Quality Assurance in Injection Molding

One particularly notable definition of quality describes it as fitness for use. Above all, the product must satisfy the customer. Quality is a factor which is difficult to measure directly, because there is no uniform standard for evaluation. Therefore, quality must be redefined for each different part. 

Quality is generally intended to mean that a product fulfills certain individual characteristics (specifications), which are expressed by the customer in terms of specific tolerances. 

Geo me trie Dimensional deviations Shrinkage Warpage Surface texture 

Mechanical Tensile strength Flexural strength Notch impact strength Modulus of elasticity Internal stresses 

Internal Specific volume Molar mass distribution Orientation 

---

From quality control to quality assurance in injection molding... 

For metal fuel fabrication, the actinide metals are alloyed in an injection casting furnace that melts, mixes the alloy and injects the molten metal into quartz molds. After quick cooling, the quartz mold is removed from the metal pin, which is cut to length and undergoes quality assurance measurements. These pins are placed into new fuel cladding that contains a small amount of metallic sodium, which provides a thermal bond in early irradiation in the nuclear reactor. These fuel elements are welded closed and are ready for the reactor. Recent research in this area has focused on modifying the process to minimize the volatization of americium, which is a key component in U/TRU recovered for fast reactors and has a high vapor pressure. 

The handling system or robot gives a signal to quality assurance when the product is placed on the measuring tool. According to the result of the quality che, the robot receives an T(y or NIO signal. At lO, the plastic parts are placed on a conveyor or directly into a box. At NIO, the part is placed in the rejected line of the conveyor belt. No-one is required to check the quality of inserts before they are placed in the injection mold. The decision on whether the produced parts are lO or NlCy is... 

During the injection process, observation sensors are used for the quality assurance of the manufacturing process. In the pressure-assisted injection, ultrasound measurements or dielectric measurements can be used for this application. The sensor system has to be included into the mold and has to be designed to withstand loads using a validated analysis. 

In line with these four points, there is a need for know-how along the entire process chain from formulas for thermoplastics through injection molding, structuring, and metallization to final placement of the electronic components. Correspondingly, in-process quality assurance with defined interfaces between stakeholders is of tremendous importance. It is in this context that this book addresses each individual process step with the purpose of avoiding possible mistakes in MID projects. 

After the optimization test finishes, the optimized molding condition should be maintained. Also, there is a need to have means assuring the part quality immediately in the shop floor for the quahty control purpose. Another contribution of the PMS to the injection molding process would be the immediate represaitation of part qu ity. In order to utilize the PMS for the purpose, the pressure or temperature profiles cannot be used as it is. Even well trained engineers have difficulty in telling the difference by reading the profiles only. Therefore, a proper index from the measurement of toe PMS should be made to represent a quality target. It can be called as the PMS index. Usually the cavity pressure peak has been widely... 

Injection molding of thermoplastics is probably the most important and popular plastics forming process. In order to manufacture high quality parts, it is important to assure balanced flows during the filling of the mold. In this condition, the boundaries of the mould are filled at the same time with more uniform pressure leading to a decrease of the maximum required injection pressure and clamp force. 

---