In many industries, shorter and shorter cycle times are required. In the case of bonding, the question of curing often arises, i.e. when parts can be further processed reliably after joining. This is largely determined by the adhesives used and the process technology employed. Cyanoacrylates have the advantage that they cure extremely quickly at room temperature. Short cycle times are therefore no problem, but they must be mastered in the process. In addition, many applications place high demands on the quality of a bond. In medical technology, for example, membranes or other components have to be bonded to plastic parts. The challenge is that the adhesive not only bonds the two parts, but that this bond also remains tight under higher pressure. The choice of adhesive and its optimal application are the central prerequisites for this.
The solution - dispensing with jet valves
In contrast to a peristaltic pump that works in contact, the cyanoacrylate is applied without contact in individual droplets at a very high frequency with the PDos X1 jet valve, thus creating a sealing bead. The droplets can be between 250 µm and 2.5 mm in size. The adhesives are dispensed with a repeat accuracy of 99% in relation to the dispensing volume. With the jet valve, dispensing can be done freely in space. This opens up new degrees of freedom in component design and allows simpler and thus more cost-effective machine designs. The usual errors and problems caused by deviating adhesive quantities are also virtually eliminated with this process. This improves component quality and minimises rejects. The fully automatic and stable dispensing process on which this method is based also contributes to this.
The perfecdos dispensing valves are - from a mechanical point of view - designed as a "normally closed" system (NC). Care was taken in the design to ensure that leakage is reliably prevented in the event of a failure of the supply media. When dispensing cyanoacrylates, particular attention must be paid to their reaction time. Material selection and design of the precision valves are optimised to avoid a rapid reaction of the material in the valve, which would lead to clogging. Furthermore, the quick and easy cleaning of the valves contributes to the realisation of effective cyanoacrylate jetting processes. In practice, dispensing from cartridges has proven successful for these adhesives. Ideally, one cartridge is sufficient for one shift, which also simplifies cleaning routines. Cartridges are available with volumes up to 950 ml. The modular design of the valve also allows easy adaptation to the respective tasks - regardless of whether it is a simple retrofit in existing systems, e.g. as a replacement for a contact dosing solution, or new systems.
"In practical use, many aspects speak in favour of contactless application," Benjamin Kratz, Managing Director of perfecdos GmbH, and continues: "While dispensing by peristaltic pump comes close to contactless dispensing in terms of process integration and safety as well as dispensing results, there is considerable potential in jet technology due to savings opportunities, through high product quality, minimised rejects and shorter production times.
Truss:
perfecdos GmbH specialises in solving individual and demanding dispensing tasks. The company develops, manufactures and sells micro-dispensing systems that can be used in industry for the application, filling and dispensing of liquids of all kinds in line with requirements and processes. The basis of the solutions is the "PDos X" product series - an electro-pneumatically driven jet dispensing valve that has very harmonious, precise and fast switching characteristics thanks to a special aeration and deaeration process. This allows the dispensing of low to highly viscous liquids in the low nanolitre range. More than 17 years of experience with electropneumatically as well as piezoelectrically driven jet dispensing systems went into the development.
