Hoppers & Feed Rolls
Having an efficient means to feed material is important to maximize the throughput of a granulator. For simple general purpose press side granulators a manual feed may be fine. But as throughput requirements increase a more automated solution may be in order. Also, part sizes and shapes will be a critical factor in determining the granulator input configuration.
The first decision to make is on what kind of hopper works best for the parts and materials being processed. Then, for thinner scrap it often makes sense to add a powered feed roll that meters material into the hopper at an optimal feed rate.
Choosing the right hopper design depends on the shapes of materials being processed. Obviously, the hopper needs to be large enough to accommodate the likely scrap forms. Also, will the hopper be fed manually or with a conveyor or some other form of automation? It’s also extremely important that the hopper is designed for safety to minimize the risk of injuries to operators.
Standard hoppers are intended for general purpose applications. Special hoppers can be designed for:
- Pipe or profile extrusions
- Film or sheet with manual feed or powered feed roll
- Bulky parts such as bumpers or gas tanks
- Conveyor feed
- Robot or sprue picker feeds
Feed rolls are used to automatically feed or meter thin materials you’d expect such sheet, films and flexible tubing. A very different application is with thermoformed materials – such as cups or other packaging products – for trim skeletons, edge trim or non-conforming parts. Often roll fed granulators will be integrated in-line with a thermoforming process to automatically reclaim trim skeletons and edge trim.
Historically feed rolls were designed to fit a single granulator model. However, newer designs can be integrated with a variety of granulators bringing much more flexibility to customize hoppers, in-feed chutes and feed roll orientation.
The feed roll is usually mounted to a box hopper on a granulator. A custom box hopper may be necessary for the application to meet the requirements for height and orientation. Some systems have both a feed roll and a second feed location for loose parts and other scrap. In-feed chutes can be used to direct material into the granulator while protecting operators from getting their hands caught in the feed rolls.