25. Trouble Shooting Undersize cutting of internal thread Bad surface, surface damaged Description of products Improve cutting Selection and design of tap Work material Improve cutting Prevent welding Check cutting condition performance performance ●Check workmaterial. ●Use workpiece which has even structure and hardness. ●Pay attention to tapping ●Pay attention to tapping position and material thick- position and material thick- ness. ness. ●Adopt bigger bored hole. ●Prevent work hardening of material. ●Prevent work hardening. ●Provide bigger bored holes. Prevent slanting of hole. Feed according to pitch. ●Use the tap holder of floating type. ●Prevent vibrating of axis of tap ●Prevent centering-off with work piece. ●Reduce cutting speed. ●Provide proper timing for changing or filling-up of cutting oil. ●Prevent mixing of other oil into cutting oil. ●Use other cutting oil which prevents cold welding. ●Use cutting oil of insoluble type. ●Adjust flow of cutting oil and method of lubrication. ●Remove unnecessary chips ●Provide Nitride on taps. Use oversiza taps. ●Use spiral pointed taps Provide oxide coating on Use oil hole taps. (for through hole). taps. Provide larger cutting angle. ●Adjust relief angle on cutting Provide larger cutting angle. ●Change of no. of flutes on ●Reconsider length of cutting chamfer. ●Adjust relief angle on cutting taps. chamfer. Provide thread relief. chamfer. Provide more narrow margin. ●Increase re-sharpening ●Provide better surface frequency. finishing on flutes. ●Increase re-sharpening frequency. Information Technical ●Provide precise re-sharpening. ●Be careful about burning during re-sharpening. Technical-74 845