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Epoxy granite is a synthetic composite material made up of epoxy resin and granite chips used as a high-performance alternative to steel and cast iron machine tool bases. The finished material is tough and durable with excellent vibration damping characteristics and a long service life. The use of epoxy granite also allows for a high degree of production flexibility, as ancillary parts such as mounting points, slides and coolant pipes can be added to the composite during casting, greatly reducing production costs. Additional cost-saving characteristics of epoxy-based granite composites are the cold curing manufacturing process and the ability to use low-cost fillers to add bulk to the material. Disadvantages of epoxy granite composites include low shock or impact tolerance and low strength in thin castings.
Traditionally, precision machine tools such as milling machines, drill presses, lathes and shapers were mounted on bases made of steel, natural granite or cast iron. These materials lent the bases the required stiffness, stability and vibration damping, but required expensive machining processes to produce the required accurate surface dimensions. Materials such as natural granite are also becoming increasingly scarce and expensive. Developments in the composite materials arena has, however, seen increased use of synthetic products such as epoxy granite in these roles. Not only does synthetic granite exhibit the same desirable qualities of traditional materials, but it generally delivers far better values with increased production flexibility at a greatly reduced cost.
Synthetic granite is an aggregate of crushed granite chips suspended in a specially-formulated epoxy resin. Once mixed, the fluid product is cast in a mold and cold cured at ambient temperatures. This allows for a huge amount of flexibility in the production process regarding possible shapes, surface textures and cast-in ancillary features. Machine slides, mounting lugs or studs, and mounting plates can be included in the casting, eliminating the need for costly and labor-intensive post-production machining. The overall cost of the products may be reduced further by the inclusion of inexpensive fillers in the aggregate.
Machine bases made of epoxy granite most often exhibit outstanding working qualities, which often far exceed those of traditional materials. For example, the material features internal damping characteristics up to ten times better than that of cast iron, three times better than natural granite and almost 30 times better than steel. The thermal stability and torsional stiffness of epoxy granite are also good, as is its internal stress resistance. It is impervious to lubricant and coolant degradation and offers excellent noise absorption as well as low production cost. The only noteworthy disadvantages of the composite are its low thin section strength and impact shock resistance.