The tonnage factor is derived from this thickness: 1.00 (1 mm and below 1.35, 3 mm 1.00, 5 mm and above 0.85). If the flow length is long, work near the upper end of the band.
The choice of series depends on the application as well as the tonnage — there are separate series for fast packaging, medical, PET and PVC.
If you have a 3D file of the part you do not need to measure the area — upload the STL on the 3D File tab and the projected area and volume are calculated automatically.
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.
During injection the melt generates a force that tries to open the mold. That force is the projected area of the part perpendicular to the parting line multiplied by the cavity pressure. The clamping force of the machine has to exceed it; otherwise the mold opens by a few microns and flash appears.
The coefficient falls in the 0.3 – 0.8 t/cm² band depending on the material and the type of part: low for easy-flowing materials (PE, PP), high for high-viscosity ones (PC, PMMA). The larger the flow length / wall thickness ratio, the higher the pressure needed — that is why thin-wall packaging sits near the upper end of the band. Fillers such as glass fiber raise the viscosity, so the additive content enters the calculation as a factor too. A safety margin of 10 – 20% is added to the result.
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.