How an air knife and ionizing bar removed particles and eliminated static attraction.

A cleanroom by itself doesn’t prevent static electricity; and if you want to remove inert particles without using a water wash process prior to the parts entering the cleanroom, it’s an even bigger challenge. All too often, the manufacturing debris on components is not soil (foreign material), but rather clean dry particles of the same composition as the finished assembly. Wiping or blowing particles off doesn’t address the problem of statically charged surfaces or the statically charged particles you are trying to remove. By using an air knife with ionizing bar you can remove particles and eliminate static attraction. This in turn prevents electrostatic discharges (ESD) from the parts before packaging. However, although eliminating a water wash process for your parts is a nice idea, the thought of blowing particles all over your cleanroom sounds like you’re trading one problem for another.

Particle contamination due to static
A manufacturing issue arose for Kirwan, a manufacturer of electrosurgical devices such as single-use bipolar and monopolar medical cords. Particles from the assembly process tended to adhere to the outside surfaces of cords, and they had to expend extra effort and time to prevent particles from ending up in the final packaging of the cables. “Our volume dictates that we hank (twist-tie) and keep the cords hanked early in their processing, which makes the removal of particulate from each wrapped electrical cord an even bigger problem,” said Kevin Prario, RA Manager. They experimented with blowing compressed air onto the cables which showed that they could remove most of the particles, but a portion still remained due to static electricity. They concluded that they needed a system to blowoff and make static-neutral the particles while also collecting all of the debris to prevent contamination of the cleanroom.

Kirwan was in the process of planning a new cleanroom to accommodate the four new assembly stations needed for the new product line. Although they had now proven the particle blowoff concept with compressed air, they knew that the energy costs of compressed air for a full scale system with four assembly lines would be substantial. Additionally, they had not had an air ionizing bar touse during the compressed air tests to ensure complete particle removal.