How do you help reduce risk in the nation's most dangerous occupation? Researchers at Oregon State University are partnering with Blount International to help make timber harvesting equipment safer. To understand a specific type of accident that occurs in the field, they’ve designed and built a machine to recreate it in the safety of a shipping container.
John Parmigiani (right), associate professor of mechanical engineering, and graduate student Alex Orawiec inspect chainsaw bars.
- Video of a timber harvester in action
- Oregon Mechanical Timber Harvesting Handbook [PDF]
- Blount International website
- ATAMI website
OWEN PERRY: Here in the Pacific Northwest, it’s hard to escape the classic images of rugged flannel-clad lumberjacks busy felling giant evergreens with axes and massive pull saws.
While those images may be outdated, timber harvesting is still a multi-billion dollar industry. It employs tens of thousands of people in Oregon alone. And it’s way more high-tech than you might imagine.
I’m Owen Perry, and today we’ll be talking about research at Oregon State that is helping to make current harvesting practices safer.
NARRATOR: From the College of Engineering at Oregon State University, this is Engineering Out Loud.
PERRY: Decades ago, axes gave way to chainsaws as the primary tool of the lumberjack. But today, even chainsaws seem antiquated when you see a mechanical timber harvester in action.
PERRY: Picture an excavator you might see on a construction site, but instead of a shovel at the end of the boom, there’s a large claw and chainsaw combination called a harvesting head. The claw grabs a tree at the base and the saw comes in, cutting the tree down just inches from the ground, and wheels feed the trunk past knives that remove its limbs—leaving a nice, processed log. You can check out the show notes for this episode for a link to a video of a harvester in action.
All of this action is controlled from the other end of the boom by an operator sitting in the relative comfort of a heated and cooled cab.
Timber harvesters were first introduced in Europe in the 1970s, and their use spread quickly across the globe. It’s not hard to see why.
NATHAN FRECHEN: In the span of 30 seconds, it can take a 100-foot Douglas Fir from standing into 40-foot logs that can then be loaded onto a truck and taken away.
PERRY: That’s Nathan Frechen.
FRECHEN: I am one of the product design engineers in the Blount Forestry Design Group.
PERRY: Blount International manufactures saw chains and other equipment for the forestry, agriculture, and construction industries. For this story, we’re just going to focus on timber harvesters, and more specifically, the chainsaws on the harvester heads and how researchers at Oregon State University are working with Blount to make them safer.
JOHN PARMIGIANI: My name is John Parmigiani. I'm a Research Associate Professor at Oregon State University. I was the principal investigator on this project. I think a lot of times when we think of chainsaws, we think of something that has a bar that's maybe two feet long. These tend to be bigger than that.
Everything is kind of taken up to another level of bigger components that are moving faster with greater forces. And that's largely why you have this possibility of the saw chain breaking.
PERRY: It’s very rare, but occasionally, the saw can run into a rock or piece of equipment, breaking the chain. The broken chain can whip out with enough force that a secondary break may occur, potentially sending a smaller section of chain through the air at speeds exceeding 300 meters per second. And that presents the potential for serious injury to anyone nearby.
Blount is determined to work towards understanding the factors that can lead to these incidents, and to making improvements wherever possible. To do that, they first need to understand exactly what happens when a chain breaks.
The instigator of this project is Mike Harfst, the director of engineering for Blount’s Forestry Product Design Group.
MIKE HARFST: The project itself was to research the physics of the accident, to understand it, to characterize it, to build a machine to replicate it, simulate it, and then be able to distinguish some of the features and physics of the actual event themselves, when it occurs, all for the purpose of being able to use it do design safer products.
PERRY: Blount had already worked on a number of projects with John Parmigiani, so he was an obvious choice to partner with on the project.
HARFST: The sort of parameters of the project require that we have a fairly heavy dose of high-level engineering as well as a very capable group of people designing the actual test fixture itself, which seemed to be very well-suited to the OSU Engineering Department, where they had access to a wide range of different people that had skill sets that they were developing, as well as having access to John, who would be able to oversee and manage the high-level physics and engineering in development of the understanding of the events.
PARMIGIANI: When we started this project, the biggest concern that I had was to make sure that it was safe. And one of the first ideas, I think it might have been Mike's idea, was to build the machine in a shipping container. We pursued that idea; we made it safe by lining it with a layer of steel, and on top of the steel a layer of polyethylene. So, a plastic layer over top of the steel.
