PurposePolishing　is　a　crucial　process　in　mechanical　manufacturing.　The　use　of　industrial　robots　to　automate　polishing　is　an　inevitable　trend　in　future　developments.　However,　current　robotic　polishing　tools　are　too　large　to　reach　inside　deep　holes　or　grooves　in　workpieces.　This　study　aims　to　use　a　pneumatic　artificial　muscle　(PAM)　as　the　actuator　and　designs　a　force-controlled　end-effector　to　reach　inside　the　deep　and　narrow　areas　in　the　workpiece.Design/methodology/approachThis　approach　first　addresses　the　challenge　of　converting　the　tensile　force　generated　by　the　PAM　into　pushing　force　through　mechanism　design.　In　addition,　a　dynamics　model　of　the　end-effector　was　established　based　on　the　three-element　model　of　the　PAM.　A　combined　control　strategy　was　proposed　to　enhance　force　control　accuracy　and　adaptability　during　the　polishing　process.FindingsExperiments　were　conducted　on　a　robotic　platform　equipped　with　the　proposed　end-effector.　The　experimental　results　demonstrate　that　the　end-effector　can　polish　the　inner　end　face　of　holes　or　grooves　with　diameters　as　small　as　80　mm　and　depths　reaching　200　mm.　By　implementing　the　combined　control　strategies,　the　target　force　tracking　error　was　reduced　by　48.66%　compared　to　the　use　of　the　PID　controller　alone.Originality/valueA　new　force-controlled　end-effector　based　on　the　PAM　is　designed　for　robotic　polishing.　According　to　the　experimental　result,　this　end-effector　can　polish　not　only　the　outer　surfaces　of　the　workpiece　but　also　the　internal　surfaces　of　workpieces　with　deep　holes　or　grooves　specifically.　By　using　the　combined　control　strategy　proposed　in　this　paper,　the　end-effector　significantly　improves　force　control　precision　and　polishing　quality.