Processing machining conditions

As previously mentioned in Chapter 5, one of the most severe disturbances for the power recovery train (PRT) is a generator breaker opening. This event often causes the PRT to trip on overspeed or other process or machine conditions. A control solution has been developed to keep the PRT and the process under control during breaker opening. 

Comparative analysis directly compares two or more data sets in order to detect changes in the operating condition of mechanical or process systems. This type of analysis is limited to the direct comparison of the time-domain or frequency-domain signature generated by a machine. The method does not determine the actual dynamics of the system. Typically, the following data are used for this purpose (1) baseline data, (2) known machine condition, or (3) industrial reference data. 

In order to understand potential problems and solutions of design, it is helpful to consider the relationships of machine capabilities, plastics processing variables, and product performance (Fig. 1-10). A distinction has to be made here between machine conditions and processing variables. For example, machine conditions include the operating temperature and pressure, mold and die temperature, machine output rate, and so on. Processing variables are more specific, such as the melt condition in the mold or die, the flow rate vs. temperature, and so on (Chapter 8). 

The speed of closure to the form is a function of machine condition and sheet thickness, with the thicker sheets being more difficult to move rapidly. The designer should indicate this to the sheet former when form stability at elevated temperatures is critical and the process must be tailored to improve this condition. One should also select a material which is intrinsically more stable and easily formed to minimize the possibility of unmolding. These factors must be considered in conjunction with the design of the product to minimize sheet stretching differentials in the part. 

A distinction should be made between machine conditions and processing variables. Machine conditions are basically temperature, pressure, and processing time (such as screw rotation/rpm, and so on) in the case of a screw plasticator, die and mold temperature and pressure, machine output rate (lb./hr), and the like. Processing variables are more specific such as the melt temperature in the die or mold, melt flow rate, and pressure used. 

The distinction between machine conditions and fabricating variables is a necessary one to avoid mistakes in using problem-and-solution or cause-and-effect relationships to advantage. If the processing variables are properly defined and measured, not necessarily the machine settings, they can be directly... 

Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title (emphasis added). 

A better understanding of and advanced mathematical formulation of all the basic mechanisms under realistic machine conditions with a single polymeric feed or a mixture of them, with the goal of simulating the process as a whole ... 

Prior to startup one must check certain machine conditions and process control that should be listed on some kind of worksheet from the machine manufacturer, plastic supplier, and/or the more important plant setup person with experience (Chapter 3). Checkup includes the... 

Figure 2.25a shows the removal rates for five dies locafed at different positions in a wafer. If represenfs fhaf fhe removal rafe of fhe confer of the wafer is relatively lower than that of fhe edge. This resulf cannof be explained simply because fhis kind of non-uniformify can be caused by a lot of factors such as machine characteristics, machine conditions, consumables, and wafer shape. The WIDNU is abouf 20% as shown in Figure 2.25b, which is inevifable because fhere are various paffern densities in a die for fhe pracfice of paffern densify effecf. Therefore, we can see thaf fhe paffern densify in a die musf be kepf uniform in real CMP process. 

Furthermore, the use of EMM will widen the range of materials application for electronic industries, MEMS, etc. The role of convective mass transport and current distribution in surface finish and shape evolution is very important. Effective EMM process can be achieved by optimal combination of the process parametric conditions. In order to achieve the effective and highly precise material machining of the order of microns, the predominant process variables of the EMM system will have to be optimally controlled. 

Henry Ford implemented work division, assembly line, subassemblies, and pilot plant of assembly in the assembly of the Ford Model T automobile. While the assembly could be decreased, the process was conditioned by labor cost. The process of replacing people by machines started (Boothroyd 2005). 

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