What feeder for? Masterbatch.

The short answer is more of less any gravimetric feeder configuration may be used for masterbatch but typically it will be a single or twin screw feeder and sometimes a vibratory or rotating tube device.

Masterbatch is often the most critical and expensive ingredient in the end product “recipe” and accurate control is crucial. A high accuracy Brabender loss-in-weight system will give you this control. The pellet size and feedrate range will determine the best feeder choice.

Small pellets and low rates tend towards a single or sometimes a twin screw configuration but may also suit a vibratory feeder. Typically it is the low end of the feedrate range where most problems may arise as you try and control a flow that can be down to one or two pellets per second. Rotating tube feeders also work for these very low rates but then may struggle to speed up enough to meet the high end of the feed rate range required.

Lab tests will allow this best combination to be determined for each particular extrusion line and sometimes a number of screw sizes may be needed to cover applications which have a very wide operating requirement. In the most severe cases two feeders can be used, either side by side or by swapping the feeder installed on the loss in weight scale between product change overs.

Careful consideration of the installation of the feeder should is also necessary as vibration must be reduced as much as possible to allow low feedrate accuracy to be maintained. It is also key to consider any refilling needs and to provide a clear path from the outlet of the feeder to the extruder inlet.

Some examples of masterbatch feeders from Brabender include:

Single screw loss in weight

Twin screw loss in weight

Rotating tube loss in weight

We would love to help and can quickly arrange product trials of we need to. Please drop us a line or give us a call and we can make a recommendation for your process.