Time to read: 7 min
Aesthetic design is in the eye of the beholder, but functional prototypes have a different standard—testing—and for most of us, exam day has never been something to which we look forward. However, test day doesn’t have to fill you with the fear you felt going into high school Calculus exams: By setting clear design expectations ahead of time and doing a series of small evaluations as the design is developed, you can approach the final design tests with a smile. Here’s how to take the dread out of test day.
Begin with the End in Mind: Your Requirements Document
设计需要做什么？您怎么知道它是否实现了这个目标？您的requirements document应该是具体的，并包括测试标准以验证每种要求。
For instance, let’s say you’re creating a case, andit needs to be waterproof。说一个案例本身就是“防水”是一个几乎毫无意义的要求。这是否意味着可以承受雨水？如果您将其放在游泳池中怎么办？你能参加深海潜水吗？
Waterproof can mean any of these things, but you’ll need to note to what level you’ll be testing and what the goal is. This level of granularity in your requirements, before you ever begin working on the design, won’t just help with making test day easier; it will also help you steer your design decisions.
And if you’re not quite sure how severe to make your tests, consider deferring to an international standard: ASTM has hundreds of different test standards, covering everything from hardness to UV resistance to drop resistance. Just try googling “ASTM standard” and whatever area you’re thinking of; you’ll be sure to get more detail than you thought possible.
有了罕见的要求，您可能需要更具创造力。在上面的案例示例中，我们还说一个要求之一是按钮需要设计for activation by someone wearing gloves. That’s a nebulous requirement, but you can do some experiments ahead of time on minimum size, minimum protrusion, and maximum depth of activation, which allows that to be easy, then incorporate those findings into the requirements document.
这不是所有你之前很多工作要做begin your design? Well, yes. But it’s much less work than completely throwing away a design and restarting because your design doesn’t function well. Just like in high school Calculus, the key to making exam day easy is front-loading the work earlier in the semester. (Suddenly, I sound like my parents.)
Testing Design Elements
And speaking of front-loading work (because apparently, I’m old enough to lecture on that now), another way to make final tests more predictable is to test each element of your design separately. Waiting till you have a complete design and then running all the tests is an almost surefire recipe for failure. Instead, look at each function of the design, and ask how you can test just that function, or even just that function on one area.
Going back to the waterproof case design, if you wanted to create a new GoPro housing, you would want to separate out each unique button design and test that for waterproofness separately, and then create a case with no buttons to test how waterproof the main seal is. If you test it all at once and have a leak, you’ll have no idea which area to improve; by testing the elements out one at a time, you can perfect each element separately before testing the whole.
In the same way, tease apart the functions. You don’t need to do a drop test on the fully assembled hundred-thousand-dollar-with-functioning-electronics version of your company’s new product and shatter all the hard work of the electronics team (unless you have an enemy over there at whom you need to get back, in which case, shatter away, and maybe add in a sledge-hammer test, too); drop test just the mechanical housing to see how it holds up, first, before seeing how it dampens the electronics.
Less dramatic tests benefit from sectioning, too. On a recent housing, my client wanted a very specific feel for thesnap-fit closuresfor the case, but there was no reason to print out the entire, large case for each test: We cut just the ends of the case, with the snap fits, and have been running tests on geometry for just those parts, saving hundreds and still getting the function just right.
即使是非技术测试，您也可以做类似的事情。最终的原型真是令人惊讶，可以真正获得设计的感觉，但是一旦您获得了团队的批准，以了解设计的感觉和美学CAD型号和渲染，尝试便宜3D打印to make sure you haven’t missed anything before you get too far into the design.
Sectioning your parts and function tests does bring up a small conundrum, though: Each of these tests would likely benefit from a different material. How do you choose what to material to use for your prototypes?
为您的测试选择材料
一般知识3D打印ed materials不仅可以为每个原型测试选择材料，还可以帮助您设计测试本身。虽然您总是可以直接跳入测试最昂贵，最逼真的材料，但仔细的选择可以节省您的公司大量资金。
For a general form test, such as for size and shape,FDMmakes very fast turnaround parts that cost almost nothing. You can print and iterate several times within a week and get the design dialed in.
