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30.3 Flash Troubleshooting 297
30.3.4.3 Material: Regrind
Reground material is normally perfectly fine for reuse in a process, and in fact
generation studies out to the fifth generation show that many materials lose very
little in their physical properties. The above statement is only true if regrind is
handled properly, not contaminated, and either dried or reused immediately. If
regrind becomes degraded it will impact the viscosity of the material, which in
turn may lead to flash.
Whenever using regrind try to reuse it at the point of generation. To be able to
achieve this it is important to design runner systems that are smaller than the
allowable regrind percentage. Also do not try to regrind and reuse parts that were
degraded. In other words, if a part is scrapped because of splay do not regrind it
because all that is going to happen is that the problem on that part will be diluted
and spread across many more parts.
Use of regrind is not bad but it must be treated correctly. Keep it clean, dry if
necessary, grind to a consistent size, limit dust, and try to reuse it as quickly as
possible.
