Clamp Force Calculator
Sizing a press needs cavity pressure, which is the one number nobody has. Enter what you can read off the layout — part area, cavity count, runner — pick the resin, and this supplies a pressure band and sizes the press off the top of it.
Size the press at 7 US tons
560 mm² of projected area — 4 cavities plus the runner — needs 3.8 to 6.3 tons across the 600–1000 bar band, and the recommendation adds your 1.1× factor to the top of it.
Flash starts at the top of that band, not the middle, which is why the recommendation sizes off the high end. A press chosen on the low figure runs fine until the day somebody raises the pack pressure.
Why a band, and where it comes from
Cavity pressure is not injection pressure. It is what the melt actually reaches inside the cavity, a fraction of what the machine reads at the nozzle, and entering the nozzle figure here overstates the tonnage and quotes a bigger press than the part needs.
The band above is a typical range for the resin family and a rule of thumb rather than a specification — the real figure tracks flow length over wall thickness much more closely than it tracks the resin, so a long thin part can sit above it. Both fields are editable. If the part has been molded, a cavity transducer beats every estimate here; if it has not, a flow simulation will give you a better number than a table can.