Material thickness affects die clearance, pressure, feed consistency, and whether the fastener can pierce and set correctly. Thin fabric, laminated signs, board, and layered materials may need different adjustments even when the same grommet size is used. Test the full material stack rather than one layer. The attachment should close firmly without cutting through the surrounding area or leaving movement between the parts. If the material varies during production, define acceptable thickness limits and keep separate settings where needed. Operators should not increase force blindly to solve poor setting, because the die, fastener, or preparation method may be wrong. Consistent samples and documented settings support safer repeat work.