Scrap rate

Insistence on all dimensions as critical will result in the process being restricted to one narrow set of operating conditions, usually at a low production rate, with a high scrap rate and high product costs. In cases where the dimensions are critical, it may be that the extrusion process should be discarded in favor of molding or machining of the product. However controlling all dimensions can be accomplished at a cost. 

To this productivity gain, must be added the gains of Improved machine utilization and of reduced scrap rate. The actual results of these combined effects as determined by an extensive production trial of fascia manufacture Is tabulated In "Table V" The total gain realized (60.5%) Is significant. It Is typical of the Increased productivity an effective self-releasing system can provide to a RIM process manufacturing operation. 

Compression molding usually requires a large initial investment and produces semistructural parts. The simplicity of the process minimizes part setup time, reduces secondary finishing, and allows high-volume production with a low scrap rate. 

There is a high scrap rate, or the cost of scrap is high. 

The results of tests on molded test pieces and finished products can in many cases be influenced by the way the material has been processed. This in turn is influenced by the materials processability. Indeed there are very many cases of product failure resulting from processability changes, while misunderstandings and lack of information can also result in reduced output rates, high scrap rates, and general production inefficiencies. 

In high quality decorating and coating operations, the costs of untreated static can be tremendous. Some plants expect scrap rates to be around 10 percent and price their products accordingly. Much, but not necessarily all, of that 10 percent can directly be attributed to static, and, if the proper equipment is employed, scrap rates can be significantly lowered. Nobody who decorates plastic is immune to static bottle printers, painters of automotive parts, hot stampers of toothbrushes, pad printers of cellular phone buttons or coaters of lenses, they all can be affected. 

Use of self-adhesive labels is another option, but this approach poses similar problems. Labeling operations can have high scrap rates (up to 30% in some operations) due to off-center placement of labels, which may slip before the adhesive is fully set, or which may tear or be scuffed during handling. 

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