Troubleshooting is the art and science of remedying defects after the process has demonstrated the ability to produce
acceptable production parts. Most defects respond to one of a variety of process and/or material changes. The goal is to correctly identify which problem is actually causing the defect and to know when a particular solution will work. When making adjustments consider the following recipe:
• Create a mental image of what should be happening,
• Look for obvious differences,
• Make only one change at a time, and
• Allow the process to stabilize after any change is made.
Studies have determined that about 60% of defects result from machines and equipment, 20% from molds and dies, 10% from material, and 10% from operator error. Software programs, either already installed on the machine’s processor controller or available as a software package, can provide some help.
With all types of equipment, materials, and products, troubleshooting guides are set up (usually required) to take fast, corrective action when products do not meet their performance requirements. This problem-solving approach fits into the overall fabricating-design interface.
To understand potential problems and solutions (and eliminate myths), it is important to consider the relationships of machine and equipment capabilities, plastics processing variables, and product performances. A distinction has to be made between machine conditions and processing variables. Machine conditions could include operating temperatures, back pressures, screw rotation speed, die temperature, etc. Processing variables are more specific, such as melt conditions in the plasticator and die, melt flow rate versus temperature, etc.
When setting up troubleshooting guides, as well as reviewing any problems or even open discussions on the subject of fabricating, it is important that the terms used to identify a problem be understandable, clear, and properly defined.
Different terms are used throughout the industry to identify defects in plastic materials, fabricating equipment, and products. They include adhesive stringing, air bubble, applesauce, arrowhead, black speck, bleed, blister, blockage, bloom, blowhole, blush, burn line, chalking, coating defect, cosmetic defect, compressive buckling, crazing, degradation, electrostatic charge, fin, fines, fish-eye, flash, fracture, flaw mark, freeze-off, frosting, gas pocket, gel, globule, hairline, migration, orange peel, paint framing, pimple, pin hole, pit, plastic pocket, plate-out, pocket, pock mark, puckering, run, sag, scale, segregation, shark skin, sink mark, speck, splay mark, stain, starved area, streak, stress whitening, striation, surface finish, trim, void, weld line, yellowing, and so on.