Brake pad surface inspection
Brake pads on a conveyor pass a station lit at a low angle from four sides. Image processing searches the friction face for cracks and chipped edges and measures the centre slot; a defective pad is pushed off the line.
Crack length, chip length and slot width are recorded for every pad and shown on the operator display with the processed image. The verdict is sent to the line PLC; a defective pad is pushed onto the reject table at belt height and the stack light signals the result.
- 01 Infeed
- 02 Acquire
- 03 Analyse
- 04 Decide
Pads approach the station with the friction face up.
- Crack length
- —
- Edge chip
- —
- Slot width
- —
Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
The friction material is a dark, matt, granular compound: fibres and metal particles sparkle under direct light and a fine crack disappears in this texture. A crack or an edge chip has to be told apart from the centre slot and the chamfers that are there by design.
Solution approach
The camera looks straight down; light comes from four sides at a shallow angle (dark field). The flat friction face stays dark, while steps such as a crack mouth, a chipped face or a slot edge face the light and light up. Four-sided light works for any crack direction. Line-like traces are classed as cracks, missing contour area as chips; slot width is measured between its two edges.
Process steps
- 01
Infeed
Pads approach the station with the friction face up.
- 02
Acquire
Low-angle light strobes: the flat face stays dark, cracks and edges light up.
- 03
Analyse
The face is searched for cracks and edge chips; slot presence and width are measured.
- 04
Decide
Findings are compared with the limits; a defective pad is pushed onto the reject table.
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