Tight Corner Lids – How Melt Flow and Grind Quality Impact Part Aesthetics

Jason Rycroft

Borouge International (Nova Chemicals)

Material selection and powder quality play a critical role in rotational molding performance. In particular, melt flow index and grind quality influence feature definition, including the formation of voids or holes in finished parts.

This presentation introduces Borouge International (legacy NOVA Chemicals) torturous lid #1 (“tight s) as a tool to evaluate material performance. Geometry combines varying angles in a matrix that highlights differences in melt flow behavior. The results demonstrate that higher melt index resins can replicate tighter features more effectively than lower melt materials, in some cases exceeding typical design guide expectations.

The study also examines the impact of grind quality, showing how poor grind can significantly reduce a material’s ability to fill features without defects. This provides a practical example of how grind quality directly affects part consistency and performance. The Tight Corner Lids approach offers a more application-relevant assessment compared to traditional flow time methods.

This work provides molders, pulverizes, and compounders with a new tool to evaluate material selection and powder quality, while also enabling greater collaboration across the value chain.” Practical method for evaluating how material selection and grind quality impact part performance, especially in achieving tight feature definition without defects. The “tight corner lid” tool offers a more real-world way to compare materials, helping improve consistency, optimize processing, and guide better collaboration with suppliers.