The Modern Sawmill
September 4, 2018 3:33 pm Leave your thoughts
As you may know, over my internship I was primarily working on the finishing steps of production in the planer. Although I was pretty tied up working on projects there, I did get a chance to look at the rough products in the sawmill more than a few times throughout my internship
The sawmill is one of the oldest manufacturing facilities in human civilization. Of course, it has had many facelifts from generation to generation, but the principle is still the same. Break down round logs into rectangular pieces. There are many hurdles to this problem, and I’ll try to explain some.
The first problem is that trees grow in a tapered fashion; that is narrower on the top than the bottom. As a result, optimizing length becomes a challenge. This is dealt with in 2 ways. Most logs are bucked (trimmed) to a target length. Bucking allows for smaller more uniform logs, that are optimized for the lengths of lumber we run. On top of this we also have software in place to determine if the piece needs to be trimmed to remove any defects caused by the log taper.
Second problem, trees don’t always grow straight. On top of trees being conical, depending on the slope on which they grow, they can also bow and twist. This causes more problems than geometric problems since the bent wood has significantly different physical properties. This problem is solved by yet another piece of software. Turning the logs allows us to maximize the amount of straight wood we can extract from the piece.
These two problems are the ones I was concerned with, as the defects caused by log taper are the biggest issue that carries on to the planer where I work.
Besides the issues I was chasing, I learned a lot about the general operation of interior sawmills. Unlike coastal mills which tend to use significantly larger diameter logs, interior mills use much smaller logs. In the initial breakdown of the log, coastal mills use big head rigs to break down the logs lengthwise. These sawmills will pass the log through the head rig multiple times. In interior mill such as the one I work at; the logs are passed through once through a canter which uses band saws and chippers to square the log into a cant. The side boards that are cut off by band saws are then separated from the cant and processed separately in an edger. This process is enables our mill to process a log quantity that is not attainable in a coastal mill.
These days everything goes back to the topic of fires. How are we getting our logs when all the forests are on fire? Well while some logging operations are down for safety, much of the province is not on fire. In addition to this, the log yard stockpiles for months of operation at a time. Some of the piles are so big that the logs buried in the middle of the piles were still frozen when passed through the sawmill in mid-August!
I wish I could have spent more time in the sawmill this internship there is so much more to learn about every little process. Maybe next internship with West Fraser.