Casting and Molding Materials for CNC Machining(3d printed motorcycle parts Bernice)

  • Time:
  • Click:12
  • source:DAHLER CNC Machining
Computer numerical control (CNC) machining utilizes programmed commands to control machinery that cuts and shapes stock material into custom parts and products. While CNC machining is incredibly versatile, the types of materials that can be machined are limited by the material's hardness, brittleness, and machinability. For many applications, casted or molded materials are ideal choices for CNC machining as they can produce near-net shaped parts from metals, polymers, and ceramics.
Metal Casting
Metal casting involves pouring molten metal into a mold cavity and allowing it to solidify into the desired shape. Popular cast metals for CNC machining include aluminum, magnesium, zinc, bronze, brass, iron, and steel alloys. The casting process allows for the production of complex part geometries that would be difficult or impossible to produce via CNC machining alone.
After casting, secondary CNC operations are often required to achieve final part dimensional accuracy and surface finishes. Common metal casting processes compatible with CNC machining include:
- Sand Casting: Used for high-volume metal parts. Molten metal is poured into a sand mold that is broken away after solidification.
- Die Casting: Used for high production of complex, thin-walled metal components like aluminum alloy automobile parts. The molten metal is injected at high pressure into re-usable steel molds.
- Investment Casting: Produces fine detailed castings by using a wax pattern embedded in ceramic slurry to create the mold. Ideal for intricate, low volume metal parts.

The cast microstructure and post-pour cooling rates significantly impact the mechanical properties of the metal part. CNC machining is used to ensure tight dimensional tolerances and create features like threads, holes, and slots on the near-net shape casted part.
Polymer Casting and Molding
Many polymeric materials are well-suited for casting and injection molding processes prior to CNC machining. Typical castable polymers include polyurethane, epoxy, acrylic, polyester, and polyamide resins. After curing, these casted polymer parts have improved machinability compared to fully dense plastic stock.
Thermoplastics like acrylonitrile butadiene styrene (ABS), polycarbonate, nylon, polyethylene and polypropylene can also be injection molded into near-net shapes before CNC machining. Benefits of polymer casting and molding for CNC include:
- Complex geometries and thin walls are easily produced
- Minimal material waste
- Consistent part dimensions
- Variety of material options
- Smooth surface finishes
Common CNC operations on polymer castings and moldings include trimming, drilling holes, creating threads, texturing surfaces, and adding precision features. The combination of casting/molding and CNC machining is ideal for short production runs of plastic components requiring tight tolerances.
Ceramic Casting and Machining
Technical ceramics, including alumina, zirconia, and silicon carbide, have excellent hardness, corrosion resistance, and high temperature capabilities. However, their brittle nature makes conventional machining of fully dense ceramic materials challenging. To improve machinability, ceramic parts are often produced via 'green' casting and molding processes.
In green casting, ceramic powder is mixed with an organic binder and plasticizer before being poured or injected into molds. After curing, the fragile 'green' part maintains the shape but is softer and easier to machine than the final ceramic. The structured green part is then CNC machined to specifications, allowed to dry, and finally sintered at high temperatures to produce the fully dense ceramic component.
Benefits of ceramic casting and CNC machining include:
- Ability to produce complex ceramic geometries
- Improved material removal rates over fully dense ceramics
- Excellent dimensional accuracy and surface finishes
- Less tool wear compared to pure ceramic machining
The combination of casting and CNC techniques makes precision ceramic component manufacturing much more viable for applications like automotive turbochargers, industrial valves, and medical implants.
CNC Machining Castings and Moldings
While cast and molded components utilize shaping techniques that CNC machining cannot match, integrating secondary CNC operations provides critical benefits:
Precision - CNC machining removes excess material and creates features to tight tolerances unachievable by casting or molding alone. This includes dimensions, surface finishes, holes, threads, slots, grooves, etc.
Flexibility - CNC programming can be readily changed to accommodate design revisions. This is much faster and cheaper compared to altering casting/molding tools and processes.
Economical - Near-net shape casting and molding minimizes raw material requirements. Automated CNC machining also maximizes manufacturing efficiency.
Scalable - Low volume prototyping to high volume production runs can be accomplished by adjusting mold availability and CNC operation times.
Overall, utilizing casted and molded materials as blanks for CNC machining combines the geometrical freedom of shaping techniques with the precision of computer numerical control. The process integration minimizes manufacturing costs while still achieving demanding specifications needed across medical, automotive, aerospace, and consumer product industries. Continued improvements in casting methods, molding technologies, CNC capabilities, and material options will drive future innovations in precision component production. CNC Milling CNC Machining