Luke Metcalfe
Uniloy UMA25 Blowmoulding Machine
June 2021 - October 2021
For Seecor Blowmoulding Solutions, I helped rebuild a large blowmoulding machine for an important client. The machine was designed to produce large 25 litre plastic drums and was to be upgraded to a modern spec.
Responsibilities
Previous changes to the machine were poorly documented, which required us to carefully follow and document each and every wire in the machine – a very long and tedious process! This was also important to enable us to make changes to the existing design and upgrade it to a modern spec. Given the numerous discrepancies and the large number of electrical changes to be made, I redrew the machine’s schematics from scratch (in SEE Electrical), formulated electrical design changes and additions, and documented these in the new schematics. I was involved in every aspect of the project, from electrical design to integrating and repairing hydraulic and pneumatic components, creating schematics and writing software (Siemens Step 7 and WinCC) to automate the running of the machine.
Design Changes and Additions
One major electrical change involved upgrading the controller of the “extruder” motor drive from a DC drive to a LS variable frequency AC drive, giving us much greater control of this key component.
Other major changes included installing a new Siemens IPC477E Human-Machine Interface (HMI), increasing the number of input and output cards on the Siemens PLC, integrating new sensors and actuators, improving the power supply scheme, and changing the control scheme of the “takeout” motor from a contactor-based switch to an electronic motor drive. Some less significant changes included changes to the wiring layout and designing new sensors such as a level switch for the hydraulic tank.
Machine Operation
The principle of the machine is as follows:
Plastic material is heated to around 190°C in the section known as the “extruder”. This consists of a large rotating screw which warms the material by friction, contained in a “barrel”, which is heated with external heaters. The molten material then moves into the “head” section, which is a large, heated cylinder in which the material accumulates. Once the “head” has filled enough, the material is pushed out hydraulically and extruded into a molten, hollow cylinder known as a “parison”. A large, hydraulic mould then closes on the parison, into which pressurised air is blown, and the parison forms to the shape of the mould. The newly moulded bottle is then removed by the “takeout” unit, excess material is removed by the “deflashing” unit, and the bottle is rotated and placed on a conveyor belt.
Conclusion
This was an incredible experience in which a learnt an incredible amount and gained a wealth of experience. Due to COVID complications at my office, the responsibility to deliver the project fell squarely on my shoulders for several weeks, and it was a challenging but motivating period in which I had to step up, dig deep and get my hands (very) dirty. I rose to the occasion, and in the end, we delivered a robust and beautiful machine to an important client.
Disclaimer
I am morally opposed to the plastic industry and passionate about the environment, but appreciate the wealth of engineering knowledge I have gained through working with these complex machines whose engineering components and principles are common and applicable to every other industrial machine and several other technologies. I am incredibly passionate about the environment and have used this opportunity as a stepping stone to my ultimate ambition of designing technology that helps the environment. : )