Ultra-high molecular weight polyethylene has been micro-scratched with 90° cube corner tips. The scratch mode was flat-on, uni-directional and single pass. The micro-scratches and cross-sectional scratch profiles were characterised with atomic force microscopy. No detached debris is produced. Cross-sectional scratch profiles have been analysed using Zum Gahr's formalism giving an fab ratio slightly above zero. This is consistent with expectation for ductile polymers where none or little

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... debris is produced. However, the observation contrasts with that for other polymers, such as PMMA, PEP and PC, for which inconclusive results suggest an excess pile-up implying an inconceivable change of mass density or material gain.