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How much electricity does an electric injection molding machine use?

2024/05/22 By Topstar

How much electricity does an electric injection molding machine use

Electric injection molding machine don’t have a single power-consumption figure that applies to all production facilities. This is because actual power consumption depends on machine configuration, the material being processed, shot weight, molding cycle time, temperature settings, and production schedules. To estimate costs, multiply the measured average power by the operating time to get total power consumption.

According to Topstar’s reference data, the power consumption of its 90T to 460T electric injection molding machine series ranges from 3.8 to 17.9 kWh. However, to use this data to estimate hourly or daily power consumption, you must clearly define the measurement period and test conditions. For a reliable assessment, power consumption must be correlated with the specific products being manufactured.

electric injection molding machine 90
Please note: The experimental data is for reference only, the actual data is determined by the process parameters of the product.

Energy Consumption of Electric Injection Molding Machines

Before estimating energy consumption in electricity costs, distinguish between the machine’s rated power, average operating power, and actual measured energy consumption. These figures reflect different metrics: equipment capacity, actual operating requirements, and electricity usage over a specific time period. Understanding the production factors behind these figures helps ensure accurate energy consumption calculations and enables you to compare machines under comparable conditions.

Energy Consumption of Electric Injection Molding Machines

Why Does Electric Injection Molding Machine Energy Consumption Vary with Production?

While equipment specifications certainly influence energy consumption, clamping force alone cannot accurately predict the electricity required to produce a specific product. Even on the same electric injection molding machine, different production tasks may involve varying shot weights, injection pressures, plasticizing requirements, and cooling times.

Generally, the larger the shot size, the more material requires heating and plasticizing. Higher processing temperatures increase thermal energy requirements, while longer holding or cooling times shift the balance between energy used for active motion and base energy consumption. All these factors influence the energy consumption of an electric injection molding machine.

All-electric injection molding machines use an electric drive system to perform the primary molding actions. Compared to traditional hydraulic systems, this design reduces energy loss during hydraulic power transmission. However, electric drive cannot completely eliminate all continuous loads. Even when the machine is not actively injecting, the barrel heater, control system, and auxiliary systems continue to consume electrical energy.

Why Does Electric Injection Molding Machine Energy Consumption Vary with Production

How to Calculate the Electricity Consumption of an Electric Injection Molding Machine?

The most straightforward method is to record the electricity meter readings at the start and end of a specific production cycle; the difference between the two readings represents the energy consumption for that period.

If the average actual power is known, the following formula can be used:

Electricity consumption (kWh) = Average actual power (kW) × Operating time (h)

Suppose an electric injection molding machine has an average power consumption of 8 kW during 8 hours of steady production; the total electricity consumption would be 64 kWh. Assuming an electricity rate of $0.12/kWh, the electricity cost would be $7.68.

The above is merely a calculation example and does not represent actual equipment performance data. These calculations are based on the assumptions of continuous production, a constant average power, and no scrap. Actual electricity bills may also include demand charges, taxes, and other surcharges. Never multiply the average power by both the cycle time and the total operating time. If calculating on a per-cycle basis, divide the measured total energy consumption by the number of completed production cycles.

Also, clearly define the scope of measurement. The machine’s own power consumption should be distinguished from that of dryers, chillers, mold temperature controllers, robotic arms, and other auxiliary equipment. When estimating total production costs, account for shared utility energy consumption separately.

Energy consumption varies with production conditions.

Which parameter settings affect energy consumption and product quality?

Reduce the power consumption per qualified product while maintaining a set production rate. Simply reducing power consumption does not necessarily indicate higher process efficiency.

Although lowering the barrel temperature reduces the load on the heaters, an insufficient melt temperature may make it difficult to fill the mold or may reduce surface quality. Excessively reducing holding pressure or holding time may result in sink marks, voids, or dimensional deviations. Shortening the cooling time too much may cause warpage during demolding. Reducing the molding cycle and eliminating unnecessary waiting time can improve energy efficiency, as long as the changes do not increase defects. Even if the average power consumption increases, the energy consumption per product may actually decrease due to the higher number of qualified products produced per hour. Therefore, the final results must be verified through actual measurements.

Consider a hypothetical “one-hour comparison”:

If one process consumes 8 kWh of electricity and produces 400 qualified products, the energy consumption per product is 0.020 kWh; if another process consumes 7 kWh but produces only 300 qualified products, the energy consumption per product rises to approximately 0.023 kWh.

As shown, lower hourly power consumption does not necessarily mean lower energy cost per qualified product.

We recommend the following improvement measures:
Eliminate unnecessary wait times, correct uneven cooling issues, select an appropriate injection volume, and maintain heaters, sensors, and drive components. Any adjustments to temperature, pressure, or time must be verified against the product’s dimensions, appearance, weight, and acceptance criteria.

Calculating Electricity Consumption Based on Overall Production Data

An electric injection molding machine’s power consumption depends on its average power—measured under specific production conditions—and its operating time. Calculate the kWh, then correlate it with acceptable output and local electricity rates. This lets you assess the machine’s power consumption and how electricity costs affect your product’s actual cost. Therefore, an electric injection molding machine’s actual power consumption depends on its configuration, materials, cycle time, and temperature settings.

 

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