Brake Caliper Cylinders

Brake calipers squeeze brake pads against brake rotor surfaces to stop a vehicle. The brake pads are pressed against the brake rotor by pistons that are moved by pressure from brake fluid injected into brake caliper cylinders. The cylinders have grooves machined into their surfaces to hold seals that contain the brake fluid. During manufacture the grooves can accumulate metal chips and shavings that prevent proper insertion of the seals. The inspection process determines whether the cylinder and grooves are clean and ready for assembly into a brake caliper unit.
Figure 1 is a photo of a brake caliper base that contains two brake caliper cylinders. Figure 2 is an approximate surface profile of the entrance to a brake caliper cylinder. Figure 3 shows a scan obtained with an IOMS 2D reflective probe of a clean cylinder groove. The cylinder could also have been scanned with a displacement probe that could display the surface profile. Chamfers appear in green. Figure 4 shows the same cylinder with a metal shaving in the groove.