Screw Soybean Oil Press Machine

In the way of oil pressing, screw type oil press produces high temperature through screw extrusion and extracts oil from oil. The hydraulic press uses the liquid as a medium to pressurize oil, to extract oil.

Soybean oil expeller machine: This is the most common type of machine used for soybean oil extraction. It uses mechanical pressing to extract oil from soybeans. Expeller machines are known for being cost-effective and efficient for small to medium-scale oil extraction.

To produce soybean oil, the soybeans are cracked, adjusted for moisture content, heated to between 60 and 88 °C (140 and 190 °F), rolled into flakes, and solvent-extracted with hexanes. The oil is then refined, blended for different applications, and sometimes hydrogenated.

Soybeans require specific pre-treatment to maximize yield and protect equipment:​

Cleaning: Use vibratory sieves and air separators to remove stones, dirt, and broken seeds—impurities can damage the screw or cage and contaminate oil.​
Dehulling: Remove hulls (2–3% of soybean weight) with friction or impact dehullers. Hulls are low in oil and high in fiber, which clogs the cage and reduces extraction efficiency.​
Flaking (optional but recommended): Crush soybeans into thin flakes (0.3–0.5 mm thick) with roller mills. Flaking increases surface area by 50–100%, making oil easier to extract and boosting yield by 3–5%.​
Drying/Conditioning: Adjust moisture to 8–10% using heated air. Wet soybeans (over 12% moisture) stick to the screw; dry soybeans (under 6%) shatter and leave oil trapped in fragments.

Screw soybean oil press machines are engineered for soybeans’ unique properties: low oil content (18–22%, vs. 40–50% for peanuts/sunflowers) and hard, dense kernels. Key design differences include:​

A tapered screw with deeper flights: Gradually increases pressure over a longer compression zone (critical for extracting oil from low-oil seeds) instead of the steeper taper used for high-oil seeds.​
A thicker, more durable cage: Resists wear from hard soybean kernels, with smaller perforations (1–2 mm) to prevent fine solids from mixing with oil.​
Pre-heating integration: Many models include a built-in heating jacket around the cage to maintain temperatures of 60–80°C, softening soybeans to improve oil flow (unnecessary for softer, high-oil seeds).​
These adaptations ensure efficient extraction from soybeans, whereas using a generic screw press would result in low yields (often <10%) and rapid equipment wear.

Yes, but it requires modifications (since soybean presses are optimized for low-oil, hard seeds):​
High-oil seeds (peanuts, sunflowers):​
Adjustment: Widen the discharge gap to reduce pressure (40–80 bars, vs. 80–120 for soybeans) to avoid overheating oil. Use a cage with larger perforations (2–3 mm) to prevent clogging from softer meal.​
Note: Yield will be lower than a dedicated high-oil press (30–35% vs. 40–45% for sunflowers).​
Medium-oil seeds (canola, rapeseed):​
Adjustment: Reduce screw speed to 10–20 RPM (canola is softer than soybeans) and use a medium-pressure setting (60–90 bars).​
Low-oil seeds (cottonseed):​
Adjustment: Keep pressure high (80–110 bars) but add a pre-heating step (70–80°C) to soften cottonseed hulls.​
Critical note: Never process seeds with hard shells (e.g., walnuts) or high moisture (over 15%)—this will damage the screw or cage.

Safety is critical due to the machine’s high pressure and moving parts:​

Emergency stop button: Easily accessible (front of the machine) to halt operation during jams or operator risk.​
Screw/cage guards: Metal enclosures around the rotating screw and cage to prevent clothing or hands from getting caught.​
Overload protection: A sensor that shuts down the motor if the press is overfed (prevents motor burnout and screw damage).​
Heat shields: Insulation around the heated cage to protect operators from burns (especially important for soybean presses, which run at 60–80°C).​
Non-slip base: Heavy-duty rubber feet to stabilize the machine during high-vibration operation (prevents tipping).​
Pressure relief valve: Releases excess pressure if the discharge port clogs, avoiding cage or screw damage.