Fillet or Chamfer which is better?

A fillet is preferred if the following conditions are present:

Parts Will Be Subjected to High Loads: Fillets reduce stress concentrations at edges and interior corners and distribute load across a larger surface. They help increase the part’s load-bearing capacity and improve its fatigue resistance  to make the part more durable.

Presentation Parts: Fillets create seamless, smooth surfaces and are more visually appealing than chamfers. Because of these smooth surfaces, it is easier to uniformly distribute coatings and paints.

Benefit of Fillet Outweighs Cost: Fillets are more expensive to fabricate than chamfers due to the complexities of machining radii and the longer machining time required. Different tools may be needed to cut different-sized fillets, further increasing the overall cost.

A chamfer, on the other hand, is preferred if the following conditions are present:

Parts Are Not Subjected to High Loads: Chamfers are better suited for parts that aren’t subjected to high loads.

Paired Parts: The angled surfaces of chamfers allow parts to easily slide against each other when mated together. Or for parts that must fit together in an assembly. Examples include a pin, bolt, or drive screw that must fit into a hole.

Requires Lower Cost: Chamfers are easier to manufacture than fillets since tool paths are simpler. Different-sized chamfers can be cut with the same tool, which reduces the need to change tools and therefore reduces the overall machining time.