Injection molding tool Return on investment in less than a year

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PHOENIX CONTACT Deutschland GmbH

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The result of renewing an injection molding tool for ejector levers of relay modules at Phoenix Contact: less waste, less material, less energy, less CO₂ emissions. The replacement of older tools can pay off.

Thorsten Sienk is a specialist editor for sustainability and technology, Corporate Communications, Phoenix Contact GmbH & Co. KG, Blomberg.

What potential lies in injection molding to handle plastic granules and energy more sparingly? What potential do tools in particular open up, which already have a construction year far in the past because of their longevity? After all, they come from a time when climate change and sustainability were hardly perceived by the general public.

Phoenix Contact has found answers to these questions by exemplarily converting a tool for ejector levers for relay modules. Less waste, less material, less energy, less CO₂ emissions: The cost of around 100,000 Euros for building the new tool was quickly recouped. The Return on Investment (ROI) was less than a year. So it is worth taking a closer look, especially at older tools.

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At Phoenix Contact, relay modules consist of a power contact relay with a relay base and an ejector in lever form. These components have been established technology in the electrical industry and control cabinet construction for decades. Production quantities are accordingly high. Since relays are so-called continuous runners, their production means are used for a long time. Evidence of this is the injection mould for the orange ejectors used to separate the relay from the socket, which was built in 1996. Thus, the unit has been serving for nearly 40 years. If it were a car, the injection mold would be classified as a vintage car with an H license plate. The fact that Phoenix Contact has now commissioned a new tool for this component is not due to a lack of manufacturing quality, but to aspects of sustainability—in this case, specifically to protect scarce resources.

Sprues cannot be used as recyclate

No waste, but instead the most economical and targeted use of non-renewable resources. Such sustainable action also pays off economically, as the example of the injection mould for the ejectors shows. Modern tools often come with a high five-figure cost. As already mentioned, the new tool for the ejectors costs about 100,000 Euros. This high investment sum makes it understandable to use tools that have been built once for as long as possible—even if they are long past tax depreciation periods.

This statement also applies to the ejector tool that went into operation in the mid-1990s. But why create a new one when the existing unit is still running well according to the principle "never change a running system"? Apart from climate protection and sustainability, the current shortage of raw materials is one of the key triggers for investing money at this point. The decision can be validated with a few figures. Before the tool change, the Phoenix Contact site in Bad Pyrmont consumed about 21 tons of granulate for the levers each year. The plastic is a dyed polyamide granulate, which is reinforced with glass fibers due to the required mechanical strength. Glass fibers provide stability and are effective against bending forces. However, this property makes it impossible to reintroduce sprues as recyclate back into the production cycle.

Eleven tons of material saved with hot runner system

So what is the key difference between the old and new tool? The new sixteen-compartment tool dispenses with all sprue channels and works in principle with a so-called hot runner system. Fine nozzles inject the liquid plastic directly into the mold while it closes precisely to vent. The visible sign of injection molding with hot runners is a small depression in the manufactured parts—known as a cap. "It results from the fact that the nozzle is placed in the tool there," explains Marco Schröder, team leader in component manufacturing at Phoenix Contact in Bad Pyrmont.

In the case of the ejector, the indentation is located in an area that lies invisibly inside the relay terminal after assembly. What sounds simple at first required a challenging approval process due to the design change. Despite this, the work and effort invested in completely redesigning the tool paid off—with a return on investment (ROI) of less than a year.

More waste than used plastic

With the old eight-compartment tool, the actual parts weighed only 6.8 grams—hence rounded 0.8 grams per ejector. However, the shot weight per cycle was an additional 7.5 grams. The non-usable waste thus amounted to a larger amount than the plastic for the eight ejectors. This is where the key reason for the quick amortization through saved resources comes in. The investment amount was—as mentioned—recouped after just a year solely by reducing the granulate. Marco Schröder: "The elimination of the sprue amounts to about eleven tons of material annually—which corresponds to around 100,000 Euros in purchasing. The total savings from the new tool are a little higher at 150,000 Euros."

Another advantage of the conversion results from the CO₂ balance. With the newly conceived tool, CO₂ emissions improve by 70 to 75 tons per year based on the calculation basis of database values. As an extended workbench of Phoenix Contact, Hadi-Plast GmbH also benefits from the new tool. "With us, the runners were constantly jamming and piling up into towers. Machine malfunctions hinder the workflow," remembers owner Dr. Karsten Anger. The fact that the double number of parts per cycle also saves production space and time also proves to be a plus point when evaluating this measure.

Develop optimization strategies together

Lack of raw materials, climate protection and above all, sustainable action out of inner conviction: The initial impulse to develop a new tool and replace a unit that has been running smoothly until now came from Hadi-Plast for the reasons mentioned. Even though the company from Hövelhof near Paderborn can initially be described as a supplier in its role: The cooperation between the two companies quickly led to a real partnership. This includes achieving process improvements together as well as producing in a more sustainable and resource-saving way. "We see ourselves as a system supplier who can master a process very well and thus can achieve more than a simple contract manufacturer," emphasizes Karsten Anger.

His company alone invested four million euros in new machines in 2022 and has thus developed into a flagship operation in terms of injection molding, Angerer says. This classification also includes how Hadi-Plast deals with its energy and the resources used. "Everything with us is designed for high efficiency. We want to increase the efficiency and consequently effectively limit losses." As an example, the managing director mentions the use of waste heat from production to heat the office building. "We no longer need gas at the site and even generate more heat than necessary."

Do more for climate protection

Anger draws his motivation to do more for climate protection from the future of his four children. "My family has been using green electricity for many years. This is personally important to me. I don't want to ruin anything on the back of the future. Balance is needed here." Karsten Anger views the close and reliable partnership with Phoenix Contact as a stable basis, which is necessary for long-term strategies. And it is precisely this aspect that Marco Schröder also appreciates, as Hadi-Plast has brought its competence into the project of the new injection moulding tool.