This is part two of a multi-part series covering how medical device firm Southmedic used virtual simulation technology to bring OxyArm, the first open oxygen delivery system, to market. Part one, discussing how flow simulation determined optimal airflow and predicted real-world performance can be accessed here.
Now that we understand how the OxyArm will deliver air and react to its operational environment, it’s time to consider which plastic materials best suit the design. In this post we’ll run through a number of factors that will influence decision making. It’s certainly a decision that should not be taken lightly as choosing the right materials can be the difference between a winning product and an expensive boat anchor.
When you approach a design like the OxyArm you need to think of how the product will go to market. In this case, Southmedic wants to manufacture these on a large scale. This means selecting a material to maximize throughput. In other words, you want to make as many OxyArms possible as quickly as possible. Sounds simple enough right?
Well to make this a reality, we need to consider which plastic materials can minimize fill and cooling times, avoid warpage and maintain uniformity. Minimizing fill and cooling times means the product can be produced at a faster rate. SOLIDWORKS Plastics allows us to investigate weld lines, shrinkage, air traps and venting to ensure we minimize and manufacturing defects. A very common defect is warping, which can cause parts to shrink and not meet specifications. This could result in problems with pieces not aligning. For consistency, we need to make sure all of these products appear as advertised. Imagine opening a can of Coke and you taste Pepsi. Every OxyArm should look, feel and work exactly the same.
To meet these requirements, four common plastic materials were analyzed for manufacturability. The purpose is to determine which material best fit the OxyArm from a plastic injection molding standpoint. Within SOLIDWORKS Plastics we evaluated ABS (acrylonitrile butadiene styrene), HDPE (high density polyethylene), PC (polycarbonate) and PP (polypropylene).
As you can see from the materials properties, HDPE topped out the list in fill and cool times as well as in shrinkage, making it the best material from an injection molding perspective.
We can also go one step further and evaluate cost to produce, product weight, and ecological concerns. For the OxyArm, we want to create a product that is cost-effective (isn’t this always the case?), lightweight (people are wearing the device) and is environmentally conscious. With SOLIDWORKS Sustainability we can again compare materials and determine the right fit for our needs.
From the materials library we can see that PP tops out weight and environmental impact categories, while HDPE leads in cost.Now we have insight into which material is best for manufacture, cost, weight, and ecological.
Thus far, HDPE and PP are the best material candidates, but there can be only one. In our next post, we’ll conduct a drop test to determine durability and come to a final conclusion on the best materials for the job.