Reacting quickly to lateral flow device demands
Lateral flow testing is an established technology that has been important in the ongoing fight against the COVID-19 virus that is causing so many problems worldwide.
The test is a hand-held device, with a plastic top and bottom casing enclosing a composite strip onto which various chemicals are impregnated. A blood sample mixed with a re-agent is introduced through one opening and flows along the strip causing a line to appear at a specific position in a viewing window if it is a positive result, approximately 20 minutes later.
In March 2020, Amies Innovation of Chesterfield (UK) was asked by an existing customer to look at the top and bottom cover parts for a lateral flow device.
Established in 1929 Amies is a technical moulder with many years’ experience in the development and manufacture of medical devices and other tightly toleranced plastic parts. The medical moulding division holds ISO 9001:2015 and ISO 13485:2016 quality management standard for medical components and assembly as well as having the modern quality testing and measuring equipment that are critical for this kind of application.
Production requirements in the pandemic meant that initially one 8 impression tool was required for the top cover and another one for the bottom, followed up by 2 x 32 cavity moulds. Of course, the pandemic required that mouldings were able to be supplied in the shortest possible time and the challenge for Amies was then to also identify the technically capable toolmaker and hot runner supplier with whom to work to achieve these goals. Because of the importance of these parts to the fight against COVID-19, Amies, the toolmaker RDMS and Gunther Hot runner Systems worked together to ensure that the 8 impression tools, including full valve gate hot runner, were delivered in just 5 weeks and even the completed 32 cavity moulds in an impressive 10 weeks.
Simon Stewart-Smith, technical director of Amies said: “Knowing the importance of the project in the context of COVID-19, although already very busy, both companies pulled out all the stops to achieve very difficult lead-times for which I can only commend them.
"In the background, Amies also needed an additional new press to support the manufacturing volumes. Our long-term trusted machinery partner Arburg, who supply all Amies' injection moulding machines, was able to provide exactly what we needed to meet the project timelines.
"To complete the picture we also needed some high-quality cooled conveyors with integrated box handling automation which UPM Conveyors again stepped up and provided in the required timeline to a high quality standard.”
Chosen toolmaker Manchester based RDMS, had developed similar tooling in the past where push fits were also critical and were therefore able to take a clinical approach to obtain first-time parts. They are able to take CAD data for the new part along with similar existing parts already produced by Amies and verify CAD vs part with high accuracy guaranteeing they would match each other to give the required push fit.
To keep competitive RDMS use an unmanned running system, which combined with their choice of machines and automation enables them to machine and spark erode to a very high accuracy. The use of their 3 CMM machines verifies the tooling surfaces for quality and dimensions which helped with the fast lead times required for these tools.
Neil Richardson, director of RDMS, said: “Our customer, Amies, wanted to hit the ground running for obvious reasons and so choosing a hot runner company that would respond quickly and who offer committed technical support to feeding these parts was important and Gunther was chosen. Designing and manufacturing the 8 impression tools in 5 weeks followed by 2 x 32 cavity moulds in just 10 weeks was very demanding and we were very proud to be part of this successful project”.
Valve gate systems from leading German hot runner manufacturer Gunther, were chosen for this project based partly on successful medical projects undertaken between Gunther and Amies in the past and because of the company’s extensive experience in the supply of systems for medical device production worldwide. Requirements of the hot runner system were particularly for clean gate vestiges, cavity balance across all parts and reliability.
All Gunther nozzles feature patented bi-metallic titanium shafts which ensure a very homogenous temperature profile across the whole length of the nozzle meaning the material is delivered to the cavity in its best possible condition. Standard nozzle type 6NMT were used with the heads machined to achieve the required small pitch centres. Gunther valve gate systems also feature unique PM insert technology, essentially a replaceable needle guide and gate insert. Tolerances on these are extremely tight which, in combination with the homogenous temperature profile, gives the moulder the required high quality gates. Another big benefit of the PM inserts is that costly reworking of gates over time is avoided as they can be easily exchanged without stripping the whole hot runner. Manifolds are fully balanced and activation is via a single lifting plate to ensure all valve pins open and close at the same time. Via small access holes in the back valve pins with the Gunther system can be simply exchanged without even taking the back plate off.
Deliveries of these systems were brought forward because of the importance of tackling COVID-19 and the 8 drop systems took just 4 weeks and even the 2 x 32 cavity hot runners were delivered in just 5 weeks. The tight delivery schedules meant that a hot half option was not considered and the systems were all installed, wired and tested by the engineer of Gunther UK at RDMS.
Reiner Heendeniya, sales director of Gunther UK, said: “We are all trying to help in the fight against COVID-19 and there is no denying that the technical solution and delivery, including design, was a challenge but it was one we rose to and it was a real achievement to be moulding full production parts in high volumes in such a short space of time.”