Surface Waviness - Sealing's Hidden Enemy

Modern, metal-based, static seal technologies are more sensitive to component flange surface finish effects than their softer, composite cousins. Non-averaging or skidless profilometer instruments are capable of accurately resolving the short-wavelength roughness and long-wavelength waviness components of a surface profile. Simple roughness measurements of a surface often ignore the important waviness features that can result in sealing difficulties with these seal technologies. This paper presents techniques for proper surface profile filtering and investigates the impact of waviness conditions on basic, static sealing performance.