24 - Which criteria need to be considered for material flow?
The set-up of an economically sustainable as well as technically sensible material supply concepts start with the storage of the source material. The storage concept must meet specific criteria that are dictated by the supplied production line and the required throughput.
Injection moulding production with multiple material changes requires different planning than, for example, extrusion of multilayer films or compounding or large and small batches of specific polymers. Dependent on this are the number of stored materials and the required amounts. Silos are more economic if storing small containers (sacks of 25kg/container) or bulk material (BigBags, octabins of up to 1000kg). Silos are divided into full chamber silos, multiple chamber silos with up to 4 chambers, and mixed silos. In addition, the internal logistic of the day bins and the material supply stations need to be considered as required.
Further decision criteria such as required floor space, consideration of level of automation and transport distances, which influence the handling costs, and cleanliness and hygiene aspects (keyword: medical technology) arise from this. The disposal of packaging must also be considered. Safety aspects such as dust emissions or inflammability should not be disregarded.
The material properties influence storage and later conveying. The most important factor for hygroscopic plastics moisture absorption, which can be particularly problematic in summer. A suitable preventative solution for material stored in boxes is blanketing with dry air.
The flow behaviour is also a material property that depends on the type of material, for example if using granulate, flakes, powder, regrind or fibres. One must take into account whether bulk material is free or poor flowing, if it is sticky lumped or agglomerated, or if it behaves bridgingly. Some materials tend to compact due to their heavy bulk weight. Materials with a very low softening temperature can already soften in the dosing screw and sleeve due to frictional heat. These difficulties in conveying and dosing can easily be overcome with the appropriate measures.
How can storage look in practice? For equipment and more visit www.motan.com