What's the Best Process for Machining a Precise Hole in Aluminum?
This small hole is actually large enough that any of three different processes might be used.
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.)
In carbon fiber reinforced plastic (CFRP), the material removal mechanism is shattering instead of shearing. This makes it different from other machining applications.
Composites are replacing metal in certain applications. What does this mean for machining?
Though it won’t replace high speed machining, Boeing sees “low speed machining” as a viable supplement to higher-rpm machines. Using new tools and techniques, a shop’s lower-rpm machining centers can realize much more of their potential productivity in milling aluminum aircraft parts.