当您处理密封表面时，您将需要具有光滑的表面饰面，精细分辨率和足够刚度的材料来压缩密封。对于初始测试，您可以使用SLA或PolyJet，但是一旦您准备好进行关键零件的最终测试，我建议您为CNC铣削parts—you’ll get the most reliablesealsandtolerances。
Snap-fits and similar springy geometry have an added challenge: The material must be very similar to the final manufactured product to get meaningful results. For geometry like this, you’ll need to carefully examine thematerial data sheets, paying especially close attention to the modulus of elasticity and strength numbers, and find a material similar to what you plan to use in manufacturing.
So now you’ve created clear test plans, separated parts of your design for different tests, and printed or machined those prototypes in the right materials. What’s next? It’s time to run some tests.
跑步和记录测试
Running tests may look very much like a college lab, or even a full-blown government facility run, but it doesn’t always need to: Just as often, a garage-style test will give you the information you need. To decide how “NASA” you need to be, consider the goal and audience for your tests.
这项测试是否满足了财富500强公司的安全和责任问题？GO Full NASA：遵循实验室环境中字母的适当测试标准，并使用视频和手写音符记录测试的每个部分，并用被动语音，第三人称风格的硬性实验室笔记本编写。
但是，如果这是新产品的早期开发阶段，没有真正的安全问题，其中测试不需要复杂的设备（例如在拉伸测试或缺口冲击测试中），请考虑将更适合水平的东西放在一起。我最近的大多数测试都用iPhone或GoPro录制，并且我在游泳池和海滨码头上进行了防水测试。满足了关键要求（正确的深度和持续时间），但成本小于类似实验室测试的1/20。
Talk with your team and end client about what’s really required for your tests, and also keep in mind that you may need to perform different levels of testing as the product develops, performing quick desktop tests on form and function early in the design process and more thorough and formal tests while finalizing your design for production. Throwing a small housing into the watercooler may be fine for your initial test (to my old coworkers who may be reading this, I would just like to reiterate that though it was my housing, it wasn’t me—really), but you may also need to bring in a NIST-certified lab to test your final design.
了解测试结果
If you’ve set up your tests and requirements well, then you have a clear pass/fail standard for each test. For instance, for IP testing, the standard states “no visible ingress”, so if you open up your case after the test and there’s no water inside, you’ve passed. Like Tolstoy’s families, every pass result passes in the same way, but each failure fails uniquely, and you’ll need to take some time post-test to try to understand what went wrong. Fortunately, your tests and failures should provide clues.
For waterproof testing, hopefully you’ve already sectioned each element, so if the design does leak, you’ll know exactly which part is failing. When that happens, go back over the design carefully, and make sure you have good, smooth surfaces in contact with gaskets, and ensure that the geometry is giving you sufficient compression. By examining the design and comparing it with best design practices, you’ll typically find the flaw.
And it’s the same for other tests: if you know how to design it, then you should have a good idea of where to look for the failure. Don’t hesitate to dig deep, too, with full measurement inspections and even microscopic examinations of material failures.
Once you’ve pinpointed the issue, you’ll need to design around it and begin the test again. This can seem discouraging, but keep in mind that it’s completely normal: Great designs aren’t born, they evolve.
Testing Your Design
如今，通过快速的周转3D打印，您可以在此过程中测试设计的每个元素，并且还具有廉价，功能齐全的原型来测试。只需将每个测试都与特定的设计要求绑定在一起，并记住要将不同的区域分开以进行小型测试，那么大型测试的一天将变得轻而易举。
Does your boss need a look at setting up a clear requirements document? Send over a copy of this article to get her started.
Or are you ready to get started with your first test? Take a look at ourCapabilities Guide，然后前往我们3D打印ingandCNC machining servicespages to get your first part by tomorrow!
