Introduction to Casted Materials in CNC Machining(types of rivits Una)
- source:DAHLER CNC Machining
Casting is a manufacturing process where liquid metal is poured into a mold cavity and allowed to solidify. The resulting casted part has the shape of the mold cavity. Casting allows for the economical production of complex metal parts in a variety of metals including aluminum, iron, steel, and alloys. Casted parts can have excellent mechanical properties and casted materials are commonly machined using CNC equipment.
Benefits of CNC Machining Casted Parts
There are several benefits to using casted metal parts in CNC machining:
- Complex shapes: Casting creates intricate shapes and contours that would be difficult or impossible with other processes. CNC machining can then add precise dimensions, holes, slots, threads, and other features to the complex casted form.
- Low cost for high volume: Once the casting die is created, the incremental cost per part is very low when producing a large volume of casted parts. CNC machining paired with casting is economical for large production runs.
- Wide range of metals: Casting can utilize iron, aluminum, magnesium, zinc, stainless steel, bronze, brass, and more. Each material has different properties that can be leveraged.
- Consistent quality: The casting process consistently reproduces the same shape and metal composition for each part. CNC machining further improves consistency and precision.
- Improved strength: The fine grain structure of casted metals can provide better strength than wrought metals or 3D printed metals. Heat treating casted parts can also enhance physical properties.
CNC Machining Operations on Casted Parts
There are many CNC machining operations that are commonly performed on pre-casted metal parts:
- Facing: A facing operation mills a flat surface on the side of a casted part to create a reference surface and consistent part dimensions.
- Drilling: Precise holes are drilled into the casted part using CNC drilling centers or CNC milling machines. Holes may be fully drilled through or produce blind hole depths.
- Boring: The boring operation enlarges existing holes to precise diameters using single point boring bars or boring heads.
- Counterboring and countersinking: These operations create flat bottomed and angled openings for screws and fasteners.
- Tapping: The tapping process cuts internal threads into holes using a CNC tapping head. This allows screws to be used in the machined part.
- Milling: CNC mills use end mills and other rotary cutters to cut slots, pockets, surfaces, and complex 3D contours into the casted part.
- Turning: CNC lathes remove material from the outside diameter of casted parts that are round in shape using cutting tools and can also cut grooves, chamfers, and other features.
Preparing Casted Parts for CNC Machining
Proper preparation of the casted part is crucial before CNC machining can begin. Here are some important steps:
- Cleaning: All sand, scale, and debris must be removed from the casting using chemical baths, grinding, or blasting. Trapped material can damage machine tools.
- Heat treating: Casting alloys may require solution heat treatment, annealing, or other thermal processes to refine the metallurgical structure and achieve the desired material properties before machining.
- Fixturing: The irregular casted shape must be properly held in a fixture or clamping system to access all necessary features in the CNC machining process.
- Inspection: The dimensions and geometry of the raw casting are verified. The inspection data aids in programming the correct tool paths for CNC machining.
CNC Programming Considerations for Casted Parts
CNC programmers must consider several factors unique to casted parts:
- Irregular casting shape: The potential for shape deviations in the casting necessitates probing operations to map the actual part geometry. Robust adaptive machining strategies account for variations.
- Excess stock: More machining stock allowance is required during programming to ensure full material removal on inconsistent casted surfaces.
- Reduced rigidity: Cast parts can distort or deflect more under machining forces compared to wrought metals. Slower feeds and speeds may be required.
- Tool deflection: Material and tool deflection can be significant when machining deeper cavities or thin walls in castings. The tool paths must be programmed to account for this.
By understanding the properties and behavior of casted parts during CNC machining, optimal tool paths can be generated to create highly accurate finished parts from casted metals.
Casting provides an economical way to produce complex metal part shapes that can then be precision machined with CNC equipment to achieve tight tolerances, mechanical integrity, and reliability. With the correct casting techniques, heat treatment, fixturing, inspection, and programming, casted metals are an excellent material option for CNC machined components and end-use parts across many industries. The combination of casting and CNC machining leverages the advantages of each process. CNC Milling CNC Machining