Comparison of pultrusion dip molding and closed-mold injection molding processes

In the field of fiber-reinforced composite pultrusion, the impregnation process is the core factor determining product performance, production efficiency, and environmental standards. The traditional open bath and the modern closed injection molding processes each have their merits. As a leading equipment manufacturer, GOOGIO will provide an in-depth analysis of these two processes and demonstrate how our advanced pultrusion injection machines can help customers achieve industrial upgrading.

Part 1: Process Comparison – Open Bath vs. Closed Injection

1. Open Bath Impregnation：This is the most traditional and common pultrusion impregnation method. Fibers are pulled through an open tank containing resin, with resin content controlled by scrapers or rollers.

• Advantages:

• Low Initial Investment:Simple equipment structure results in lower manufacturing costs.

• Intuitive Operation:Easy to observe resin status and fiber impregnation; relatively convenient for material changes and cleaning.

• Wide Compatibility:Good compatibility with various resin systems and fiber types.

• Disadvantages:

• High VOCs Emission:Large exposed resin surface area leads to significant volatilization of styrene and other VOCs, causing serious environmental pollution and health risks for workers.

• Resin Waste:Exposed resin can cure and be wasted, and precise resin content control is difficult.

• Product Quality Fluctuation:Prone to air entrapment and uneven impregnation, affecting mechanical properties and appearance consistency.

• Cumbersome Cleaning:Significant cleaning effort and downtime required for color or resin changes.

2. Closed Injection Molding：This is a more advanced closed impregnation technique. Fibers are introduced into a sealed mold cavity, where resin is precisely injected under pressure to fully saturate the fiber bundle.

• Advantages:

• Superior Product Quality:Pressure injection effectively removes air bubbles, ensures perfect fiber wet-out, and delivers excellent and highly consistent mechanical properties.

• Environmental Safety & Health:The nearly fully closed system drastically reduces VOC emissions, creating a cleaner and safer working environment.

• High Material Utilization:Precise injection control significantly reduces resin waste, lowering production costs.

• High Automation:Easily integrated into automated production lines for continuous, stable, and efficient operation.

• Disadvantages:

• Higher Initial Investment:The injection mold and equipment system are more complex than an open bath.

• Less Flexibility for Material Change:Changing resin formulas or colors requires more thorough cleaning of the injection system.

• Mold Design Dependency:Requires specially designed injection molds for specific product cross-sections.

Part 2: GOOGIO's Solution – The Future-Forward Pultrusion Injection Machine

Recognizing the immense potential and industry trend towards closed injection molding, GOOGIO is dedicated to developing high-performance, highly reliable pultrusion injection machines designed to address the pain points of traditional processes.

Core Advantages of Our Pultrusion Injection Machines:

• Precise Metering & Mixing:Utilizes precision metering pumps and static mixers to ensure extremely accurate resin/hardener ratios and homogeneous mixing, laying the foundation for high-quality products.

• High-Pressure Permeation Technology:Powerful injection pressure enables rapid and thorough impregnation of high fiber volume content reinforcements, perfectly saturating even complex structures like multi-axial fabrics and mats.

• Intelligent Control System:Integrated PLC touch-screen control system allows for precise setting and monitoring of injection pressure, flow rate, and ratio. Process parameters can be stored and recalled, ensuring production consistency and repeatability.

• Efficient Seal Design:Proprietary mold interface and sealing technology effectively prevent resin leakage, improving material utilization while ensuring a clean working environment.

• Strong Compatibility:Our equipment is compatible with various resin systems (e.g., Epoxy, Vinyl Ester, Polyurethane) and can be customized based on customers' product cross-sections and capacity requirements.

The transition from open bath to closed injection is an inevitable trend for the pultrusion industry moving towards high-quality, high-efficiency, and green production. GOOGIO, as your trusted partner, provides technologically advanced, reliable pultrusion injection equipment and comprehensive process support to help you stand out in the competitive market.