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Abstract
Hypereutectic aluminium–silicon (Al–Si) alloys offer high wear resistance and low thermal expansion, but their primary silicon particles can make machining difficult because of their hardness and abrasive action. This paper re-examines experimental dry-turning results for an AlSi18/A390-type hypereutectic alloy machined with polycrystalline diamond (PCD) inserts. The source study compared an unmodified alloy with a strontium-modified condition at cutting speeds of 500, 600, and 700 m/min, while feed and depth of cut were held at 0.1 mm/rev and 1 mm, respectively. Tool life was evaluated using a maximum flank-wear limit of 0.30 mm; surface quality was assessed using arithmetic mean roughness (Ra), and chip morphology was described qualitatively. Re-analysis of the tabulated results indicates that tool life decreased with increasing cutting speed in both material conditions. At 500 m/min, the reported tool lives were 38 min for the unmodified alloy and 40 min for the Sr-modified alloy; at 700 m/min, they were 15 and 18 min, respectively. The mean of the tabulated Ra measurements increased from approximately 0.806 to 1.025 μm for the unmodified alloy and from 0.795 to 0.995 μm for the Sr-modified alloy as speed increased from 500 to 700 m/min. The modest life advantage associated with Sr modification is consistent with the limited influence of Sr on primary silicon compared with modifiers specifically used to refine that phase. Because the source experiment does not report independent replicated cutting trials or inferential statistics, the observed differences should be interpreted descriptively rather than as statistically significant effects. The paper identifies practical implications and data-verification requirements for a submission-ready follow-up study.