Accurate grading and stacking of veneer via automation
New automation solutions for Plytec’s plywood lines.
Plytec is a Lahti-based engineering company that designs machines and devices for the plywood industry, utilizing experience spanning more than two decades. Makron was selected to design and realize electrical automation systems for veneer grading and stacking lines that Plytec delivered to two plywood factories in Estonia this year.
These lines will be used to sort cut and dried veneer. They are equipped with a camera system that analyzes the quality of the veneer and assesses properties such as the number and size of knots.
Veneer is graded and stacked on the basis of quality. Because each line carries many sheets of veneer in rapid succession and these must be stacked precisely, the system needs to be able to apply efficient and accurate positioning processes. The control system takes care of situating the veneer correctly. Once a stack is completed, a warehouse cart transports it to the storage location. This is a rapid process, with the line covering about 180 meters per minute.
The new lines apply a programmable logic system that marks a departure from previous systems supplied by Plytec. Makron promised to seek a system that would stand up well over time. A solution that met these requirements was found in the comprehensive Siemens TIA Portal automation tool, which was used for realizing the control system.
“The main challenge for the automation design process was posed by the need to position the sheets of veneer with extreme accuracy,” explains Makron project engineer Tatu Parviainen, who began designing the positioning software at the start of this year. A solution for veneer grading and positioning was created by means of TIA Portal’s technology objects. They identify the sheets’ location precisely and use this information to control the logic system’s outputs to within milliseconds’ accuracy.
Makron was responsible for manufacturing the electrical control cabinets also. Each line includes about 60 engine connections, 80% of which are frequency-converter connections. The control cabinets are 5.4 meters wide and have six distribution units.
The collaboration between Plytec and Makron goes back more than a decade. Earlier Makron deliveries were for control systems employed in layup and stacking lines. “The collaboration has always been seamless,” says Plytec Technology Director Tomi Virolainen. Typically, Makron is responsible for the complete delivery of the electrical automation system, including its design, control cabinet manufacturing, installation, and commissioning.