When designing CNC machined parts, how can we reduce machining costs through structural optimization?

When designing CNC machined parts,reducing machining costs through structural optimization is key to balancing functional requirements and manufacturing affordability.The following specific optimization strategies are provided from multiple dimensions:

1. Material Selection Optimization
   • Prioritize Easy-to-Machine Materials:Materials with good machinability,such as aluminum alloys and low-carbon steel,can reduce tool wear and machining time.For example,replacing stainless steel with 6061 aluminum alloy can reduce machining costs by more than 30%(if strength permits).
   • Minimize Precious Metal Usage:Use local reinforcement designs(such as using titanium alloy only in stressed areas)instead of overall precious metal structures.
   • Match Material Form:Choose blanks that are close to the final shape of the part(such as bars or plates)to reduce machining allowances.For example,using a rectangular blank to machine a square part can avoid excessive waste from a round blank.
2. Control of Geometric Complexity
   • Avoid Deep Cavities and Narrow Slots:
     • Deep cavities(depth>5 times the tool diameter)require multiple layered machining and are prone to tool vibration and breakage.Consider using shallow cavity combinations or split structures.
     • Narrow slots require small diameter tools,which have low machining efficiency.It is recommended that slot widths be≥1.2 times the tool diameter.
   • Simplify Thin Walls and Sharp Angles:
     • Thin walls(thickness<3mm)are prone to deformation and require reduced cutting parameters or added support.Optimization can be achieved through local thickening or adding reinforcement ribs.
     • Sharp angles(internal angles
   • Reduce Multi-Axis Dependency:Avoid unnecessary curved surfaces or inclined holes;instead,use stepped structures or standard angles(such as 45°,90°)to complete machining with a three-axis machine.
3. Rationalization of Tolerances and Surface Roughness
   • Relax Non-Critical Tolerances:Relaxing tolerances on non-mating surfaces from±0.05mm to±0.1mm can reduce the number of finishing steps.For example,the positional tolerance of mounting holes can be moderately relaxed,while only critical bearing positions retain high precision.
   • Lower Surface Roughness on Non-Functional Surfaces:Reducing the surface roughness of non-aesthetic surfaces from Ra1.6 to Ra3.2 can cut down on finishing time.For example,internal structural surfaces do not need to be polished.
   • Specify Economical Tolerances:Refer to the medium precision standards in ISO 2768 to avoid over-specification.
4. Standardization and Modular Design
   • Unify Feature Dimensions:Use standard drill bit sizes(such as M6,M8 threaded holes)instead of non-standard holes to reduce tool change frequency.
   • Modular Decomposition:Break down complex parts into multiple simpler sub-components,which can be machined separately and then assembled through bolts or welding.For example,a shell with a deep cavity can be split into a"main body+cover plate".
   • Universal Interface Design:Employ standard flanges,keyways,or snap-fit structures to reduce the need for custom tooling.
5. Software-Assisted Machining Optimization
   • CAM Automatic Feature Recognition:Utilize software to automatically identify features such as holes and slots to reduce programming time.For example,the feature recognition function in Fusion 360 can shorten programming time by 30%.
   • Tool Path Optimization:Implement high-speed machining(HSM)strategies,such as helical tool entry and continuous cutting,to reduce non-cutting time.For example,optimized paths can reduce machining time by 15%.
   • Simulation Verification:Use virtual machining to check for interference and over-cutting,avoiding scrap from trial cutting.
6. Balancing Lightweight and Strength
   • Topology Optimization and Hollowing:Use finite element analysis(FEA)to determine load paths and retain only necessary materials(such as biomimetic bone structures).
   • Localized Heat Treatment for Strengthening:Apply laser hardening to high-stress areas(such as gear roots)instead of overall heat treatment.
   • Hybrid Process Combination:After CNC machining the main structure,add lightweight grids through additive manufacturing(3D printing)to balance weight reduction and strength.

• DFM(Design for Manufacturing)Analysis:Communicate with the machining plant in the early design stage to identify high-cost features.
• Priority Sorting:Optimize in the order of"material waste>machining time>post-processing".
• Prototype Verification:Test functionality with 3D printed or simple CNC prototypes to avoid rework after mass production.

By implementing the above strategies,CNC machining costs can be reduced by 20%-50%while ensuring functionality,particularly suitable for cost reduction needs in mass production or high-complexity parts.