A masking line is the boundary where coating application was intentionally stopped. Its intended position comes from the drawing, mask layout or approved sample. An irregular edge is a departure from the approved boundary. A visible line can be intentional, and an intentional boundary can still show local overspray, an uneven edge or a missed section.
Compare position and edge profile separately
Use a fixed viewing setup and compare several parts from the same run. Start with the location of the boundary relative to a stable feature such as the rim. Then inspect the shape of the transition. Note where it becomes wavy, blurred or discontinuous. If the whole line is offset consistently, check mask placement. If only short sections vary, examine local mask contact and the receiving surface before assigning a cause.
Check the purpose of the bare zone
If the uncoated area is a fitting or sealing surface, compare the boundary with the functional land as well as the appearance sample. An otherwise straight line can still leave coating where parts need to seat. Record the side and location on a photograph and keep a representative part for the process review.
Packaging sample showroom of SamBound New Material Technology Company Ltd. Company information: sambound.com.
SamBound New Material Technology Company Ltd.
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