How To Choose An Injection Molding Machine? A Complete Analysis of The Key Points

In modern manufacturing, injection molding machines are core equipment for plastics processing. Their performance and adaptability directly impact product quality, production efficiency, and production costs. Whether purchasing for the first time or upgrading, selecting the right injection molding machine requires comprehensive consideration of multiple factors. This article will provide a scientific selection guide based on product characteristics, equipment parameters, production requirements, and other factors.

Clearing Product Characteristics: The Basis for Selection

The specific parameters of the product are the primary consideration when selecting an injection molding machine, as they directly determine the machine's core configuration. First, consider product weight and volume. The injection molding machine's shot volume should be aligned with the product weight—typically, it should be 1.3-2 times the product weight to avoid material waste and ensure stable filling pressure. For example, to produce a 100g plastic part, it's recommended to select a machine with a shot volume of 130-200g.

Secondly, consider the product material. Different plastics have significant variations in fluidity and melting temperatures. Materials with good flowability, such as PE and PP, require lower injection pressures. Engineering plastics like PC and POM, however, have high melting points and high viscosities, requiring machines equipped with higher injection pressures and temperature control precision. Furthermore, for glass fiber-reinforced materials, the wear resistance of the equipment must be considered, and hardened screws and barrels should be selected.

Product structural complexity is also crucial. Products with deep cavities, thin walls, or complex patterns require injection molding machines with higher injection speeds and more stable holding pressure to avoid defects like underfill and flash. Furthermore, product precision requirements (such as dimensional tolerances and surface finish) influence the selection of equipment for positioning accuracy and repeatability.

Matching Core Equipment Parameters: Ensuring Production Feasibility

Key parameters of injection molding machines must be precisely matched to production requirements, primarily including the following:

Clamping force is a key parameter, required to overcome the expansion force generated by the molten plastic within the mold. The calculation formula is: Clamping force (kN) = Part projected area (cm²) × Material pressure (MPa) × Safety factor (1.2-1.5). For example, for a product with a projected area of 500 cm², using PS material (material pressure approximately 30 MPa), the required clamping force is approximately 500 × 30 × 1.3 = 19,500 kN, which means that equipment with a clamping force of at least 200 tons is required.

The injection volume should be calculated based on the product weight and material density, ensuring that the single shot volume is between 30% and 80% of the equipment's rated injection volume. This ensures both production efficiency and extended equipment life.

The injection speed and pressure should be adjusted based on the material properties and product structure. For thin-walled products, the injection speed should be increased to prevent the melt from cooling too quickly; for high-viscosity materials, the injection pressure should be increased to ensure complete mold filling.

Consider production scale and efficiency requirements

Production scale directly influences equipment selection and configuration. For small-batch, high-mix production, a general-purpose injection molding machine is suitable. It offers strong adaptability and flexibility, allowing for the production of multiple products through mold changes. For high-volume, single-product production, it's recommended to choose a dedicated injection molding machine. Equipment parameters can be customized based on product characteristics, and automated feeding and removal systems can be installed to improve production efficiency and stability.

Production efficiency is also closely related to the machine's cycle time, which includes injection, pressure holding, cooling, mold opening, and part removal. While ensuring product quality, shortening the cycle time can significantly increase production capacity. Therefore, it's important to pay attention to indicators such as the machine's hydraulic system response speed, cooling system efficiency, and mold opening and closing speed.

Evaluating Equipment Performance and Reliability

Equipment performance and reliability guarantee long-term stable production. First, consider the power system. Hydraulic injection molding machines offer stable operation and low cost, making them suitable for most general products. Fully electric injection molding machines offer high precision, low energy consumption, and low noise, making them suitable for precision products and applications requiring high cleanliness, such as medical and food packaging.

Secondly, consider the control system. Advanced control systems enable precise parameter adjustment and stable operation, support remote monitoring and fault diagnosis, and facilitate production management and maintenance. The structural stability of the equipment should also be considered. The rigidity of key components such as the frame and platen directly impacts mold clamping accuracy and product consistency. Therefore, choose equipment made of high-quality steel and featuring high machining precision.

Focus on Brand and After-Sales Service

Choosing an injection molding machine from a reputable brand generally offers more reliable quality assurance and comprehensive after-sales service. Branded manufacturers offer advantages in technology research and development, production processes, and quality control, ensuring greater stability and durability.

Also, consider the manufacturer's after-sales service system, including equipment installation and commissioning, operator training, spare parts supply, and troubleshooting. Timely after-sales service can minimize equipment downtime and production losses. It's recommended to choose a manufacturer with local service locations for rapid response to service requests.

Summary

Selecting an injection molding machine requires a comprehensive consideration of multiple factors, including product characteristics, equipment specifications, production requirements, performance reliability, and brand service. It's important to identify core requirements based on your own production practices and balance cost-effectiveness and long-term operating costs while ensuring product quality and production efficiency. Only through scientific selection can you provide efficient and stable equipment support for your production, helping your company achieve high-quality development.