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The key success factors for caps & closures moulding

The key success factors for caps & closures moulding

News 02.09.2020

Through Mastip's extensive experience in caps and closures applications we believe that in order to respond to future trends and improve your competitive advantages, injection moulders should focus on the following key success factors:


The balanced flow of plastic melt from sprue to each cavity of the mould has a direct impact on the consistency and dimensional accuracy of closure products. Balanced filling in hot runners is particularly crucial for future production of lightweight closures with more complex structures.

Leveraging leading SIGMASOFT technology and its expertise in mould making and moulding process, Mastips engineering teams can simulate complex moulding processes. Accurate simulations allow product or mould optimisation in the early stage of mould design and save unnecessary trial and error cost. After mould optimisation, Mastip ensures precise control of melt temperature and flow to achieve thermal balance and uniform mould filling.

Many injection moulders encounter extended downtime during the colour change process. In the future, more colour changes in closures manufacturing are expected in order to catch consumers attention and differentiate brand images. As a result, hot runner suppliers will need to implement specific design and manufacturing processes around colour change to minimise downtime and material wastage.

In response to faster colour change requirements, Mastip ensures high performance through accurate calculation and optimisation of the melt residence time. In addition, specially designed deviation plugs and tip insulators are incorporated into colour change systems to ensure smooth melt flow even in areas that resin tends to stagnate, such as the transition of the melt channels, and the gate area between nozzle tips and mould.

These critical approaches avoid polymer degradation or colour variations on the finished products and reduces the shots required for colour change process.


For multi-material or multi-colour closures, injecting two or more materials (e.g. rigid and soft resins) or colours within the same injection moulding machine, can significantly reduce the processing steps and assembly labour cost to improve production efficiency.

However, it also means that the hot runner system is relatively complex, and if the system fails, product quality and production schedule will be compromised. Hence, the repeatability and stability of the hot runner system is critical when multi-colour and multi-material injection moulding is adopted.

With decades of experience in multi-material applications, Mastip provides tailor-made hot runner solutions to support customer’s product innovation. In order to provide the most durable and long-lasting solution, Mastip equips all systems with the latest heating technology, tool steels including 420 stainless steel and powder sintered tips when required to enable them to perform under the most demanding conditions.

The aesthetic standard of closures is increasing day by day. For cosmetic closure application, the gate quality can significantly define the overall quality of a closure. As a result, valve gate hot runners are typically considered the ideal solution for demanding cosmetic closures applications. Compared to thermal gates systems that rely heavily on cooling conditions, valve gates accurately control melt flow with valve pins resulting in no gate vestige.

Mastip’s Guided Open Valve Tip employs valve pin guidance to guarantee the accurate valve pin positioning at the gate, reducing risk of wear and achieving the best gate quality.

Except for hot runner gating method, there are many other factors that could contribute to gate quality, for instance gate location, dimple design, cooling design around the thermal gate and wear of the valve pins. Mastip provides mould makers and moulders with professional recommendations and design guidelines to eliminate variations in each factor to achieve excellent gate quality.

Reducing cycle time has always been essential for moulders to improve production efficiency, reduce the costs and ultimately achieve the goal of cost-effectiveness for closure products. High performance hot runner systems with excellent thermal control can reduce the cycle time even further. Additionally, specialised hot runner systems such as high-cavity, stack and cube moulds double productivity without increasing additional capital investment.

Mastip's expert teams can design and manufacture single or multi-level systems with thermal or valve gates to help closure customers reduce cycle time and improve production efficiency.

More and more injection moulders are adopting the concept of total cost of ownership to evaluate the real cost instead of purchase cost alone during their decision-making process. The total cost of ownership includes not only the initial investment of the machine or mould but also associated costs such as assembly, repair, service, maintenance, and energy consumption during operation. Closure products usually have a longer life cycle while requiring high volume production. As a result, in addition to the investment of moulds and machines in the early stage, high maintenance and operating costs may be incurred during the lifetime of the system. To increase the overall return on investment, moulders need to make decisions by considering the total cost of ownership before investing.

With total cost ownership concept in mind, Mastip aims to not only provide cost-effective hot runners but also reduce the operational cost in the long run, to help our customers achieve the lowest cost of ownership, for example:
• Wear Resistant tips and nuts
• Adjustable valve pin
• Nexus Pre-Assembled Hot Runner
• Hot Half Systems
• Front loading heater and thermocouples for easy maintenance
• Leak proof nozzles

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