At the corner of quality and assembly, design engineers are frequently confronted with unexpected, complex fluid process issues in the prototyping phase. These obstacles are reflected in voice-of-customer sprints and surveys revealing that medical devices companies in particular stall out in the research and development stage when it comes to assembling critical components. Fluid process technologies are often overlooked, unknown, or not considered to play a role in quality assurance.

To heighten those new-product development blues, fluid process engineers are quite a rare breed and generally not found serving on a research and development team. Simultaneously, design trends have rapidly evolved toward smaller-than-ever devices integrated with electronics in the medical industry and other fields. While manufacturers can effectively produce exceedingly small-scale components to tight specifications, it’s the “putting them together” phase that can be fraught with technical issues. This circle of circumstances culminates in a situational churn and burn in the product development cycle, wasting precious time and money. This shooting-in-the-dark phase occurs when fluid process knowledge is simply missing from a company’s talent portfolio.

Facing the unknown

There are many unknowns in the world of fluid-related assembly, according to Nordson EFD, a veteran player in this industry sector. Nordson engineers excel in a specialty discipline—the dispensing of highly accurate, consistent amounts of adhesives, sealants, lubricants, and other fluids used in almost every assembly application in the manufacturing process. Nordson’s engineered solutions can deposit adhesive microdots that are 300–400 microns in diameter, which is roughly the thickness of five or six human hairs. Sophisticated fluid dispensing technologies are necessary to achieve these miniscule deposit sizes as well as determine the right fluid for the job at hand.

Modern validation laboratories such as Nordson’s provide hands-on testing environments to determine whether a customer’s fluid dispensing requirements can be achieved to the most stringent specifications and standards. These fluid process professionals observe diverse assembly applications and evaluate the proposed type of fluid or adhesive and its associated viscosity. Once a fluid reaches a material or substrate, it must be able to restructure and recover to keep it from spreading and contaminating other components on the substrate.

Thixotropy is a material property that depicts how some fluids and gels become less viscous when agitated, but return to their original state over a period of time. The thixotropy of fluids is a major factor in effective microdispensing operations.

The other half

Each component must pass rigorous inspection: A poor-quality tip or nozzle can introduce unintended consequences such as fluid contamination into production, affecting fluid deposit accuracy.

Analytical fluid process testing is only one half of the quality equation. The construction of precision assemblies also requires everything from handheld dispensers to high-tech robotic dispensing systems. These solutions utilize single-use or one-part components based on individual assembly operations—syringe barrels, cartridges, pistons, nozzles, dispensing tips, and more. Nordson-engineered components are interoperable and quick to swap out, while ensuring tolerances are held and quality results are routine for system operators.

To make sure dispensed dots are the exact same size and micron-level fluid lines are identical, every touch point in the production process must have inspection rigor baked in, from first article inspection to the careful sourcing of raw materials, resins, and colors. Nordson technicians don’t need to adjust or change parameters or processes during operations, because even the smallest single-use component is made to stringent specifications. For example, syringe barrel pistons are meticulously engineered to optimize fluid flow consistency and seamlessly fit and seal within a dispensing system. Hundreds of studies have been conducted in Nordson laboratories to garner the best shape of a piston for fluid travel and maximum usage. Single-use components are also rigorously tested using a range of fluids with low- to high-viscosity parameters to ensure customers don’t waste expensive adhesives, greases, or other liquids they dispense.

Fluid quality translated to the smallest tip

Single-use components that are consistently precise maintain certainty standards in the assembly process. In this industry, there is a stiff price for poor quality that can result in costly downstream effects. Each component must pass rigorous inspection, because a poor-quality tip or nozzle can introduce unintended consequences such as fluid contamination into production and affect fluid deposit accuracy.

A two-component epoxy is being dispensed on a small medical device with embedded electronics.

These consumable products are found in clean mass-production assembly environments, veterinary practices, and fluid process labs. In these settings, a maximum level of cleanliness is required for fluid delivery as well as the assembly of products like medical devices and electronics. Therefore, single-use products cannot contain defects or contaminants. With an emphasis on purity with each fluid dispense, most of these consumables are manufactured in certified silicone-free facilities.

At Nordson EFD, the inspection process for syringe barrels is fully automated and captures data to analyze the results. If a barrel doesn’t meet product specifications, it will be discarded.

In the fluid dispense arena it’s important to maintain the highest industry expectation for dispensing outcomes, from low-volume work to mass-assembly requirements. The batch-to-batch consistency of single-use components, such as barrels or pistons, is the top priority. Whether a customer application requires a micron-width line of adhesive to assemble a cell phone or a cardiac pacemaker, the engineered quality of the fluid dispense must be reliable down to the smallest deposit. When dispensing components and fluid deposits are consistently accurate, the bottom-line result is a profitable reduction in material and fluid waste, and less downtime for consumers waiting for life-changing medical devices.

Handheld dispensing tech

Automating the human movements necessary to build an advanced hearing aid or an ablation catheter is often impossible. Many highly skilled people still perform extremely precise actions to construct small workpieces. To apply dispensing fluids manually, specialized dispensers and chamfered tips are used for exact, repeatable microdeposits on or between delicate surfaces. In the 33-ga size, dispense tips are capable of consistently placing a 0.10 mm (0.004 in.) line of dispensed fluids. These solutions provide contamination-free and static-free performance necessary for contemporary medical devices that are pushing the boundaries of material and manufacturing capabilities. For example, a modern catheter that was once 2 mm in diameter is now 1 mm in diameter or smaller. These microsize catheters can deliver pacemakers into the body and offer stenting, valving, suturing, and pacing properties.

Fast and focused

As global demand for medical devices continues to grow steadily, manufacturers are looking for automated solutions to keep up with the progress. Nordson EFD’s PICO Nexµs jetting technology connects fluid dispensing with factory networks and production systems, enabling remote management, two-way communication, and data capture for process management.

The need for enhanced quality in assembly was behind this new-generation advancement. The IIoT innovation lies within the machine’s ability to provide extreme precision and repeatability with its unique self-regulating calibration for improved valve-to-valve jetting performance.

Specifically, the solution’s microdeposit capability—as small as 0.5 nL—can be applied precisely at up to 1,000 deposits/second. These capabilities, coupled with micron-level stroke adjustment, are designed for noncontact assembly applications such as cardiac catheter manufacturing. The system’s web-based interface enables remote programming and on-demand inspection of fluid dispensing functions from a personal computer, laptop, and other mobile devices. Not only can manufacturers add speed and improved performance to their assembly playbook, but their users can control, manage, and monitor jetting functions directly at the point of dispense via industrial Ethernet protocols from their choice of human machine interface.

Design is fluid

As engineers continue to pursue new possibilities in product design, the actual building of future devices and products will remain an ongoing challenge. Unfolding right now is the requirement for nanoliter and smaller fluid deposit sizes in the medical devices field for innovative ablation catheters. Moving from microliter to nanoliter specifications, with deposit sizes specifically at four nanoliters, is a significant evolution in manufacturing and assembly. And when accurate assembly becomes a point of focus, this is the stage when fluid process experts become valuable collaborators.

The old adage “tactical considerations can change rapidly given the fluidity of the situation” is more poignant today than ever. The long game for the development of medical breakthroughs and emerging electronics will be rooted in advanced fluid mechanics and the essential delivery systems. Behind the scenes in dedicated laboratories, fluid process professionals around the world are working on complex assembly quandaries faced by diverse bioengineering teams and other market innovators. And it turns out that quality will remain the question— and the answer—to pioneering product designs into the foreseeable future.