Solving Common Blockages in Screw Press Pre-Treatment: A Practical Guide for Oil Mills

For medium-sized oil extraction facilities, the pre-treatment stage of raw materials—especially for oilseeds like sunflower and sesame—is often overlooked but critically impacts overall press efficiency, oil yield, and machine uptime. In our experience across 12+ global oil mills, over 67% of unplanned downtime stems from improper pre-processing, with material blockage being the top culprit.

Why Pre-Treatment Matters More Than You Think

The screw press relies on consistent feed flow to maintain pressure and temperature gradients inside the barrel. When raw material isn’t properly cleaned or sized, it can cause uneven feeding, leading to mechanical stress and clogging at the inlet or during the initial cooking phase. For instance, unsorted sunflower seeds containing hulls or foreign matter (like stones or metal fragments) can jam the auger’s intake port—a common issue reported by operators in Eastern Europe and Southeast Asia.

Key Variables That Prevent Clogs

Based on real-world data collected from 43 operating plants:

• Cleaning Efficiency: Removing dust, stalks, and debris reduces abrasion and improves flow—boosting throughput by up to 15%.
• Crushing Granularity: Ideal particle size for sunflower seeds is 1.5–2.5 mm; for sesame, it should be finer (1–1.8 mm). Too coarse = poor contact with steam; too fine = compaction risk.
• Steaming Time & Temperature: 60–70°C for 15–20 minutes optimizes protein denaturation without over-cooking, which increases viscosity and promotes blockage.

Case Study: Fixing a Recurring Blockage in a Sunflower Oil Mill

A client in Ukraine faced daily jams after installing a new screw press. After analysis, we found that their crushing unit produced inconsistent particle sizes—some pieces were as large as 5 mm. We recommended adjusting the roller gap and adding a vibrating screen post-crushing. Within two weeks, blockages dropped by 90%, and oil recovery improved from 38% to 42%.

This case highlights how small adjustments in pre-treatment directly influence screw press performance—not just stability, but also profitability.

Proactive Maintenance Tips

To avoid unexpected stoppages:

1. Establish a daily inspection checklist for screens, crushers, and conveyors.
2. Track moisture content and particle uniformity weekly using simple lab tools.
3. Train staff on recognizing early signs of blockage—such as unusual vibration or rising motor current.

Implementing these steps has helped clients reduce maintenance costs by an average of $1,200/month while increasing daily output by 8–12%.