AA - Laboratory Grade
Used in constant temperature gaging rooms and metrology laboratories.

A - Inspection Grade
Used for general use in quality controlled inspection rooms.

B - Tool Room Grade
Used for shop work and production checking.

Why use granite as opposed to steel or aluminum?
 

• Granite will react to changes in temperature about 1/2 as much as steel, and about 1/4 as much as aluminum.
• Granite will deflect under load about 1/8 as much as steel, and about 1/20 as much as aluminum.
• Granite is HARD. Equivalent to around 80 Rockwell C.
• Granite is non-conductive, and by itself is non corrosive.
• Granite can be finished to tighter flatness tolerances more quickly than steel or aluminum.
• Weight per cubic foot:
  • Granite (185 lbs.)
  • Aluminum (168 lbs.)
  • Steel (490 lbs.)
• Electrical conductivity (Silver=100)
  • Granite (0.0)
  • Aluminum (63.0)
  • Steel (12.0)

Last Updated Thursday, September 10 2009 @ 12:34 PM EDT|1,384 Hits

Copyright © 2007 P W Calibrators, Inc. dba U S GRANITE STANDARDS
San Jose, California
Manufacturer of: Granite Machine Bases, Granite Surface Plates, Granite Angle Plates, Granite V-Blocks, Granite Straight Edges, Granite Parallels, Granite Air Bearing Surfaces, Granite Drilling, Granite Slotting, Precision Setting of Stainless Steel Inserts.