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Title: Airborne ultrasonic inspection of hides and leather

Author
item Liu, Cheng Kung
item Latona, Nicholas - Nick

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2011
Publication Date: 11/1/2011
Citation: Liu, C., Latona, N.P. 2011. Airborne ultrasonic inspection of hides and leather. Journal of American Leather Chemists Association. 106(11):326-331.

Interpretive Summary: Animal hides are the highest value coproduct of the meat industry. The U.S. beef industry produces approximately 35 million cattle hides annually. The export market for raw and wet blue hides is currently valued at more than $2.2 billion annually. Hides are visually inspected and ranked for quality and sale price. Because visual inspection is not reliable for detecting defects when hair is present, hides cannot be effectively sorted at the earliest stage of processing. Furthermore, this subjective assessment is non-uniform among operators, and leads to disputes over fair price. Development of an objective and nondestructive method to accurately evaluate the quality of hides is needed. We have developed Airborne Ultrasonic C-scan imaging techniques that can reveal the presence of defects in hides and leather that could affect the leather quality. This system offers great potential for testing entire hides in the manufacturing plant. Data can be gathered from different sections of the hide and during different stages of the manufacturing process. Therefore poor quality hides and leather will be detected earlier and possibly reprocessed before it is carried all the way through the expensive tanning process. The variations in the amplitude were colored coded into C-scan images to reveal the location and shape of the defects or some other physical discontinuity that could affect the hides or leather quality. Using AU C-scan images could advance the industry in how it assesses and grades raw hides and finished leather.

Technical Abstract: Currently, hides and leather are visually inspected and ranked for quality, sale price and usable area. Visual inspection is not reliable for detecting defects, which are usually hidden inside the material. This manual assessment is non-uniform among operators, and often leads to disputes over fair price. Development of a nondestructive method to accurately evaluate the quality of hides and leather is needed. We have investigated airborne ultrasonic (AU) testing using non-contact transducers for the nondestructive evaluation of hides and leather. The AU test system is designed for automated and moving process applications, thereby providing an ideal inspection method for large hides or leather. This research examined the ability of AU to reveal defects in hides and leather that are difficult to be found during visual inspection. The AU transducers were mounted on a computer-controlled X-Y scanner that allows the transducer array to be moved over the entire surface of the hide. The AU testing involves pulsing ultrasonic waves and measuring the amplitude of those waves transmitted through the material. The key for success in AU testing is to use AU transducers with low resonant frequencies, which leads an effective transmission of ultrasound waves through the leather or hides. The variations in the amplitude were colored coded into C-scan images to reveal the location and shape of the defects or some other physical discontinuity that could affect the hides or leather quality. Using AU C-scan images could advance the industry in how it assesses and grades raw hides, wet blue, wet white and finished leather.