Case Study: External Circulation Vacuum Emulsifier in Cosmetic Cream Production
In the cosmetic industry, high-quality creams and emulsified products require strict control over texture uniformity, particle size distribution, emulsification stability, and bubble-free appearance. Traditional internal-circulation emulsification equipment often struggles with insufficient material circulation, uneven shear force distribution, and residual air bubbles in large-batch production, leading to inconsistent product quality and limited production efficiency. This case study details how an external circulation vacuum emulsifier addressed these core challenges in large-scale cosmetic cream manufacturing, optimized production processes, and improved product consistency—presented objectively without promotional language, adhering to industry standards and regulatory requirements.
1. Background and Production Challenges
The production facility focuses on large-scale manufacturing of premium cosmetic creams, including moisturizing creams, anti-aging creams, and sunscreen creams. Prior to upgrading equipment, the facility relied on conventional internal-circulation vacuum emulsifiers, which gave rise to persistent issues after long-term mass production, hindering product quality stability and production scalability.
First, emulsification uniformity and particle size control were subpar. Conventional internal-circulation systems had limited material turnover efficiency, resulting in uneven shear force distribution within the mixing chamber. This led to inconsistent particle sizes (average 10-15 μm) and visible agglomerates in some batches, causing a grainy texture and poor skin-feel of the finished creams. Batch-to-batch variation in particle size distribution (Span value >1.2) also affected product efficacy and consumer experience.
Second, residual air bubbles and oxidative degradation were recurring problems. The internal-circulation design struggled to completely remove air trapped in high-viscosity materials, leading to surface porosity and bubble formation in the finished products. Additionally, inadequate vacuum retention during emulsification exposed sensitive ingredients (e.g., plant extracts, vitamin E) to oxygen, accelerating oxidative degradation and shortening product shelf life.
Third, production efficiency and scalability were limited. The internal-circulation system required prolonged emulsification time (40-50 minutes per batch) to achieve basic uniformity, and the chamber design restricted effective capacity utilization (only 60-70% of nominal volume). Frequent manual intervention to adjust material circulation further increased labor intensity and batch variation. Moreover, the equipment’s difficulty in cleaning hard-to-reach areas of the internal circulation path raised cross-contamination risks between different formulations.
To resolve these issues, the facility sought an emulsification solution capable of achieving precise particle size control (≤5 μm), complete air bubble removal, efficient large-batch processing, and compliance with cosmetic industry hygiene standards (GMP, FDA). After rigorous pilot testing and technical evaluation of various emulsifier types, an external circulation vacuum emulsifier with customized parameters was selected for integration into the production line.
2. Equipment Selection and Technical Adaptation
Considering the production requirements of cosmetic creams—high viscosity (8,000-80,000 mPas), large-batch capacity (1,000L per batch), strict texture standards, and sensitivity to oxygen—the selected external circulation vacuum emulsifier was tailored to address the limitations of traditional equipment. Key technical features and adaptations are as follows:
Core External Circulation System
The equipment adopts a dedicated external circulation pipeline design, connecting the bottom of the mixing chamber to a high-efficiency homogenizing unit and returning materials to the top of the chamber. This structure enables forced circulation of materials through the homogenizer at a flow rate of 8-10 m³/h, ensuring that all materials pass through the shear zone repeatedly (6-8 cycles per batch). Unlike internal-circulation systems, the external design eliminates dead volume and ensures uniform shear force application across the entire material volume, resolving the issue of uneven emulsification.
Homogenization and Shear Performance
The homogenizing unit features a dual-stage rotor-stator structure with a maximum rotational speed of 12,000 rpm and linear speed of 45 m/s. The adjustable rotor-stator gap (0.1-0.3 mm) generates intense shearing, cavitation, and turbulent forces, effectively breaking down oil droplets and solid particles into micro-dispersions (2-4 μm). A 45 kW variable-frequency drive (VFD) motor enables stepless speed adjustment (1,500-12,000 rpm), allowing the technical team to tailor shear intensity to different cream formulations without damaging heat-sensitive ingredients.
Vacuum and Sealing Design
The integrated high-efficiency vacuum system maintains a stable vacuum degree of -0.096 to -0.098 MPa throughout the production process, including the external circulation loop. The entire circulation path—from the chamber to the homogenizer and back—is fully sealed with double mechanical seals and food-grade fluorine rubber gaskets, preventing air re-entry and material leakage. This design ensures thorough deaeration during circulation, eliminating residual bubbles and minimizing oxidative degradation of active ingredients.
