Search results
Results from the WOW.Com Content Network
A bronze casting showing the sprue and risers. A riser, also known as a feeder, [1] is a reservoir built into a metal casting mold to prevent cavities due to shrinkage.Most metals are less dense as a liquid than as a solid so castings shrink upon cooling, which can leave a void at the last point to solidify.
The "method" thus ensures the molten metal is delivered, the mould filled correctly, and the risers filled to "feed" the "shrinking volume" of liquid to the casting during solidification. This "method" is done by a "methods engineer", who may be a patternmaker (with additional training), a founding engineer, or metallurgist who is familiar with ...
This typically takes tens of minutes. The part will shrink on cooling, coming away from the mold, and facilitating easy removal of the part. The cooling rate must be kept within a certain range. Very rapid cooling (for example, water spray) would result in cooling and shrinking at an uncontrolled rate, producing a warped part. Removal of the part.
Most metals and alloys shrink as the material changes from a liquid state to a solid state. Therefore, if liquid material is not available to compensate for this shrinkage a shrinkage defect forms. [3] When progressive solidification dominates over directional solidification a shrinkage defect will form. [2]
Shell molding was developed as a manufacturing process during the mid-20th century in Germany. It was invented by German engineer Johannes Croning. [3] [4] Shell mold casting is a metal casting process similar to sand casting, in that molten metal is poured into an expendable mold. However, in shell mold casting, the mold is a thin-walled shell ...
Despite higher computational resource requirements and complexity in implementation compared to the finite difference method and finite volume method, the FEM provides high accuracy in modeling boundaries, complex geometries, and temperature fields, which is critically important for predicting defects in castings and optimizing casting processes.
Freeze-cast alumina that has been partially sintered. The freezing direction in the image is up. Freeze-casting, also frequently referred to as ice-templating, freeze casting, or freeze alignment, is a technique that exploits the highly anisotropic solidification behavior of a solvent (generally water) in a well-dispersed solution or slurry to controllably template directionally porous ...
The generic term sledding refers to traveling down a snowy hill using a sled such as a Flexible Flyer with wooden slats and metal runners. It is usually done during the winter when there is snow. [2] Flat plastic or aluminum discs and improvised sleds (carrier bags, baking trays, cafeteria trays, sheets of cardboard, etc.) may also be used.