If you’re one of those cutting-edge manufacturers who is constantly looking to increase speeds and yields in your dispensing line, this blog post might be one of the most important items that you’ve read in a long time.
If you’re not familiar with the meaning of the number 101 as it is used in the title of this blog post, it is a designation in some schools meaning that this is an introduction to the topic—in this case an introduction to the usage and technical attributes of the fastest dispensing technology ever offered, the Piezo Jet Valve.
In some manufacturing applications, accuracy up to 99% is not of high value, and a dispense of 0.10 gram of material on one product and a 0.101 gram dispense on the next product rolling down the assembly line doesn’t matter all that much.
However, for some applications, especially those where maximum speed and premium quality is vital, such a high degree of variation could lead to a lot of expensive scrap and costly downtime.
Such was the case for a large multinational electronics manufacturer that recently contacted Techcon. Working to meet demand for a hot new premium electronic device, they had high speed potting lines going in several facilities throughout Asia, and on each line at each facility the problem was the same. They were using a series of time/pressure valve dispensers, and from product to product on the line the volume of silicon being dispensed varied from inadequate to overflowing.
In fact, their extensive quality control procedures were rejecting device after device where not enough silicon entered the cavity, leaving the printed circuit board assembly on the innovative new product open to prying competitive eyes as well as vulnerable to vibration damage in shipping and in use. And, they also found themselves continually having to reject devices where the silicon was actually oozing out of the case, making the product unsalable and even creating a clean up need on the line. To compensate, they were frequently stopping the lines to adjust settings, but, with lowered yields and high waste levels, they knew that they needed a better solution long term.
Variations in viscosity doesn’t have to be a problem anymore
As folks familiar with dispensing applications likely conjectured, the environments were subject to ambient temperature and moisture fluctuations, a very common issue. In an open system like a time/pressure valve, this can wreak havoc on the consistency of the flow of any material, changing viscosity—and the resulting size of the bead dispensed—minute to minute. And, since these valves—and all dispensers for that matter—are unable to compensate, a wide variety in the amount of material dispensed each time is the inevitable result.
The exception is the progressive cavity pump. It differs dramatically in operation from a time/pressure valve, which is simply an “open and close” type of mechanism—whatever volume of material has happened to flow into the cavity during the set time interval is what the pump dispenses when it fires. As a result, variations can be as high as ±5%-±10% or more, which was the variation this manufacturer was being challenged with.
The progressive cavity pump works differently. It is a closed system with the precise volume of material fed under positive pressure to a series of rotors/stators, and so it is impervious to changes in viscosity or any other variables that can impact dispense volume. Indeed, whether dispensing anything from plain water to high viscosity materials rating 300,000 centipoise or more, dispense rates have been shown to be up to 99% accurate, which is what this company quickly enjoyed, instantly increasing their yields and slashing their scrap rates.
Vigorous testing beforehand proves out ultimate success
Well, I say “instantly,” but, truth is, there was some reasonable degree of “prove out” time invested beforehand. Like many strategically run companies, especially large multinationals, this organization needed to be sure of the efficacy of a new potential solution before making such huge changes to their global production infrastructure. This started with a demo at our facility using the Techcon progressive cavity pumps and the actual silicon material in use at their facilities. The results were excellent, so this was followed by a six week test run at their main factory, and only when these results were also excellent—the difference was clearly night and day—did they implement the progressive cavity pumps on all of their mass production lines. By now, they are running several hundred pumps at every assembly line throughout Asia and the results are universally outstanding—consistently meeting up to 99% volume goal over thousands and thousands of devices.
Fluid dispensing has come a long way. In the early days, the only dispensing option is to use a plunger to manually push fluid out from a syringe. With the rapid advancement of technology, today there are various dispensing techniques available and within each technique there are quite a few types of dispensing equipment options. They range from simple manual dispensing device to sophisticated positive displacement pumps. Faced with too many choices, selecting the right dispensing equipment can be a daunting task if you are not familiar with the dispensing technology. This downloadable paper can help you make a good selection.