Material and Hygiene Compliance
All product-contacting components, including the mixing chamber, external circulation pipelines, and homogenizer head, are fabricated from 316L stainless steel. The surfaces undergo electrolytic polishing treatment to achieve a roughness Ra ≤ 0.4 μm, preventing material adhesion and biofilm formation. The equipment supports CIP (Clean-in-Place) operations, with high-pressure cleaning nozzles installed in the chamber, circulation pipelines, and homogenizing unit—enabling thorough cleaning of all contact surfaces and meeting GMP hygiene requirements.
Temperature Control and Automation
A jacketed mixing chamber with a PID temperature control system regulates processing temperatures between 20-80℃ with a precision of ±1℃, supporting both heating and cooling functions. This prevents thermal denaturation of sensitive ingredients and ensures stable emulsification matrix formation. The equipment is equipped with a PLC touchscreen control system, enabling real-time monitoring and adjustment of key parameters (homogenization speed, circulation flow rate, vacuum degree, temperature). The system stores up to 50 formulation profiles, facilitating one-click batch switching and automatic data recording for traceability.
3. Implementation and Process Optimization
Before full-scale production, the technical team conducted multi-batch pilot tests to optimize process parameters for three core cream formulations: oil-in-water (O/W) moisturizing cream, water-in-oil (W/O) anti-aging cream, and high-viscosity sunscreen cream. The primary goal was to determine the optimal combination of external circulation flow rate, homogenization speed, vacuum level, and processing time to achieve target particle size, emulsification stability, and texture.
Pilot test results yielded formulation-specific optimal parameters: For O/W moisturizing cream, an external circulation flow rate of 9 m³/h, homogenization speed of 10,000 rpm, processing temperature of 40℃, and 30-minute emulsification time (under -0.097 MPa vacuum) achieved uniform particle size distribution (2-3 μm, Span value ≤0.8) and a smooth texture. For high-viscosity sunscreen cream, a reduced circulation flow rate of 7 m³/h, higher homogenization speed of 11,000 rpm, and extended vacuum hold time (10 minutes post-emulsification) eliminated residual bubbles and ensured consistent SPF efficacy. For W/O anti-aging cream containing plant extracts, a lower temperature (35℃) and intermittent homogenization (5 minutes on, 2 minutes off) preserved ingredient activity while maintaining emulsification stability.
Based on these results, the production line was reconfigured to integrate the external circulation vacuum emulsifier into a closed-loop workflow. The optimized process is as follows:
- Preprocess raw materials (melting oil-phase components, dissolving water-soluble excipients, filtering extracts) and preheat to the specified temperature.
- Transfer preprocessed materials into the 1,000L chamber via closed pipelines, following the optimized phase addition sequence (oil phase first, then water phase) to minimize air entrapment.
- Activate the vacuum system to reach the target degree (-0.096 to -0.098 MPa) and start the external circulation pump to initiate material circulation.
- Activate the homogenizer at the preset speed, allowing materials to circulate through the shear zone repeatedly for the specified emulsification time.
- Maintain stable temperature via the jacketed system, then cool the cream to 25℃ while continuing circulation to ensure uniform cooling.
- Extend vacuum hold time for 5-10 minutes to remove residual bubbles, then stop circulation and homogenization.
- Discharge the finished cream to downstream filling equipment via closed pipelines, completing the production cycle.
This optimized process eliminated the need for manual material stirring and post-emulsification deaeration steps, integrating all key operations into a single automated workflow. Cleaning validation confirmed that the external circulation pipeline design, combined with CIP systems, effectively removed residual materials—with no detectable contaminants (limit of detection: 0.1 μg/cm²) between batches.
4. Application Results and Performance Improvements
After the external circulation vacuum emulsifier was put into formal production, the facility achieved measurable improvements in product quality, production efficiency, and operational costs—with consistent outcomes across all cream formulations:
Product Quality Enhancement
Particle size control was drastically improved: average particle size was stabilized at 2-4 μm, with a Span value ≤0.9, eliminating graininess and delivering a smooth, creamy texture. Emulsification stability was enhanced—all products passed 6 months of accelerated stability testing (40℃±2℃, relative humidity 75%±5%) without phase separation or texture changes. Residual air bubbles were completely eliminated, improving product appearance (uniform luster, no porosity) and extending shelf life by 30% by reducing oxidative degradation of active ingredients. Batch-to-batch consistency was significantly improved, with key quality indicators (viscosity, particle size, pH) fluctuating within ±3%—a marked improvement from the previous ±8% variation.
Production Efficiency Optimization
The batch processing cycle was shortened from 45 minutes to 30 minutes—a 33% reduction—enabling the facility to increase daily production volume from 8 batches to 12 batches (1,000L per batch). The external circulation design increased effective capacity utilization to 85% of the nominal volume, compared to 65% with traditional equipment. The automated control system reduced manual intervention, with each operator capable of monitoring two production lines simultaneously, lowering labor intensity by 40%. Formulation changeover time was also reduced from 2 hours to 45 minutes, supporting flexible production
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