Investigation of Vibration Isolation Strategies for Precision CNC Machine Tools in the Nigerian Manufacturing Environment

Vibration transmitted to precision CNC machine tools from factory floor sources including adjacent heavy machinery, vehicle movement, and building structural vibration degrades machining accuracy and surface finish quality in Nigerian engineering workshops. This study investigates passive and active vibration isolation strategies for CNC machining centres deployed in the manufacturing environment of Nnewi, Anambra State, South East Nigeria. Floor vibration characterization surveys were conducted at six engineering workshops in Nnewi using a PCB Piezotronics tri-axial accelerometer and signal analyser to quantify dominant floor vibration frequencies and amplitudes. Passive isolation systems including anti-vibration mounts of varied stiffness and damping characteristics and air-spring isolators are experimentally evaluated for insertion loss performance across the measured frequency range. A semi-active isolation system incorporating magnetorheological fluid dampers with real-time current modulation based on accelerometer feedback is developed and evaluated on a machine tool isolation test rig. The semi-active MR damper system achieves 18 dB greater vibration attenuation at the critical 8 to 25 Hz frequency band compared to the best passive isolator configuration, at the cost of added complexity and power supply requirement. A guideline for vibration isolation selection based on floor vibration characterization severity and machining accuracy tolerance class is developed for Nigerian workshop application. The study quantifies the relationship between residual tool vibration amplitude and surface roughness Ra for representative milling operations. Keywords: vibration isolation, CNC machine tool, magnetorheological damper, machining accuracy, manufacturing