These calculations produce guide values; the final selection has to be based on the part geometry, the mold design and the data from the material manufacturer. For an assessment specific to your application, contact our technical support team.
The peripheral speed at the outer surface of the screw determines the shear load the material experiences. At the same rpm a large-diameter screw produces far more shear than a small one — which is why the limit is not the rpm but the peripheral speed.
Running above the limit accelerates thermal degradation and screw and barrel wear; with sensitive materials such as PVC and PC the limit is markedly lower.
The method, the formula and the limits of each tool are explained directly underneath it, and the explanation changes with the tab you select. The results are engineering guide values; for an assessment specific to your application when choosing the final machine and equipment, contact our technical team.