With the improvement of mechanical life and material strength, so that more and more difficult to cut materials, product integration so that the parts are more and more complex, product miniaturization and put forward the need for microfabrication, as well as the processing requirements of easy automation, etc., so that the traditional machining is difficult to meet the society's increasing demand for machinery manufacturing. From the 1930s to the 1980s, the first manufacturing revolution broke out as manufacturing technology was combined with electric and electronic technology. In these years, one after another, invented and applied in the machinery manufacturing industry with a series of traditional processing completely different from the new processing methods, which are collectively referred to as special processing, including physical and chemical processing, referred to as physicochemical processing; electro-physical and electrochemical processing, referred to as electro-processing and its composite processing.
From narrow processing to broad processing
Both traditional and special processing, there are broad processing and narrow processing. Broad processing includes: deformation processing, joining processing, material reduction processing and modification processing.
Deformation processing is referred to as molding, is a certain volume of material to make its deformation into the desired shape, size and properties of the blank, semi-finished products or parts of the process method. In the traditional processing of deformation processing cold solid state deformation, mainly by more than the elastic limit of the material mechanical force, such as cold forging, cold pressing, cold drawing, cold rolling and cold extrusion, etc.; There are also hot solid state deformation, mainly by the role of thermal energy and mechanical force, such as hot forging, hot pressing, hot drawing, hot rolling and hot extrusion, etc.; In addition, there is a liquid state deformation or semi-liquid deformation, mainly by the role of thermal energy, and sometimes also add the role of mechanical force, such as casting, Die casting and injection molding. In the special processing of deformation processing discharge molding, electromagnetic forming and laser three-dimensional forming.
Joining processing is referred to as connection, is two or more materials or semi-finished products connected together, so that they become semi-finished products or parts of the process. In the traditional processing of joining processing have crimping, riveting, welding and gluing, etc.. In the special processing in the jointing process have discharge impact welding, electron beam welding, laser welding and plasma welding, etc..
Reduced material processing, referred to as removal, is a large piece of raw material or have a surplus of blanks gradually remove excess material, and get the desired shape, size and properties of the part of the process method. In the traditional processing, material reduction processing mainly use the role of mechanical force to remove the excess of raw materials or blanks, i.e., with a high hardness tool cutting raw materials or blanks into parts, such as turning, planing, shaving, sawing, drilling, boring, milling, pulling, hinging, tapping, and other cutting and grinding processes. Special processing in the material reduction processing of electrical discharge processing, electrolytic processing, laser processing, ultrasonic processing, electron beam processing, chemical processing, plasma processing and ion beam processing.
Modified processing referred to as processing, is the use of cold, heat and chemical treatment as well as corrosion, polishing, coating, alloying and shot blasting to change the material, blank, semi-finished products or parts of the internal, surface or surface of the physical, chemical or geometric characteristics of the process methods.
Narrow machining refers to material reduction machining alone. Although both conventional and specialty machining encompass broad machining, they both use material reduction machining as the primary means of machining. With the progress of precision deformation processing and precision joint processing technology, machinery manufacturing industry to reduce material processing as the main means of finishing the situation was broken, replaced by a variety of broad processing methods and the situation.
From subtractive processing to additive processing
In the 20th century since the 1990s, facing the dynamic and changeable market machinery manufacturing industry, shorten the product cycle, product renewal accelerate, more varieties, batch size reduction; product quality, price and delivery has become the three decisive factors to increase the competitiveness of enterprises. The manufacturing industry with material reduction processing as the main means, it is difficult to meet the above requirements. For this reason, with the combination of manufacturing technology and materials technology, energy technology, microelectronics technology and information technology, to additive processing as the main content of the second manufacturing revolution should happen.
Additive processing, referred to as growth, is a growth-like method to gradually increase the material until the generation of the desired shape, size and traits of the sample or part. On the basis of conventional machining, although there have been attempts to develop additive processing with shape melting or welding, as well as three-dimensional welding, but there has been no practical progress. Additive processing was later developed on the basis of specialty machining. It is the use of bonding, fusion and polymerization or chemical reactions, such as selective solidification of liquid materials or bonding of solid materials, etc., in order to manufacture parts of the desired shape, size and properties. This manufacturing technology is a multidisciplinary synthesis of CAD technology, CNC technology, energy technology, and materials technology. With this manufacturing technology, it is possible to create a new prototype for the customer in just two days, which is not a picture displayed on a computer screen, but an actual object. If the customer is not satisfied, you can immediately modify the CAD system, and then create a new sample, until the customer is satisfied. Experts predict that this new manufacturing technology to the impact of manufacturing, comparable to CNC technology. It was initially called rapid prototyping or rapid prototyping, and the name is still widely used today.
