时间阅读时间：9分钟
我们喜欢发明和设计发展过程。我们喜欢看到概念融合在一起，喜欢通过迭代的迭代工作prototypes最后（最后！）恰到好处的设计，履行所有技术和审美要求。但你知道更好的是什么吗？以满量程查看您的设计生产。
Unfortunately, once your design is beautiful and working well, that’s only half the battle won. For most塑料部分s, you’ll need the design to be injection molded, which is the most common low-cost technology for producing large numbers of plastic parts. (Rarely, for very specific geometry, parts aremilled with CNC, but that usually costs 50-100 times as much per part.) And that comes with its own set of specific requirements, or you could be looking at $100,000 molds for your parts. But never fear! With the design guidelines below, you can keep tooling costs low and still have your design looking as beautiful as ever.
但在我们进入如何调整你的细节之前3D printed design对于注塑成型，让我们首先看看制造过程：注射成型如何工作？
注塑成型Basics
在它的核心，injection molding很简单：两个大型金属模具一半一起走到一起，一个plastic或者rubbermaterial is injected into the cavity they form, it all cools, and then the part pops out while the two halves separate again. Repeat ten thousand times, and you have your first run of parts ready for marketing. (Quick note on terms: The direction in which the molds move is called the “mold pull”, while the line around the part where the two halves meet is called the “parting line”.)
In practice, it can get more complicated. Generally, even though the plastic materials being injected are melted, they aren’t really heated: The material is pressed into the injection ports (called gates) via a large auger screw. As the material is compressed, it heats and begins to flow into the molds.
And the molds themselves have to be “negatives” of the part being molded, and that geometry can get quite complex. If you look at a very simple red cup, the kind we all played beer pong with in college, you can see how the interior of the cup would be formed with geometry from one half of the mold, while the exterior is formed from the other half. That’s about as simple as it gets, and already you have a large cone of material from one side protruding into the other.
As the shapes being produced become more complex, the molds get more complicated, too. Instead of the classic red cup, imagine a simple plastic coffee mug. The interior comes from one mold, the exterior comes from another—but wait! What about the handle?
当部分几何形状不能从一条直线一起形成的两个模具形成时，模具需要有“动作”：“幻灯片”（从侧面进入的模具的碎片）这个视频) or “screws” (parts of the mold which twist into place). With mold action, very complex shapes can be formed, including线程用于螺母和螺丝。但这种多功能性出现了价格：通常在简单的“直拉”模具和带有动作的人之间的价格差异差异。
在花式模具工具上的那种价格标签，花时间设计零件易于成型。几何形状会导致问题，以及哪些设计将使您的首席会计师突破他的令人愉快的书呆子笑容？
Preparing Your Design for Easy Molding
The biggest rule for reducing cost in mold tooling is this: Avoid削减。Undercuts are when one part of the geometry is underneath another, when that part of the geometry can’t be formed with either mold half or will keep the part stuck in the mold.
For example, look at a common feature:snap fits。The snap fit on the left can’t be formed by a simple injection mold in this case because the underside of the snap fit isn’t accessible from the bottom—the other part of the case is in the way. To fix this, we can cut away a little material from the case, as in the picture on the right, and then the snap can be formed easily.
当我们评估设计时，我们经常想象这件作品在一张玻璃桌上，一个光线从下面发光，另一个光线从上面发光。如果灯触摸件的每个表面，那么它易于模具;如果任何区域都在阴影中，那么它是一个底切，我会找到一种方法来重新设计该地区。
在模塑中思考的另一件事是一旦将其冷却并且模具分开，部分就会容易地从模具中释放。几个几何形状将使零件容易释放，使模塑困难，并增加循环时间，并最终是每份成本。
Whenever possible, if you have straight sides on your part that are in the same direction as the mold pull, you’ll need to add a small amount of draft or taper to the part. Like with the red cups, having the parts taper a little makes them release from the mold more easily, and when appearance is critical, that taper can be as little as one to two degrees, which is barely noticeable, but the longer the straight sides are, the higher the draft angle will need to be.
