Determination of the Fifth and Sixth Digits for Injection Molded and Die Cast Parts

(Used under permission of Dixon and Poli,
Engineering Design and Design for Manufacturing)


Fifth Digit

For Injection Molded Parts:

For a surface finish of SPI 5-6 the fifth digit is 0.

For a surface finish of SPI 3-4 the fifth digit is 1.

For a textured surface finish the fifth digit is 2.

For a surface finish of SPI 1-2 the fifth digit is 3.

(SPI stands for Society of the Plastics Industry.)

For Die Cast Parts:

The surface finish for die cast parts will not differ and thus the fifth digit is always 1.


Sixth Digit

For both Injection Molded and Die Cast Parts:

For commercial tolerances the sixth digit is 0.

For tight tolerances the sixth digit is 1.