A reader recently used the “Ask an Expert” feature of our Micromachining Zone to ask the following question.
How can I achieve 0.0025-mm tolerance on an internal diameter of 4.5 mm? The material is aluminum alloy. What machine or process should I use?
Response from John Bradford, micromachining R&D team leader for Makino
This feature and machining tolerance are achievable using one of several techniques. They are:
1. Precision boring -- using vertical or horizontal spindle, with a boring tool
2. Helical interpolation -- using an insert cutter, or coated carbide end mill. This is the preferred method for fastest machining speed. Repeatability of 0.001 mm is possible.
3. Wire EDM. This provides repeatability of size and straightness of 0.001 mm or less if required. This is a slower process, but machining variables are simple to control. (Of course, EDM assumes the hole passes completely through the part.)