Casted Materials in CNC Manufacturing(scrap brass price per pound Payne)

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Computer numerical control (CNC) manufacturing utilizes computer software to automate and control machine tools like lathes, mills, routers, grinders and laser cutters. This allows for highly accurate and repeatable machining of parts from various materials like metals, plastics, wood and composites. One of the key materials often used in CNC processes is casted metal.
Casting is a manufacturing technique where liquid metal is poured into a mold cavity and allowed to solidify, taking the shape of the mold. The resulting casted part is then used in subsequent CNC machining operations to achieve final dimensional accuracy and desired finish characteristics. Common casted metals used include aluminum, iron, steel, stainless steel, brass and bronze.
Benefits of Using Casted Metals in CNC
There are several benefits to using previously casted metal material in CNC machining:
- Cost Savings - Casting is often a cheaper way to produce an initial rough shape vs machining the entire part from scratch from a solid block of metal. This reduces raw material costs.
- Reduced Machining - Because the general shape is already formed via casting, less CNC machining is required to obtain the final part dimensions and features. This saves on machining time and tooling costs.
- Complex Shapes - Intricate shapes and internal features like cavities are easily produced via casting compared to machining which is limited by tool access.
- Material Versatility - Many different metal alloys and grades, including exotics like stainless steels, can be casted then CNC machined.
- Inventory - Casted stock material can be kept in inventory at various sizes to enable faster production starts when CNC work is needed. No raw material ordering delay.
Preparation of Casted Parts for CNC
To make effective use of casted metals in CNC operations, the parts must be properly prepared. Key steps include:
- Cleaning - All residual sand, scale, and foreign debris must be removed from the as-cast part surface to prevent damage to CNC tooling. Typically abrasive blasting and chemical baths are used.
- Cutoff - The casted parts are separated from the gating and riser system used in the casting process via cutoff sawing or other methods. This must be done without inducing mechanical or thermal damage.
- Inspection - The dimensions and surface finish quality of the casted blank are verified prior to CNC work. This checks for casting defects like porosity or inclusions that could affect subsequent machining.
- Fixturing - The workpiece must be properly aligned and held in fixtures or workholding devices like vises or chucks. Care is taken not to stress or deform the casting. Soft jaws and padding are often used.
Machining Considerations
During CNC operations on casted metals, the following should be considered:
- Tool Paths - More stock allowance is left to account for casting surface irregularities. Roughing is done gradually to avoid tool chatter on uneven surfaces.
- Tool Materials - On cast irons and steels, carbide tools with advanced coatings are selected to withstand abrasive wear from the metallurgical structure of these materials.
- Feeds/Speeds - Conservative cutting parameters are used initially during roughing, then increased for finishing based on sound, finish, and tool life. Feed rates account for lower rigidity of some castings.
- Fixtures - Depending on part geometry, castings may require periodic re-fixturing to allow access for 5-axis machining or to avoid fixture collisions. Soft jaws help grip irregular surfaces.
- Tolerances - Castings have relatively higher dimensional variance. Tighter tolerances may require more semi-finishing steps before final precision machining. Statistical process control helps dial-in tolerance capabilities.
In summary, casted metals provide an excellent starting point for subsequent precision CNC machining. With proper preparation, fixtures, tooling selection, and machining techniques, castings can be transformed into high quality finished components combining the near net shape of casting with the accuracy and repeatability of CNC. This hybrid approach is an efficient way to manufacture metal parts with reduced cost and processing time. CNC Milling