SURFACE FINISH SPECIFICATION FOR HIGH QUALTITY MOLDS
Published: February 18th, 2009
The surface finish for very smooth molds is typically described by such terms as:-
SPI-A1, SPI-A2, SPI-B1, SPI-C1etc. . Ra numbers appear to have been attributed to these finishes in industry but the SPI master referenceis an ABS plastic plate without traceability to ISO, ANSI, MIL or any definition of finish
Can anyone explain this and who assigned the Ra numbers to the commonly used SPI finishes ?