同样，尖角倾向于被粘在模具中，因此您应该将鱼片添加到模塑部件的所有角落中。一个例外是角落也是分开线（模具的两半在一起）;因为角落由模具两种不同的部件形成，所以可以保持角落锋利。
在喷射和喷射之间进行冷却，并指示更多的几何形状。一旦填充腔，部分将开始冷却，并且冷却从外部开始，几乎立即从外部开始在材料上形成皮肤。随着部分冷却，它会缩小。如果零件上的所有区域具有相似的厚度，那么部分将在弹出时均匀地缩小并看起来很好。
但是，如果该部件有一些非常厚的区域和非常薄的区域，那么薄区域将冷却并先硬化，而厚区域仍在冷却。因为这种几何形状周围的薄区域已经冷却，并且皮肤已经形成在部分表面上，因为熔融中心冷却并收缩它将吸收表面，导致沉降标记 - 未吸引人的光滑表面上的沉降部分。
To avoid sink marks, keep the thickness of material relatively uniform throughout your part, no more than a ratio of two to three between the thin and thick sections, and don’t transition suddenly from a thin to thick area.
最后，当您设计零件时，尝试可视化顶部模具一半将形成哪个表面，该表面将由底部模具一半形成，并且当这些模具半部相遇时，该表面恰好是分散线的位置。这需要练习井，但使模制过程基本上更容易。
虽然上面的设计规则将涵盖大部分部件设计，但有时产品对于单件的简单成型来说太复杂，对于那些您需要看的设计......
Sectioning Complex Geometry
Take a look at the picture below, a golf swing training device (the “swing coach club”) I helped a client design a few years ago. Obviously, with the hollow interior going in a different direction than the shaft mount, this wasn’t going to be an easy part to manufacture. Worse, inside the club head is a latch for the ball cradle (the blue piece), and the lines across the face are undercut. So how did we prepare the design for injection molding? Sectioning.
我们不能尝试将整个头作为单件塑造成单件，而是将头部几何形状切成三个单独的碎片，然后在模制后超声焊接在一起。头部的底部和轴安装件是一件，以及支架的闩锁，模具拉方向与轴相同。对于沿外边缘的那些重量的切割线和安装圆筒以及沿着外边缘的凹槽，是单独的件，模具垂直于面部拉，而壳体的顶部是第三件。
虽然这种方式切断件似乎是一个复杂的设计问题，但这通常是获得右侧美学和功能的设计的唯一方法。即使我们有三件而不是一个，那么工具和成型仍然比设计模具的成本更便宜，而设计将需要设计。
Obviously, though, when you make changes this drastic to your design, you’ll have to make new prototypes to test out the new geometry, which brings us to…
使用3D打印测试您更新的设计
Again, you ask? I know, I know! You thought you were past this part. But inevitably, as you alter your design for easier molding, you’ll end up making significant changes which will require further prototype testing. In addition to the changes above, you’ll also need to make sure that you’ve allowed clearance between assembled or sectioned parts, so that they come together smoothly.
为了测试所有这些，我们建议使用尽可能靠近模塑的材料，特别是考虑tolerances和surface finish。大多数注塑成型部件都有0.010-0.020英寸的标称（虽然您可以指定更近，更昂贵的公差）并具有光滑的表面饰面。这些条件的最接近近似值是PolyJet printing，各种塑料可用方法是手段，您可以选择一种密切近似的材料力量和僵硬of your final parts.
通过调整和测试的几何，您可以直接移动到注塑成型。但是，大多数注塑公司将需要初始运行5,000至10,000份，并且您必须在开始之前从2,000-2000美元的任何地方支付2,000-2000美元（每件事）。如果你还没准备好提交一个大的订单，怎么办？
Low-Volume Production
Between the stages of prototype testing with 3D prints and full-scale manufacturing lies a happy medium:氨基甲酸酯铸造。该过程类似于注塑 - 两个模具一半，材料流入腔体，然后零件弹出 - 但是用室温材料和软模具。然而，大的不同是在工具的成本和制造运行的规模：工具通常会是十分之一的价格，你可以像你一样小的零件运行（通常在20-500件范围内）。
When you’re preparing parts for氨基甲酸酯铸造, all the design geometries are the same, and so many companies have used urethane casting for decades as a way to test out part in pilot builds before committing to the full tooling and production costs of injection molding. These days, with so many products going throughcrowd funding, urethane casting can allow you to satisfy your backers with real parts, without needing to set an enormous funding goal. Check out theFictiv urethane casting info pagefor more information.
踩到注射成型世界
So now you’ve adjusted your design for easy injection molding, sectioned apart the pieces which couldn’t be adapted, tested out all the new designs in a high-quality print, and even run a pilot of the new design in urethane casting—what’s next? Now, you’re ready to run with the big dogs: It’s time to get quotes on injection molding your design.
Check out our website tolearn more about Fictiv’s injection molding service capabilities和to get a rapid quote for injection molding with low minimum order quantities,create your free Fictiv account here。
