Advantages, Disadvantages, and Process Fundamentals of Dowell BMC Injection Molding

BMC injection molding has its advantages and disadvantages. First, let's understand what injection molding is. Injection molding involves machines that manufacture shoes by injecting materials such as PVC or TPR directly onto an aluminum last through a turntable machine, forming the sole in one piece. Nowadays, PU (chemically known as polyurethane) injection molding is also used, which involves different machinery and molds compared to standard injection molding.

Advantages:

- High Output and Low Cost: Since the process is machine-driven, it allows for mass production, resulting in lower costs.

Disadvantages:

- Complexity in Style Changes: If there are multiple styles, changing molds can be cumbersome.

- Difficulty in Shaping: It is challenging to shape the shoes precisely, and they do not have the finesse of cold-glued shoes. Therefore, it is generally suitable for orders with single sole designs.

Process Fundamentals:

1. Temperature, Pressure, Speed, and Cooling Control: The purpose, operation, and outcomes of controlling temperature, pressure, speed, and cooling during the injection molding process.

2. Influence of Injection Machine Settings on Process and Quality: How adjustments to the injection machine settings affect the process and the quality of the final product.

3. Optimizing Screw Control Settings: Techniques for optimizing the control settings of the screw used in the injection molding machine.

4. Multi-Stage Filling and Multi-Stage Holding Pressure Control: The impact of crystallization, non-crystallization, and molecular/fiber orientation on the process and quality.

5. Effects of Internal Stress, Cooling Rate, and Plastic Shrinkage on Part Quality: How internal stresses, cooling rates, and plastic shrinkage affect the quality of the molded parts.

6. Rheology of Plastics: Understanding how plastics flow, orient, and change viscosity; the relationship between shear and molecular/fiber orientation.

7. Relationship Between Gating System, Cooling System, Mold Structure, and Injection Molding Process: The interplay between the gating system, cooling system, mold structure, and the overall injection molding process.