A sand casting or a sand molded casting is a cast part produced by forming a mold from a sand mixture and pouring molten liquid metal into the cavity in the mold. The mold is then cooled until the metal has solidified. In the last stage the casting is separated from the mold. There are six steps in this process:

• Place a pattern in sand to create a mold.
• Incorporate a gating system.
• Remove the pattern.
• Fill the mold cavity with molten metal.
• Allow the metal to cool.
• Break away the sand mold and remove the casting.

Patterns for castings are created by a skilled pattern maker. They build a pattern of the object to be produced, using wood, metal, or a plastic such as expanded polystyrene. Sand can be ground, swept or even strickled into shape. The metal to be cast will contract during solidification, and this may be non-uniform due to uneven cooling. Therefore, the pattern must be slightly larger than the finished product, a difference known as contraction allowance. Pattern-makers are able to produce suitable patterns using 'Contraction rules' (these are sometimes called "shrink allowance rulers" where the ruled markings are deliberately made to a larger spacing according to the percentage of extra length needed). Different scaled rules are used for different metals because each metal and alloy contracts by an amount distinct from all others. Patterns also have core prints that create registers within the molds into which are placed sand cores. Such cores, sometimes reinforced by wires, are used to create under cut profiles and cavities which cannot be molded with the cope and drag, such as the interior passages of valves or cooling passages in engine blocks. Paths for the entrance of metal into the mold cavity constitute the runner system and include the sprue, various feeders which maintain a good metal 'feed', and in-gates which attach the runner system to the casting cavity. Gas and steam generated during casting exit through the permeable sand or via risers, which are added either in the pattern itself, or as separate pieces.

Spectrum Machine can supply Bronze Castings to your specifications. Bronze is our specialty, so our professional staff is able to produce your products quickly and efficiently. Our warehouse staff is equipped to package your order, from a cushion envelope to custom wooden crates, we are prepared for immediate delivery of your product.

From concept to delivery allow our experienced staff to provide you with quality bronze bearing and bushing products. We stock all available mill sizes in C93200, C86300, C95400, C86300, C95500, C90300, C90500, C90700, C36000, C63000, and C46400 along with may non-stock sizes and large diameter sizes in these alloys. Please see our stock list for more information. If you have any questions please contact us, or call 330-626-3666.