Chip Length Is Set at the Knife, Not the Motor: Sizing a 6–8 t/h Drum Chipper Line — Weiwei Machinery - Product knowledge

Most buyers start the conversation with kilowatts, and that is the first thing to move past. A chipper is a size-reduction machine working inside a narrow window: feed it something it cannot swallow and it stalls, feed it too slowly and you have paid for 90 kW and used 40. The 217 drum chipper is rated at 6–8 t/h, and whether you see 6 or 8 depends far more on how the material is presented to the drum than on the nameplate.

The machine itself is a 650 mm drum running at 580 rpm inside a steel housing, with a feed opening of 700 × 400 mm and a maximum log diameter of around 200 mm. Chips come out at 30–50 mm, and that figure is not fixed: it is set by the knife protrusion and by the screen under the drum, so moving from a boiler that wants 30 mm to a gasifier that wants something coarser is a knife adjustment rather than a new machine. What makes it a line rather than a machine is what sits on either side. A 5 m infeed conveyor brings branches and offcuts up to the feed opening, and a powered feed roller pulls them in and holds them against the drum — without that roller, long thin material bounces and comes back at the operator. On the outlet side a 650 mm belt carries chips 10 m away to a pile or a trailer, which is the difference between a machine you can run continuously and one you have to stop every twenty minutes to shovel clear.

Power is split across five motors, and buyers should look at all of them rather than the headline figure: 90 kW on the main drum, 5.5 kW on the infeed conveyor, 5.5 kW on the feed roller, 4 kW on the discharge belt and 1.5 kW on the hydraulic pump that opens the housing for knife changes. That hydraulic opening is not a luxury — a drum chipper needs its knives checked far more often than a hammer mill needs its hammers, and a housing that has to be unbolted by hand is a housing that stays shut.

Starting a 90 kW motor direct-on-line is what makes people think they need a bigger transformer than they do. This machine starts star-delta, which cuts the starting current to roughly a third and lets it run from a supply that would not otherwise carry it. The conveyors, the feed roller and the emergency stop are all on a remote handset, so one operator can load at the infeed and still watch the discharge.

Zhengzhou Weiwei Machinery has been manufacturing wood and biomass machinery since 1980, with CE and ISO 9001 certification. Tell us the log diameter, the tonnage per shift and the chip size your boiler specifies, and we will confirm the drum speed and screen before quoting, because the wrong screen is the most expensive cheap decision in chipping. Full details are on www.weiweimachinery.com.

90kw wood chipper