Energy-Efficient Servo Injection Molding: Cutting Electricity Costs for Plastic Packaging in BD

1. The Industrial Energy Challenge in Bangladesh

In Bangladesh, industrial electricity tariffs, coupled with peak load surcharges and reliance on captive diesel/gas generators during grid fluctuations, place power consumption at the top of operating expenses for plastic packaging converters. Traditional injection molding machines with fixed-displacement vane or gear pumps waste up to 40% of their electrical input by throttling hydraulic oil across relief valves during non-movement cycle stages.

2. Working Principle of Servo-Driven Hydraulic Systems

A servo injection molding machine utilizes a permanent magnet synchronous servo motor coupled to an internal gear pump, governed by a high-speed digital servo drive. The motor speed dynamically modulates based on instantaneous process requirements:

• During Mold Opening / Clamping: The motor delivers precise high RPM to achieve rapid dry cycle times.
• During Injection & Holding: The servo drive regulates exact pressure and velocity curves with microsecond feedback.
• During Cooling & Dwell: The motor drops to near 0 RPM, consuming negligible power (often under 5% of rated capacity) while holding pressure.

Depending on the cycle profile of the product (e.g. thick-wall preforms vs thin-wall food containers), total electricity savings range from 30% to over 50%.

3. Hydraulic Oil Longevity & Chiller Load Reductions

Because hydraulic oil is not constantly pressurized and sheared through relief valves, oil operating temperature remains significantly lower (35°C–45°C) compared to older machines (often exceeding 60°C). This offers two decisive advantages:

• The external water chiller load required to cool hydraulic oil is cut by half.
• Hydraulic seals and proportional valve O-rings remain supple, preventing internal leaks and extending hydraulic oil drain intervals by double.

4. Precision Tooling & Valve-Gated Hot Runners

Energy-efficient machines must be matched with high-precision molds to achieve high operational throughput. For bottle closures (28mm PCO 1881 / 30/25 water caps) and PET preforms, Food Plast International supplies hardened S136 stainless steel molds equipped with balanced hot runner manifolds and pneumatic needle valve gates, eliminating gate vestige and ensuring zero flashing at high speeds.