Kasey7
Mechanical
- May 1, 2003
- 125
Hi,
I work in a machine shop that manufactures engine components for various companies. We're often dealing with tolerances to <.0005", and there seems to be quite a difference when machining material supplied by our clients (usually AMS barstock), and material we buy ourselves (usually ASTM barstock).
Could someone explain/confirm the differences between ASTM barstock and AMS (both aluminum and SST), or even better point me to somewhere on the web that would offer an explanation?
I've been told, (from various sources that, again, I'm unable to confirm), the following:
• ASTM bar is extruded, AMS is extruded/drawn.
• A final product made from either ASTM or AMS bar offers identical properties (strength, corrosion resistance, etc.) to the customer.
• AMS bar, though more expensive (?), is better suited for precision machining.
• AMS is less likely to distort during the machining process (less internal stresses during the mfg of the bar?)
• AMS turns beautifully, ASTM seems gummy and often the surface appears to have fur on it when roughing.![[ponder] [ponder] [ponder]](/data/assets/smilies/ponder.gif)
• ASTM seem more prone to vibration when finishing.
• AMS barstock came into being primarily to satisfy the needs of the aerospace industry.
I've been told that alot of the problems I have had with turning some barstock we use is in my head, or the coolant oil/water ratio is wrong. Is there really no difference, where machinability is concerned, between ASTM versus AMS?![[ponder] [ponder] [ponder]](/data/assets/smilies/ponder.gif)
I work in a machine shop that manufactures engine components for various companies. We're often dealing with tolerances to <.0005", and there seems to be quite a difference when machining material supplied by our clients (usually AMS barstock), and material we buy ourselves (usually ASTM barstock).
Could someone explain/confirm the differences between ASTM barstock and AMS (both aluminum and SST), or even better point me to somewhere on the web that would offer an explanation?
I've been told, (from various sources that, again, I'm unable to confirm), the following:
• ASTM bar is extruded, AMS is extruded/drawn.
• A final product made from either ASTM or AMS bar offers identical properties (strength, corrosion resistance, etc.) to the customer.
• AMS bar, though more expensive (?), is better suited for precision machining.
• AMS is less likely to distort during the machining process (less internal stresses during the mfg of the bar?)
• AMS turns beautifully, ASTM seems gummy and often the surface appears to have fur on it when roughing.
![[ponder] [ponder] [ponder]](/data/assets/smilies/ponder.gif)
• ASTM seem more prone to vibration when finishing.
• AMS barstock came into being primarily to satisfy the needs of the aerospace industry.
I've been told that alot of the problems I have had with turning some barstock we use is in my head, or the coolant oil/water ratio is wrong. Is there really no difference, where machinability is concerned, between ASTM versus AMS?
![[ponder] [ponder] [ponder]](/data/assets/smilies/ponder.gif)