PU Injection Molding Production Line Introduction

Figure 1 illustrates a typical rotary table molding line, where each mold carrier is equipped with pneumatic or hydraulic cylinders for automatic mold opening and closing. Power and mold temperature control water are delivered to the mold carriers via the central rotating shaft. Due to the diameter limitations of the rotary table, the number of molds it can hold is limited. This setup is generally suitable for medium-scale production.

Figure 1: Rotary Table Molding Line Diagram

2. Oval Track Molding Production Line

This layout allows flexible adjustment of production line length to meet different scales of molded product manufacturing. It is especially suitable for mass production. Figure 2 shows a typical setup for dual-hardness car seat (backrest) production. The system uses a three-component material setup with two different polyol blends for the hard and soft parts of the seat, sharing one isocyanate component. A dual-mixing-head robotic pouring system can operate in unison for dual-hardness products or independently for single-hardness items. Dual-position mold carriers can hold single or dual molds to accommodate various product specifications. Ventilation systems at demolding agent spraying and pouring stations ensure a healthy working environment. After spraying, four pre-positioning stations allow easy placement of inserts. This oval line operates continuously, with adjustable speed and computer control for stable, coordinated production. A 30-station line can produce up to 240 rear seats or 480 single seats per hour.

To support high-volume, multi-spec production, mold carriers must be quickly removable. A technical solution extends a section at the end of the oval track, enabling mold carrier removal or insertion for maintenance or mold changes without stopping the line.

Figure 2: Dual-Hardness Seat Oval Track Molding Line Layout

This method is typically used for large or bulky molded products with heavy molds. It's also common in small-scale production.

The production of refrigerator rigid foam insulation layers often uses this method. Figure 3 shows such a line, where a mobile mixing head is used to pour polyurethane rigid foam into several stationary support molds, typically serving 8–10 molds.

Figure 3: Refrigerator Rigid Foam Pouring Line Diagram

Another type of refrigerator pouring line uses a multi-head system (Figure 4). Each support mold is paired with its own mixing head. The electronic control system manages each head via shut-off valves according to individual pouring programs. This supports multi-station production, maximizes the use of metering systems, and increases pouring frequency for high-volume output. A key advantage is that repairing one mixing head does not halt the whole system. Also, the optimal head can be chosen based on product size for better results.

Figure 4: Multi-Mixing Head Pouring System Diagram