The plastics injection moulding industry has advanced dramatically over the past couple of decades, but it continues to be an energy-intensive one. This, in turn, can lead to considerable costs.
Injection moulding plants can reduce their energy consumption, however, by developing a structured strategy comprising practical management, maintenance and investment actions. If done well, it could lead to energy consumption savings by up to 30%!
There are a number of ways to do so – including picking the right hydraulic oil, which was highlighted in our earlier article.
Below are 5 other ways:
In an injection moulding plant, energy use is variable, controllable and directly related to production. The key to understanding energy consumption is the Performance Characteristic Line (PCL), which provides a unique ‘energy fingerprint’ of a plant.
Armed with this, injection moulders can predict plant energy usage for any period based on actual or anticipated production volumes and integrate that data into their business accounting system for reporting and monitoring purposes.
They can also compare their PCL result against other plants, to monitor and benchmark their performance against global averages.
The base load (i.e. the energy used at zero production) can account for 75% of a standard injection moulding machine’s energy consumption.
By examining the moulding cycles through a machine’s power draw, the base load can be optimised through slight adjustments of the injection speed, clamp force, hold and cooling time.
Additionally, it is important that businesses pay attention to the technological advancements and adapt accordingly.
Today’s injection moulding machine technology is far more energy efficient than 20 years’ ago with the arrival of all-electric and hybrid machines. At a conservative estimate, modern hydraulic injection moulding machines are 25% more energy efficient than those manufactured in 1997. Meanwhile, the best all-electric machines may be up to 80% more energy efficient than their hydraulic predecessors.
By investing in more energy efficient machines and methods, it will not hinder but instead increase production rates too. It’s an all-round win-win situation.
Plastics processors should pay attention to their peripherals too. Often ignored, peripherals can provide significant energy savings in an injection moulding plant.
Simply fitting insulation to barrel heaters (which account for up to 25% of the energy input of an injection moulding machine) can cut heating costs by 50%!
Elements such as compressed air, chilled water and dryers are essential in any injection moulding plant, and can be effectively managed and optimised to reduce energy use. These alone account for an approximate 30-35% of energy used.
Reducing leaks, dropping pressures and improving pipework for compressed air can cut compressor energy consumption by up to half. Additionally, installing insulation and variable speed drives (VSDs) to cooling tower fan can cut the cost of chilled water by up to 25%.
Similarly, the energy use during the drying process can be minimised too. Limit drying to the materials that truly need it and store them properly in a warm and dry environment.
Motors should not be overlooked as well. Turn off motors that are not contributing to production – every kW of fully loaded motor costs around $1,000 a year. Plants should ideally install VSDs to match motor speeds to demand, practice good maintenance and upgrade to new technology when possible.
Energy efficiency is not all about hardware; the way a moulding plant operates plays a major role too. Staff can be trained and empowered to switch off machines, processes and services, which can lead to energy reductions of up to 20%!
Buildings and their associated services account for around 8% of total energy use in a typical injection moulding operation. It might be a small percentage, but there is room for improvement. For instance, LED lamps can be used instead as they are highly energy efficient, offer a long life, provide high quality illumination and require very little maintenance.
And heating – traditionally a low energy priority for injection moulding sites as process losses provide considerable amounts of space heating – can also be optimised. Improvement measures include air leakage reductions, better insulation as well as optimised setting and control.
To find out more and develop your own edge in today’s competitive industry, download the free ‘Energy Saving Guide for Injection Moulding Companies’.
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IT IS AMAZING TO SEE HOW THE PLASTIC PROCESSING INDUSTRY HAS EVOLVED, A FEW YEARS AGO WHEN I STARTED MY WORKING LIFE, I WAS IN A COMPANY WHERE PLASTIC INJECTION WAS DONE IN MOLDS PIECE BY PIECE WHERE YOU HAD TO INJECT THE PLASTIC calculating the strength and velocity with which it was injected into the mold so that NO lumps and bubbles were made to the piece, it was all an art manufacturing, and machines so rudimentary that it oiled the crank with any grease that was it had at hand, and the amount of Energy that was used to have ignited the resistances of the machine with which the plastic pellets melted to inject, imagine, filling container with pellets (which reached approximately 10 downloads), EXPECTED TO MELT, PUT THE MOLD, DO THE WORK OF INJECTION, TAKE OUT THE MOLD, OPEN it, CLOSE it again (it was a great job to open and close the molds), to put mould again and again the same process, the cranks that had to go down and climb with the fuer were very hard because of the lack of an adequate grease, the electrical Energy to get a piece was exaggerated, now with the new technologies and with the appropriate greases the work is simplified and energy consumption.
Excellent information about the steps that must be followed to reduce energy costs in the molding process.