Study finds camera-based safety system fastest in stopping sliding table saw blades

Photo By Altendorf Group

MINDEN, Germany — Up to 120 reportable accidents involving sliding table saws occur in Germany every month, and a new report from Fraunhofer IPA found that an effective safety assistance system would reduce injury as well as the “immense” costs associated with these accidents. 

According to the study, the associated costs for lost work time and medical treatment are immense and an effective safety assistance system would bring "important benefits to craft businesses as well as society as a whole."

Due to their design, sliding table saws are among the machine types with a high risk of injury. As a consequence, various manufacturers have taken on the development of safety assistance systems. 

The Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, Germany, examined two current safety assistance systems – capacitive and camera-based sensor technologies, said Dr. Birenbaum, group manager manufacturing systems, Fraunhofer Institute for Manufacturing Engineering and Automation IPA. 

“Both the capacitive and the camera-based system reliably detected the test pieces under the selected test conditions and led to the lowering of the saw blades," said Birenbaum. "However, only the camera-based system was able to avoid damage to the test specimens in all tests."

The camera-based Hand Guard system from the Altendorf Group was the model tested by Fraunhofer. The system was recently certified by the BGHM, the German Employers' Liability Insurance Association for Wood and Metal.

Alterndorf's camera-based safety system was the fastest technology to stop a sliding table saw blade before injury. 

Peter Schwenk, CEO of the Altendorf Group, a pioneer in the field of sliding table saws, said "We are the world's only supplier of sliding table saws to offer an AI- and camera-based safety assistance system on series machines. With the successful certification by the German Employers' Liability Insurance Association for Wood and Metal, we are setting the future standard for safety in sliding table saws."

Testing
The Fraunhofer IPA study is based on results for capacitive and camera-based safety assistance systems. Both principles use suitable sensors to first detect a hazardous situation and then remove the saw blade from the danger zone in the shortest possible time, thus preventing injury to the hand. Typical working speeds from practice were used in the investigations (0.2 m/s = slow working speed, up to 2.0 m/s = typical slipping speed).
 
Since most accidents with serious injuries occur during rapid hand movements in everyday work, special attention was paid to this. Among other things, capacitive systems react to the presence of human tissue. If a hazardous situation has been detected, the system triggers the safety function.

However, due to its short sensor range and the associated triggering threshold located only a few millimeters in front of the saw blade, it only offers protection against serious injuries at slow working speeds.

The camera-based system used in Hand Guard, on the other hand, monitors a wide area around the saw blade. As soon as the camera system detects hands entering this space, the saw blade is lowered. This prevents fingers and hands from coming into contact with the source of injury in the first place. Even at approach speeds of 2m per second, the system triggers in time to prevent injury.

 

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Larry Adams | Editor

Larry Adams is a Chicago-based writer and editor who writes about how things get done. A former wire service and community newspaper reporter, Larry is an award-winning writer with more than three decades of experience. In addition to writing about woodworking, he has covered science, metrology, metalworking, industrial design, quality control, imaging, Swiss and micromanufacturing . He was previously a Tabbie Award winner for his coverage of nano-based coatings technology for the automotive industry. Larry volunteers for the historic preservation group, the Kalo Foundation/Ianelli Studios, and the science-based group, Chicago Council on Science and Technology (C2ST).