Sunday, October 1, 2023
These are acceptable porosity standards for machined surfaces. Acceptance to these standards is on a visual judgement basis without magnification.
Pin Point Porosity, not larger than 0.25mm ( 0.01") in any direction is acceptable providing it is widely distributed. (Not grouped or connected.)
Random pits, not larger than 0.375mm ( 0.15") in any direction are allowable providing they are widely distributed. (Not grouped or connected.) They must be completely surrounded by dense parent metal and be a minimum of 6mm (0.25") apart.
Frequency of pits must be minimal.
Pin Point Porosity, not larger than 0.375mm ( 0.015") in any direction is acceptable providing it is widely distributed. (Not grouped or connected.)
Random pits, not larger than 0.75mm ( 0.30") in any direction are allowable providing they are not grouped or connected.
Frequency of pits must not be excessive.
Pits not larger than 1.25mm ( 0.05") in any direction are acceptable.
Exposed chain porosity must not exceed 3mm (1/8 ") in length.
Unless otherwise specified, exposed porosity on machined diecast parts will conform to this level.