WHAT IS CYCLE TIME IN ROTOMOULDING?
The cycle time in Rotomolding can be defined as the period needed to complete a sequence of steps in the manufacturing process of a rotomoulded part. These steps include loading the mould with polymer, heating and rotating the mould to melt the material and ensure its uniform distribution, cooling the mould to solidify the material, and finally, unloading the finished part.
Accurate calculation and optimization of cycle time is essential to maximize productivity and minimize production costs. A reduced cycle time means greater efficiency and, consequently, lower operating costs and well-formed parts.
INFLUENCE OF PART THICKNESS ON CYCLE TIME
One of the critical factors influencing cycle time in rotomoulding is the the thickness of the part. Thicker parts take longer to reach the necessary processing temperature and then cool to demoulding temperature.
Heating
During the heating phase, the heat must penetrate the entire thickness of the polymer added to the mould. Thicker parts, therefore, require longer heating times to ensure all the raw material is uniformly melted and ready for proper moulding.
There are some accessories, such as Rotoline's The temperature controller , which is designed to manage the machine's operation based on the pre-programmed temperature reached by the moulds, regardless of environmental fluctuations or the temperature at which the mould returns to the oven. This control allows the cycle to resume effectively, as the temperature tends to rise faster in the next cycle, enabling greater gas savings.
Cooling
The cooling process is also affected by the part's thickness. Thicker materials retain heat longer, prolonging the time required for the part to reach a suitable temperature for handling and finishing. Cooling control is crucial, as a rapid cooling scenario can cause distortion or stress in the material. Therefore, the use of fans with a constant and comprehensive air volume is important.
Rotoline fans are ideal for the rotomoulding process and can be even more efficient with the addition of sprayers that combine water and compressed air. These sprayers generate a continuous mist that evaporates instantly upon contact with the hot mould, eliminating the need for water collection trays under the moulds.
HOW PART SIZE AND WEIGHT AFFECT ROTOMOULDING
The size and weight of the part are other significant factors that directly impact cycle time in rotomoulding.
PART SIZE
Larger parts require larger moulds. That is, these moulds need more time and energy to reach the processing temperature and to cool down. A larger mould requires special attention to logistical and thermal aspects during the rotomoulding process.
PART WEIGHT
The part's weight adds another dimension to the complexity of the process. Moulds that need to handle heavier parts require controlled rotation and speed to ensure uniform material distribution. Proper weight management directly influences the total time required to heat and cool the mould, ensuring high-quality production.
STRATEGIES TO OPTIMIZE CYCLE TIME
USE OF SUITABLE MATERIALS
Choosing materials with optimized thermal properties is key to significantly reducing the time required to heat and cool parts in rotomoulding. Polymers with high thermal conductivity, for example, allow for more efficient and faster heat distribution, which can result in shorter production cycles and greater productivity. Additionally, these materials contribute to superior thermal uniformity, ensuring the quality and consistency of final products. Therefore, investing in polymers with good thermal properties is a smart strategy for achieving a more efficient and competitive operation.
PREVENTIVE MACHINE MAINTENANCE
Maintaining the rotomoulding machine in perfect working order is essential to prevent problems that can prolong cycle time. Performing precise calibrations of rotation speeds and regular inspections of all moving parts and control systems are indispensable practices. This care not only ensures the efficient and continuous operation of the equipment but also prolongs its life and improves the quality of final products.
OVEN HEATING SYSTEM
Oven heating systems play a crucial role in optimizing cycle time in rotomoulding. A good control and monitoring system for the oven allows, for example, safe operation, ensuring that the equipment always operates at the maximum performance set point. This means that the oven quickly reaches the ideal temperature and maintains it consistently throughout the process, reducing the time needed to heat and cool the moulds.
COOLING EFFICIENCY
Advanced cooling methods are essential to speed up the cooling phase without compromising the part's quality. Techniques such as adequate ventilation and the use of sprayers that create a continuous and efficient cooling mist can significantly reduce the total cycle time. These methods ensure that the part quickly reaches the desired temperature uniformly, improving productivity and maintaining the structural integrity of the final product.
HOW ROTOLINE STANDS OUT FROM THE COMPETITION
BURNER EFFICIENCY AND EXTENDED OVENS
The efficiency of burners and the use of extended ovens provide Rotoline with remarkable performance compared to the competition.
OVENS
These elements are strategically developed to maximize heat transfer and reduce the time needed to reach the ideal processing temperatures. More specifically, Rotoline machine ovens are designed in circular or semicircular shapes, generating homogeneous airflow around the mould. This unique configuration ensures uniform, efficient, and controlled heating, minimizing hot and cold spots that can compromise the quality of the final part.
Burners
The superior efficiency of Rotoline burners allows thermal energy to be used optimally, promoting faster and more consistent production cycles.
Software
Rotoline stands out for the robustness and security of its systems, evidenced by the in-house development of all the software for its machines. The data generated during operation do not go through third-party software, guaranteeing total control and security of the information. The operator must log in with a username and password before any operation to access the software.
This measure ensures accurate recording of operating hours, as well as facilitating the auditing and monitoring of activities. Without logging in,the operator does not have access to the software, further reinforcing system security and integrity.
FINAL CONSIDERATIONS
For any company involved in the rotomoulding process, understanding and optimizing cycle time is crucial. Factors such as part thickness, size, and weight significantly influence this time. By adopting appropriate strategies and using advanced technologies, such as those offered by Rotoline, it is possible to effectively reduce cycle time, improve production efficiency, and ensure the quality of the final product.
With this information, you will be better prepared to optimize your production processes and achieve greater success in your rotomoulding operations.
