Rutland Plastics is one of the UK's leading plastic injection moulders, proudly holding the title of Processor of the Year 2021. The family-run business, now in its third generation, has built an impressive reputation over 70 years of continuous operation. The company holds patented electrofusion processes; their expertise extends far beyond basic injection moulding, providing comprehensive services including design for manufacture, prototyping, mould tool making, machining, assembly, and warehousing.

Rutland Plastics needed to automate the insertion of M8 brass inserts into plastic components using a heat-staking process. Heat-staking, a critical joining process in manufacturing, uses localised heating and cooling to raise the temperature of plastic components above their glass transition temperature. This allows the plastic to be reformed around inserts, creating a secure mechanical bond without requiring additional fasteners or adhesives.
The most significant challenge emerged from temperature variations in the plastic parts coming from the moulding process. This variability demanded sophisticated control strategies:

• Cold parts required slower insertion motion and longer dwell times for proper heat transfer
• Hot parts risked melting too far into the component or binding with the heating element
• The process needed to be completed within a 15-second cycle time to meet production demands

A servo-based motion system with real-time temperature feedback and dynamic control logic was essential—far beyond the capabilities of standard pneumatic solutions.
Modbus communication was an additional requirement for the cobots that would move and position the inserts and injection-molded part.

Rutland selected Unitronics' UniStream platform to manage the entire application—from motion and temperature control to HMI, cobot communication, and data logging, achieving all project goals:

• 15-second cycle times maintained consistently across varying part temperatures
• Automated insert placement with reliable engagement mechanisms
• Temperature-adaptive process control with real-time parameter adjustment

• Seamless cobot integration through UniStream’s simple, robust Modbus communication
• Operator-friendly interface enabling easy recipe management and monitoring System Architecture and Control
• Controller: UniStream USC-B5-T42 PLC (24 DI, 16 TO, 2 AI, PWM support)
• Temperature Monitoring: UIS-08TC Thermocouple Input Module (8 channels)
• HMI: USL-050-B05 5” Resistive Touchscreen (800x480 resolution)
• Motion Control: Unitronics Servo Drives & Motors with EtherCAT
• Software: UniLogic—one environment for all programming, free of charge —to commission hardware, develop and design PLC logic, HMI screens, servo motion, and communication protocols

• Dynamic Temperature Management: The system incorporates an infrared thermometer connected to the controller's analog inputs, providing real-time part temperature measurement. Based on this data, the application loads appropriate motion parameter sets for different temperature ranges, ensuring consistent results regardless of part temperature.
• Multi-Loop PID Control: 4 PID loops maintain precise temperature control of the heating elements, with the UIS-08TC module providing accurate thermocouple feedback. This closed-loop control ensures optimal heating profiles for different part geometries and materials.
• Advanced Monitoring and Diagnostics: Trend graphs display motor torque during insertion, providing real-time feedback on process quality. The system also uses PWM to control temperature warning LEDs.
• Recipe Management System: the HMI interface enables operators to create and manage different recipes for various part types, allowing quick changeover between different heat-staking applications without requiring programming expertise.
• Cobots for Part Handling: UniStream’s built-in Modbus communication enables direct interfacing with robotic systems. According to Hooper, "UniStream has the best Modbus functionality in my experience”.
• Scalability and Future-Proofing: the system's modular design, comprehensive I/O capabilities, and recipe management system ensure adaptability to future heat-staking applications.

Unitronics Unified Hardware Ecosystem meant that everything—PLC, HMI, I/Os, servos & motors—works together transparently, out of the box.

Free UniLogic software eliminates licensing costs, making team training more accessible and cost-effective. As Hooper explained: "Providing UniLogic for free makes training my team much easier as they can all have access to the software without incurring hefty license costs."

"The ability to program all the hardware within one programming environment made for a much neater, more efficient programming experience. The servo setup was simple and programming with PLCopen function blocks was effortless.”— Jamie Hooper, Rutland's automation team leader