White plastic highlights defects including contamination with other colors (or materials), burn marks, and shrinkage. It is common for one injection machine to be used for many colors and types of plastic, but since white is such a pure color, it is very easy to see swirls or traces of other colors in the part. Even different batches of white plastic can cause unsightly marks; getting some nylon in your ABS part will certainly ruin it. Burn marks (which are dark) obviously stand out more against white than any other color, and are generally caused by either the mold or plastic being too hot. Shrink marks are caused by uneven cooling of the plastic because of machine settings or part design, and are most visible on white because of uneven reflections and small shadows. Even tiny scratches can ruin the glossy finish of a smooth part.
Since Apple has huge volumes, they can dedicate machines to injecting a single mold, and ensure that plastic colorants are matched across batches; the rest of us (with volumes of less than ~100-500k/yr) have to settle for grey.
If anyone wants to chat about part design and manufacture, let me know.
Since Apple has huge volumes, they can dedicate machines to injecting a single mold, and ensure that plastic colorants are matched across batches; the rest of us (with volumes of less than ~100-500k/yr) have to settle for grey.
If anyone wants to chat about part design and manufacture, let me know.