Permanent Mold Castings and Products are designed to produce high strength non-ferrous castings with higher density, closer dimensional tolerances, and smoother finishes than parts made by sand-cast methods. Engineers have found over the years that close tolerances in the “as-cast” product can greatly reduce or eliminate secondary finishing cost. Weight reduction is also a major benefit of utilizing permanent mold castings. BUNTING also offers complete secondary machining where required, as well as capabilities in assembling a finished product. We will assist you in material recommendation and engineering considerations on form, fit, and function. If needed, we have excellent outside sources for plating, heat-treating, and powder coating.
MAJOR BENEFITS OF PERMANENT MOLD PROCESS
Enhanced Physical Properties
Rapid solidification creates a fine grain structure with superior metallurgical and mechanical properties.
Smooth Mold Filling
Gating design allows for smooth mold filling which eliminates defects caused by turbulence and inclusions that are inherent to sand castings.
Near Net Shape
The process allows for intricate shapes to be cast, which in many cases eliminates additional machining or assembly.
Excellent Surface Finishes
Cast surface finishes are typically 100 to 200 RMS, and the dense surface structure allows for easy polishing.
Dimensional Control and Low Casting Defects
Metal dies allow for close dimensional tolerances with typical part-to-part variation of only +/-0.002". Metal dies have far fewer casting variables than sand-casting, which makes the process much more uniform from part-to-part and run-to-run. Casting defects caused by sand inclusions, mold shift, and other variables are eliminated.
Sections as thin as 1/8" can be cast in typical applications, with some as thin as 0.090” depending on the design. Sections as thick as 2" are also possible.
Metal cores as small as 0.187" can be cast into the parts. Tolerances as close as +/-0.003" can be held which in many cases can eliminate the need for secondary drilling operations.
Rapid solidification produces a very sound casting with no micro-porosity that is typically found in sand castings.
Metal inserts (typically steel) can be inserted into the dies and then molten metal can be cast around the insert. This is ideal for inserting shafts into pump impellers and all types of arms and handles.
With the permanent mold process, all gates and scrap are recycled through our own furnaces. There is no contaminated sand to dispose of and typical permanent mold alloys contain no lead.
Advantages Versus Sand Castings:
BUNTING PERMANENT MOLD PROCESS
- Weight reduction by taking advantage of the higher physical properties and thinner sections.
- Greatly reduced scrap and rework costs.
- Elimination of machining, drilling and/or assembly operations.
- Reduction of finishing and polishing operations.
- State of the art electric melting furnaces produce high purity, clean, consistent molten metal heats.
- An Emission Spectrometer provides accurate chemical analysis of each heat produced.
- Semi-automatic molding machines use programmable controllers to produce extremely consistent casting results.
- High quality permanent mold dies provide rapid solidification and precise dimensional control.
- Trimming room equipment for rapid removal of gates, risers, and flash.
- Trim dies provide for fast, accurate methods of removing gates, risers, and flash.
- Complete machining capabilities give Bunting the ability to provide our customers with completely finished parts and assemblies.
- CNC machining center provides for fast, precision machining operations.
- Coordinate measuring machine provides for fast, accurate measurements of all casting and machining requirements.
- Mechanical testing equipment assures Bunting products are of the highest quality materials.
- SPC control charts and capability studies are used throughout the plant to assure parts of the highest quality are produced. Process instructions provide each of our operators with critical information during each step of the manufacturing process.