Rotational molding (roto-molding) is widely used for manufacturing complex plastic parts such as kayaks, where uniform material distribution and precise thermal control are essential for product quality. One of the key challenges in this process is ensuring consistent temperature conditions across the entire part during cooling and transition stages.
Accurate temperature profiling directly affects critical production steps, including the timing of insert placement and part release from the mold. Traditional single-point measurement methods are often insufficient, as they fail to capture the full thermal behavior of large and complex geometries.
Process Characteristics and Measurement Challenges
In kayak production, linear polyethylene is processed using rotational molding, allowing manufacturers to control wall thickness and material density by adjusting mold movement and dwell time.
However, this results in uneven thermal distribution:
• areas with higher material density retain heat longer
• complex geometries create localized temperature variations
• cooling behavior differs across the hull surface
• critical operations depend on precise temperature thresholds
Single-spot sensors cannot capture these variations, making it difficult to determine the optimal timing for inserting components such as plugs, anchors, or threaded fittings.
Need for Full Thermal Profiling
To ensure consistent product quality, manufacturers require a complete temperature profile of the entire kayak hull rather than isolated measurement points.
Infrared thermal imaging enables:
• simultaneous monitoring of hundreds of measurement points
• visualization of temperature distribution across the full surface
• identification of hot and cold zones in real time
This comprehensive approach provides the data necessary to optimize process timing and improve production consistency.
Optris Solution: Infrared Camera-Based Monitoring
A practical and cost-effective solution is the use of an infrared camera such as the Optris Xi 400, combined with PIX Connect software.
Optris Xi 400
The Xi 400 is a compact industrial infrared camera designed for continuous process monitoring.
Key features:
• operation in long-wave infrared range (8–14 µm), ideal for plastics
• high emissivity compatibility for accurate measurement of polyethylene
• compact and robust design for industrial environments
• cost-effective solution compared to multiple single-point sensors
The camera can monitor the entire kayak hull, capturing detailed thermal images immediately after the part is released from the mold.
PIX Connect Software and Measurement Tools
PIX Connect software enables flexible and scalable temperature analysis without the need for custom development.
Key capabilities include:
• point, line, ellipse, and polygon measurement tools
• real-time visualization of temperature distribution
• calculation of average temperatures in defined areas
• data export and integration with PLC systems
This allows operators to define critical zones on the kayak and monitor temperature behavior with high precision.
Process Optimization Through Thermal Data
By analyzing temperature distribution, manufacturers can determine optimal timing for key production steps.
Examples of temperature-based decisions:
• insertion of small components (e.g., drain plugs) at ~85 °C
• installation of larger inserts at ~80 °C
• placement of accessories such as rod holders at ~75 °C
• release of the part from the mold based on overall temperature profile
This ensures that each operation is performed under optimal thermal conditions, reducing the risk of defects.
Advantages of Infrared Temperature Profiling
Implementing infrared thermal imaging in roto-molding processes provides several significant benefits:
• precise timing of insert placement based on actual temperature data
• improved product quality through full-surface monitoring
• reduction of waste and rework caused by incorrect timing
• enhanced process understanding via visual thermal feedback
• lower system cost compared to multi-sensor solutions
Additionally, automated data capture using trigger signals (e.g., photoelectric sensors) allows consistent monitoring at the same production stage.
Application Value in Industrial Production
Infrared temperature profiling transforms roto-molding from a partially controlled process into a fully data-driven operation.
Manufacturers can:
• achieve consistent product quality across complex geometries
• improve repeatability of production cycles
• reduce dependency on manual inspection and operator experience
• integrate temperature data into automated control systems
As a result, production becomes more efficient, predictable, and aligned with modern industrial requirements, including digitalization and process automation.
