How Much Electricity Does an Injection Moulding Machine Consume Per Kg of Plastic Produced?

A Practical Guide for Plastic Manufacturers in India

In today's competitive manufacturing environment, electricity cost is one of the largest expenses in injection moulding operations. Whether you are producing household products, automotive components, packaging items, electrical parts, or industrial products, understanding energy consumption per kilogram of plastic processed is essential for maximizing profitability.

A common question asked by factory owners and production managers is:

"How much electricity should an injection moulding machine consume per kilogram of plastic produced?"

The answer depends on several factors including machine technology, machine condition, mould design, cycle time, and production efficiency.

In this article, we explain how to calculate energy consumption, industry benchmarks, and practical ways to reduce electricity costs in your injection moulding plant.

Why Measure Electricity Consumption Per Kg?

Many factories monitor electricity bills monthly but do not analyze power consumption relative to actual production.

Measuring electricity consumption per kilogram of plastic processed helps:

1. Evaluate machine efficiency
2. Compare old and new machines
3. Identify production losses
4. Calculate actual manufacturing costs
5. Estimate ROI for machine upgrades
6. Improve plant profitability

The most useful measurement is:

kWh per kg of plastic produced

This value indicates how much electrical energy is required to produce one kilogram of finished parts.

How to Calculate Electricity Consumption Per Kg

The formula is simple:

Electricity Consumption (kWh/kg) = Total Electricity Consumed (kWh) ÷ Total Plastic Produced (kg)

Example

Suppose a machine consumes:

1. 120 kWh during a shift
2. Produces 400 kg of molded components

Calculation:

120 ÷ 400 = 0.30 kWh/kg

This means the machine requires approximately 0.30 units of electricity to process one kilogram of plastic.

Typical Industry Benchmarks

The actual consumption varies based on machine technology and production conditions.

Conventional Hydraulic Machines

1. Typical Range: 0.8 – 1.5 kWh/kg

Characteristics:

1. Constant motor operation
2. Higher heat generation
3. Greater hydraulic losses
4. Lower overall efficiency

Servo Hydraulic Machines

1. Typical Range: 0.3 – 0.8 kWh/kg

Characteristics:

1. Motor operates only when required
2. Reduced hydraulic losses
3. Lower oil temperature
4. Significant energy savings

Fully Electric Machines

1. Typical Range: 0.2 – 0.5 kWh/kg

Characteristics:

1. Highest efficiency
2. Precise motion control
3. Best suited for high-precision applications

Factors That Affect Electricity Consumption

1. Machine Technology

The largest factor influencing energy consumption is machine design.

Modern servo-driven machines adjust motor speed according to actual machine demand.

During cooling periods, power consumption drops significantly.

Traditional hydraulic machines continue running at full motor speed even when little power is required.

2. Cycle Time

Longer cycle times generally increase electricity consumption per kilogram.

Reducing cycle time improves productivity and spreads fixed energy consumption across more production output.

Optimized mould cooling can dramatically improve energy efficiency.

3. Machine Utilization

Machines running below their ideal capacity often consume more electricity per kilogram produced.

For example:

A 450-ton machine producing a small part may consume substantially more energy than a properly sized 200-ton machine producing the same component.

Machine selection plays an important role in energy efficiency.

4. Mould Design

Poor mould design can increase:

1. Injection pressure
2. Cooling time
3. Clamp force requirements
4. Cycle duration

All of these factors contribute to higher power consumption.

Well-designed moulds improve productivity while reducing energy costs.

5. Material Processing Conditions

Excessive:

1. Barrel temperatures
2. Back pressure
3. Injection pressure
4. Screw recovery time

can increase electricity consumption.

Proper process optimization often reduces energy usage without affecting part quality.

Hidden Costs of High Energy Consumption

Many manufacturers underestimate the financial impact of inefficient machines.

Consider a machine consuming:

1. 1.2 kWh/kg
2. Processing 500 tons annually

Annual electricity consumption:

500,000 kg × 1.2 kWh = 600,000 kWh

At ₹8 per kWh:

Annual Electricity Cost = ₹48,00,000

Now compare with a servo machine consuming:

0.5 kWh/kg

Annual Consumption:

500,000 × 0.5 = 250,000 kWh

Annual Cost:

₹20,00,000

Potential Annual Savings: ₹28,00,000

This demonstrates why energy efficiency has become a major consideration when purchasing new injection moulding machines.

How to Reduce Electricity Consumption

Upgrade to Servo Technology

Modern servo hydraulic machines typically reduce energy consumption by 30% to 70% compared to conventional hydraulic machines.

Benefits include:

1. Lower electricity bills
2. Reduced oil temperature
3. Improved machine responsiveness
4. Lower maintenance requirements

Optimize Process Parameters

Review:

1. Injection pressure
2. Back pressure
3. Barrel temperatures
4. Cooling times
5. Screw speed

Small adjustments often produce significant energy savings.

Maintain Hydraulic Systems

Regular maintenance helps prevent:

1. Pump inefficiencies
2. Internal leakage
3. Excessive oil heating
4. Energy losses

Proper maintenance improves both reliability and efficiency.

Improve Cooling Efficiency

Cooling accounts for a substantial portion of cycle time.

Optimizing water flow and mould cooling channels can:

1. Reduce cycle time
2. Increase productivity
3. Lower electricity consumption per kilogram

Match Machine Size to Application

Oversized machines consume unnecessary power.

Selecting the correct machine tonnage for the application improves overall plant efficiency.

Why Modern Servo Injection Moulding Machines Deliver Better Efficiency

Modern servo-driven injection moulding machines use intelligent motor control systems that supply only the power required for each machine movement.

Benefits include:

1. Lower energy consumption
2. Faster response times
3. Reduced hydraulic oil temperature
4. Stable processing conditions
5. Lower operating costs

For manufacturers operating multiple machines, even modest energy savings per machine can translate into substantial annual cost reductions.

Frequently Asked Questions

What is a good electricity consumption figure for an injection moulding machine?

For modern servo hydraulic machines, a range of 0.3 to 0.8 kWh per kilogram is generally considered efficient, depending on the application and part design.

Do servo machines really save electricity?

Yes. Many processors report energy savings of 30% to 70% when replacing conventional hydraulic machines with modern servo-driven systems.

Does cycle time affect electricity consumption?

Yes. Faster cycle times improve productivity and often reduce electricity consumption per kilogram of production.

Should electricity consumption be measured per hour or per kilogram?

Per kilogram is usually the better metric because it accounts for actual production output and allows meaningful comparison between machines.

Conclusion

Electricity consumption is one of the most important performance indicators in injection moulding operations. Measuring energy usage in kWh per kilogram of plastic processed provides valuable insight into machine efficiency and production costs.

Modern servo hydraulic injection moulding machines can significantly reduce operating expenses while improving process stability and productivity. For manufacturers seeking greater profitability and competitiveness, monitoring and optimizing energy consumption should be a key operational priority.

As energy costs continue to rise, investing in efficient injection moulding technology is no longer just an environmental decision—it is a business decision.