A couple of weeks ago I spent a very pleasant week down in Fort Lauderdale, and while enjoying a drink with far too many bits of fruit and umbrellas for me to be completely comfortable, I found myself looking over at a beach-front store covered with buckets, shovels, towels and the like. Looking at all this plastic hanging on the wall got me thinking about the new SolidWorks Plastics module and the engineering aspects of a beach shovel. I started to think "how SolidWorks could help me design the optimum beach shovel?"
Once I got back to the office I fired up SolidWorks (for some strange reason my wife banned the use of SolidWorks on holiday), and in short order I’d built a rough beach shovel surface model. Now, in order to design the best beach shovel I could, I was going to use all the tools at my disposal as early as possible in the design process. Because the later you use your engineering analysis or design tools the more expensive any change is and the few design choices you have.
Using a surface model allows for quick analysis to optimize the material selection, wall thickness and rib placement for both its structural strength and manufacturability. The first step is to find out how good (or bad) my first design is. SolidWorks Simulation lets me know that although the stress in the shovel is almost good enough ( I would prefer it lower to give me a greater factor of safety), the shovel is too flexible.
So it’s time for a quick redesign, thickening up the wall thickness and adding some stiffening ribs (shown in grey). Re-running the analysis shows that my new design has almost overcome the flexibility problem, but before I spend too much time on this I need more data to guide me in the design process.
The shovel would almost certainly be made by plastic mold injection, so before I spend too much time on structural analysis, I should double check to see if my design can even be molded. The first check I am going to carry out with SolidWorks Plastics is to see if my chosen material can fill the cavity required to make my part.
Straight away we can see we have a ‘short shot.’ The combination of material and geometry has resulted in the plastic freezing before the cavity was filled. We can also see that where we put the injection gate would result in a weld line (where two fronts of plastic merge) weakness. So I am going to have to both move the injection gate and adjust the handle / rib wall thicknesses to make my design moldable. The SolidWorks Plastics solvers are so fast that in short order I have my new design validated, and the plastic now completely fills the part.
I now have a full 3D model of my shovel, but as the design has changed since the last structural analysis, it is prudent to re-run the simulation just to double check our answers.
As you would expect by increasing the wall thickness for mold ability, you have increased the structural strength as well. So now we have a good initial design, and it’s not ready for manufacture yet, but SolidWorks can help with the ability to check the part draft, generate parting lines for the mold, ect.
Design is not a discrete function--all products have multiple design goals and constraints even something as simple as a beach shovel. SolidWorks has the tools to help you do your jobs, and if you use them often and early in the design process, you will end up with a robust design that meets your customers’ expectations and delivers value to your company.
SolidWorks Plastics 2012 is currently available in North America, with other regions and countries to follow later this year. Visit our website to learn more about SolidWorks Plastics and to watch our First Look: SolidWorks Plastics video.