How Does an Oil Press Work in Commercial Edible Oil Production?

In commercial edible oil production, an oil press is not a standalone machine. It serves as a critical link within the entire vegetable oil processing line, bridging raw material pretreatment with downstream extraction and refining. Its performance directly affects initial oil recovery, oil cake quality, and the operating cost and stability of subsequent processes.

From an engineering perspective, whether an oil press is properly selected becomes evident within the first few months of operation.
Stable oil yield, minimal parameter adjustments, and reasonable refining loads are all determined at the pressing stage.

Engineering Definition：
In commercial edible oil production, an oil press uses continuous mechanical pressing based on screw conveying and progressive pressure buildup to separate pretreated oilseeds into crude oil and oil cake, serving as a key interface between pretreatment and extraction or refining sections.

This article explains—based on real oil mill engineering experience—how oil presses work in commercial production, how they operate continuously, and how they interact with other processing stages, helping investors and producers make informed equipment selection decisions. 👉( Single Screw vs Double Screw Oil Press )

1. Basic Requirements for Oil Presses in Commercial Edible Oil Production

Unlike household or small workshop oil pressing, commercial oil production focuses on long-term operational efficiency, not merely the ability to extract oil.

In practice, commercial oil mills typically require oil presses to meet the following criteria:

• High processing capacity: Capable of handling several to hundreds of tons of oilseeds per day

• Continuous and stable operation: Suitable for 24-hour uninterrupted production with minimal downtime

• Wide raw material adaptability: Stable processing of soybeans, rapeseed, peanuts, sunflower seeds, cottonseed, and more

• High oil yield with low residual oil: Press cake residual oil content typically controlled below 6%

• Easy system integration: Seamless connection with pretreatment, extraction, and refining sections

For these reasons, screw oil presses have become the most widely adopted and mature solution in commercial oil mills.

2. Core Structure and Working Principle of a Screw Oil Press

A screw oil press extracts oil through mechanical compression, with its core principle summarized as: screw conveying combined with progressive pressure buildup.

Main Structural Components

A commercial screw oil press typically consists of:

• Frame and feeder: Ensure mechanical stability and uniform, continuous feeding

• Gearbox: Transmits power to drive screw rotation

• Pressing chamber: Composed of press cage, bars, and cake outlet, where compression occurs

• Screw shaft: The key functional component, forming a pressure gradient through changing pitch and depth

• Motor and electrical control system: Provide power and operational monitoring

• Oil collection and cake discharge system: Separate crude oil and oil cake 👉( Screw oil press vs hydraulic oil press )

Pressing Process in Commercial Operation

Under normal operating conditions, the pressing process follows these steps:

1. Pretreated oilseeds (cleaned, crushed, flaked, cooked) enter the feeder

2. The screw shaft rotates, continuously conveying material forward

3. As screw pitch and chamber volume decrease, mechanical pressure gradually increases

4. Friction and compression raise material temperature (typically 80–120°C), breaking cell structures

5. Oil is released through press cage gaps and collected as crude oil

6. Solid oil cake is discharged continuously for further processing

Commercial oil press process summary:
Pretreatment → Continuous feeding → Screw conveying → Progressive compression → Oil release → Crude oil collection → Cake discharge

This continuous, enclosed, and self-discharging process is well suited for large-scale and long-term edible oil production.

3. Continuous Operation in Commercial Oil Plant

In real oil plants, screw oil presses operate as part of a fully integrated continuous production line and follow strict engineering operation standards.

• Parallel installation: Multiple presses operate in parallel to meet capacity demands and ensure system redundancy

• Automatic temperature and load control: Modern presses use digital temperature control and current monitoring to adjust operating conditions based on raw material moisture and temperature

• Coordination with pretreatment: Cleaning, crushing, flaking, and cooking directly determine pressing efficiency

• Residual oil monitoring: Regular oil cake analysis allows optimization of pressing parameters

Thanks to this system-based operating logic, commercial screw oil presses consistently achieve oil recovery rates above 60%, significantly outperforming traditional hydraulic presses.

4. The Role of the Oil Press Within the Entire Edible Oil Production Line

An oil press is only one stage of the vegetable oil processing line, and its performance depends heavily on upstream and downstream coordination.

Front-End: Pretreatment Determines the Pressing Limit

Raw materials must undergo proper cleaning, crushing, flaking, and cooking to reach optimal pressing conditions.
For example, insufficient cooking of rapeseed prevents cell wall rupture, leading to poor oil release.

Mid-Section: Pressing Combined with Extraction Improves Total Yield

For low-oil-content seeds such as soybeans, pressing alone leaves relatively high residual oil (around 6–8%).
Therefore, commercial oil mills typically adopt a pre-pressing + solvent extraction process:

• The oil press removes part of the oil as pre-pressed oil

• Press cake is sent to solvent extraction

• Final residual oil can be reduced to below 1%

Back-End: Refining Efficiency Depends on Crude Oil Quality

Impurities, phospholipids, and color in crude oil directly affect degumming, neutralization, bleaching, and deodorization loads.Better pressing control reduces refining costs and improves overall plant efficiency.

Engineering summary:
The oil press acts as a bridge within the production line. Stable performance depends on high-quality pretreatment input and efficient refining output.

5. Why Do Oil Yields Vary Significantly Between Similar Oil Presses?

During project consultations, this question is frequently raised.

From an engineering standpoint, the main factors include:

• Equipment design differences: Compression ratio and press cage structure

• Material and wear resistance: Screw and cage wear directly impact long-term oil yield

• Raw material matching: Different oilseeds require specific screw designs and parameters

• Pretreatment quality: Inadequate pretreatment cannot be compensated by higher pressure

• Operational control: Unstable feeding and poor temperature control cause yield fluctuations

This is why professional manufacturers such as QIE GROUP provide customized oil press solutions based on raw materials, capacity, and process routes rather than selling generic machines.

6. QIE GROUP: Engineering-Driven Oil Press Solutions for Commercial Oil Mills

With over 40 years of experience in edible oil processing equipment, QIE GROUP designs and delivers oil presses from a complete engineering system perspective.

We provide more than machines—we deliver:

• Customized designs based on oilseed characteristics

• Stable operation with high oil yield and low energy consumption

• Seamless integration with pretreatment, extraction, and refining systems

• Full lifecycle support from selection and installation to training

In many projects, oil yield differences are not caused by equipment price, but by whether the engineering solution truly fits the process.