特种加工工艺人类通过使用工具和智能来制造使其生活变得更容易和更舒适的物品这种方法，把他们自己与其他种类的生命区别开来。许多世纪以来，工具和为工具提供动力能源的种类都在不断地发展，以满足人类日益完善和越来越复杂的想法。在最早的时期，工具主要是由石器构成。考虑到所制造的物品相对简单的形状和被加工的材料，石头作为工具是适用的。当铁制工具被发明出来以后，耐用的金属和更精致的物品能够被制造出来。在20世纪中，已经有了一些由有史以来最耐用，同时也是最难加工的材料制造的产品。为了迎接这些材料给制造业带来的挑战，工具材料已经发展到包括合金钢、硬质合金、金刚石和陶瓷。给我们的工具提供动力的方法也发生了类似的进步。最初，是由人或动物的肌肉为工具提供动力。随后，水力、风力、蒸汽和电力得到了利用，人类能够通过采用新型机器、更高的精度和更快的加工速度来进一步提高制造能力。每当采用新的工具、新的材料和新的能源时，制造效率和制造能力都会得到很大的提高。然而，当旧的问题解决了之后，就会有新的问题和挑战出现。例如，现今制造业面对着下面一些问题：你如何去钻一个直径为2 mm，长度为670 mm的孔，而不产生锥度和偏斜？用什么办法能够有效地去除形状复杂的铸件内部的通道中的毛刺，而且保证去除率达到100%？是否有一种焊接工艺，它能够避免目前在我的产品中出现的热损伤。从20世纪40年代以来，制造业中发生的大变革一次又一次地促使制造厂家去满足日益复杂的设计方案和很高耐用度，但是在许多情况下几乎接近无法加工的材料所带来的各种要求。这种制造业的大变革不论是现在还是过去都是集中在采用新型工具和新型能源上。这样做的结果是产生了用来去除材料、成型、连接的新型制造工艺。这些工艺目前被称为特种加工工艺。在目前所采用的常规制造工艺中，材料的去除是依赖于电动机和硬的刀具材料进行的，诸如锯断、钻孔和拉削。常规的成型加工是利用电动机、液压和重力所提供的能量进行的。同样，材料联接的常规做法是采用诸如燃烧的气体和电弧等热能进行的。与之相比，特种加工工艺采用按照以前的标准来说不是常规的能源。现在材料的去除可以利用电化学反应、高温等离子、高速液体和磨料射流。过去非常难进行成型加工的材料，现在可以利用大功率的电火花所产生的磁场，爆炸和冲击波进行成型加工。采用高频声波和电子束可以是材料的联接能力有很大的提高。在过去的50年间，人们发明了20多种特种加工工艺，并且将其成功地应用于生产之中。这么多种特种加工工艺存在的原因与许多种常规加工工艺存在的原因是一样。每一种都有他自己的特点和局限性。因而不存在一种对任何制造环境来说都是最好的工艺方法。 例如，有时特种加工工艺或者通过减少生产某一产品所需要的加工工序的数量，或者通过采用比以前使用的方法更快的工序来提高生产率。 在另外的场合中，采用特种加工工艺可以通过增加重复精度，减少易损坏工件在加工过程中的损伤，或者减少对工件性能的有害影响来减少采用原来加工工艺所产生的废品数量。 由于前面所提到的这些特点，特种加工工艺从其诞生时起就开始了稳定的发展。由于下列原因，可以肯定这些工艺将来会有更快的增长速度： (1)目前，同常规工艺相比，除了材料的体积去除率外，特种加工工艺几乎具有不受限制的能力。在过去几年中，某些特种加工工艺在提高材料去除率方面有了很大的进展，而且有理由相信这种趋势在将来也会继续下去。 (2)大约半数的特种加工工艺目前采用计算机控制加工参数。使用计算机可以使人们所不熟悉的加工过程变得简单，因而加大了人们对这种技术的接受程度。此外，计算机控制可以保证可靠性和重复性，这也加大了人们对这种技术的接受程度和其应用范围。 (3)大多数特种加工工艺可以通过视觉系统，激光测量仪表和其他加工过程中的检测技术来实行适应控制。例如，如果加工过程中的检测结果表明，产品中正在加工的孔的尺寸在变小，可以在不更换硬的加工工具(如钻头)的情况下，修正孔的尺寸。 (4)随着制造工程师，产品设计人员和冶金工程师们对特种加工工艺所具有的独特能力和优越性的了解的增加，特种加工工艺的应用范围将会不断增加。Nontraditional Manufacturing Processes The human race has distinguished itself from all other forms of life by using tools and intelligence to create items that serve to make life easier and more enjoyable. Through the centuries, both the tools and the energy sources to power these tools have evolved to meet the increasing sophistication and complexity of mankinds ideas. In their earliest forms, tools primarily consisted of stone instruments. Considering the relative simplicity of the items being made and the materials that were being shaped,stone was adequate. When iron tools were invented, durable metals and more sophisticated articles could be produced. The twentieth century has seen the creation of products made from the most durable and, consequently, the most difficult-to-machine materials in history. In an effort to meet the manufacturing challenges created by these materials, tools have now evolved to include materials such as alloy steel, carbide, diamond, and ceramics A similar evolution has taken place with the methods used to power our tools. Initially, tools were powered by muscles; either human or animal. However as the powers of water, wind, steam, and electricity were harnessed, mankind was able to further extend manufacturing capabilities with new machines, greater accuracy, and faster machining rates. Every time new tools, tool materials, and power sources are utilized, the efficiency and capabilities of manufacturers are greatly enhanced. However as old problems are solved, new problems and challenges arise so that the manufacturers of today are faced with tough questions such as the following: How do you drill a 2-mm diameter hole 670-ram deep without experiencing taper or runout? Is there a way to efficiently deburr passageways inside complex castings and guarantee 100% that no burns were missed? Is there a welding process that can eliminate the thermal damage now occurring to my product?Since the 1940s, a revolution in manufacturing has been taking place that once again allows manufacturers to meet the demands imposed by increasingly sophisticated designs and durable, but in many cases nearly unmachinable, materials. This manufacturing revolution is now, as it has been in the past, centered on the use of new tools and new forms of energy. The result has been the introduction of new manufacturing processes used for material removal, forming, and joining, known today as nontraditional manufacturing processes. The conventional manufacturing processes in use today for material removal primarily rely on electric motors and hard tool materials to perform tasks such as sawing, drilling, and broaching. Conventional forming operations are performed with the energy from electric motors, hydraulics, and gravity. Likewise, material joining is conventionally accomplished with thermal energy sources such as burning gases and electric arcs. In contrast, nontraditional manufacturing processes harness energy sources considered unconventional by yesterdays standards. Material removal can now be accomplished with electrochemical reactions, high-temperature plasmas, and high-velocity jets of liquids and abrasives. Materials that in the past have been