In this article, we analyze the multiple factors that contribute to the third industrial revolution, thus to sum up the machine tool manufacturing technology innovations and applications under the new era environment. Finally, we put forward the machine tool development prospects.

In the 21st century, it is asserted that we have entered the era of the third industrial revolution. As a part of modern manufacturing, machine tool manufacturing is also experiencing dramatic changes.

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Interaction of energy and communication gives birth to an industrial revolution

Just as the birth of steam engine and cheap newspaper gave birth to the first industrial revolution while the invention of telephone and telegraph and the birth of the electric power gave birth to the second industrial revolution, so the interaction of Internet computer communication technology and new energy has given birth to the third industrial revolution. This revolution got started at the beginning of the 21st century. First it was touched off in Germany while Italy and Japan paid close attention to the contents of this revolution. Based on current estimation, it will experience a 25~35-year reserve period and then, we will witness the gush of a new round of industrial revolution.

As we can find out, substantial resources are exhausted: Oil exploration cannot meet the needs of such developing countries as China and India; Waste gas and exhaust emission lead to serious air pollution; discharge of wastewater and hazardous substances lead to water quality pollution in rivers, lakes and the sea; incontinent urbanization leads to farmland disappearance, deforestation and damage of ecological environment; hiking labor cost, all these become factors to touch off the third industrial revolution.

Impact from the third industrial revolution on machine tool manufacturing technology

Affected by the third industrial revolution, machine tool manufacturing technology begins to emphasize R&D work on energy saving, environmental protection and green operation while high efficiency, high speed and high precision become a constant target pursued by the machine tool industry. These factors become the prelude of the machine tool revolution. We would sum up these findings below.

Machine tool structural innovation

Invention of parallel machine tool

At IMTS (International Manufacturing Technology Show) Chicago at the end of the previous century, USA-based G&L debuted the prototype of their parallel machine tools, which was the 6-leg measuring platform. This marked the trend of transformation for machine tools to transform from traditional C-type transmission chain structure to parallel mechanism.

The so-called parallel machine tool refers to the principle of parallel mechanism which is based on space parallel mechanism, uses CNC software in place of some hardware, uses electronic devices and elements in place of some mechanical devices, changes the length of truss rod and the position of its movement pivot to accomplish relative position change for tools and workpiecs and thus go beyond the foundation of traditional machine tools using rectangular coordinate system.

Parallel machine tool has its disadvantage of poor rigidity and is now forging ahead in the direction of parallel and serial combination. Tsinghua University, Harbin Measuring and Changzheng Machine tool take a leading position in R&D concerning this sector.

Invention of inverted machine tool

The inverted machine tool from German EMAG is ideal for batch machining of lightweight rotating components. This gave birth to many new models such as inverted machining center, inverted combined machining center and inverted welding machine.

Innovation of machining process

Combined machining

Undoubtedly, combined working machine tool and technology brings benefits for large workpiece machining operators. The reason is that process integration substantially reduces idle time between workpieces, thus dramatically reducing time in the entire production process compared with conventional equipment; reduces fixed asset investment because it eliminates the need to buy more than one machine tool; reduces warehouse space and warehousing cost; and reduces cross-docking time.

WFL turning-milling machining center.

In the middle 1990s, Austrian WFL invented turn-milling machining center. On the other hand, Japanese MAZAK concluded that “done in one”, i.e., all operation is done on one machine tool, represents the development direction of CNC machine tools.

Laser machining

With the constant development of laser cutting and laser forming technology, DML40 SL system from DMG can input CAD drawings directly into the machining process. With 3 straight axles, two deflecting mirror revolving axles and one coilaxis, laser beams shoot into workpiece surface within the range of ≥200o.

Specifically, laser pulse is YAG, loser power is 100W, laser beam diameter is �0.04~0.1mm and metal removal rate can reach 25mm3/min.

Ultrasonic vibration machining

Special milling cutter, drill bit or grinding wheel made of industrial diamond particle go through 20,000 cycle/s ultrasonic vibration and high frequency impact to provide high precision machining for ultrahard materials.

Speed of mainshaft: 6,000r/min; drive power: 10kW; high frequency vibration power for mainshaft: 1.5kW.

Waterjet cutting

Working diagram of abrasive waterjet cutter.

Waterjet cutter is a process where ordinary water goes through an ultrahigh pressurizer to increase pressure to 380Mpa (55,000psi) or higher, and then goes through a fine nozzle (�0.01-0.040mm) to create a 915m/s waterjet (about three times of sound speed) to complete cutting operation. Waterjet cutter includes two types: Pure waterjet cutter and abrasive waterjet cutter.

Flexible manufacturing (FMS)

FMS analysis should focus on main control system, transport carriage, pallet exchanger and cleaning device and the machine tool (mainly horizontal machine tools) is only one of the machines units. The reason is that FMS is mainly evolved from robots and its key function depends on the adaptive ability of the machining units as well as the capability of moving objects around the workstation and the ability to respond to remote data.

