Industrial Optical Measurement Systems (IOMS)

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.

In this example a bored combustion cylinder has been scanned using a displacement probe that can generate data which can be used to produce a two-dimensional image of the surface or a three dimensional profile image of the surface. The data is taken only once, but can be processed in different ways as desired. An image of the inside surface of the cylinder is shown in Figure 1. The diameter of the cylinder is about 80 mm.

In addition to inspecting smooth diamond turned surfaces for surface flaws, IOMSprobes can inspect tapped threads for proper thread count, thread spacing, pitch and thread defects such as crossed threads and other flaws. An example of a scan of the entire surface of a threaded part is shown in the figure below.

The red areas in the top and bottom of the image of Figure 1 indicate reversals of the axial velocity of the honing stones. The number of bright red areas indicates the number of honing stones in the tool. The cross hatch angle has been calculated from the data and is indicated at various locations on the image.

Castings are designed to minimize the amount of metal removal in machining operations. However, if the cutting tool is not precisely aligned relative to the part being machined, a non cleanup condition could result. This is shown in Figure 1 in which a honing operation has failed to remove residual fine boring marks from the previous machining operation.

Another technique for finishing combustion cylinders is to spray the bored surface with liquid metal to eliminate the formation of pores when the surfaces are honed. This technique has its own problems, however, since the spray nozzle that deposits the liquid metal could leave solidified drops of metal on the surface of the cylinder or cause cratering of the surface if drops of metal splatter on the surface during spraying. Figure 1 shows an image of a surface that has been coated by a rotating nozzle. Figure 2 is a scan of a cylinder showing solidified droplets and surface craters caused by the bombardment of small drops of metal. Dark spots on the image of Figure 2 are solidified drops of metal that protrude above the surface. Light colored regions are craters produced by metal droplets bombarding the surface.