Calculating an Injection Molding Machine’s Carbon Footprint

As the European Union’s Green Deal takes effect and companies strive toward climate neutral production by 2050, knowing the product carbon footpring (PCF) of the entire supply chain will become increasingly important for European businesses. Arburg notes that in Germany the laws go even further, enforcing a 65% reduction in CO₂ emissions by 2030 with carbon neutrality by 2045.

Using the internationally recognized Greenhouse Gas Protocol, which organizes emissions into three areas—Scope 1, Scope 2 and Scope 3—Arburg says its machines are considered Scope 3 assets. These assets include indirect emissions from upstream and downstream business processes.

“As a machine manufacturer, Arburg is actively and comprehensively involved in carbon accounting in order to provide reliable and comparable indicators and meet the ambitious climate targets,” the company stated in release, noting it earned an “above-average” B grade in the Carbon Disclosure Project (CDP).

Unlike the corporate carbon footprint (CCF), which is calculated for an entire company on an annual basis, PCFs include the quantities of greenhouse gases emitted and removed over the entire service life of a product.

Cradle to Gate

In the first step, Arburg looks at the “cradle to gate” carbon footprint of its machines—that is the amount of carbon emitted in the manufacture of the press. This extends through raw material extraction and the manufacturing phase. All told, this portion of the machine’s existence only accounts for 5% of its CO₂ emissions. On a cradle-to-grave basis, which weighs a machine’s entire life, most of the PCF is generated during the use phase at the customer’s factory. The remaining remnant is associated with emissions made during the machine’s distribution and disposal.

As a rule, the specific energy requirements of an injection molding machine decreases with its capacity utilization.

For its purposes, Arburg records CO₂ in four process steps it undertakes when building a press: painting or coating; mechanical machining and processing; electrical production; and assembly.

Accounting for 11,000 Components

When you drill down to the level of an individual screw, the complete parts list of an injection molding machine could consist of 11,000 indivdual items. To help it better manage that figure, Arburg categorizes all its raw materials into eight distinct materials groups. On this basis, an Allrounder consists of more than 55% plastic-coated cast iron, and another 35% of steel and sheet metal, whether they’re hot-treated, painted, plastic-coated or untreated. Plastic components, drives and electronic components account for only about 7% of the total weight.

Although these different material groups differ significantly in terms of the CO₂ emissions generated during their production, Arburg says a weighted mean value can be determined along the lines of the distribution. This so-called emissions factor is around 1.83 [kg CO₂ equivalent per kg product] for an Allrounder. The CO₂ equivalent for the complete injection molding machine thus corresponds to the emissions factor multiplied by the press’ weight.

To illustrate this, Arburg explains that a hybrid Allrounder 570 H with a clamping force of 204 metric tons (m.t.) and a net weight of approximately 18,000 lb has raw material-related emissions of around 15,190 kg of CO₂ during its manufacture. At the other end of the scale, a 61 m.t. Allrounder 370 weighing 7275 lb generates a CO₂ equivalent of around 6040 kg.

Manufacturing Phase Emissions

Arburg calculates that electricity related CO₂ emissions during production generate an emissions factor of 0.366 [kg CO₂ equivalent per kWh] for the standard German electricity mix in the year 2020. On that basis, the electricity requirement is 2900 kWh for the Allrounder 370 H, with a CO₂ equivalent of around 1,160 kg, while for the Allrounder 570 H, the electricity requirement would be 7295 kWh with emissions around 2670 kg CO₂.

However, Arburg notes that two aspects of how and where it makes its machines change the calculation. Vertically integrated, Arburg manufactures around 60% of its Allrounder components itself, with this production occurring exclusively at its central location in Lossburg, Germany. That facility utilizes carbon-neutral renewable energies such as solar, wind and geothermal energy, as well as combined heat and power. Beyond that, since 2016, electricity purchased regionally has come entirely from sustainabile sources. This means that the emissions factor for Arburg’s electricity mix is actually only 0.17 instead of 0.366—53% lower than the German average.

Using that figure, the electricity-related CO₂ equivalent for the Allrounder 370 H is actually only 490 kg versus 1160 kg, while for the Allrounder 570 the emissions amount to 1240 instead of 2670 kg CO₂.

The Complete Footprint

If the raw material and electricity-related emissions are added, the total CO₂ equivalent for a “cradle to gate” analysis is 6530 kg for the Allrounder 370 H and 16,430 kg for the Allrounder 570 H. So what does that actually mean? By comparison, Arburg says each person in Germany generates an average carbon footprint of around 12,000 kg/yr, depending on personal consumption, mobility, housing and nutrition.

Molding Machine’s In-Use Footprint

Remembering that fully 95% of an injection molding machine’s PCF is attributed to its operation, Arburg says a key parameter to assess that is the specific energy requirement [kWh per kg], which is calculated from power consumption per material throughput. As a rule of thumb, the shorter the cycle time and higher the shot weight, the smaller the specific energy requirement and better the CO₂ equivalent.

Most impactful to the calculation is whether the machine utilizes an electric, hydraulic or hybrid drive. Going further, the calculation is also impacted by whether one or two-circuit pump technology or hydraulic accumulators are used, as well as other options like servo-electric dosing or ejection. Arburg notes that any features that enable simultaneous, dynamic and fast movements and shorten cycle times have a positive effect on the carbon footprint during use. The same applies to the screw diameter and installed power, so that the greater the shot weight and the smaller the power consumption, the better.

Application Impact

Ultimately, the parts the machines are molding also have an impact on the press’s PCF. In general, Arburg notes that the specific energy requirements for the production of technical molded parts in smaller quantities is significantly greater than for the production of fast cycling packaging items.

All-electric machines generate up to around 50% less CO₂ than hydraulically driven ones, depending on the equipment and material throughput.

Going forward, Arburg’s goal is to calculate “a scientifically sound, holistic lifecycle assessment for injection molding machines.” Arburg says such an effort is underway at the Institute of Plastics and Circular Economy (IKK) at

Leibniz University in Hanover. There, Professor Hans-Josef Endres is working on in collaboration with Arburg, among others.