Manual masking doesn't need to be

Reposted from December issue of Medical Design

Semiautomatic system applies disposable masks and eliminates residue.

There are a variety of “masking” practices that medical device manufacturers use for protecting their products during the coating process, including the laborious and costly manual application of self-adhering flexible tape with a paraffin wax coated surface. This provides a waterproof seal when wrapped around a device. Device sections requiring protection are hand-wrapped with the tape. Once wrapped, the shaft runs through the coating process, and the tape and waxy residue left behind are scraped off by hand. The masking and de-masking process can take anywhere from 1.5 to 3 minutes per part.

However, a semiautomatic masking alternative has been developed by Oak River Technology, Oakdale, MN. The MX System is a semiautomatic masking machine that uses a disposable, uniform mask to effectively seal off portions of a device during the coating process, without leaving any waxy residue.

The compact (6 in. × 9 in. × 13 in) MX System requires no electricity and runs on compressed air. The modular components - clamps and guides that hold the masking and guide the shaft through the masks -allow for multiple part diameters, ease of use, versatility, and cleaning. The system can fit devices with diameters from 0.8mm to 3.0mm, with masks that come in three different lengths: 25mm, 50mm and 75mm. These lengths and diameters will fit the majority of medical shafts, though custom components and mask sizes are available for special devices. The system requires minimal training and yields total cycle times around 45 seconds. Ergonomic features include a tilting base and foot-actuated operation. The module's polymer and stainless steel construction can be cleaned with standard solvents. The system's hard-stop feature allows for repetitive and consistent maskings and makes it easier to achieve a mask length repeatability of ± 0.5 mm.

Furthermore, the MX masking process produces a smaller transitional ridge measuring around 3 to 25 microns. Compare that to the hundreds of microns that result from hand scraping the self-adhering tape off the shafts. In addition, the masks do not deposit wax or other residue on the shaft. This removes much of the human error that can occur during the wrapping and scraping of the shaft. By not having to wrap and scrape each individual shaft by hand, the number of contaminations or faulty products due to scrapping drops dramatically.

A major benefit of the system is its impact on productivity. As previously noted, to hand mask and de-mask something like a stent with the paraffin-coated tape takes 1.5 to 3 minutes. The MX can cut labor time for higher productivity. This is illustrated by the following: Manufacturer A coats 100,000 devices. At 1.5 to 3 min. per stent, that's the entire work year of one or two employees. Manufacturer B, however, uses the MX System and takes about 30 to 60 sec. to mask and de-mask. This brings the total labor costs to a fraction of a full time position.

OakRiver studies show, in fact, that the MX is anywhere from 1.5 to 9 times more productive than hand wrapping.