CUPPING TESTS

The Swift cup test is the determination of the limiting drawing ratio for flat-bottom cups. In the Erichsen and Olsen tests, cups are formed by stretching over a hemispherical tool. The flanges are very large so little drawing occurs. The results depend on stretchability rather than drawability. The Olsen test is used in America and the Erichsen in Europe. Figure 20.1 shows the set up.

The Fukui conical cup test involves both stretching and drawing over a ball. The opening is much larger than the ball so a conical cup is developed. The flanges are allowed to draw in. Figure 20.2 shows the set up. A failed Fukui cup is shown in Figure 20.3.

Figure 20.4 shows comparison of the relative amounts of stretch and draw in these tests.

LDH TEST

The cupping tests discussed above are losing favor because of irreproducibility. Hecker attributed this to “insufficient size of the penetrator, inability to prevent inadvertent draw in of the flange and inconsistent lubrication.” He proposed the limiting dome height (LDH) test which uses the same tooling (4 inch diameter punch) as used to determine forming limit diagrams. The specimen width is adjusted to achieve plane-strain and the flange is clamped to prevent draw-in. The limiting dome height is greatest depth of cup formed with the flanges clamped. The LDH test results correlate better with the total elongation than with the uniform elongation as shown in Figures 20.5 and 20.6.

This book is about the design and application of industrial cleanroom robots in electronics manufacturing. It is intended as a hands-on technical reference for engineers and factory managers involved in manufacturing electronic devices in cleanroom environments. The book provides insight into the principles and applications of industrial cleanroom robotics, in particular in semiconductor manufacturing, the most demanding process in terms of cleanliness requirements. Other examples are the hard disk, flat panel display, and solar industries, which also use high levels of cleanroom automation and robotics. In contrast to the complex manufacturing process, the typical robotic designs often utilize relatively simple robot kinematics in the highly structured environments of process and metrology tools. Some industries, for example the semiconductor front-end industry, are governed by technical standards and guidelines, which are generally helpful during the design process of robotic systems. On the other hand, robotic engineers in electronics manufacturing face challenges that are unknown in other markets, most importantly the cleanliness required in certain factories. Strict cleanliness requirements have resulted in two categories of cleanroom robots: ‘atmospheric robots’ for high-quality cleanliness at ambient atmospheric pressure, and ‘vacuum robots’ for extreme cleanliness in enclosures under various vacuum pressures. These two categories are the focus of this book.

Robotics refers to the study and use of robots (Nof, 1999). Likewise, industrial robotics refers to the study and use of robots for manufacturing where industrial robots are essential components in an automated manufacturing environment. Similarly, industrial robotics for electronics manufacturing, in particular semiconductor, hard disk, flat panel display (FPD), and solar manufacturing refers to robot technology used for automating typical cleanroom applications. This chapter reviews the evolution of industrial robots and some common robot types, and builds a foundation for Chapter 2, which introduces cleanroom robotics as an engineering discipline within the broader context of industrial robotics.

History of industrial robotics

Visions and inventions of robots can be traced back to ancient Greece. In about 322 BC the philosopher Aristotle wrote: “If every tool, when ordered, or even of its own accord, could do the work that befits it, then there would be no need either of apprentices for the master workers or of slaves for the lords.” Aristotle seems to hint at the comfort such ‘tools’ could provide to humans. In 1495 Leonardo da Vinci designed a mechanical device that resembled an armored knight, whose internal mechanisms were designed to move the device as if controlled by a real person hidden inside the structure. In medieval times machines like Leonardo's were built for the amusement of affluent audiences. The term ‘robot’ was introduced centuries later by the Czech writer Karel Capek in his play R. U. R. (Rossum's Universal Robots), premiered in Prague in 1921.