Saving energy in the plastics industry

Electrex - Saving energy in the plastics industry

Introduction to the plastics industry

It has been estimated that the plastics processing industry is responsible for 4% of global energy consumption. So any attempts to save energy by this industry are likely to lead to significant advantages. In 2012, 288 million tons of plastic were produced worldwide, with most production centred in China (23.9%), Europe (20.4%) and NAFTA countries (19.9%) (Source:

The industry is very process-specific and its energy use can be mainly attributed to the following applications:Electrex - Saving energy in the plastics industry

  • Melting of raw materials.
  • Cooling (mould, gauges, oil, etc.).
  • Driving peripheral equipment such as grinders, compressors, pumps, pre-driers, mixers, etc.
  • Vacuum formation of semi-manufactured products.

Plastic processing machines

The biggest consumers at a plastics processing plant are the machines. Moulding machines are used to produce the plastic products and are hydraulic, electric and hybrid.

The most efficient machine are electrically driven, although have the disadvantage of a higher purchase price. Hybrid machines are generally less expensive to purchase than fully electrical ones, but they are not as energy efficient, although this is changing as the technology matures.

The energy consumption of production machines in the plastics industry amounts to 60 per cent of total energy consumption

as shown in the diagram here below:

Energy consumption in a plastics processing plant

Electrex - Saving energy in the plastics industry


If one looks at the purchase price and consumption of a moulding machine, the purchase price of a moulding machine is lower than the energy costs of operating the machine over its working life. Energy-saving machines will save money in the long term. It is therefore not the purchase price that should be the top priority when purchasing a new machine, but rather the consumption or ‘total cost of ownership’.

Many different production processes are used in the plastics industry, with the most commonly used being:

  • extrusion,
  • injection moulding
  • and blow moulding.

Description of the production processes

Electrex - Saving energy in the plastics industry


Extrusion is a continuous process for the production of semi-manufactured products such as pipes, profiles, cable sheaths, films, sheets, and plates.

Plastic pellets are added to the extruder. A screw pushes the grains through a heated barrel. The grains are pressed together and melted. To heat the barrel, thermal oil is often used, usually heated electrically. The plastic is pressed into the correct shape in the mould at the end of the screw and cooled by water or air. When the product has reached the desired length, it is cut to size.

Electrex - Saving energy in the plastics industry


The biggest energy consumers in the extrusion process are the motors, heating units, cooling processes, and compressors. To gain a clearer understanding of energy management, it is advisable to look at energy consumption in relation to time. It can then be seen if energy consumption is commensurate with production. The large energy consumers in particular must be carefully matched to the process to ensure they do not operate unnecessarily.

Electrex - Saving energy in the plastics industry

Injection moulding

Injection moulding is a cyclical process mainly used for making plastic parts. Fluid plastic is forced into a mould using an injection technique. It is a fast process used for the production of identical parts.

The injection unit used for injection moulding corresponds to that of the extrusion process. The plastic is added, heated, and forced through the nozzle into a mould, which is a template into which the plastic is forced. The mould consists of two parts that are electrically or hydraulically pressed against each other. After the product has hardened, the mould is opened and the product is further processed.

Electrex - Saving energy in the plastics industry


Energy consumption with injection moulding can be divided into two phases. In the first phase, there is high energy consumption during the injection of the plastic and when the parts are removed. The other phase has lower energy consumption over a longer period when the plastic is cooled. The majority of the energy is used by the heaters and motors. The remaining energy is used by peripheral and other equipment.

Electrex - Saving energy in the plastics industry

Blow moulding

Blow moulding is used to make hollow objects such as plastic bottles. Molten plastic is blown by compressed air to form the desired shape.

Electrex - Saving energy in the plastics industry


The energy consumers for blow moulding are the same as extrusion and injection moulding because the main process to produce the plastic is essentially the same. As blow moulding is a derivative of extrusion or injection moulding, the same energy-saving measures are equally applicable to blow moulding.

Energy efficiency in the plastics industry

There are several tips that may be used in order to reduce energy consumption in the extrusion or moulding machines. Some of them are related to the configuration of the machine and  application of the production process:

  • Optimize the speed of the extruder.
  • Switch off as many energy consumers as possible when there is no production.
  • Make sure the housing of the extruder is well insulated.
  • Keep the melting temperature of the plastic pellets as low as possible.
  • Optimize the cycle time. Determine if the cycle time can be reduced.
  • Set a correct  pressure for the product being formed.
  • etc.

Anyway the greatest benefits will derive from a monitoring system applied to the machines. Indeed, a monitoring system will permit to gather real-time and historic data on the machinery and the performance of the production process. Thus it will be possible to discover abnormal consumption and define  benchmarks.

The most important parameters to be monitored in the plastics processing plants are the power consumption (in kW) and the product produced (in kg/hour) per machine.

The Electrex solution for energy monitoring, Power Quality analysis and Energy Automation

Electrex, one of the first companies providing energy monitoring  and management solutions  since 1993, has acquired over the years a considerable experience and competence that few other companies can claim to have.

The Electrex solution for the plastics industry makes possible the acquisition, analysis and management of data not only related to the electrical energy but also regarding the machinery operating status and other energy carriers used (gas, water, steam, etc.).

Indeed, the Electrex hardware equipment and software integrate in a seamless way the information coming from the different parts of the production line and match this information with the measurements coming from a constant and  direct sampling of the load.

In this way it possible to go beyond the main parameters provided from the moulding or extrusion machines and have a wider panorama on the production process and the energy consumption related.

The table below shows the key steps that lead not only to an efficient energy consumption but also to additional benefits in terms of optimized performance, maintenance and servicing.


" If You cannot measure it, You cannot improve it." Lord Kelvin's quote is totally suitable for energy efficiency programs. Without measurement devices it is not possible to set a benchmark or create a profile of the current consumption.

 Data Analytics (DA) is the activity of examining raw data with the purpose of drawing conclusions about that information. Data Analytics is a fundamental step for making intelligent, data-driven decisions.

New trends, previously not achievable because of the data fragmentation,  become visible. Cost centers which are benchmarking below their peers are immediately detected.
Visualize trends over time and discover what is considered an abnormal energy consumption or device state. 

Energy Automation is the use of control systems and information technologies to optimize the energy efficiency in the production of goods and delivery of services. The automated tasks are driven by energy consumption / production data.

A case study from the plastics industry

Premium company specialized in the Sale, Maintenance and Repair of injection molding machines  integrates the Electrex solution for monitoring full lines of injection molding machines.

Customer:  Premium company specialized in the Sale, Maintenance and Repair of injection molding machines for over 20 years. Its customers are well-known producers of plastic parts all over the world, in the automotive industry, the pharmaceutical industry and the production of technical parts, containers and household products.

Application: full line of injection molding machines.

Electrex is a brand of Akse s.r.l. - Via Aldo Moro, 39 - Reggio Emilia - Italy - Tel: +39 0522 924244 Fax: +39 0522 924245 - VAT IT01544980350 -
Joomla! is Free Software released under the GNU/GPL License.