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<p>Evaluating the microstructural characteristics of polymer nanocomposites and establishing baseline process parameters are essential for their successful application in microscale manufacturing. In this study, PMMA/Graphene Nanoplatelet (GNP) nanocomposites containing 1 wt.% GNPs were fabricated via solvent casting followed by hot pressing. Microstructural characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy confirmed uniform dispersion and effective encapsulation of the GNPs within the PMMA matrix, revealing minor residual compressive strains due to thermal expansion mismatch. To identify the baseline process window and prevent tool damage, systematic micro-milling experiments were performed on pristine PMMA using a central composite design (CCD) under dry cutting conditions; all machining trials in this work were therefore limited to the unreinforced polymer, and machining of the reinforced films is planned as a follow-up study. Spindle speed and feed rate were identified as the primary factors affecting cutting forces and surface roughness. The minimum cutting forces were observed at high spindle speeds (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\ge 25000~\text {rpm}\)</EquationSource> </InlineEquation>), attributed to the reduced chip load per tooth together with thermal softening of the polymer, whereas the optimal surface roughness (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(R_a \approx 0.12~\mu \text {m}\)</EquationSource> </InlineEquation>) was measured at a high spindle speed (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(25000~\text {rpm}\)</EquationSource> </InlineEquation>) combined with a low feed rate (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(15~\text {mm/min}\)</EquationSource> </InlineEquation>). Post-machining analysis of the micro-tools revealed adhesive wear and flute clogging, consistent with the low thermal conductivity and low glass transition temperature of PMMA. Furthermore, burr width measurements indicated greater burr formation on the down-milling side, dominated by a continuous wavy morphology. These baseline micro-milling parameters provide a reference window for the subsequent micro-machining of reinforced PMMA/GNP nanocomposites.</p>

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How spindle speed and feed rate control PMMA micro-milling: baseline process optimization toward micro-milling of PMMA/GNP nanocomposites

  • 期刊论文

  • 发表日期：

    2026年8月5日

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  • Sunil Rawal,
  • Ahmed Aly Diaa Sarhan,
  • Ajay M. Sidpara,
  • Mourad Nouioua

摘要

Evaluating the microstructural characteristics of polymer nanocomposites and establishing baseline process parameters are essential for their successful application in microscale manufacturing. In this study, PMMA/Graphene Nanoplatelet (GNP) nanocomposites containing 1 wt.% GNPs were fabricated via solvent casting followed by hot pressing. Microstructural characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy confirmed uniform dispersion and effective encapsulation of the GNPs within the PMMA matrix, revealing minor residual compressive strains due to thermal expansion mismatch. To identify the baseline process window and prevent tool damage, systematic micro-milling experiments were performed on pristine PMMA using a central composite design (CCD) under dry cutting conditions; all machining trials in this work were therefore limited to the unreinforced polymer, and machining of the reinforced films is planned as a follow-up study. Spindle speed and feed rate were identified as the primary factors affecting cutting forces and surface roughness. The minimum cutting forces were observed at high spindle speeds ( \(\ge 25000~\text {rpm}\) ), attributed to the reduced chip load per tooth together with thermal softening of the polymer, whereas the optimal surface roughness ( \(R_a \approx 0.12~\mu \text {m}\) ) was measured at a high spindle speed ( \(25000~\text {rpm}\) ) combined with a low feed rate ( \(15~\text {mm/min}\) ). Post-machining analysis of the micro-tools revealed adhesive wear and flute clogging, consistent with the low thermal conductivity and low glass transition temperature of PMMA. Furthermore, burr width measurements indicated greater burr formation on the down-milling side, dominated by a continuous wavy morphology. These baseline micro-milling parameters provide a reference window for the subsequent micro-machining of reinforced PMMA/GNP nanocomposites.