Not all problems require the expense and complexity of FEA software. You can calculate many common mold design problems with programs that only require you to enter sizes, forces or other known quantities, including the following:
Reynolds Number to determine if your flow rate is turbulent or laminar. (Turbulent flow is important in cooling because it increases heat transfer. Laminar flow is important for hydraulic systems, so that the oil doesn’t absorb too much heat, which causes the oil viscosity to deteriorate).
Pressure lost through a waterline, bubbler, hose, cooling passage, etc.
How much a leader pin (core pin, ejector pin, etc.) will bend when a load is applied.
The thermal expansion for various materials that go through changes in temperature.
How much a screw, or any item in tension, will stretch.
The gallons per minute of hydraulic oil required to activate a hydraulic cylinder.
The amount a cylinder or cavity will expand due to internal pressure.
How much will a mold plate for a side action mold expand and deform due to molding pressure.
Trigonometric, electrical, production and machining problems and much more
Basically they are the problems that you can solve with a calculator, if you know or have time to find and solve the equations. This type of software organizes what a mold designer might have in his notebook binder and then automates the calculation, which reduces the risk of error.
This software acts like an intelligent calculator to solve deflection and stress in common geometric shapes (e.g., mold plates), long column buckling (e.g., ejector pins), and expansion and compression due to loading. Thermal expansion constants for various materials are available, as well as the ability to calculate the initial size, final size or the total expansion. You also can determine runner and gate sizes and shop calculations, such as effective cutting diameter, trigonometry, tooling ball dimensions, roll dimensions, etc.
These packages are very easy to use and require no training. They eliminate the drudgery and potential for errors, compared with manual calculations.
Simply choose the type of calculation you want, enter the information required and press calculate. The answers appear in a flash. They also can be a great source of reference information, such as hot runner checklists, galvanic tables, screw thread properties, three wire measurements, unit conversions, gate and runner sizes and material properties.
Calculating software is often used to check the output from an FEA package to make certain that the results make sense. For instance, while looking at the results of a cooling analysis it was noticed that there was only one Reynolds Number shown for a water bubbler inside a core pin. It was then asked, “Is that the inside of the bubbler or the outside?”
Using the calculator software, the flow rates shown on the FEA images were used to calculate the Reynolds Number inside the bubbler, calculate the equivalent hydraulic diameter between the bubbler and the drilled hole in the core, and finally the Reynolds Number of the area outside the bubbler.
Whatever your engineering calculation software requirements, choose the option that performs the type of analysis you need. Look at the training required and support needed, then after being shown that the software delivers what you need, use it.
Over-designing your molds is expensive, under-designing is more expensive and often disastrous. Under-design often results in a mold failure, and not all of them are repairable.
Molds are occasionally designed and built where the plates are not strong enough to withstand molding pressure. This is particularly true of “A-side” side-action molds, which results in flashed parting lines. Using the improper sizes for bubblers and holes results in unnecessary pressure losses or poor cooling, and can increase the cycle time.