锁模力设定普遍性的误区

地狱男爵

Years ago, in a monthly article, that mymentor Bill Tobin wrote for a monthly magazine, he touched on the importance ofclamp force and the mistakes many Molders make by using too much clamp tonnage.

几年前，在一份月刊的文章里，我的导师Bill Tobin 为一份杂志写了一篇文章，是关于锁模力的重要性，里面谈到了许多注塑员在日常工作中，经常会使用过大的锁模力。

We all know that if you don’t have enoughclamp force for the projected area of the parts, flash will result. Enoughclamp force is essential, but too much can be detrimental and counterproductive.

我们都知道对于相应的产品投影面，如果没有足够的锁模力的话，可能会有飞边产生。足够的锁模力是必不可少的，但如果合模力太大的话，也是有害的，而且经常是事与愿违。

Too much clamp tonnage, whether it is beingapplied trying to correct a flash condition (Again, fix the mold!), or beingapplied out of a (poor) habit has its consequences. Excess clamp puts moreabuse than is necessary on the press. Toggles, tie bars and platens aresubjected to more mechanical abuse than is necessary. If the molding questionis too small in area, platen damage can be accelerated. The platens canactually “wrap around” the tool, or hob in the center areas. Minimum mold areasfor platen size should always be observed, even in minimum clamp situations.Too much clamp puts a bigger than needed load (burden) on the pumps ofhydraulic machines, especially a direct-clamp hydraulic press, and even toomuch of a burden on the servos, and of course mechanical links of an electricpress.

较大的锁模力，有的时候可以改善产品的飞边（备注：也可以通过修模改善），但同时也是一个不好的习惯。过量的锁模力，对设备是一种“虐待”。注塑机的肘杆，拉杆以及模板承受了超出额定的机械力。如果模具的尺寸相对较小的话，模板的破坏将会增加。模板可能四周变形或在中心位置产生压迫。我们经常看到的是安装尺寸较小的模具（接近最小的模具安装尺寸），然后用最小的合模力。较大的锁模力设置，需要液压泵提供较高的压力值，特别是对于直压式模板来说，或者引起伺服马达过载，和电动机的机械连接破坏。

Over-clamping, or using more clamp thannecessary, also wastes energy, be it hydraulic, mechanical, or electrical. Weare all looking for ways to lower our energy costs, mainly in our presspurchases; we have to also examine our operating practices.

过量或超出必要的锁模力设定，同时也是对能源的一种浪费，不管是液压机，机械式的，电动的。我们总是在寻找方法来降低我们的能源成本，主要是我们的成型机；我们也在检查我们的操作方法。

Heaping on the clamp force, makes the moldharder to “breathe” or vent, and over time, can permanently hob closed thevents on the parting line. This makes the mold harder to fill, and more injectpressure is used, more flash is created and it all turns into a vicious circle.

多余的锁模力，可能让模具无法“呼吸”或排气，周期超时等，对模具分模线的挤压。使模腔难以充满，更高的注射压力需求，或者造成更大的飞边。以上种种，形成了一个恶性循环。

In addition to abusing the mold’s vents,too much clamp, will mistreat the whole mold, subjecting plates, supportpillars, and other components to needless wear.
A Molder’s rule of thumb for maximum clampforce is usually 3.5 tons per square inch of projected part area, for most wallthicknesses and for most resins. I’ve seen resins like polyolefins run at under2 tons per square inch, and resins like fast fill PC, Nylons, LCP andThermoplastic Rubbers that want close to 5 tons per sq in. If this doesn’t holdthe tool shut, FIX THE DARN MOLD!

需要注意的是对模具的排气造成影响的同时，多余的合模力，也将影响整个模具，包括支撑板，导柱，以及其他部件的不必要磨损。通常对于不同模厚的模具，以及大多数的原材料，最大的合模力设定在3.5吨/每平方英寸。我看到过polyolefin（聚烯烃）的合模力设定在2吨/每平方英寸以下，但高速的PC (聚碳酸酯），Nylons(尼龙），LCP(液晶材料)以及一些热塑性橡胶的合模力接近5吨/每平方英寸。如果无法使模具完全闭合时，导致产品不良，如飞边等，建议考虑修模，而不是不断的提高锁模力。

Modern presses make it easy to adjust clampforce, even on toggle presses, so there is no excuse for overdosing on clamp.Remember, don’t abuse the machine, and don’t abuse the mold, FIX THE MOLD, andkeep the clamp where it should be.

现代的注塑机可以很容易的调整合模力，甚至肘杆压力，免去了很多设定的烦恼。但记住不要“虐待”设备，也不要“虐待”模具，在模具出现问题时，及时地进行维护，保持合理的锁模力。

驰骋纵横

路过，了解！