Troubleshooting sizing problems

Stand-alone computer systems, usually based on a personal computer (PC) or programmable logic controller (PLC), provide a separate computer system for each pilot plant. This allows for economical expansion for new units, separates pilot plants completely for maintenance and troubleshooting, and often has the lowest initial cost. Standardization can be a problem and software control, data gathering, and storage packages can be limited in size, scope, and capabiUty these are usually acceptable trade-offs. 

Anticipated problems and counter measures for the listed protocols have been included in individual steps of the basic protocols. In addition, a detailed troubleshooting section for particle size analysis can be found in unit d.u however, the difficulty of properly conducting accelerated tests should again be stressed. While the method is extremely useful, as it can drastically reduce the required time for the overall test, results may not accurately reflect... 

The primary factors that affect the flowability of the final blend (or almost any powder), such as moisture content, particle shape/size/distribution, temperature/humidity and others, are discussed in more detail later in this chapter. Note that the measurement of flow properties and the design parameters they provide can also be applied to troubleshooting and developing corrective actions for flow problems in the preblending steps. 

Rotomolding and transfer molding are also affected by a number of variables that are difficult to control and hard to scale when the size and design of the part changes. It is important to follow a set of troubleshooting guidelines to take corrective action when the part is defective. Tables 10.15 and 10.16 provide lists of problems and suggested corrective actions. 

Much useful information on problems and solutions in extrusion is available from material and equipment suppliers. Trade journals publish special issues on this subject with very useful tables, and industrial literature includes practical guides with helpful details (see reference 2 and Chapter 18). The size of this book does not permit such treatment, but an excellent summary of troubleshooting is given in Table 3-11, from Plastics World (185). 

In troubleshooting of molded part defects, it is important to look at the shot size, injection speed, injection pressure, cushion, decompression, and nozzle tip. The following troubleshooting flow charts will help to resolve a majority of the problems. The forming of weld lines wherever polymer flow fronts meet is one of them [1]. 

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