Large production runs

Spraying, dipping, and mechanical-roll coaters are generally used on large production runs. Dipping is also used to cover large areas quickly. Areas that do not require adhesive can be masked off. Manual dipping is often effective and baskets, screens, and perforated drums are available to facilitate immersion of the part into the adhesive bath. 

Heating the adhesive before atomization enables heavier adhesive buildup, reduces overspray losses, and minimizes contamination from atmospheric water vapor. Spray methods can be used on both small and large production runs. The liquid to be sprayed is generally in solvent solution. Sizable amounts of product may be lost from overspray. Two-component adhesives are usually mixed prior to placement in the spray gun reservoir. Application systems are available, however, that meter and mix the adhesive within the spray gun barrel. This is ideal for fast-reacting systems, but guns must be thoroughly cleaned to avoid buildup of polymerized product. 

Preferably for large production runs, to minimise the process costs including machinery requirements No licence required, including corresponding restrictions and costs... 

In most processes, for either small or large production runs, the cost of the plastics used compared to the total cost of production in the plant may be at least 60 percent. The proportion might be only 30 percent, but it is more likely to exceed 60 percent so it is important to handle material with care and to eliminate unnecessary production problems and waste. Where small-quantity users or expensive engineering resins are concerned, containers such as bags and gaylords are acceptable but for large commercial and custom processors, these delivery methods are bulky and costly. Resin storage in this form is also expensive. 

Thermoset moldings produced by injection moulding are used widely in the electrical and automotive fields, thus large production runs are common. 

The disadvantages of rotation molding include material costs that are relatively high because most materials are produced as pellets and then must be reduced to a fine powder. The process is not suited for production of parts with wall thickness of less than 0.030 in. It is also not suited, generally, for large production runs of small parts. 

For large production runs and automated applications via industrial robots, the applicator nozzle must be cleaned at regular intervals to ensure a consistently clean finish. It is also advisable to maintain a constant working viscosity - independent of ambient temperature and humidity - by regulating the temperature of the delivery hoses, thus ensuring the reproducibility of the application process. 

The process is typically not well-suited to very large production runs of smaller parts— for smaller parts blow-molding or even injection molding may be more competitive (although high-production rates can be achieved through the use of multiple molds and machines, e.g., children s play-balls). 

Accurate re-grinding of the broaching tool required on large production runs, which uses expensive fixtures and grinding machines. 

---