Overview of HP-RTM Forming Process

HP-RTM (High Pressure Resin Transfer Molding) is an advanced and efficient composite material molding process widely used in the manufacturing of new energy vehicle battery covers. This process injects liquid resin into pre laid fiber preforms under high pressure, and rapidly solidifies to form high-strength composite components. Compared with traditional metal or thermosetting material processes such as SMC and PCM, HP-RTM has significant advantages in lightweight, flame retardancy, production efficiency, and product consistency, and has become one of the mainstream technologies for covering power and energy storage battery packs.

Core Technical Principles of HP-RTM Process

1. Process Steps

• Preparation of prefabricated parts: Continuous fibers (such as glass fiber and carbon fiber) are laid in the design direction to form a prefabricated structure.
• High pressure injection: In a closed mold, polyurethane or epoxy resin is injected into prefabricated parts under high pressure (usually up to 80-120 bar) to ensure that the resin fully wets the fibers.
• Fast curing: Using high-temperature molds to accelerate resin curing, shorten the molding cycle (usually 5-8 minutes), and achieve efficient mass production.
• Natural cooling: By natural cooling, the product is fixed and formed.
• Laser cutting: Remove burrs and make holes through laser cutting technology.
• Air tightness testing: Manually inspect the battery case to ensure its sealing meets industry standards.

2. Key Technological Innovation

1. Outstanding Lightweight Performance

The average thickness of the battery cover formed by HP-RTM is only 1.5mm, and the thinnest can reach 0.8mm, which is 60% lighter than traditional steel, 50% lighter than SMC, and 20% lighter than aluminum alloy, significantly reducing the weight of the battery pack and improving the range of electric vehicles.

2. Excellent Security Performance

The material has passed UL94 V-0 flame retardant certification and does not burn through or catch fire for 5 minutes at a high temperature of 800 ℃, meeting the strict fire protection requirements of battery packs.
High glass fiber content (55% -60%) and surface carbonization layer design, no additional fireproof coating is required, and the flame retardant performance is significantly better than traditional solutions.

3. Production Efficiency and Cost Advantages

Automated production processes shorten the mold development cycle, for example, the HP-RTM battery cover development cycle of Times New Materials only takes 27 days, which is nearly half shorter than the industry average of 55-60 days.
After large-scale production, the localization of raw materials and equipment further reduces costs, with individual unit costs 10% -15% lower than PCM processes.

4. Environmental Protection and Sustainability

Compared to metal processes, HP-RTM reduces carbon dioxide emissions, which is in line with the low-carbon trend of new energy vehicles.

Typical Application Cases

1. Times New Material’s Breakthrough

In 2024, Wuxi PHP successfully delivered 3500 tons, 2500 tons, and 2000 tons of HP-RTM molding presses to Zhuzhou Times New Material, supporting Times New Materials to successfully deliver the first energy storage battery cover sample. Using domestically HP-RTM PRESS and materials, it reduced weight by more than 60% and passed the 10kV insulation test, marking its technological leadership in the energy storage field.

2. Carbontech leads the industry development

As a leader in HP-RTM technology for new energy battery cases, Carbontech Technology is supported by PHP's 3000 ton molding press, 300 ton pre-molding press, and 5-ton cold press, which help Carbontech Technology develop rapidly and provide stable and reliable battery case covers for CATL.

Challenges and Development Trends