When it comes to the world of consumable products, most experts know that economies of scale are everything. Whether they be food containers or medical supplies, producing these items quickly and cheaply enough in order to be enjoyed by the world’s population is only possible with mass production and the technologies that make it possible, such as plastic injection molding.
As if producing vast quantities of products wasn’t already challenging enough, the world’s supply chains have faced an unprecedented challenge in the face of the 2020 novel coronavirus pandemic. Shortages have cropped up in everything from bottled water to toiletries, and of course medical equipment.
Most companies manufacturing plastic products probably don’t plan on making changes to their process during times of high demand, but unfortunately the current crisis has mandated just that. For example, supplies of many common plastics, such as the PET used in viral testing kits, have occasionally run low.
Planning for Production
In that type of environment, coming up with a new solution quickly is critical for maintaining a steady supply of products, and searching for alternative materials is one area where injection molding simulation software like SOLIDWORKS Plastics can help.
Running directly from within the SOLIDWORKS environment, this add-in can simulate the mold filling process on any solid-body part file, either native or imported. The only necessary inputs are the material and gate location on the part:
The Fill analysis run on this blood vial shows that the existing design works fine. The Results Advisor states it will fill in the desired time of 0.5 seconds, with a low injection molding pressure. But what would happen to production if this grade of Ultrablend PET were to run out, and the molder was forced to find to an alternative?
The polymer library in SOLIDWORKS Plastics has roughly 4,700 thermoplastic materials (and counting). Finding another option isn’t too hard, especially taking advantage of the material search tool. In this case, it appears BASF also has a similar plastic available, Ultrablend KR 4084.
By duplicating the study and re-running the analysis with this material, we can see what will happen. A few moments later, the study completes, and the Results Advisor gives us a summary.
Unfortunately, this grade of PET has slightly lower viscosity, just enough to raise the required molding pressure, triggering a warning. Even though we haven’t exceeded the specified limit of the machine, this amount of pressure could become an issue once we design a large multi-cavity mold with the required runner system, or if the mold starts to wear out after long hours of constant production.
In order to find another solution, we can try a design change (such as modifying the wall thickness or other features), again taking advantage of the Duplicate function. We can also change the gate design. By adding a split line feature to the top of the part, we can select that area to be the new injection location and see if it brings the pressure back down.
Success! We now have a setup that will work with the new material. We can also decide if this change has introduced other negative qualities to the product, such as weld lines, and try out other ideas before we take a risk on reworking the mold.
The best part of SOLIDWORKS Plastics is that this kind of fill analysis can be done with any license of the program, with minimal setup, so that you can run these simulations every time you make a change to a part. When you’re ready to go deeper, such as optimizing the runner or cooling system in the mold, an upgrade beyond SOLIDWORKS Plastics Standard is always available.