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CASE STUDY

Cut-to-Length Line Control System Upgrade

Modern PLC Controls & HMI Replace Legacy System on HVAC Fabrication Line

The Challenge

A confidential HVAC equipment manufacturer in Cheney, WA operates a cut-to-length line central to its sheet metal fabrication process. The existing control system had reached the end of its serviceable life — aging relay logic, no operator interface, and no means to program batch cutting runs without manual intervention at the machine.

Key pain points included:

• No programmable batch capability — operators were required to manually count and measure each cut, creating throughput bottlenecks and opportunities for error
• Obsolete control hardware with no vendor support, increasing downtime risk and making spare parts difficult to source
• Feed roller positioning and material straightening that relied on fixed, non-adjustable mechanical setups, limiting flexibility across material sizes
• No variable speed control on the feed drive, restricting the line's ability to handle different material gauges or optimize cycle times
• No network connectivity between the machine and the engineering office, requiring operators to receive job parameters verbally or by paper

The Solution

Logic Control Systems designed and delivered a complete control system replacement for the cut-to-length line — modernizing the machine's controls, adding operator-facing automation, and connecting the line to the engineering office for batch job management.

PLC Control Panel

LCS designed and fabricated a new free-standing electrical enclosure to replace the existing control panel. The panel is built around an Allen-Bradley CompactLogix PLC with discrete I/O modules, providing reliable, scalable control logic for the line's cut sequencing, feed drive, and shear operation. The panel includes a panel disconnect, UPS for power conditioning, terminal blocks, wireway, and all necessary panel hardware.

VFD Drive Panel

A separate enclosure was built to house the Yaskawa variable frequency drive (VFD), replacing the existing hydraulic starter panel. The VFD provides variable speed control of the feed roller motor, enabling precise material feed rates and soft-start capability — extending mechanical life and reducing cycle time variability across different material gauges.

C-More HMI

A C-More 10" color touchscreen HMI was integrated into the control panel, giving operators a clear visual interface to monitor line status, initiate cut sequences, and respond to alarms. Screen layouts were reviewed with the client prior to final installation, with requested changes incorporated before go-live.

Encoder & Cut-Length Feedback

A new encoder was installed on the feed roller system to provide accurate real-time position feedback to the PLC. This closed-loop measurement ensures each cut is made to the programmed dimension, eliminating the measurement error associated with manual counting and mechanical stops.

Office Batch Networking

An Ethernet connection was run from the cut-to-length line to the engineering office, and batching software was loaded onto an existing office computer. Engineers can now enter job cut dimensions and batch quantities directly from the office, with the PLC receiving and executing the job queue automatically — eliminating paper-based job handoffs and reducing setup time between runs.

Machine Modifications

In addition to the control system, LCS performed targeted mechanical modifications to improve material handling and cut quality:

• Feed rollers repositioned further aft to improve material support through the shear zone
• Floating straightening system installed with an entrance ramp and side rollers, accommodating material variation and reducing edge damage on entry
• Stabilizing roller added between the shear and feed rollers to reduce material bounce and improve cut accuracy
• New electric motor and gearbox mounted to the feed roller system, enabling VFD speed control

The new system gives our engineers direct control over the job queue from the office — no more walking the floor to set up cuts. It's a meaningful change to how the line operates. — Client Operations Team

Technology at a Glance

Commissioning & Startup

Prior to programming, LCS conducted a detailed operating sequence review with the client and documented the approved control logic as the basis for all PLC and HMI programming. Commissioning included:

• Full electrical I/O checkout — verifying all field devices, sensors, and control wiring against the AutoCAD schematics
• PLC program testing — step-by-step verification of cut sequence logic, batch execution, encoder feedback accuracy, and safety interlock functions
• VFD tuning — feed drive speed calibration across the material feed range, with ramp and decel parameters optimized for the mechanical system
• HMI screen validation — operator walkthrough of all screens, alarm pages, and batch entry workflows
• Four hours of operational training delivered to client operators, covering normal operation, batch job setup, alarm response, and manual override procedures

Results & Impact

The upgraded cut-to-length line delivered immediate operational improvements across the client's fabrication workflow:

• Batch cut programming from the office eliminates manual setup steps and reduces per-job configuration time.
• Encoder-based closed-loop length control improves cut accuracy and consistency across the full production range.
• Variable speed feed drive allows the line to be optimized for different material gauges without mechanical adjustments.
• Obsolete relay-based controls replaced with a modern, supportable Allen-Bradley platform with full vendor parts availability.
• New AutoCAD electrical schematics provide the client with accurate as-built documentation for future maintenance and troubleshooting.
• Operator training and documented control sequences reduce dependency on institutional knowledge and shorten new-operator onboarding time.
• Modernized control architecture positions the line for future integration with plant-wide networking or MES systems.

About Logic Control Systems

Logic Control Systems (LCS) is a Texas-based industrial automation integrator specializing in PLC programming, SCADA/HMI development, process control, electrical panel fabrication, commissioning, and remote automation maintenance. LCS serves clients across the U.S. in industries including food processing, fabrication, chemical, oil and gas, pharmaceutical, and water/wastewater.

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