Small diameter cylinders

This is an example of the inspection of small diameter valve guides. The diameter of each guide was 6 mm and the length of a guide was 30 mm. The valve guides were bored with a fine boring tool to remove the reaming marks from the previous machining process. All of the guides were bored with the same tool. The objective of the measurements was to determine the effect of tool wear on surface finish. Image (a) was a guide bored when the tool was new. Image (c) is the finish that was obtained after the tool machined a few hundred pieces. The worn tool used to produce the surface finish in image (c) is no longer able to remove the reaming marks. Image (b) shows a cylinder with a large number of pores of different sizes and shapes.
                 (a)                                        (b)                                            (c)