From time-to-time. I’m asked about the differences between drum and disc style chippers. While there are some advantages in certain applications for the disc chipper in smaller ranges, this article focuses on where drum chippers excel. By the way, Morbark predominantly offers drum chippers with the exception of the 6″ and 8″ capacity TW Series disc chippers.
Let’s start with how well drum chippers are at handling large volumes of mixed, bulky material like brush and logs. They’re great for strong self-feeding and consistent throughput for big jobs with less prep work.
With a drum chipper, you spend less time trimming forks or straightening limbs before feeding. Whether you’re processing varied material such as crooked/ forked limbs, brush or large logs, there won’t be a need for significant pre-trimming. That means less prep work to get your jobs done faster. And with Morbark’s hydraulic lift/crush feature, you’ll have more than 1000lbs of additional crushing power to pull stubborn material through the feed wheels to the drum.
More material processed in less work time = less engine hours = less maintenance = more revenues earned.
When it comes to consistent power, drum chippers have you covered. Between Morbark’s auto-feed feature and the mass of the rotating drum, load variations from different wood thicknesses are smoothed out, ensuring steady power use. That means less wear on your engine. With a disc chipper, you’ll experience more noticeable load changes as knives engage depending on wood types.
Let’s talk about knives. The rotating drum pulls material inward and shears continuously as opposed to a spinning disc slicing material at a fixed point. This means less excessive wear on knives so they last longer. That said, drum chippers are more forgiving of dull knives and will continue to process material, even if the chip quality decreases, whereas disc chippers require sharper knives to function effectively.
The image below illustrates how a log approaches the drum and the knife slicing wood chips into the pocket on the edge of the anvil. When the drum spins around, chips are broadcast through and out of the chute. As you can see, the drum’s orientation and rotating motion pull material directly into the cutter, creating a strong, “no-push” feeding experience. The knives grabs, pulls, and shears material, whereas disc chippers often require more manual feeding.
Disc-style chippers use blades to crush wood into waste, slicing material into larger pieces before it’s broken into chips. Disc chippers can deliver more uniform cuts, depending on the size and quantity of the wood being fed and the sharpness of the knives.
While drum chippers may create slightly less uniform chips than discs (which are better for precise, uniform, small-diameter material), the drum is superior for high-volume, varied material, and heavy-duty, large-diameter wood. They also process most fibrous materials common in warmer climates much better than disc chippers
Disc chippers are often more energy-efficient for smaller loads, produce larger chips with potential for stringy ends, and are better for light to moderate use.
The Quick List of Drum Chipper Advantages
- Drum chippers handle large volumes of mixed, bulky material like brush, logs and heavy-duty, large-diameter wood..
- Drum chippers don’t require significant pre-trimming.
- Drum chippers offer smooth steady engine power regardless of load variations from different wood thicknesses.
- Less excessive wear on knives so they last longer.
- Drum chippers are more forgiving of dull knives and will continue to process material, even if the chip quality decreases
- and more.
Of course, there are many factors and variables to consider when you’re comparing drum chippers to disc chippers. In reality, they’re two, completely different chipping experiences with different outcomes based on the materials being fed.
The data in this article is pulled from my personal experience and from conversations with operators who’ve used both disc and drum chippers. For your unique needs, I would suggest you connect with a local chipper dealer and demo both model types. That way you can see for yourself how they operate and how one might be better suited to your workflow.
