RIM（reaction injection molding)反应注射成型
在论坛上看到很多关于询问RIM工艺的帖子，由于RIM工艺在国内的应用较少，了解的人也少，所以关于这方面的知识不是很多，即使在网上搜索也是一知半解的，这里我就总结了一下RIM的相关知识，希望大家参考，同时也希望门内人给予补充。
先把中文版的发出来，英文版我会在以后补充的，不过本人的英文水平有限，估计要耗费些月子。

RIM(reaction injection molding)反应注射成型

RIM（reaction injection molding)，中文俗称反应注射成型，是20世纪70年代后期在欧美率先发展起来的。是一种区别于传统注塑和其他成型工艺的一种特殊的工艺。

其原理是：

将两种反应原材料(聚氨酯组分和树脂混合物)分别放入带有搅拌器可控温度的进料罐中,经过精确计量,在高压下进入混合头.注射开始时,混合头的阀门打开,反应物在一定压力下进入混合室,高速激烈碰撞,然后在接近大气压的压力下流入模具,经放热化学反应,在模具中形成聚氨酯聚合体。
简单的说就是：两种聚氨酯(PU)原材料在模具中通过热化学反应成型出聚氨酯((PU）零件。
Reaction Injection Molding (RIM) is the process by which molded polyurethane(PU) parts are made. In the process, 2 liquid components are mixed and injected into the mold where they chemically react and cure,which forms the polyurethane polymer parts.

RIM工艺尤其适合成型大型小批量的零件。

PU（聚氨酯）树脂首先由德国拜耳（Bayer）（PU工业奠基人）教授于1937年发明，至今已有七十年历史。

聚氨酯具有强度高,耐磨性,抗撕裂,耐屈挠性,耐低温性和耐油,耐化学品性能优异及良好的血液相容性等优点等特点.聚氨酯树脂制成的产品有泡沫塑料,弹性体,涂料,胶粘剂,纤维,合成皮革以及辅面材料等品种,它广泛应用于运输，机电,船舶,土木建筑,轻工以及纺织等部门,产品与品种逐年递增,在材料工业中占有相当重要的比例，目前PU的使用量仅次于PP,ABS,PVC. 自本世纪30年代末问世以来,它的应用领域不断拓宽,产量逐年增加,发展非常迅速.

RIM工艺的优点（自己总结的，希望大家来补充）：

1,缩短产品开发周期,降低产品开发成本
get your product to the market quickly at much low risk
由于RIM工艺的低压注射性,对模具的要求较低,模具通常采用环氧树脂或铝做材料,故其成本只相当于注塑模具的很少一部分,其加工周期更是注塑模具不能比拟的,特别适合於短流程生产和样机生产,可大大缩短产品开发周期和节省产品开发成本,快速进入市场占有先机；
RIM tooling can make large and complex, 3-dimensional parts at a fraction of the tooling investment of a comparable injection molding tool because such a low-viscous material exerts very little stress on the tool,and allows for ease of modification in economical challenging time. It allows you to get your product to the market quickly and at much lower risk than the tooling needed for injection molding.
2,适合生产大型、小批量且高质量的产品
Excellent choice for larger plastic parts produced in short run or low volume production quantities.
RIM工艺使产品设计更能体现设计者的奇思妙想,由于反应原料的粘度低,流动性好,可以在压力很小的情况下成型复杂的零件,对成型较大面积的壳体具有不可比拟的优势,壁厚变化范围非常大,同一模塑件的横截面可以从6mm到28mm间变化,这是其他工艺所不能比拟的,故可整体成型壁厚变化较大的制品以提高产品的品质可靠性;其制品尺寸稳定,外表美观（可达A级曲面）,耐冲击性及耐腐蚀性良好（可以达到PC/ABS的性能）;通过调整原料的配制比例可以制作成表层坚硬的聚氨酯结构的泡沫塑料等密度不同的产品,满足客户的各种需求;
Designers have more creative ideas with RIM (Reaction Injection Molding) because it can mold thin and thick walls easily in the same part because of the excellent flowability of the materials and the part shrinks a slight amount during the molding process,inserts, ribs and bosses can be molded in the part without sink marks.PU-RIM parts are durable,chemically resistant,wear resistant,low weight and have high insulation values,and they can be rigid and solid like an injection molded ABS or they can be a structural foam or elastomeric like rubber.
3,制品封装镶嵌件工艺简单 Superb encapsulation ability
很多种嵌入件都可以在注塑RIM材料前放入模具中,这样,在成型过程中RIM材料就完成了嵌入件的封装,钢或铝合金的结构框架,电子传感器,电路板,电池,天线,磁铁,玻璃,金属部件等都可以用RIM工艺封装,进而减少甚至是消除二次加工环节,这样可以：保护您的重要敏感元件免受灰尘,油污,化学药品的腐蚀污染等；使您的产品可以在潮湿甚至是水中工作；增加您的产品强度,保护重要部件免受冲击或减缓冲击带来的损害；这样从而使您的产品可以在更为恶劣的环境下工作。
Insert molding and encapsulation of delicate components is much easier with Reaction Injection Molding (RIM) because pressures and temperatures are low. RIM provides for reliable, structural ‘one-piece’ solutions wherever added functionality is needed or where sensitive equipment needs protection from the environment. Components to be encapsulated are fully or partially surrounded by the molded part which provides for the structural and cosmetic properties of the finished unit. Reinforcements or attachment hardware, electronic components, magnets, batteries or antennas can be molded right into the RIM part.This can reduce your assembly costs, make assemblies tamper-proof or solve sealing problems for you.
4,表面涂装性能好且模内漆喷涂工艺方便
Superior cosmetic appearance for visibly critical applications
PU-RIM零件表面涂装性能良好,但涂装工艺较为繁琐,在RIM工艺中,可以在注射前将胶衣和聚氨酯漆涂在模具中,在成型过程中和聚氨酯材料结合为一体,从而在模具内完成了零件的装饰,大大降低了二次喷漆的费用及提高后处理效率。
PU-RIM parts have good peRealhaoormance in decorating,we can deliver your parts complete with silk-screened or pad-printed letters and logos or what your expectations,but one of the largest costs of painted plastic parts is the painting and finishing process,in RIM process,we can painting the mold cavity immediately prior to injecting the polyurethane materials,during the molding process the coating chemically bonds to the polyurethane thereby eliminates the possibility of the paint chipping and flaking-off. These options give you tremendous flexibility to decortate your parts while saving you time and money.

RIM工艺因其卓越的产品性能广泛应用于汽车零部件及改装零部件、工程机械覆盖件、医疗设备，仪器仪表、电子、机械设备覆盖件，工业部件、化工部件、运动休闲等领域,作为对金属等材料的替代品,有着无可比拟的优势与前景。