Van's Air Force
Western Canada Wing
|
Van's Air Force
Western Canada Wing |
As a practical matter, how important are RPMs for drilling aluminum?
Someone suggested that aluminum likes high speed drills. More correctly we might say that small bits like high speeds. The cutting edge on #30 bit is making a much slower speed over the aluminum than that of a 1/2 inch bit. The larger the bit the slower you need to turn it. Slow way down for the fly cutter!
Generally, the harder the material, the slower the speed of the edge needs to be. Here are a few speed recommendations from an old handbook:
| Annealed 4340 steel | 60 fpm |
| Stainless 410 | 30 fpm |
| Aluminum alloys | 250 fpm |
Also, the recommended coolant for aluminum is water based solutions. (Milk?) I believe many who complain of non-round holes are feeding too fast. Feed (pushing the drill into the work) is given in inches per revolution. If one pushes a slow drill as hard as a fast one, the feed will be faster. Feed for aluminum should be 0.007 ipr, and steels about one fourth that.
[Drilling RPM can be determined from the cutting speed for the material and the diameter of the drill:
N =12xV/PIxDwhere N is the drill motor speed in RPM, and V is the cutting speed of the material in fpm. Using values from Machinery’s Handbook, the correct RPM for drilling a #30 hole in aluminum is:
N= (12 x 500) / (0.1285 x PI)which works out to 14,800 RPM! Clearly, you’re not going to exceed the recommended drilling speed with a hand drill. This emphasizes the importance of Hal’s advice to not feed the drill into the work too fast—Webmaster.]
A member of the Web Standards Project |
Support free speech. |
Built on...
...FreeBSD |
|
|
Van's Air Force Western Canada Wing is not affiliated in any way with Van's Aircraft Incorporated. Western Canada RVator is not a publication of Van's Aircraft or any other corporation. All products reviewed or mentioned are not necessarily recommended for use by RV builders, but are described for information only. All builder's tips are presented only as a source of information and a forum for exchange and the sharing of ideas and construction methods. No responsibility is assumed, expressed, or implied as to the suitability, accuracy, safety, or approval thereof. Any party using the suggestions, ideas, or examples does so at his or her own risk and discretion and without recourse against anyone. The members of Van's Air Force Western Canada Wing, the editor of the Western Canada RVator, and all authors and contributors are not responsible for any product or builder's tips misuse, incorrect construction, or design failure, nor any other peril. All material on this web site is copyright Van's Air Force Western Canada Wing, or copyright the attributed author, unless otherwise noted. | |||