The primary parameters of a plastic molding machine define its performance, helping assess its capacity for creating injection-molded products, selecting materials, and ensuring high-quality output. These parameters guide the design, manufacturing, and operation of the machine, ensuring optimal efficiency and performance.
Injection Volume
The injection volume indicates the maximum amount of material the injection system can handle during a single stroke under air injection conditions. This parameter reflects the plastic molding machine‘s processing capacity and defines the maximum weight of plastic products it can mold.
- Measurement Methods:
Injection volume is typically expressed either as the mass (g) of the melted material, using polystyrene (PS) as the standard, or as the volume (cm³) of the melt. - Calculation Formula:
The theoretical injection capacity is calculated as:
QL=π4⋅D2⋅SQL = \frac{\pi}{4} \cdot D^2 \cdot SQL=4π⋅D2⋅S
Where:- DDD = Screw head diameter
- SSS = Screw stroke
Q=αQL=π4⋅D2⋅SαQ = \alpha QL = \frac{\pi}{4} \cdot D^2 \cdot S \alphaQ=αQL=4π⋅D2⋅Sα
α\alphaα: Injection coefficient (typically 0.7 to 0.9). - Usage Recommendations:
To maintain efficiency, the combined weight of the product and gating system should fall between 25% and 70% of the machine’s injection volume.
Injection Pressure
Injection pressure is the force exerted on the molten plastic to fill the mold cavity. This parameter impacts product shape, precision, and material properties. It varies based on plastic molding machine structure, mold design, material viscosity, and production requirements.
- Typical Pressure Ranges:
- 340–540 Kgf/cm²: For materials like LDPE with high fluidity and simple shapes.
- 680–980 Kgf/cm²: For PS or HDPE with moderate viscosity and general precision.
- 980–1370 Kgf/cm²: For PP or PC with high precision and complex shapes.
- 1370–1670 Kgf/cm²: For thin-walled, intricate products using materials like reinforced nylon or polysulfone.
- 2260–2450 Kgf/cm² or more: For high-precision micro-products.
Higher injection pressures are increasingly required for complex, high-precision, and structural engineering components.
Injection Time (Injection Speed)
The injection time refers to the duration required to fill the mold cavity with molten plastic. This ensures uniform, dense, and high-precision results. Shorter injection times require sufficient pressure and a specific melt flow rate to ensure even distribution within the cavity.
Plasticizing Capacity
This parameter defines how much material the plastic injection molding machine can plasticize per unit time. It depends on factors like screw speed, drive power, material properties, and screw design.
- The plasticizing system must supply a uniform melt volume within the designated cycle time.
- To accommodate various production needs, the theoretical plasticizing capacity should be about 20% greater than the actual requirement.
Basic Parameters of the Clamping System
1. Clamping Force
The clamping force is the maximum pressure the machine applies to keep the mold closed during injection. It ensures the mold does not open under the expansion force caused by cavity pressure.
- Clamping Force Calculation:
F=K⋅Pcp⋅AF = K \cdot P_{cp} \cdot AF=K⋅Pcp⋅A
Where:- FFF = Clamping force (Kg)
- KKK = Safety factor (typically 1–2)
- PcpP_{cp}Pcp = Average cavity pressure (Kgf/cm²)
- AAA = Maximum projected area of the product and gating system (cm²).
A well-calculated clamping force prevents defects and ensures precision molding.
2. Clamping System Dimensions
The clamping system’s dimensions determine the range of mold sizes and product types the plastic molding machine can accommodate. Key measurements include:
- Template Size and Tie Rod Spacing:
- Indicates the mold installation area.
- Template area should be 4–10 times the maximum molding area.
- Mold Opening Distance and Thickness:
- Defines the operational flexibility for mold installation and removal.
Summary
Understanding the main parameters of plastic injection molding machines, such as injection volume, pressure, and clamping force, is critical for optimizing performance, improving product quality, and meeting diverse manufacturing demands. At Daoben Machinery, we ensure our plastic molding machine excels in all these aspects, delivering precision and reliability to meet your production needs.
