Today's KNOWLEDGE Share : Rheology: The Most Overlooked Part of Injection Moulding

Today's KNOWLEDGE Share

Rheology: The Most Overlooked Part of Injection Moulding? 🔍

Rheology is one of those topics that quietly sits in the background of injection moulding… yet it influences almost everything we do.

🔬 At its core, rheology is simply about how a polymer flows under different speeds and pressures. But what’s happening behind the scenes is far more interesting, those long polymer chains are constantly untangling, aligning and resisting movement as we push them through the tool. That behaviour is a huge part of why our parts look the way they do.

📉 A good rheology study can tell you an incredible amount:

• ⚡how the viscosity changes with speed

• 🔁 where the polymer flows consistently

• ⚠️ where the process becomes unstable

• 🚫 how far you can safely push the fill before defects start to appear

⚙️ In an ideal world, we’d always optimise fill speed perfectly… but in reality, tooling restrictions, gate design, part geometry and the material itself often dictate what’s possible. In my experience, true optimisation is rare, and rheology often doesn’t get the attention it deserves.

💡 Understanding the why behind the flow can transform the way you troubleshoot and build a process, it’s a core part of a scientific moulding mindset.

🏭 At Sierra 57 Consult Ltd, we take a scientific approach to every element of the process, including rheology. Our training courses are accredited by the Institute of Materials, Minerals & Mining (IOM3), with a strong focus on helping moulders build stable, consistent and repeatable processes.

❓ Curious to hear from others: how often do you get the chance to run a proper rheology study, and what challenges do you face when trying to optimise the fill? 👇

source : James Hayward