Intelligent manufacturing

As a part of advanced manufacturing technology, intelligence integrates information technology, photoelectric technology, communication technology and sensing technology to promote constant development of machine tool manufacturing. Through extensive research and development, many Japanese companies such as MAZAK and OKUMA have won a full range of patents. As system supplier, Heidenhain of Germany integrates Adaptive Feed Control (AFC), Automatic Calibration and Optimization Machine Tool Accuracy (KinematicOpt) and Active Chatter Control (ACC) into their software as options for customers.

Mikron intelligent machining center.

Currently, high-end machine tools are generally provided with thermal deformation control systems to ensure stable working accuracy for machine tools. For example, the high-precision horizontal coordinate machining center from Japanese Yasuda is provided with “body temperature control system”.

Intelligent machining from Swiss GF Agie Charmilles Group is all intended to improve technical capability. Their Mikron series intelligent machining module may help users to control milling process to ensure higher performance, higher quality and higher safety.

Micro and nano manufacturing

Nano grinding machine from Shanghai Machine Tool Ltd. is mainly used for nano-level precision grinding of micro mechanical and electric components of ultrahard brittle alloy, ultrahard alloy, mold steel and electroless nickel. Machining range: Nonsphere curve diameter <�10mm; Positioning accuracy ≤0.1�m (100nm); Repositioning accuracy ≤0.05�m (50nm); Surface roughness Ra<0.01�m (10nm); functions such as online measurement compensation machining, online grinding wheel repair and online sharpening function.

Two revolutionary measures

3D printing

As a new processing mode, 3D printing was born when needed in the third industrial revolution. Additive manufacturing can work out metal and nonmetal components of high precision and complicated faces. This precise machining mode can avoid cutter interference and can machine the part where laser beam is shaded off.

3D printing technology involves many methods. Roughly, they include laser powder forming method, melted plastic forming method and photosensitive resin forming method. In technical principle, material adding method is used to form 3D subject no matter what forming method is used. Each time, it prints a layer of material no thicker than 0.1mm-0.2mm. Compared with 2D printer, 3D printer has an additional dimension, i.e., axis Z. Through X-Y-Z axis movement, it stacks materials layer by layer, such as melted plastics forming method where the nozzle sprays out melted plastic filament, bearing platform engages in 3D movement and thus builds up 3D subject (just as it sticks up one layer after another).

Liquid nitrogen frozen machining

MAG has developed a cutting cooling system going beyond conventional techniques — “Ultralow temperature liquid nitrogen cutting cooling technology”, becoming a revolutionary innovation for the machine tool industry. MAG Asia-Pacific president Mr. Li Li indicated: “Application of this technology will impose revolutionary impact on the machine tool and tool industry. Specifically, high efficiency and long service life will help reduce the consumption of machine tools and tools and reduce the consumption of the resources on our planet.”

Cutting heat generated in the cutting process leads to quick wear of tools when machining ultrahard materials and thus increases tool consumption. As a result, the cost of tools is even higher than the cot of machine tools. In ultralow temperature liquid nitrogen cutting cooling technology, liquid nitrogen is output from the microvoid on the cutting blades at the mainshaft center and handle center and the heat generated in the process of tool cutting is instantly taken away by liquid nitrogen vaporization. Particularly, when machining ultrahard materials and composite materials, it can accomplish better effect, substantially accelerate cutting speed and extend cutter service life.

Based on the statistic data of MAG cutting test in the past years, metal removal rate is increased by 3 times and tool service life is extended twice on average when cutting difficult-to-cut materials such as titanium and nickel alloy, spheroidal graphite cast iron or vermicular graphite cast iron. This means one machine tool is equivalent to three machine tools and one blade can be used as three blades, thus substantially saving equipment, space and personnel and energy consumption.

This technology is environment friendly. Generally, the approach for metal cutting cooling is to use cooling fluid or cooling oil. Cooling fluid and cooling oil may cause environmental pollution and need recycling. On the other hand, nitrogen is a non-hazardous gas which causes no pollution when released into air and does not need recycling.

Future vision for machine tools

Puzzling entangling machine

Components of such materials as carbon fiber can be machined using entangling approaches.

Rail milling and grinding wagon

Rail milling and grinding wagon from Austria.

Machine tool can be a running train, where the front wheel serves as face milling cutter to mill up damaged rails; and the rear wheel serves as grinding wheel to polish milled rails.

OKUMA conception and MAZAK model

Japanese OKUMA envisions the development direction of future machine tools: SPACE CENTER, features high SPEED, high POWER, high ACCURACY, COMMUNICATION and ECOLOGY.

Meanwhile, MAZAK envisions the model for future machine tools: 100,000r/min mainshaft speed, 8g acceleration, 2 mach cutting speed, simultaneous tool exchange, dry cutting, integrated with turning, milling, laser machining, grinding and measurement.

In the era of the third industrial revolution, advanced manufacturing technology features higher speed and shorter cycle than ever. CNC machine tools are also expected to witness constant development.