|
Original Date: 05/08/1995
Revision Date: 01/18/2007
Information : High Speed Machining System
McDonnell Douglas Aerospace (MDA)-St. Louis considers High Speed Machining (HSM) a critical technology which addresses part design flexibility, weight savings, part accuracy and part quality, all accomplished while maintaining a high degree of productivity. At MDA-St. Louis, HSM represents surface cutting speeds in excess of 1300 feet per minute (FPM), and feedrates exceeding 100 inches per minute (IPM). Presently, the company is using HSM to fabricate machined parts to replace sheetmetal assemblies with numerous labor-intensive pieces.
The MDA-St. Louis cutting process significantly reduces the cutting forces to operate at ten times normal speeds and feeds for cutting aluminum parts. MDA-St. Louis maintains a goal producing lighter weight parts with thin cross sections and smaller radii with better quality, increased productivity, increased design capabilities, and lower production costs.
To better understand HSM technology, MDA-St. Louis established a laboratory with a Rambaudi 2000 vertical milling machine which was retrofitted with an IBAG 20,000 rpm, 50 HP spindle, with feedrate capability of 236 ipm. One experiment used 20,000 rpm and a 126 ipm feedrate, and achieved a surface finish of 180 radium. The second cut was at 6,000 rpm and 42 ipm with results of a 30 radium finish. Feeds and speeds were increased in incremented amounts (Figure 2-11).
MDA-St. Louis has found that HSM creates lower cutter forces on the work piece which results in the ability to have reduced rib and web thicknesses, smaller corner radii, reduced tolerances, superior surface finishes, reduced residual stresses/distortions, and a high material removal rate. For these reasons, MDA-St. Louis expects to replace sheetmetal sub-assemblies with a one-piece, HSM aluminum plate, resulting in reduced assembly time, fewer fabrication tools, and lighter parts which are stronger and less expensive.
MDA-St. Louis will increase the use of HSM in the future because it can maintain a high metal removal rate, produce complex parts cost effectively, and reduce the use of multiple part assemblies.
Figure 2-11. Surface Finish vs. Speed
For more information see the
Point of Contact for this survey.
|
