Project & Industry
The project involved modernising the control system of a Milacron 500 injection moulding machine used in the plastics manufacturing and fabrication industry.
The machine remained mechanically sound and continued to play a critical role in the customer's production process. Its ageing control system, however, was becoming an increasing threat to production availability.
Rather than replacing a mechanically viable asset, the project focused on modernising its control architecture to extend the machine's useful life and reduce the operational risks associated with obsolete technology.
Project Outcome
The modernisation improved equipment availability, diagnostics and maintainability while protecting the customer's investment in an otherwise serviceable production machine.
Key outcomes included:
• Improved equipment availability
• Improved diagnostics and maintainability
• Protection of the customer's existing investment
• Reduced financial exposure
• Reduced machine lifecycle risk
• Reduced operational risk
The project provided a way to retain an important production asset while addressing the increasing risks presented by its ageing and increasingly difficult-to-support control technology.
Biggest Challenge & Our Solution
Two particularly complex technical challenges had to be overcome.
The first was the machine's DOS-based FACTIS SCADA system. Very little information about the system could be found through conventional searches. By accessing internet archives, the engineering team located a deleted product website and was able to recover manuals and software needed to understand the legacy system.
FACTIS used scripting and ladder logic to perform its basic functions, with the printed control logic extending to 476 pages. During the modernisation, some of this scripting and logic was replaced by standard SCADA functionality, while the remaining control requirements were programmed into the PLC.
The second major challenge involved replacing the Delta motion controller card responsible for controlling the machine's hydraulic injection motion. The original controller generated a cam profile from parameters entered through the SCADA.
Hydraulic motion control proved considerably more complex than conventional servo motor motion control. Following investigation and development, a PLC-based solution using Siemens' SimaHyd technology library was selected to provide the required hydraulic motion functionality.
Given the complexity of the machine and its importance to production, risk was managed through thorough planning and preparation, software pre-testing and Factory Acceptance Testing (FAT). The work was also divided into phases to minimise customer risk and production downtime.
Key Technologies & Tools Used
• Siemens S7-1500T PLC
• WinCC Unified SCADA
• Siemens SimaHyd Technology Library
These technologies provided a modern replacement for the ageing FACTIS SCADA and legacy motion-control architecture while allowing the existing mechanical machine to remain in productive service.
One Thing We'd Do Differently
The machine incorporates more than 80 heating zones on movable nozzles. Damage to heater cables is relatively frequent, making short circuits a recurring issue. Although fuses protect the solid-state relays, they consequently require frequent replacement.
For similar future projects, the team would investigate the use of quick-trip circuit breakers. These would need to be carefully matched with solid-state relays capable of tolerating the longer trip time without sustaining damage.
Unique Selling Point
This was an extremely complex modernisation project involving a machine critical to the customer's production process. Risk was managed through detailed planning and preparation, pre-testing and FAT of the software, and phased implementation to minimise downtime.
The completed project extended the useful life of an important production asset while being delivered at a cost significantly lower than the OEM quotation.
| Tel: | +27 31 702 5767 |
| Email: | [email protected] |
| www: | www.abacus-automation.co.za |
| Articles: | More information and articles about Abacus Automation |
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version