The Moldflow Design Principles are a set of rules that influence the design of a part and tools to optimize the filling of a part. When these principles are followed, higher quality parts and faster cycle times are the result. Not following these plastics design principles leads to problematic designs.

These plastics design principles include:

• Unidirectional and controlled flow pattern
• Flow balancing
• Constant pressure gradient
• Maximum shear stress
• Uniform cooling
• Positioning weld and meld lines
• Avoid hesitation effects
• Avoid underflow
• Balancing with flow leaders and flow deflectors
• Controlled frictional heat
• Thermal shutoff for runners
• Acceptable runner/cavity ratio