DMLS vs SLM 3D Printing for Metal Manufacturing

3D printing is revolutionizing the world of manufacturing, allowing companies to produce prototypes quickly and specialized components at relatively low cost. Most applications of 3D printing use molten plastic to produce objects in a wide variety of designs; However, 3D printing of metal is also emerging as a popular technique in the metal forging and fabrication industries.

用于执行金属添加剂制造的技术与用于打印塑料的技术略有不同。两种主要技术是直接金属激光烧结和选择性激光熔化。

直接金属激光烧结

One of the most effective additive manufacturing techniques for metal is direct metal laser sintering, also known as DMLS. This process can be used to build objects out of almost any metal alloy, unlike other 3D printing techniques, which only work with polymer-based materials or specific metal alloys.

直接金属激光烧结涉及在待印刷的表面上展开非常薄的金属粉末层。激光在表面上缓慢且稳定地移动以烧结该粉末，这意味着金属内的颗粒融合在一起，即使金属不足够加热以使其完全熔化。然后施加另外的粉末层并烧结，从而一次“打印”物体一个横截面。通过这种方式，DMLS逐渐通过一系列非常薄的层构建3D对象。

一旦DMLS进程完成，打印对象会留下冷却。可以从构建室中回收过量的粉末并再循环。

DMLS的主要优点是它产生了可以困扰传统制造的金属部件的残余应力和内部缺陷的物体。这对于在高应力下运行的金属部件非常重要，例如航空航天或汽车部件。传统上制造的金属部件需要在制造以除去可能导致部件失效的内部应力后进行热处理。

DMLS的主要缺点是，到目前为止已经非常昂贵，这限制了对非常高端应用的用途，例如航空航天工业中的制造金属原型零件。然而，在密歇根州技术大学工作的科学家开发了一个3D金属打印机，只需1,500美元即可建造。相比之下，大多数商业金属3D打印机每个都花费超过半百万美元。打印机仍在开发时仍然很早;然而，这种突破可以使DMLS技术在未来更实惠。

Selective Laser Melting

Another method of 3D metal printing is selective laser melting (SLM), in which a high-powered laser fully melts each layer of metal powder rather than just sintering it. Selective laser melting produces printed objects that are extremely dense and strong.

目前，选择性激光熔化只能与某些金属一起使用。该技术可用于不锈钢，工具钢，钛，钴铬和铝部件的添加剂制造。研究人员希望SLM将有一天用于制造由其他金属制成的零件，但仍有困难仍然需要解决。许多其他金属没有使它们适合于SLM所需的正确流动特性。

Selective laser melting is a very high-energy process, as each layer of metal powder must be heated above the melting point of the metal. The high temperature gradients that occur during SLM manufacturing can also lead to stresses and dislocations inside the final product, which can compromise its physical properties.

美国国家航空航天局正在研究使用选择性激光熔化，以便为其航天器生产高度专业的零件。2013年8月，美国宇航局发布了一份新闻稿，描述了它如何使用SLM来生产3D印刷火箭发动机注射器。3D印刷部分在2013年8月22日执行的测试发动机射击期间成功执行。

NASA表示，SLM提供的大型优势是它允许工人整体制造金属设备，而不是必须生产各个组件并组装它们以创建最终产品。例如，2013年8月测试的发动机注射器仅由两部分组成，而先前测试的类似注射器中的115份。具有更少的部件意味着复杂的设备更容易组装。

The use of SLM in metal manufacturing is also being pioneered by the German company SLM Solutions. This company produces SLM machines for use in factories. The company’s 3D metal printing machines are used by the industrial group Siemens to produce replacement blades for gas turbines. The time taken to produce a turbine blade using SLM Solutions’ 3D metal printing machines could be reduced to as little as four weeks, compared to 44 weeks using current technologies.

3D打印可以显着加速金属制造，减少企业的停机量，同时在等待替​​换金属部件时，当必要的设备崩溃时要创造。这可能具有减少许多不同行业的延误的多米诺效应，这些行业使用金属工具和机器来制造其产品。

电子束熔化

Electron beam melting (EBM) is an additive manufacturing process that is very similar to selective laser melting. Like SLM, it produces models that are very dense. The difference between the two techniques is that EBM uses an electron beam rather than a laser to melt the metal powder.

Currently, electron beam melting can only be used with a limited number of metals. Titanium alloys are the main starting material for this process, although cobalt chrome can also be used. The technique is used primarily to manufacture parts for the aerospace industry.

3D金属印刷的未来

激光技术的开发，例如引入飞秒激光，可以扩大使用添加剂制造技术，使得它们可以与更大范围的金属和金属合金一起使用。飞秒激光器对于3D金属印刷是有用的，因为它们可以提供非常短的高能激光脉冲，使它们能够熔断金属粉末，具有更高的精度水平。

三维金属印刷技术继续发展p and the costs of the technology fall further, 3D printing could play an ever-greater role in metal manufacturing. 3D printing techniques avoid many of the typical pitfalls of metal manufacturing, such as the need for post-production heat treatments and specialized machines for milling and finishing the metal object. 3D metal printing could also significantly speed up production in many areas of metal制造业。