Accumulation Upgrade – Chinese Pallet Wrapper MACHINE

Written By Izack Ralph

Overview

This project involved upgrading a Chinese-supplied pallet wrapper to enable controlled accumulation from an upstream palletiser.

Out of the box, the machine operated as a standalone unit with basic start/stop functionality and no ability to manage upstream flow. This created inefficiencies, including pallet backups, unnecessary stoppages, and increased operator intervention.

Peak Control was engaged to redesign the control logic and integrate the wrapper into the palletiser cell for seamless operation.

The Challenge

The existing system had several limitations:

  • No accumulation logic between palletiser and wrapper

  • Wrapper acted as a bottleneck during normal production

  • Inconsistent pallet flow and spacing

  • No reliable detection of pallet position at the wrapper infeed

  • Limited visibility and mismatched I/O between PLC and HMI

  • Machine documentation was incomplete and partially incorrect

These issues meant operators were constantly intervening to manage pallet flow, reducing overall line efficiency.

Solution Implemented

We introduced a structured accumulation control strategy, built around reliable sensing and clean PLC logic.

Key upgrades included:

  • Installation of an infeed sensor on the runoff conveyor

  • Control based on trailing edge detection of pallets

  • Automatic stop/start logic to buffer pallets between machines

  • Integration of wrapper “ready/run” status with upstream palletiser

  • Simplified and structured PLC logic for maintainability

  • Alignment improvements to ensure consistent pallet positioning

The system was designed to be robust, simple for operators, and scalable for future upgrades.

How It Works

  • A pallet exits the turntable and passes the infeed sensor

  • Once the trailing edge clears the sensor, the conveyor stops

  • This creates a controlled buffer zone before the wrapper

  • The wrapper calls for the next pallet when ready

  • Conveyor restarts automatically and feeds the next pallet

This ensures:

  • No pallet collisions

  • Consistent spacing

  • Smooth, controlled flow into the wrapper

Results

The upgrade delivered immediate improvements:

  • Reduced operator intervention

  • Improved line efficiency and flow consistency

  • Eliminated pallet bunching at the wrapper

  • More predictable machine behaviour

  • Foundation for future automation (recipes, diagnostics, optimisation)

Operators reported the system was simple and easy to run, with minimal training required.

Technical Notes

  • Platform: Siemens S7-200 SMART PLC with Smart Line HMI

  • Modifications completed without full OEM documentation

  • Logic designed to work around inconsistent I/O mapping

  • Future-ready for recipe handling and further integration

Looking Ahead

This upgrade is the first step toward a fully integrated palletising and wrapping cell.

Future enhancements may include:

  • Multi-pallet accumulation zones

  • Recipe-based wrapping parameters

  • Improved HMI diagnostics and I/O visibility

  • Line-wide interlocking between upstream and downstream equipment

Summary

This project demonstrates how targeted control system improvements can significantly increase performance—even on low-cost imported equipment.

Rather than replacing the machine, we unlocked its potential through better logic, integration, and system design.

Izack Ralph
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