For certain applications, it may be useful to apply adhesives and sealants manually rather than automatically. Planners and users should note several factors in order to achieve a consistently high quality.
28 February 2019
The so-called pump impact often has a negative effect on the manual application of adhesive. At the changeover point from the material pump’s start lift to low lift, short-term pressure fluctuations may occur that lead to increased or reduced material leakage at the applicator. It is important that the system is configured correspondingly well and the pressures are set correctly. The use of a material pressure regulator can minimize the impact. This helps with clean and even application.
Modern adhesives increasingly require a temperature conditioner to be able to be processed precisely. Epoxy resin adhesives, for example, are processed at temperatures between 40° and 60° C. Consistent and accurate temperature control is crucial along the entire system from the pump to the hose to the applicator. The applicator should therefore be designed specifically for heated systems and be well insulated to avoid injury.
Due to the trend for tempering the adhesive, the material hose must also be heatable and withstand high pressures due to the higher-viscosity material, this increases its weight and volume. When choosing the hand applicator, attention should therefore be paid to a rotating coupling, so the worker can move flexibly and is not hampered by the hose. The use of a balancer, which the applicator and hose can be hung on, is also recommended. This carries the system’s weight and therefore reduce the burden on the worker.
The ergonomics of the tool itself plays a major part in working productively and producing precise results. The applicator should be well balanced, have a large handle and if possible an additional handle. An additional handle helps balance the device better and prevents premature fatigue. In addition, the trigger affects the ergonomics: Pneumatic triggers are advantageous because the user doesn’t have to use as much force.
Producing an even adhesive bead is a particular challenge in manual applications. In practice, so-called hammer heads are a common problem in particular, for example, too much material applied at the beginning or at the end of the application. Devices that allow the material flow to be controlled provide a good solution. This distributes the material evenly and it can be individually adjusted depending on the component, application and application speed. This prevents hammer heads, reduces rework and improves the application’s overall quality and productivity.