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How to Optimize the Dispensing Process Continued from page 56
pensing process but also the material preparation and mate- rial feeding must take place under vacuum.
Material feeding After preparation, the mate-
rial is conveyed to the dispensing system. The crucial parameters for selecting the pump and feed technology are the viscosity of the material, the type and con- tent of the filler and the size of the containers. In terms of process technolo-
gy, it is important to ensure that no air is introduced, the medium is gently and evenly conveyed throughout the entire process and the selected containers are emptied as completely as possi- ble. There have been tremendous developments in pump technolo- gy in recent years. A good exam- ple is Scheugenpflug’s patented diaphragm pump. To ensure that the defined
dispensing quality is efficiently achieved the key factors to con- sider are the chosen dispensing process, the dispensing method and mixing in the dispensing system. The degree to which the
material is to be free of bubbles will dictate which dispensing process should be used. Dispen - sing under atmospheric pressure is the default for many applica- tions and components. However,
complex geometries, small work- pieces, high packing densities, the use of moisture-sensitive casting resins and high-quality require- ments may require encapsulation under vacuum. The requirements for preci-
sion and repeatability can differ considerably depending on the task. For simple requirements
October, 2022
crucial factor when deciding on a mixing system. Static mixers are easy to handle, cost-effective and maintenance-free. Here, the resin and hardener are combined in a plastic tube and mixed homoge- neously. Dynamic mixers are only used for high material require - ments and media with very short pot life and extreme mixing ratios. Here, the two compo- nents are fed separately into a chamber in a given mixing ratio and mixed by a rotating agitator.
Key Aspects of Dispensing
Dispensers are key
Scheugenpflug’s patented diaphragm pump.
dispensing by mass measure- ments (gravimetric) is used. Dispensing by time measure- ment (time/pressure) is only suitable for 1C materials, and for high demands on potting quality, dispensing by volume measure- ment (volumetric) is used. If 2C material is to be used it
must be mixed before being applied. Material behavior is a
process components. Mod ern systems are optimized for specific tasks. In addition to pis- ton dispensing, geared dispensing systems (vol- umetric dispensing sys- tems) are specially de - signed for continuous application of liquid to highly viscous potting
materials. Classic uses include the application of sealing beads on component housings and the application of adhesives as part of joining processes. Maximum repeatability and
optimum dispensing quality are key project requirements. This is accomplished through regular control of process parameters and equipment conditions, and
can also be greatly improved by using vision systems. Scheu - genpflug’s RTVision.3d image processing system allows dis- pensing equipment to “see.” The degree of automation in
a dispensing system is important to define when selecting the most appropriate process tech- nology. Quantities, cycle times, dispensing materials, quality requirements, cost-effectiveness and the production environment are the crucial parameters here. Manual, partially automated and fully automated dispensing solutions are being used at pres- ent with different levels of automation and modular system solutions. Many dispensing tasks are
becoming increasingly automat- ed. As a result, standalone sys- tems are being used less and less. Integrated in complex pro- duction environments,
the
upstream and downstream pro - cess steps (such as component and position detection, surface cleaning and pretreatment, and curing) must also be considered holistically and adapted to the dispensing systems. Contact: Scheugenpflug,
1000 Cobb Place Boulevard NW, Suite 514, Kennesaw, GA 30144 % 678-503-9295 E-mail:
gabriele.mcfarland@scheugenpfl
ug-dispensing.com Web:
www.scheugenpflug-dis-
pensing.com r
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