The diameter of a drum chipper drum relative to the size of timber it is designed to chip is very important and while there are many factors that play into what actual size the engineers end up making the drum diameter on any machine, there are a few key points to consider when comparing options on the next purchase of your drum chipper.
The larger the size a chipper drum is takes up more space and room so this is obviously a key consideration when any design team is plotting out the dimensions for a mobile wood chipper. In a fixed chipper operation size is not so critical and we often see very large drums (up to 1.4m diameter and even more) in some high-productivity industrial applications, but when a chipper is to be track mounted or on a trailer of some description, size is definitely a critical consideration and as a result, quite often the chipper drum ends up being undersized for the job at hand!
Drum chippers cut the timber in a circular arc motion (via the outside circumference of the drum diameter) as opposed to a disk chipper which cuts the timber at a constant fixed angle (as we have already outlined in an earlier blog post – Disk Chippers Vs Drum Chippers, What’s the difference between the two?). As a result and to help you understand the concept better, if you picture the cutter drum side on as a clock face and imagine the timber is being fed into the drum from the right-hand-side then to obtain the ultimate cutter performance and minimize cutting vibrations etc, you would want the cutting action to be done between the 3-0’clock line and down to the 6-0’clock line which is in the lower-half of the drum arc. When the drum is cutting the in-feeding timber this way, it is working with the timber and predominately cutting with the grain which is far easier than cutting across the grain or even against the grain which a smaller diameter drum does if the timber is up to the 2-0’clock or even 1-0’clock height compared to the drum diameter. So a larger drum will cut the timber significantly better with a lot less vibrations than a small undersized drum and also take a lot less hp to cut the same diameter timber, which will ultimately ensure the chipper lasts longer and is also far more economical to run.
The other key feature of a larger chipper drum is the inherent stored-inertia that a bigger drum has when spinning compared to a smaller drum and this is basically the key ‘flywheel’ principle which all strong-performing wood chippers are built upon. While not easy to explain, wood chippers of any kind require a certain amount of flywheel momentum behind the cutter to ensure it doesn’t stall immediately as soon as timber is fed into it, and this is another key benefit of having a larger drum with mass behind it compared to a smaller, lighter weight cutter drum.
So in summary, yes a larger diameter cutter drum is better than a smaller size and the long-term implications over the life of a chipper can be huge in terms of ROI and chipper longevity!
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