Kevin Heap, packaging expert with Sumitomo (SHI) Demag, talks about the trends in caps and closures …
Global demand for caps and closures is continuing to rise, with market volume estimated to reach 2,312.0 billion by 2018, up from 1,826.0 billion in 2012. Screw caps for canisters and bottles, in addition to plastic caps for cups, containers and pouches is driving this growth, with advancements in tamper-evident closures also pushing demand. Many fmcg manufacturers are now opting for robotic solutions. Beverages remain the dominant market in the caps and closures market, with lightweight packaging a strong trend among suppliers that are striving to satisfy both environmental and cost concerns.
Demands on injection moulding machines in the packaging industry continue to increase. In recent years, cycle times have got shorter, performance has increased, and higher cavity numbers are demanded. At Sumitomo (SHI) Demag we are seeing increasing demand for applications with cycle times of between two and three seconds. There is also bigger demand for machines with higher clamping force. Manufacturers in this sector are often contracted to produce millions of caps and closures, so to be cost effective, investment in high performance plant equipment is fundamental. Another important factor is energy efficiency. All-electric systems are fast becoming the system of choice for UK moulders. One of the most notable reasons is the figures stack up.
Electric mould machines consume up to 75% less energy than conventional equipment and the speed in which moulders are seeing a return on investment (ROI) has dropped from eight years to three. Plastic is by far the preferred material nowadays for these daily use components, replacing traditional materials like aluminum, tinplate, glass or cork. Aside from the cost advantages, the lower weight and versatility of plastic applications can further enhance product quality and security, and offer manufacturers better graphic capabilities. Polypropylene continues to be the leading caps and closure resin but there are expectations that the material may be replaced with HDPE which has economic and sustainability advantages. The use of bioplastics is also poised to play a greater role in packaging going forward. Technically speaking, a moulder doesn’t need to invest in new processing equipment to run bioplastics through it, although they do need to carefully consider how the material will perform as an end product and factor in the melt stability.
Fit for the future
Injection moulding has surpassed compression moulding, predominantly because of the widespread adoption of multi-cavity moulds. The process entails thermoplastic and thermosetting polymer granules being fed into a heated barrel where they are melted and mixed under pressure by a rotating screw until there is a homogeneous melt which is injected into a mould cavity where the shape is configurated to the cavity and is replicated exactly. The mould is then cooled and opened, ejecting the finished cap/closure. Given that the average European discards 159kg of packaging material each year, sustainability is an ongoing concern, with a strong commercial incentive to do more with less. The challenge for manufacturers of caps and closures is they are balancing a wide range of variables, including cost and functional requirements, as well as responding to demographic and lifestyle changes and environmental impact.
From a machinery manufacturer point of view, thinner wall sections bring changes in processing requirements. Among them, higher pressures and speeds, faster cooling times, and modifications to part-ejection and gating arrangements. These process changes have in turn prompted new considerations in mould, machinery, and part design. With packaging formats constantly changing, it makes economic sense to build a complete moulding system that anticipates future applications. Many of today’s manufacturers are looking towards full turnkey solutions, with robotic capabilities integrated. Speed, yield, repeatability, reliability, multi-tasking and long-term cost saving are all reasons why end users might opt for a robotic solution.
For further information please visit uk.sumitomo-shi-demag.eu