The current state of circularity in plastics production is characterised by a complex landscape of challenges and innovations. Although mechanical recycling remains a prevalent practice, the industry is also actively working towards enhancing recycling rates and the quality of recycled materials.
Some manufacturers are now adopting scrap-reduction machinery to minimise waste in production, and recycled bioplastics sourced from renewable materials are gaining momentum. Chemical recycling is also on the horizon, offering the potential to return recycled plastics to their original molecular state.
At the heart of this mission lie variable speed drives (VSDs) – also known as variable frequency drives (VFDs) or simply, drives – along with motors and programmable logic controllers (PLCs). Whether applied to extrusion lines, flat dye cast machinery, blown film lines, blow moulding machines or injection moulding machines, these technologies are pivotal to advancing sustainability in plastics manufacturing. Before we explore these solutions in detail, let’s lift the lid on plastic recycling’s environmental conundrum.
A paradox for plastics
How drives, motors and PLCs are setting new standards for circularity
Fortunately, drives, motors and PLCs can work together to enhance energy-efficiency, reliability and overall performance of plastics production, resulting in a more circular lifecycle, and reduced total cost of ownership.
As we know, industrial motors convert electrical energy into mechanical motion to power equipment and machinery. Today’s premium motors, such as those that use synchronous reluctance (SynRM) technology, offer unparalleled levels of performance, energy efficiency, and reliability for the various applications used in plastic production both as quadric and constant torque.
Pairing motors with variable speed drives brings next-level results. Direct online motors can only be on or off, and will run at a fixed speed, regardless of the process requirements. Conversely, when motors are combined with drives like ACS580 general purpose drives, they have the ability to control and regulate the speed, torque, and position of the motor shaft accurately. Eventually, this allows for synchronisation with the motion of other equipment and motor shafts. By enabling such precision control, VSDs can significantly cut energy usage and its associated carbon emissions, as well as reduce costs.
Adding PLCs, such as the AC500 – a digital computer that executes actions via user-designed logic programs – can automate a broad variety of industrial processes and machinery for further productivity gains and cost savings. Furthermore, the sensors incorporated in the motor-drive system can gather and evaluate data to pinpoint production process inefficiencies. This enables continuous enhancement and decreased resource usage, supporting circular economy objectives with the optimal machine productivity ratio.
Whether applied to flat dye cast machinery, blown film lines, or injection moulding, these game-changing technologies are pivotal to advancing sustainability in plastics manufacturing. And an especially notable example of how these technologies combine to contribute to sustainability is in the extrusion process.
A closer look at extrusion for recycled plastics
An essential operation in all plastics and bioplastics production, melting raw plastic material and forcing it through a shaped die to create a continuous and uniform plastic product is a process that demands precise control of the extruder’s speed and torque. What’s more, plasticisation in recycled plastics differs significantly from the processing of virgin materials, and this variation places a heightened demand on precise temperature control and emphasises the role of motors, drives and PLCs.
Recycled plastics often contain a mixture of polymers with diverse viscosities due to their previous use and varying degrees of degradation. To successfully process recycled plastics, extruder temperature control becomes even more critical. The motors, drives and PLCs play an integral role in carefully managing this process. They must have the capability to control both speed and torque with excellent screw heating control, catering to the distinct characteristics of recycled materials. This control is essential to ensure that the plasticisation process maintains the right temperature profile throughout the extrusion or moulding, preventing overheating or inadequate melting of the recycled polymers.
Motors and drives also need to be adaptable to the varying properties of recycled plastics. Different batches of recycled material may exhibit distinct viscosities, which can change over time. Therefore, motors and drives, especially when paired with PLCs, must be capable of intelligently adjusting the extruder’s speed and torque in real-time to match the specific needs of each batch. The ability to precisely adjust these parameters ensures consistent production of high-quality recycled plastic products and guarantees the highest productivity level of the machine. In this way, motors, drives and PLCs not only improve the efficiency of the recycling process, but also contribute to circularity goals by reducing waste and supporting the reuse of resources in plastics production.
Plastic product producer optimises performance with VSDs, motors and PLCs
Sarem Makina is an Istanbul-based manufacturer of reliable and dependable extrusion equipment to produce plastic pipe. High levels of machine reliability and uptime are essential. In the extruder business, temperature control and torque control are the most critical parameters when dealing with molten material. Poor torque or temperature results in poor pipe quality.
To achieve precise control, ABB low voltage drives have been used in Sarem Makina’s machinery from the start. Now the company uses an ever-growing number of ABB components, including drives, PLCs, motors, control panels and low voltage products to fully optimise the performance and energy-efficiency of its machinery, taking plastic production an important step closer to a truly circular lifecycle.
Putting sustainability at the heart of plastic production
The mission to make plastic production more sustainable is making promising progress, with exciting advances from mechanical recycling and scrap-free machinery, through to the creation of bioplastics from vegetables and pioneering chemical recycling.
While these new approaches are a giant leap towards reducing our reliance on single-use plastics and curbing the pollution of our planet, the industrial processes involved can, paradoxically, contribute to environmental problems.
To mitigate these negative consequences, it is vital that plastic product manufacturers of all varieties invest in energy-efficient technologies to perform their operations. Only then can this revolutionary, yet environmentally challenging material live a truly sustainable life.
