The hot runner is one of most important components of an injection mould. Under the most demanding conditions, this unit determines a significant portion of a mould’s performance. It’s not for nothing that the hot-runner is often referred to as a mould’s “engine”. If a hot runner unit no longer functions properly, individual cavities may fail, ultimately threatening a complete production shutdown. And if such a stoppage occurs at a peak time of year, these production losses can hardly ever be recovered.
Maintenance actually reduces efficiency.
The calculation is a simple one. Assuming 350 production days per year, a mould’s ideal availability is 96 per cent. A complete overhaul of a 144-cavity mould usually requires around 25 working days. This reduces the mould’s productive days to 325, and its availability drops to 89 per cent. In addition, most PET preform producers simply do not have the necessary infrastructure nor the qualified personnel to carry out such extensive and technically demanding work.
In order to maintain preform quality and mould efficiency, the industry rule of thumb calls for a total hot runner overhaul every ten to twelve million cycles. At almost twenty million cycles, this mark was clearly surpassed at the Berain Water Company in Riyadh, Saudi Arabia. The 144-cavity mould number 2027 0058 000 from Otto Hofstetter AG with its hot-runner was completed in August 2017 and entered service around a month later in Berain’s factory.
Hot runner M144-011 is uncrated and inspected for any transport damage during cleaning.
Hot runner M144-011 is uncrated and inspected for any transport damage during cleaning.
Hot runner M144-011 is uncrated and inspected for any transport damage during cleaning.
Hot runner M144-011 is uncrated and inspected for any transport damage during cleaning.
The Otto Hofstetter AG service technician uses his visit to give the employees of Berain Water Company a few tips on maintenance and cleaning work.
The Otto Hofstetter AG service technician uses his visit to give the employees of Berain Water Company a few tips on maintenance and cleaning work.
The Otto Hofstetter AG service technician uses his visit to give the employees of Berain Water Company a few tips on maintenance and cleaning work.
A worthy alternative to a long shutdown.
After surpassing an incredible 19 million cycles, Yousef Hassanin, maintenance engineer at Berain, judged it was time for a general overhaul. Unlike many other preform producers, he had neither a replacement hot runner as a backup nor the time and skilled personnel to carry out such an extensive overhaul at his factory. He therefore decided to take advantage of the unique exchange programme of his mould partner in Switzerland. With OH-Xchange®, Otto Hofstetter AG always has at least one completely revamped hot-runner system on hand and ready to run for each mould type. Choosing this option, Mr Hasannin could be confident that his system would only be down for two days. Thus, according to our calculation, the availability of the system jumped to 348 days, or 95.3 per cent, instead of 89 per cent with a conventional long shutdown.
Preparation in advance.
While the Berain Water Company was busy producing preforms, the specialists at Otto Hofstetter AG organised all the necessary steps. The replacement hot runner M144-011 was carefully packed in a crate in Switzerland and transported to the port of Antwerp. From there, it continued by ship to Jebel Ali in Dubai, where it then travelled by land to the Berain factory, just outside Riyadh. On the morning of the appointment, the technician from Otto Hofstetter AG arrived at the Berain plant. First, he opened the crate bearing the big blue OH seal and made sure that the replacement hot runner had survived the journey in good shape.
Almost twenty million cycles.
Working closely with the Berain Water Company’s service technicians, the Otto Hofstetter AG engineer inspected the running production system and recorded the condition of the mould. The shot counter showed 19,544,470 cycles – another top result in the 40-year history of PET preform moulds from Otto Hofstetter AG. This level of performance is a testament to the unrivalled longevity of the products from Uznach. The system was then shut down and, after the unit had cooled, the hot runner was carefully removed and inspected. As is unavoidable even with the highest manufacturing standards, it showed the usual contamination and signs of wear such as dust, leaky nozzles and cracked nozzle tips. These defects would be corrected in the general overhaul of the original hot runner back in Uznach.
Exchange and training at the same time.
Next, the engineer from Otto Hofstetter AG unpacked the replacement hot runner and cleaned it thoroughly. He gave the Berain Water Company staff some tips on how to carry out minor maintenance and cleaning work as well as replacing thermocouples, nozzle tips or nozzles easily and safely. The carefully inspected and cleaned OH-Xchange® hot runner was then installed in the system and heated up. After a few minor adjustments to the settings, all cavities reached their target temperature, and the hot runner’s temperature was stable.
Successful intervention in just two days.
During the test runs, the engineer from Otto Hofstetter AG also inspected the function of the cold side and the quality of the entire process. Where optimisations were necessary, these were made immediately. For other issues, the Berain service team was instructed on what to do and how to do it. The conclusions drawn after the completed test run: the original mould again works perfectly, the system runs optimally and the quality of the PET preforms is, once again, flawless. Finally, the “old” hot runner unit was crated and prepared for transport back to Uznach. In two short days, it had been replaced by an OH-Xchange® hot runner and the Berain Water Company was back in business – another record-breaking feat by Otto Hofstetter AG.
