Machine process controls

Machine process controls coordinate individual functions of the clamp, injection unit, ejector mechanism, and mold systems and accessories such as core pulls and unscrewing dies for threaded parts. The more advanced controls employ a feedback system (closed loop) to provide much tighter control over actual parameters vs. setpoints. High-level controls are capable of communicating with auxiliary equipment such as chillers, hopper loaders, mold temperature controllers, robots, etc., and displaying all machine parameters and conditions (Chapter 3)... 

Chemical-Mechanical Planarization involves often-conflicting requirements at various length scales—e.g. uniform removal at the wafer scale, but non-uniform removal of high areas to achieve planarization at the feature scale. In conjunction with machine process controls, the management of pressure by the consumables is one key to balancing these requirements. 

Different types of machine process controls (PCs) can be used to meet different requirements based on the molder s needs. PC systems range from the unsophisticated monitors (alami buzzes, light flash) to very sophisticated program controllers (personal computers (PCs) interrelate different IMM functions and melt process variables) (Figure 30). (Note that PC has different definitions see Appendix A, List of Abbreviations.)... 

A recent trend in particle analysis has been the introduction of personal computer-based automation (3). Sophisticated software packages can be used to automate and speed up the analysis. In some cases these computers can even carry out continuous process control (qv) (see Computer technology). The latest machines also allow the measurements of smaller particles and can detect a wider range of sizes. Machines based on light-scattering principles are being more widely accepted by the industry because of speed. An average analysis takes from 1—2 min, whereas those based on sedimentation principles require from 10—120 min. 

The process control functions and the operator interface, also referred to as man-machine interface (MMI) or human-machine interface (HMI), is provided by separate nodes. This approach is referred to as split-architecture, and it permits considerable flexibihty in choosing a configuration that most appropriately meets the needs of the application. 

Nutsche filters are constructed to perform a multitude of tasks including reaction, filtration, cake washing and thermal drying on a single unit. As such these are very sophisticated machines with tight process control on parameters such as pressure, temperature and pH. 

The first set of case studies illustrates errors due to the inadequate design of the human-machine interface (HMI). The HMI is the boundary across which information is transmitted between the process and the plant worker. In the context of process control, the HMI may consist of analog displays such as chart records and dials, or modem video display unit (VDU) based control systems. Besides display elements, the HMI also includes controls such as buttons and switches, or devices such as trackballs in the case of computer controlled systems. The concept of the HMI can also be extended to include all means of conveying information to the worker, including the labeling of control equipment components and chemical containers. Further discussion regarding the HMI is provided in Chapter 2. This section contains examples of deficiencies in the display of process information, in various forms of labeling, and the use of inappropriate instrumentation scales. 

Processing is extremely important in regard to tolerance control in certain cases it is the most influential factor. The dimensional accuracy of the finished product relates to the process, the machining accuracy of mold or die, and the process controls, as well as the shrinkage behavior of the plastic. 

The term process control is often used when machine control is actually performed. As the knowledge base of the fundamentals of the molding process continues to grow,... 

Example 62 If a manufacturing process involves two raw materials, each defined by three sets of specification limits, and four pieces of equipment with one control knob, then a complete validation protocol would ask for (Three settings Lo, Target, Hi) (2 materials 3 specs + 4 machines 1 control) = 3 = 59 000 experiments, even without repetitions. This product would never reach the market if one did not employ experience and scientific rationale to simplify development by testing only the presumed critical issues, say a total of three specification points for 3 = 27 experiments. 

The U.S. Army Defense Ammunition Center and School is employing the use of intrinsically safe electrical circuits in equipment designed to demilitarize and renovate munitions - from small arms to large projectiles. This is accomplished by using pneumatics and hydraulics to provide the power, while using position switches and solenoid valves linked to programmable controllers to direct the total machine process. 

A team was assembled that included experts in resins, machinery design, process controls, and plant operations. The machinery manufacturer chosen was the one that had the most knowledge and manufacturing capabilities for this size of machine and process. Again, all team members were acutely aware of the project goals and timing. 

The process control is provided by programmable process controllers (PLCs), which are flexible and upgradable. The addition of man-machine interfaces (MMls) based on personal computers and common software systems allows not only system control and interlocks, but also a history... 

Abstract To appreciate the technological potential of controlled molecular-level motion one only has to consider that it lies at the heart of virtually every biological process. When we learn how to build synthetic molecular motors and machines that can interface their effects directly with other molecular-level sub-structures and the outside world it will add a new dimension to functional molecule and materials design. In this review we discuss both the influence of chirality on the design of molecular level machines and, in turn, how molecular level machines can control the expression of chirality of a physical response to an inherently achiral stimulus. 

---