- Material Thickness and Fillet Radius:
For parts with varying material thicknesses, maintain a fillet radius that’s no greater than 20-30% of the thinner material’s thickness. This prevents weakening of the thinner sections. - Load-Bearing Areas:
In load-bearing areas, such as corners of brackets or supports, keep fillet radii smaller to ensure the material efficiently distributes stresses. Radii should be in the range of 1-2 times the material thickness. - Avoid Sharp Corners:
Completely sharp corners are stress concentration points. Always incorporate a fillet radius to eliminate these stress concentrations and improve part strength. - Die Casting and Injection Molding:
When designing parts for die casting or injection molding, a larger fillet radius (2-3 times the nominal wall thickness) is recommended to prevent cracks and voids. - Machined Parts:
For machined parts, a smaller fillet radius can often be used due to the precision of the process. Typically, a radius between 0.2 to 0.5 times the tool diameter works well. - Stress Analysis:
Conduct stress analysis to determine the optimal fillet radius. Finite element analysis (FEA) can help identify stress concentrations and inform radius sizing. - Material Properties:
Consider the material’s ductility and toughness when determining the fillet radius. Brittle materials might require larger radii to prevent fracture. - Aesthetic and Functional Balance:
Balancing aesthetics and functionality is important. While larger radii can provide stress relief, they might not be visually appealing for certain designs.
Remember that these guidelines are based on general principles, and the specific requirements of your design, manufacturing process, and material selection will influence the ideal fillet radius. Always perform stress analysis or consult with experienced engineers to ensure your design meets the necessary strength and durability criteria.