High Volume Manufacturing

Once product demand has reached the point where high-volume manufacturing is required, it is time to consider highly engineered, sophisticated process equipment. In most cases, this will be custom-designed equipment developed specifically for the application. This of course comes at a significant cost, both in capital and time. As discussed earlier in this chapter, consideration should have been made in the early stages of product development to allow for the efficient scale-up to high-volume manufacturing. Now it is time to reap the rewards of that forward thinking.

3.2.1. Dispensing

Once done in discreet sheets, high-throughput dispensing should now be considered. This means a continuous reel-to-reel process. Due to the much lower labor content, the end result is a higher-quality product. In addition, any production process such as this should include real-time 100% in-process inspection to cull out any discontinuities or other anomalies in the dispensed lines. Such a process includes a computerized inspection system to continually analyze the product relative to a set of programmed line-quality parameters and a means by which the membrane is marked to identify these rej ect zones. Reel-to-reel dispensing systems generally include a means of mounting a roll of raw membrane, a region for dispensing the various reagents, a vision inspection and rej ect marking module, an inline dryer module, and a means for rewinding the dispensed web.

3.2.2. Laminating

Diagnostic laminations are usually too thick and stiff to be rewound into a roll after lamination. Such a process tends to crack or tear the components within the lamination. For this reason, we do not generally see reel-to-reel processes for lamination of lateral-flow tests. Instead, the process is from reel to card. Reel-to-card laminators provide a means of supporting individual rolls of each of the components of the laminate and guiding them each to a point where they are laminated onto the exposed adhesive of the plastic support web. A rewind spindle is used to take up the spent release liner from the support web. Best manufacturing practice suggests that a vision inspection system be employed to inspect the laminate as the process continues, ensuring that all of the components are properly positioned within their specified tolerance ranges. Any sections that fail the vision inspection should be marked with a permanent mark indicating that that section has been identified as reject.

Finally, the output of the lamination process is a shear module that cuts the laminated web into individual cards of a predetermined length.

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