5/31/2023 0 Comments Sawmill gamma control![]() After debarking the logs are cut to the best pre-determined length by cut-off or bucking saws. These sizes help to adjust the debarker’s pressure and speed. As there are tolerances in shape, linear transducers and photoelectric analog distance sensors are used to determine log sizes. The first step of the log is to run through a debarker that removes the bark. ![]() Primary breakdown – from raw log to slabs and cants Additionally they have a large functional reserve and are very resistant to dirt and dust. These sensors work with a long measuring range. As an alternative photoelectric a thru beam sensor determines if a log is present for the final two steps on a loader. Knowing the distance enables them to control when the log is loaded on the conveyor. This is to ensure a constant distance between the logs (log gap) as they enter the sawmill. Once the log is on the loader analog distance sensors determine the distance to the end of the log from the side of the loader wall. Or a magnetostrictive position sensor (linear transducer) provides feedback of the step position of the loader to control motion and speed. Either inductive sensors sequence the steps. When a log arrives at the mill it is indexed onto the infeed conveyer (could be a step feeder or log loader). Here is the process how a log turns into lumber in a sawmill. This allows them to run faster and to increase the production rate. Independent from the logs, sawmills aim to minimize the gaps and to avoid changes in the setup. ![]() As a result bigger mills have a primary and a secondary breakdown area. To efficiently process logs to lumber, sawmills use dedicated equipment for different sizes of logs. From logs to lumber Wave feeder with analog distance sensor As they are exposed to the environment, protective housings help to protect the sensors from logs crashing into them. Mainly sensors must meet high vibration and shock standards. Therefore electrical engineers look for sensors that meet the challenges of the sawmill environment. The worst case is any downtime as it directly impacts the whole log to lumber process. Automation of log and lumber handling to minimize the gap between the logsĪll of the three areas support the sawmill’s target to get the most out of the logs at the highest speed.sawblades, knifes, canter heads…) at high velocity to increase throughput ![]() Automation of drives to position the log itself, or tools (e.g.3D measurement for optimum cutting pattern to recover most yield from a log.Therefore sawmills turn into highly automated factories with three dimensional (3D) measurement of logs, and advanced equipment for primary and secondary breakdown. Basically there are three areas of automation in a sawmill: Still the target is to recover as much yield from each log as possible. Crooked, out-of-round, or tapered logs are common and even worse: usually it is a combination of these shapes. But obviously each individual log is unique in shape. In the ideal world all logs are not only cylindrical in shape but also straight. The big difference is that there is hardly any control over the quality of the logs that enter the sawill. It is not a surprise that optimizing yield is one of the most important objectives in a sawmill (or lumber mill) as it is in any other industry. Guest contributor: Christian Holder, Balluff
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