How to choose a suitable PET injection molding machine？

Choosing the right PET injection molding machine is closely linked to product production efficiency and quality. When selecting a machine, consider multiple aspects, including the mold and product, the machine's performance, and energy efficiency.

1. Mold and Product

Before selecting a PET injection molding machine, you need to fully understand your product and mold. This is the foundation for determining machine specifications.
Product Size and Weight:
Product weight determines the machine's shot volume. To ensure stable and high-quality production, it is recommended to select a machine with an shot volume 30% to 40% higher than the product weight (including the runner system).
Product size determines the machine's main column spacing, mold opening stroke, and ejector stroke.

Mold Size and Structure:
Mold thickness must be within the machine's mold thickness range.
Mold length and width must be less than the main column spacing to ensure smooth mold installation.
Mold opening stroke must be sufficient, generally recommended to be greater than or equal to twice the product (and runner) height, to ensure smooth removal of the finished product. Ejector stroke and ejection force must also meet the mold's ejection requirements.

2. Machine Performance

After determining the basic dimensional requirements, it's time to delve deeper into the machine's performance parameters.
Clamping Force (Tonnage):
Clamping force is the force the machine uses to hold the mold closed during injection to prevent plastic from leaking out.
The calculation method is: Clamping Force = Projected Area of ​​the Part on the Parting Surface × Mold Cavity Pressure. PET plastic requires high injection pressure during molding, so sufficient clamping force is needed to counteract this force.

Injection Unit:
Screw Diameter and Length-to-Diameter Ratio (L/D): PET requires a dedicated PET screw, typically with a longer L/D ratio, to ensure adequate plasticization while preventing degradation.
Plasticizing Capacity: PET requires rapid plasticization and drying, so the machine's plasticizing capacity is crucial. An efficient plasticizing system improves production efficiency and product quality.
Injection Speed ​​and Pressure: PET has a low melt viscosity, requiring high pressure and rapid injection to ensure complete filling and product clarity.
Cooling System: PET preform production requires efficient cooling. The machine should have a large-diameter water discharge system to meet the cooling water flow required by the mold, thereby shortening the molding cycle.

3. Drive System and Energy Efficiency

While ensuring production capacity, the machine's energy efficiency also directly impacts operating costs.
Drive System Type:
Fully hydraulic press: Traditional and low-cost, but with relatively high energy consumption.
Servo motor-driven mixer: Combining the advantages of hydraulic and electric systems, it offers significant energy savings, consuming 30% to 70% less energy than hydraulic presses. This is currently the mainstream choice for PET injection molding machines, balancing cost and efficiency.
Fully electric injection molding machines: Offer the highest precision and lowest energy consumption, but also carry the highest equipment cost. These machines are suitable for products requiring extremely high precision or for factories seeking maximum energy savings.

Selecting a PET injection molding machine is a crucial starting point. You need to calculate the required parameters for the product and mold, then use these parameters to select the machine's performance and drive system. Finally, consider the supplier's service capabilities. Only in this way can you find a PET injection molding machine that truly meets your production needs.