Processing Magazine

Linear displacement transducer cuts waste, downtime

February 4, 2008
Gregory Wood Products is a leading manufacturer of dimensional lumber. It has significantly improved operating efficiency and reduced wood scrap by replacing linear displacement transducers (LDTs) in its wood machining operation with the GEMCO® 953 Series Vmax™ from AMETEK Automation Process Technologies (APT). Key to Gregory’s operation is accuracy. A laser-guided edger at Gregory’s Newton, NC, factory profiles each log, determines the optimum cut, and then machines the rough log into usable boards. LDTs installed on hydraulic cylinders accurately position and guide the edger, which averages a cut board every three to five seconds. A wrong cut immediately results in a scrap board. Severe shock and vibration are an inherent part of the operation as the edger’s hydraulic cylinders extended every three to five seconds up to 18 inches from their home position as dictated by the laser profile.

Gregory had experienced both high failure rates for its LDTs and excessive wood scrap until it replaced its installed LDTs with the GEMCO 953 Series Vmax in 2007. Since incorporating the GEMCO 953, Gregory has not experienced a single fault due to an LDT failure. The previous LDTs had faulted during some production days every 15 minutes.

“We significantly reduced maintenance time and wood scrap, which had averaged $3,000 per day due to LDT failures. In addition, we were able to install the 953 Series in minutes into the existing LDT footprint on our equipment. With the success of the GEMCO 953s in our cutting operation, we now plan to install them on the wood stackers and sharp chain as well,” comments Steve Randall, Vice President of Gregory Wood Products.

GEMCO LDTs are known for their flawless performance in extreme environmental conditions. They feature the latest generation of magnetostrictive position-sensing technology, and numerous configurations are available to meet specific end user requirements. In addition to lumber and forest products equipment, GEMCO LDTs have found application in steel mills, primary and secondary metals processing such as stamping, roll forming and die-casting, rubber and plastic injection-molding, extrusion equipment, and material handling machinery.

The GEMCO 953 VMAX is particularly well suited for demanding process applications, providing unmatched reliability and durability regardless of the application environment. That includes shock, vibration, extreme temperatures or exposure to contaminants. The 953D VMAX LDT is shock resistant to 1,000 Gs, vibration-resistant to 30 Gs and is IP68 rated. The fully digital LDT offers accurate and reliable absolute position indication with high resolution and precision repeatability. It overcomes the resolution and signal limitations of analog LDTs by offering infinite resolution and a stable position feedback for cable runs up to 1,200 feet from the host controller.

Both the GEMCO 953A (analog) and 953D (digital) VMAX LDT offer active measuring range of up to 300 inches and wide power supply voltages ranging from 7 to 30 VDC. Analog output units offer programmable zero and span. Both units feature visual and output signal diagnostic feedback and utilize standard off-the-shelf cord sets for maximum value. A tri-color LED indicator verifies proper operation and distinct diagnostics for quick troubleshooting. Their low power consumption (1 watt typical) allows direct connection to displays and control interface modules.