PARMIGIANI: That's really where things got started, was getting ourselves a safe environment to build the machine that was actually going to fracture the chain.
PERRY: Once they had a safe testing environment designed, the next question was where were they actually going build it.
PARMIGIANI: This example that we're talking with this chain-shot, the example of the chain-shot machine, is physically the biggest machine I've built. It's the size of a 20-foot long shipping container.
PERRY: Luckily, the team had access to ATAMI, the Advanced Technology and Manufacturing Institute, Oregon State University’s 80,000 square foot research and development facility.
PARMIGIANI: Being able to go to ATAMI and have a shipping container inside a building, it's readily accessible space, there's support there, we needed a high-speed camera, they have a high-speed camera. We needed some machine tools, they have machine tools. So, having access to that open space really was a key. I don't know what we would have done otherwise, just put it on the Quad or something.
PERRY: So, safety, check. Location, check.
Now the team got to work actually building a device to recreate a chain break inside the shipping container.
PARMIGIANI: We designed it so that it used the same components that would go on a harvester that was used in the field. You can use the same bars, the same chains, the same sprockets, that are used in the field and attached to the machine.
What we essentially did was we made a drive module that fits inside the shipping container, that will propel the chain around a bar. It's heavily instrumented so that we can measure all the technical qualities that are relevant for the problem. And then we use a method of driving a pin into the moving chain to suddenly stop it, and this suddenly stopping it causes it to break once. And then as the chain’s moving through the air, the broken section of the chain is moving through the air, the dynamic loads on it cause it to break a second time, and create a projectile.
PERRY: That projectile will embed itself in the plastic lining of the shipping container. Once the machine is safely powered down, the team can enter and recover the broken section. Later, they’ll perform metallurgical analysis. That data, combined with high-speed camera footage and other measurements from instruments inside the container will help determine how and why the break occurred.
Parmigiani and his team completed the machine in the fall of 2017, and it was recently relocated to Blount’s Portland facility. After a few upgrades, they’ll take over the testing.
HARFST: What we'll be doing after we begin to use the machine on a full time basis will be to increase our understanding of different reactions of different products. We would anticipate that within a couple of years, we will have moved the state of the art of these products to a higher level, which as I said before, is all oriented towards safety--how this will impact harvesting machine design, guardings, windshields, things like that. We will be using that data for quite a few different activities for a long time.
We would add also that we actually were surprised at the number of students that were involved in it. And we viewed the machine at different times down in Corvallis as well as after it got here, and from our end, we enjoy having the students working on these projects. It's great to see the youth and the enthusiasm and the excitement that goes into a lot of this stuff. It kind of reminds us what it's like to be connected to the people that are just starting their careers.
PARMIGIANI: I'd like just to add some comments from the student perspective in the sense that this project is going to project the research and the substance for two Master's degrees, for two of our students. And I'd have to check to get the count, but there's been a number of undergraduates that have gotten some real industrial experience on this project. I think it's something, 10 to 15 students that worked on this. Just for example, we had one undergraduate came in and was really a lead on that initial testing to verify that the combination of steel and high-density polyethylene would in fact stop a chain-shot projectile. And then was a nice sub-project for the student to get some real-world experience. There was another student that got involved in-- there's a framework that fits inside the shipping container, that holds the steel and the plastic lining, and he designed that and coordinated with the vendor to make sure delivery happened when it needed to happen. So he had the sub-project of experience. And there's just, I could list 6 or 8 more such scenarios, where undergraduates got a small project but it was a real-world project, and they got some industry contact, and got some exposure to exactly the kind of skills they're going to need when they get out and be a practicing engineer.
PERRY: Thanks for listening today. I hope you enjoyed learning about how this partnership with Blount is not only improving safety for the timber industry but giving our students valuable real-world experiences.
Special thanks to Mike and Nathan from Blount for agreeing to talk to us. We’ll include a link to their website in the show notes for you to learn more about mechanical timber harvesting as well as links to videos of harvesters in action.
This episode was produced and hosted by me, Owen Perry, with audio editing by Brian Blythe. Our intro music is “The Ether Bunny” by Eyes Closed Audio on SoundCloud and used with permission of a Creative Commons attribution license. Other music and effects in this episode were also used with appropriate licenses. You can find the links on our website. For more episodes, visit engineeringoutloud.oregonstate.edu or subscribe by searching “Engineering Out Loud” on your favorite podcast app.