Molded-part cosmetics

Specialized polyester resins are commonly used in processes such as hand lay-up and spray-up, to provide an attractive and weather-resistant surface finish to molded parts. These gel coats are sprayed onto the mold before the reinforcement is introduced. In addition to their cosmetic function, gel coats can also provide the RP surface with resistance to impact and abrasion. There is also anti-bacterial additive technology to gel coats, especially for applications such as baths and... 

SAN competes with polystyrene, cellulose acetate, and polymethyl methacrylate. Applications for SAN include injection-molded parts for medical devices, PVC tubing connectors, dishwasher-safe products, and refrigerator shelving. Other applications include packaging for the pharmaceutical and cosmetics markets, automotive equipmenL and industrial uses. 

Ejection is the name given both to the process of removing the molding from the mold and to the means by which it is done. Ejectors inevitably leave witness marks on the molding, and this alone may determine the disposition of the part in the mold. Once that basic choice has been made, there is usually not much further freedom to position ejectors in cosmetically acceptable positions. The choices are much constrained by other features in the mold and the need to put ejectors where they are most needed to overcome the resistance of the molded part. 

Molders Division of The Society of Plastics Industry (SPI) has developed cosmetic specifications of injection-molded parts. The purpose of this standard is to provide quantitative definitions and recommended methods of inspection and measurement of the cosmetic quality attributes in the absence of customer provided specifications. The specification addresses the cosmetic quality of molded plastic parts and related post-molding activities. Figure 16-12h shows one of the cosmetic specifications. 

The Society of the Plastics Industry Cosmetic Specifications of Injection Molded Parts... 

Figure 16-12. a) Visual defect summary chart. (From Cosmetic Specifications of Injection Molded Parts, reprinted with permission of Society Plastics Industry, Inc.) b) Cosmetic specifications. (From Cosmetic Specifications of Injection Molded Parts, reprinted with permission of Society of Plastics Industry, Inc.)... 

Over the years, the transportation industry has incorporated more and more composite materials into its vehicles. The automotive industry has used composites for exterior body panels, e.g. hoods, fascias, hatches and doors, as well as under the hood and stmctural reinforcements. The truck industry followed, by introducing composites for hoods, doors, roofs, bumpers and fairings. This paper will focus on the advancements made in composite rrraterials, from hand-spray up open molded parts to the various improvements in sheet nrolding compounds to liqrtid molded resin rrraterials. It will concentrate on parts used in the trucking industry and how quality, especially in cosmetic and surface properties, has improved over the years. 

It should be recognized that surface finish can be more than just a cosmetic standard. It also affects product quality, mold or die cost, and delivery time of tools and/or products. The surface can be used not only to enhance clarity for the sake of appearance but to hide surface defects such as sink and parting marks. The Society of Plastics Engi-neers/Society of Plastics Industries standards range from a No. 1 mirror finish to a No. 6 grit blast finish. A mold finish comparison kit consisting of six hardened tool steel pieces and... 

The blow/fill/seal process is a complete packaging technique that integrates the extrusion or IBM and container filling steps. This can provide for aseptic filling of the hot as-blown container and is used for pharmaceutical, food, and cosmetic products. The process employs a two-part mold in which the container body mold cavity blocks are separate from the neck-forming members. 

The final product may take any one of a vast multitude of final forms. These include, but are not limited to, construction materials, toys, automotive parts, kitchen aids, industrial parts, sports and recreational equipment, containers of all sizes and description, and an unlimited variety of packaging products for foods, drugs, cosmetics, and other consumer products. The processes that are used to produce or mold or fabricate the final products are also varied and depend on the design and purpose of the product. Some of these processes include extrusion, compression molding, roto-molding, blow molding, sheeting, and films. 

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