Pooling their engineering expertise and technological resources, Schöttli in collaboration with Sumitomo (SHI) Demag and HEKUMA embarked on this partnership project with focus on speed and therefore on the capability of increasing the output of tips per year. “It requires a superior hot runner technology, best in class venting, cooling alignment capabilities as well as maximum reliability,” states Schöttli’s Strategic Account Manager Benjamin Beverborg. By working together, the three companies have united the very best technology to produce more value as a whole.
“Although there’s no exclusivity, as likeminded technology companies we were eager to demonstrate the added value that can be accomplished when we collaborate and push the boundaries of innovation to solve a specific tip production challenge,” comments Sumitomo (SHI) Demag’s Director Business Development Medical Anatol Sattel.
Drawing on their complementary strengths, this outstanding cleanroom pipette tip production cell features a 32 cavity mould from Schöttli using a proprietary 8 cavity cluster technology. The cluster design reduces downtime by allowing access to all moulding parts from the main parting line. The associated 8 Star hot runner nozzle achieves perfect balancing and drool-free start-ups at outstanding cycle times. The mold includes an optimised cooling and venting set-up for dimensional accuracy as well as the unique Schöttli Core Adjustment System. This smart and simple adjustment system enables best in class concentricity and wall thickness homogeneity, achieving cycle times of 4.9 seconds. Moreover the linear take-out system enables to reduce the cycle time again to under 4.5 seconds, so that the complete high-speed pipette tip production cell is clear faster as it would be with free falling pipette tips.
Harmonious and homogenous
Responding to one of the greatest challenges for tip manufacturers – repeatable high output, rigorous technical requirements and low scrap – Schöttli engineered an innovative high-performance mould concept implementing an evolution of their unique and long-time proven Schöttli Side-Gate hot runner system.
Each cluster has 8 easily accessible and individually exchangeable cavities. With the dedicated disassembly device, the cold side cluster can be removed and handled safely on the press to access the individualy adjustable cores. Although a displacement of the core during injection is key to secure the concentricity requirements of the tips, the core and bushing are 100% aligned while closing the mould to avoid wear.
Open side gates have been one of Schöttli’s major strength for decades. The “Plug and Play” startup behaviour (free of drooling) has been highlighted as a great safety advantage by our customers.
Since the 8 Star Nozzle is designed and manufactured in the Swiss Medical Centre of excellence, every mould comes with an individual design and nozzle geometry to secure perfect balancing over all parts as well as the ideal shear-off from the injection point.
Finally, the heart of the high-performance behaviour is the optimized cooling and venting concept. To keep a homogeneous waterflow over the entire mold, with core cooling as bottle neck, every core with its pre-assembled cooling tube is individually tested before delivery. As the venting condition significantly influences the thermal situation during injection, great effort has been made to design a maintenance friendly venting system to keep uptime and quality at the highest level.
The core principle of Schöttli Pipette Tip Technology, as summarized by Beverborg, revolves around delivering overall ease of use through a straightforward and dependable mold design while upholding uncompromised quality and performance.
Speed means nothing without control
When studying machine performance criteria, right from the very start Sumitomo (SHI) Demag`s IntElect S 100 delivers. Whether it's its flexibility to accommodate various tool configurations and automation options, its energy efficiency, or its well-suited cleanroom design features, it is the natural choice for producing high-volume medical components.
Anatol Sattel explains: “The process performance associated with Pipette Tips leaves no margin for error, Sumitomo (SHI) Demag`s IntElect S 100 delivers the required repeatability and precision for high demanding applications. The need to fill 32 cavities quickly pushes the requirement for high Injection speeds, however the control of ramp-up and ramp-down of these speeds is the hidden secret to success. The IntElect’s highly dynamic direct drive technology can react quicker in these key areas, not only assisting the quality of the product, but additionally delivering faster cycle times and therefore a positive result on return on investment (ROI)”.
The 0.14 seconds required to reach the IntElect´s maximum injection speed of 350mm/sec opens up the process window in critical areas where it can be the difference sometimes between a full part or a short shot. Additionally, this filling speed can help preventing core shifts. Long, thin core pins, associated with Pipette Tips, are susceptible to the forces associated with slow injection speeds, this effect is magnified by the narrowing of the melt channel, this can occur from the material cooling as it enters the cavity under lower injection speeds. Additionally, this enables the lowering of injection pressures normally required to overcome this narrowing of the melt channel.
Anton Geissler, responsible for the automation within the pipette tip cell, agrees: “Particularly in the production of challenging parts such as pipette tips in high-cavity injection moulds, a short mould open time plays a decisive role in the economic efficiency of the system. In the case of a 32-cavity mould, every 10th of a second shortening results in up to 4 million more parts output at the end of the year.”
As the result of more than 25 years of experience in pipette tip automation and continuous improvement of technology the HEKUMA high speed side entry linear axis enables the production of pipette tips in under 4.5 seconds at ISO Class 8 cleanroom standards.
Scalable automation options for increased flexibility
Further increasing the versatility for pipette tips manufacturers, HEKUMA offers a complete suite of scalable, modular downstream options including, vision inspection systems, cavity separated handling, filter assembly and various packaging options - according to customer needs and requirements.
Benjamin Beverborg concludes: “The laws of physics are the ultimate limits of performance. By combining experience, innovation, and open mindedness in the cooperation between Sumitomo (SHI) Demag, Hekuma and Schöttli, we have managed to get closer to those limits for the benefit of our customers.”