Introduction
Implementing real-time process monitoring provides manufacturers with valuable data that improves product quality and process availability.
Dimension lumber is the most commonly used construction material for homes in North America. Quality control is essential as any off-target products can jeopardize a building’s appearance and structural integrity.
In a typical softwood sawmill, every piece of dimension lumber goes through a planer before being shipped. A planer is a machine that shaves off the rough-cut surfaces and excessive thickness, so the lumber’s dimensions comply with industry standards. This is also one of the last Quality Control (QC) checkpoints before the lumber is shipped to the end customer ready for sale.
Historically, QC was primarily performed by manually taking measurements of a sample of the finished goods. The planer would be halted if any off-sized boards were identified. It was then up to the Mill Operator to find the cause, whether it was due to obstructive objects or out-of-calibration tool parts. Precious resources could be wasted before a defect was detected. Sawmills could also unknowingly ship undersized or oversized lumber to their clients.
The industry was looking for a reliable and timely monitoring process that could alert the Operators of any defective products. They also needed an effective way to manage the machine’s constant need for setting adjustments. Intermittent stops throughout the day, despite being necessary, amount to a significant throughput loss over time. It also disrupts upstream processes, causing more needless idling time.
System Requirements
The dimension monitoring system needs to take the measurements in real-time at a speed that exceeds 1,500 ft per minute. Depending on each mill, the data accuracy must be at least within 0.025 mm or one-thousandths of an inch. Once the sensors detect any discrepancies, the system will alert a Quality Manager. A downstream software program processes the data collected from the dimension monitoring system to identify trends. The Maintenance, Repair, and Operation (MRO) team can then schedule a maintenance time based on the program’s findings.
System Description
With LRS-16HC, a monitoring system can have up to 16 heads of LRS-50 sensors working in one scan zone.
In this application, LRS-50 monitors lumber dimensions and provides real-time feedback, enabling timely process adjustments to avoid off-size lumber.
The monitoring system consists of four Single Point Range Sensors to provide real-time dimension measurements on incoming, in-process, and outgoing products. With 1,000 scans per second, the high scan rate of the LRS-50 delivers accurate measurements even when the product speeds exceed 1,500 feet per minute. The application is easily scalable up to 16 LRS-50 scanners using the LRS-16HC concentrator. Hermary’s patented temporal correspondence technology in the concentrator keeps the communication latency between scanners within a few nanoseconds (1⁄1,000,000,000 of a second, or 10−9 seconds). The temporal correspondence technology gives the captured readings a high degree of immunity to vibration to the target being measured (bouncing products).
Conclusion
The primary benefit of dimension monitoring is detecting process variations as soon as they appear and prior to manufacturing out-of-tolerance goods. The 3D measuring and monitoring system reduces the risk of undersized or oversized products by detecting problems in the production line. Immediate feedback is available to identify to correct out-of-tolerance operations.
Trends can be identified, and corrections can be made before a defective product is made. Understanding in-process tolerances enables the Quality Manager to schedule predictive maintenance and make appropriate adjustments and changes. Having visibility of the process allows tighter tolerances, thinner saws, reduced waste, and increased ROI.
The LRS family is a robust industrial solution designed for dimension monitoring that improves product quality and increases process availability. It is also deployed in concrete and cement industries, furniture manufacturing, and many more.
“We deal with thousandths of an inch of recovery in the sawmills, so if they miss manufacture by 0.01 of an inch when they cut a million board feet in a shift, that quickly adds up to many thousands if not millions of dollars over time.”
– Nick Barrett, SiCam Systems