Detection of surface defects on steel ball bearings in production process using a capacitive sensor

A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor

“…A double-probe eddy current sensor has been used to scan and inspect steel ball surfaces, with two probes symmetrically arranged at 180 degrees on the testing mechanism outside of the steel ball [ 1 ]. An instrument composed of several electromagnets and a ring-shaped capacitive sensor has been designed, yielding an instrument capable of inspecting surface defects 0.05 mm in diameter and 0.01 mm in depth on a 4 mm diameter steel ball bearing [ 3 ]. A visual inspection technique has been employed, with visual features providing a rapid means of inspection of single balls [ 4 ].…”

“…In the multi-sensor Aviko system, the meridian unfolding mechanism of the steel ball surface is set up to reduce the complexity of the unfolding wheel, but the unfolding mechanism is still complex. The system, which employs a ring-shaped capacitive sensor, needs to operate under lapping oil, despite possessing a simple unfolding mechanism [ 3 ]. The specular nature of the bearing surface makes it difficult to inspect subsurface defects of steel balls [ 4 ].…”

Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection

“…A steel ball surface-defect automatic inspection system mainly consists of a steel ball surface unfolding mechanism and a defect-inspection sensor. Commonly-used sensors for steel ball surface defect detection include vision sensors [ 3 , 4 ], eddy current sensors [ 5 , 6 , 7 ], and capacitive sensors [ 8 ].…”

Non-contact resistance and capacitance on-line measurement of lubrication oil film in rolling element bearing employing an electric field coupling method

“…Lubrication, as an effective method of reducing friction and wear, is indispensable to almost all mechanical systems. The mechanism of lubrication is the formation of a complete continuous oil film layer in the gap between moving that avoids direct contact between moving parts [1][2][3]. In radially loaded rolling bearing, all the balls are suspended in the oil film under rated load and rotating speed.…”

“…Since most mineral or synthetic lubricants are insulators, a complete oil film providing good lubrication will separate the moving parts (assumingly made of metal) and form a capacitor. The thickness of the oil film can be predicted from the capacitance change [1][2]. Moreover, the deterioration of lubricating oil is mainly due to overloading, low-speed starting, excessive temperature and electric discharge, most of which are accompanied by carbonization or emulsification, and related impurities (carbon particles or moisture) will enhance the conductivity of lubricants [14][15].…”