas where this technology can help us” stated Mr. Few.
Applied Ultrasonics’ CEO, Jim Bridges, believes this is only the tip of the iceberg in terms of maintenance benefits that the sawmill industry can obtain by adoption of the Esonix Technology. “This technology has an extremely broad array of applications and has been used and tested on everything from steel highway bridges to aircraft components. We have business offices in different parts of the world and are finding an increasing number of applications that benefit many different types of industries. The experience we had with our lumber industry client is fairly typical of the results we have seen in other applications.”
Applied Ultrasonics has established a truly global footprint with partners in Asia, Australia, and Europe. The Birmingham headquarters was largely focused on research and development from the company’s inception in 1997 until mid-2005. At that time, Esonix UIT was used primarily to treat and revitalize highway and railroad bridges, powered by research results from the Federal Highway Administration.
Since mid-2005, Applied Ultrasonics has extended its reach into a number of other industries from oil explorations and ship building to timber processing. The technology has been used to successfully treat overhead crane girders, heavy equipment, gears, automobile brake drums and rotors, iron pipe, enormous bronze ship propellers, aerospace components, offshore oil platforms, and a variety of railroad components to name a few. The typical life extension that is achieved by treating a component or structure with Esonix UIT is 3-5 times greater than normal, and these results have been verified by a number of independent research institutes and published in a wide variety of peer-reviewed journals and publications.
In addition to being recommended by the Federal Highway Administration for bridge and light pole repairs and retrofits, Esonix UIThas been certified by the American Association of Transportation and Highway Officers (AASHTO), the American Bureau of Shipping, Lloyd’s of London, and DNV Veritas.
Esonix ultrasonic treatment was developed after extensive study of the structure and behavior of metal at the microscopic level. The molecules of metal form grains that fit together similar to crystals. The size and structure of these grains has a huge impact on the characteristics of metal such as strength, fatigue life, susceptibility to corrosion, hardness, and toughness. Many of these characteristics are manipulated during the manufacture of the metal or the end product. Esonix UIT allows the improvement of the grain structure after the product is manufactured, even after it has been in use for a number of years.
Welding is one example of a process that has a huge effect on the grain structure and performance of metal parts. When two pieces of metal are welded together, the weld material shrinks significantly as it cools. This reduction in size causes tensile stresses in the weld area, and these tensile stresses are detrimental to the life of the structure. Esonix UIT imparts compressive stresses, the reverse of tensile stresses. The result is that a welded part that is under repetitive stress will last about four times longer than normal when treated with Esonix UIT. The reason for this is that Esonix UIT refines the grain structure of the metal and imparts compressive stress, removing the stress riser that is normally found at the toe of the weld.
Shafts and other mechanical components are slightly different in that in many cases they are not welded; however, they do wear out, and they frequently break at areas of higher stress concentrations such as changes in diameter and sharp radiuses. The forces that these shafts are exposed to on an almost continual basis are extreme. Take the shaft in the debarker as an example. These shafts are torqued as they continuously start and stop, they are worn as they come in contact with bearings or bushings, and they are jarred by the impact of each passing log. With all of these stresses, it is no wonder that these shafts develop cracks and break.
In this situation, Esonix UIT is used to treat the radius at the step-down where the shaft changes in diameter. This is the weak point of the shaft, and the place where they typically break. The result, after treatment, is a shaft that lasts about three times longer than normal.
The Esonix UITprocess works by delivering ultrasound deep into the granular structure of the treated metal. This is achieved using a tool that has a transducer resonating at twenty-seven thousand cycles per second (27 kHz). The transducer is connected to a steel rod that transfers the resonating energy wave. The steel rod is called the wave guide, and the wave guide moves about thirty microns or 1.2 thousandths of an inch. This high frequency and low amplitude are important because they were determined by studying the speed of sound in various metals.