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Re: Clamp force calcualtion
Jshoe,
Here is a list I had compiled about a year ago of common resins and High and Low Tonnage factors, these are all Tons/sq. in.
For your TPE question, Depending on wall thickness and what not, the range would be between 3 and 6 Tons/ sq. in. A lot of this information is not provided by resin suppliers, but some deep google searching and free time allowed me to create this reference.
However, the best way I found for a more accurate calculation is if you have Cavity Pressure Transducers in your tools.
That formula is
Proj. Area X # of Cavities = Total Proj. Area
[Total Proj. Area (sq. in.) X Max Cavity Pressure (psi)]/ 2000 (lb/Ton) = Tonnage required.
Tonnage Required X 1.3 (safety factor of 30% for viscosity changes) = Your Set Tonnage.
Let me know if you have other questions. Keep on molding!
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Re: Clamp force calcualtion
Amount of pressure exerted on parting line depends on fill speed, melt temperature, and pack pressure. Surely if you pack parts at 1,000 psi the effective pressure at end of fill is much less in most cases!
3 tons per square inch is a good starting point
If there's a tricky 3 plate mold, mechanical slides, or core pulls clamping a little tighter isn't a bad idea!
A sound method is to start at high tonnage, and slowly come down until you see very minor flash, then add 10% or so of that final tonnage.
I've found it's best to set tonnage somewhat on the lighter side of the window so when tooling adjustments are made you can always come up in tonnage if needed.
Cheers! :)