Currently there are a variety of additive processing methods, which are better applied such as the chemical method of liquid photosensitive resin selective curing, composite method of paper-based material selective cutting, thermophysical method of filamentous material selective fusion and powder material selective sintering, as well as the spray method of powder material selective bonding and based on the innovation of the digital jet RP technology, etc..
The name "rapid prototyping" or "rapid prototyping" does not make the most sense, because "rapid" does not mean fast processing, but rather short overall processing times; In addition, there are many existing methods that go beyond the scope of "prototyping". Therefore, the name "additive manufacturing" is sufficient to summarize all the methods and applications, clearly point out the principle of processing, and can be used with its acronym MAM clearly corresponds to the acronym MRM of subtractive material processing.
From Making Dead Things to Making Living Things
Since the beginning of time, manufacturing has been making dead things and has been unable to make living things because it is a human manufacturing process. Since there is life on earth, the biological community has been reproducing living things, will not reproduce dead things, because it is the natural life process. However, in the manufacturing industry is increasingly information technology and life sciences towards engineering today, if the latest achievements in the fields of manufacturing engineering, life sciences, computer technology, information technology, materials engineering combined to communicate with each other, then the manufacturing industry is not only able to create inanimate complex intelligent machines, but also the use of the achievements of genetic engineering, the manufacture of life, organs for transplantation and available bionic components.
The achievements of brain and cognitive sciences will make it possible to partially simulate brain functions and behaviors, and human beings will then be able to create artificial brains and robots that can partially simulate human intelligence in the 21st century. This creates a special kind of manufacturing engineering, i.e., biomanufacturing engineering. Bio-manufacturing engineering includes not only the manufacture of organism-like creatures or organisms, but also the use of the functions of living things for manufacturing (gene duplication, bioremoval, or biogrowth) i.e., self-formation.
From it-forming to self-forming
Before this time, no matter whether it is plastic molding by deformation processing or joining molding by joining processing, or no matter whether it is removing molding by subtracting processing or growing molding by adding material processing, they are all it-forming. The so-called "it forming" is the forming under the external forcing. Such external forcing is, for example, casting of molten metal in a mold, forging by heat and mechanical force, pressing by mechanical force exceeding the elastic limit of the material, and contour-controlled removal and growth. With? the needs of biomanufacturing, there will be very delicate and complex structures waiting to be manufactured. It molding processing methods can no longer meet the increasing requirements of biofabrication. Therefore, a new method of processing according to biological growth, development, under the control of its intrinsic genes, through the parallel division of cells and self-forming, also known as self-organizing forming or self-growth forming is about to be born. This method is the most central issue in bionic manufacturing.
Biomimetic manufacturing technology belongs to the manufacturing science and life science "distant hybrid", is to imitate the biological organization and mode of operation of the manufacturing system and manufacturing process of the general term.
The New Manufacturing Revolution
In the 20th century, humans have been designing new biogenetic blueprints of their own volition, and then creating new life forms like construction sites. New technologies such as cloning, human stem cell cultures, genetic code deciphering, the massive sequencing program of the human genome, and transgenic technology have emerged.
In the 1990s, China's Xi'an Jiaotong University Rapid Prototyping and Manufacturing Research Center, in cooperation with the Fourth Military Medical University, had already begun research on artificial bioactive bones and made promising progress. The Johns Hopkins University Wilmer Eye Institute in the United States has made promising progress. Johns Hopkins University Wilmer Eye Institute scientists and mechanical engineers at North Carolina State University, *** with the successful development of blind people to see the light of day "eye chip". In addition, the U.S. company Affymetrix has realized the high-density integration of DNA, has reached 400,000 different DNA fragments on each chip.
In the 21st century, with biotechnology, life sciences, materials science and other advanced manufacturing technology, and will certainly make manufacturing engineering to produce a new manufacturing revolution, which may be the third manufacturing revolution. As mentioned earlier, called biomanufacturing engineering or called biomimetic manufacturing technology. In short, one is the use of genetic engineering achievements, the manufacture of life, transplantable organs and bionic components available; two is according to biological growth, development, under the control of its intrinsic genes, through the parallel division of cells for self-growth molding process. This manufacturing method can grow any products needed by human beings, such as human or animal bones, organs, limbs, and mechanical parts of biomaterial structures. It can be envisioned that if people can control the shape, size, structure and material of the DNA in the gene separation, to be deciphered, and the use of advanced "atomic manipulation technology" assembly or modification of genes, then one day machine parts and even the whole machine can be in the petri dish from the corresponding "seed "grow out. In the future, the manufacture of micromachines is likely to develop in this direction.
Looking at the development of manufacturing technology, processing methods are such progress: mechanical processing → physical and electro-physical processing → chemical and electrochemical processing → biological or biomimetic processing, fully consistent with the process of scientific understanding of the development of the direction of the process from the simple to the complex, from the rough to the detailed.