Digitally retrofitting real-time production monitoring to plastic injection moulding manufacturing lines

Central machine monitoring and process optimisation offer the best way to ensure that production lines and their associated constituent parts operate more effectively and economically. Many machines in well-established production lines, which may be between 15 and 30 years old, can still perform their main functional tasks successfully. However, they do so much less efficiently than their modern-day counterparts. For example, they do not have the same level of computing power, enough memory capacity to record and store relevant data, or the ability to communicate with their modern equivalents. In many cases, these machines also use data formats and operating communication language protocols from the 1980s and 1990s, which are no longer used by today’s PLCs and industrial PCs.

A prime example of a production environment that accommodates mixed protocol legacy machines would be a plastics injection moulding machine (PIMM) line. Such machines, when well maintained, can attain as much as a 30-year operational life. However, some of the older software protocol operating languages (e.g. EUROMAP 15), cannot be directly connected to a factory MES (Manufacturing Execution System) without expensive annual custom software licensing charges. In a lot of factories these machines still require individual programming by an operator, which can be very time consuming for reasonably large installations and therefore potentially requiring input from multiple personnel.

An MES keeps track of all manufacturing information in real time, receiving up-to-the-minute data from robots, machine monitors and employees. Although manufacturing execution systems used to operate as self-contained systems, they are increasingly being integrated with enterprise resource planning (ERP) software suites. The goal of a manufacturing execution system is to improve productivity whilst reducing cycle-time and the total time required to produce an order.

By integrating IIoT/MES accessing edge computing devices directly with legacy machines across its own in-house production injection moulding lines, HARTING has proved that a return-on-investment payback period of 6-12 months can be achieved. Machine process parameters can now be remotely monitored and modified more quickly via centralised factory control stations, reducing downtime and enabling manpower to be much more effectively employed. Machine operators could even monitor and affect the process of the production line from off-site, via a smartphone or suitable tablet device.

In the near future HARTING will also be releasing a PIMM specific “MICA EUROMAP 63” variant that provides a similar solution approach for the more up-to-date EUROMAP 63 protocol based machines.

Additional real-time condition monitoring of legacy machine key operating processes can help to reduce downtime and extend lifetime, thus achieving manufacturing productivity improvements. This can be accomplished by digitally retrofitting additional stand-alone MICA devices to store, analyse and process data from existing or extra retrofitted sensors. As a result, tasks such as monitoring pressure, temperature and flow rates becomes easy, whilst allowing remote centralised process control adjustment via the MES network. Communication with the machine fitted sensors is achieved via a simple Ethernet switch and interlinked active I/O blocks. Either a “MICA Basic” or “MICA Energy” can act as a suitable device in these circumstances.

A MICA RFID variant converts the MICA device into a specific RFID Reader, which, when used in conjunction with passive UHF read/write transponders that are fitted to key replaceable mould tools, allows maintenance records to be written and stored onto that particular tool. This can ensure the optimum refurbishment scheduling of high value mould tools.

Critical operating parts of a plastic injection moulding machine which are subject to continuous wear and tear include the plasticising screw pump and associated check valves. As wear increases, this can result in a significant number of rejected parts and expensive financial losses. This situation can be resolved by monitoring the changes in the operating power curve characteristics of the screw pump and the pressure loading at the check valves.

Integration of a “MICA Energy” variant provides RS485 Modbus TCP/IP compatible I/O interfaces for linking to the appropriate functional I/O blocks on a machine that access this specific operating data. By pre-setting critical safe operational limits, the “MICA Energy” can set up alarm conditions for when these limits are breached, allowing machine operators to carry out corrective maintenance as part of the important predictive maintenance process.