Calender Line Upgrade in Rubber Manufacturing: Scrap Reduced Below 10%
Legacy controls, inconsistent product quality, and outdated safety systems are common hurdles in rubber manufacturing. When a major roofing materials producer faced all three challenges on an aging calender line, they partnered with DRM to engineer a multi-phase upgrade without stopping production.
Key Takeaways
- Calender upgrades demand deep process knowledge and careful coordination. DRM’s sprint-based method allowed progress during short shutdowns.
- Legacy modernization isn’t plug-and-play. The team reverse-engineered code, tuned drives, and delivered drop-in systems that matched the plant’s needs.
- Rubber environments are hard on hardware. Coated components, clean cable routing, and environmental prep ensured long-term reliability.
Why Rubber Manufacturing Demands a Rigorous Approach
Calender line upgrade projects in rubber manufacturing present unique challenges for automation. Calenders, mixers, and autoclaves operate in harsh conditions, often surrounded by heat, dust, and carbon black. A surprising number of facilities still run on legacy systems, including relay logic from the 1950s, obsolete PLCs, or single-channel safety circuits, that fall short of today’s reliability and safety expectations. Tight margins and frequent ownership changes in the industry lead to deferred upgrades, with many plants choosing to operate until breakdowns force action. Calender lines in particular demand careful tuning. Improper speed or pressure control can stretch rubber, introduce defects, or create excessive scrap.
The Challenge: Why a Calender Line Upgrade Was Needed in Rubber Manufacturing
This Arkansas facility relied on legacy controls and drive systems dating back to the early 1990s. The calender lines were critical to production, but ran on obsolete Modicon PLCs, aging DC drives, and single-channel safety systems. Replacement parts were hard to source, causing frequent downtime. The line also suffered from inconsistent rubber thickness and excessive scrap rates, which hovered between 20 and 30 percent.
The facility’s leadership approached DRM after seeing the results of a similar upgrade at another plant. What began as a conversation about reliability turned into a multi-year effort spanning the full line, from upstream mixer controls to downstream depalletizing and autoclave lifts.
The Solution: A Phased Calender Line Upgrade
DRM led a multi-phase modernization of the calender line over two years, working in defined sprints during scheduled downtime to minimize production disruption.
Controls Upgrade
DRM transitioned the plant from Modicon to Rockwell ControlLogix PLCs. Because the legacy code couldn’t be extracted directly, DRM reverse-engineered and rewrote the program. Remote I/O panels were added across the line to segment control zones, allowing upgrades to proceed one section at a time without shutting down the entire system. These upgrades were executed in defined “sprints,” typically three-day periods where one segment of the line would be taken offline, rewired, programmed, and restarted. The prep work for each sprint was done on night shifts during the prior week to avoid interrupting daytime production. In total, six sprints were completed, covering the full calender line.
Drives and Motors
A new motor control center (MCC) was installed with variable frequency drives (VFDs) to improve drive reliability and control. DRM replaced outdated DC motors with AC induction motors where possible to reduce maintenance and simplify integration. In areas requiring tight speed coordination, such as the wind-up rolls and accumulator, encoders were added for closed-loop feedback. Each drive was tuned on-site to ensure proper speed synchronization, which is critical in calendering applications to prevent rubber stretching or tearing.
Roll Setup and Thickness Control Automation
Before the upgrade, operators manually adjusted screw jacks to set roll gaps, often wasting material during lengthy setup trials. DRM replaced this with a recipe-based system tied to hydraulic actuators and the HMI. Now, operators select a product from the HMI, and the system automatically sets roll positions and pressures to match saved parameters. This eliminated the need for manual setup and reduced scrap during startup. It also ensured consistent setups across shifts, helping the plant maintain repeatable thickness and pressure profiles from run to run.
To maintain consistent product quality, DRM added a gauging system that provides real-time measurement of rubber thickness. The hydraulic system responds dynamically, adjusting roll spacing as needed to hold target thickness. The plant had previously dealt with tapering and sloping across the sheet. By automating both setup and pressure control, the line now runs tighter tolerances, faster changeovers, and significantly lower scrap.
Safety Upgrades
The existing safety system did not meet OSHA standards and relied on outdated single-channel wiring. DRM conducted a full risk assessment and designed a safety architecture tailored to each zone of the line. Upgrades included dual-channel E-stops and pull ropes, repositioned belly bars to meet ergonomic reach requirements, and new 24V-rated sensors for reliability. Wiring and device mounts were selected for the harsh, dust-heavy environment to prevent alignment issues and fault noise. These changes improved both compliance and uptime, reducing false stops caused by aged components or electrical interference.
Environmental Considerations for Automation
The rubber production environment places high demands on automation hardware due to heat, dust, and carbon black. To ensure reliability, DRM specified conformally coated PLCs and VFDs, sealed enclosures for sensitive components, and robust cable management. MCCs and control cabinets were positioned for access while minimizing exposure to airborne contaminants. Prep work during active production included running thousands of feet of VFD cable in pre-installed trays, staged and terminated for fast connection during short shutdowns.
Data Collection and Performance Monitoring
DRM enabled the upgraded system to log key process data, including drive speeds, roll pressures, and thickness readings, by timestamp and product type. Operators and engineers now use this data for trend analysis, recipe optimization, and quality tracking. It also confirms that the line is holding target specifications across product runs, including carbon-black rubber with scrim inserts from 0.019 to 0.045 inches thick. Over time, the system has become a tool not just for diagnostics but for continuous improvement.
Results of the Calender Line Upgrade
The phased upgrade reduced scrap, improved process control, and modernized safety—without extended downtime. Key outcomes included:
- Scrap reduced from 20–30% to less than 10%
- Fewer unplanned shutdowns due to obsolete parts
- More consistent rubber thickness and improved product quality
- Safer operation with OSHA-compliant systems
These gains improved overall throughput and reduced rework, helping the plant hold tighter tolerances across product SKUs. “We didn’t just swap parts. We rewired, reprogrammed, and tuned the whole line while keeping production running. The calender line came out stronger, safer, and easier to operate,” explained Randy Bailey, Controls Engineer at DRM.
Project Summary
From legacy PLCs to the upgrades at this facility addressed multiple points of failure across the line. The result was less scrap, fewer unplanned stops, better thickness control, and improved safety. What started as a calender line retrofit expanded into a broader modernization effort, guided by engineering decisions rooted in process knowledge and plant conditions.
“We had to keep them running while we modernized everything: controls, safety, motors, the works,” added Bailey. “It took prep, planning, and a lot of night shifts, but in the end, that calender ran better than it ever had.”
If you’re evaluating how to modernize a calender line or similar legacy system, this project shows what’s possible with a phased approach and deep process alignment. Contact DRM to start a conversation about your own plant conditions.
