Equipment automated dispensing systems

Microplate EIA have also been automated. These systems consist in microplate carriers, dilution and dispenser devices for multiple samples, washers and shakers, photometer (through-the-plate reading) and a processor for multiple reading (desk-top calculator or microcomputer interfaced with the measuring equipment). Compared to other systems, EIA requires less sophisticated equipment for reliable results, available from various commercial sources. 

A wide variety and numerous suppliers of automated dispensing equipment are available as listed in Table 4.22. An important consideration in selecting an automated, contact-type dispensing system is the pump used in the system, of which there are three types time-pressure, auger, and linear piston or positive displacement. " ... 

Bulk delivery systems are the t3q)ical piped systems. The materials used in the transfer system should be compatible with the materials being transferred. Pressure should not exceed 15 psi. The systems should be equipped with an excess flow valve, secondary containment where spills may occur, manual shutdown at point of dispensing. Redundant fill level monitors and preset meters should also be provided on automated delivery systems. 

The cycle time has an important bearing on the investment required to automate the system and the number of operators or workstations that may be necessary. Whether manual, semi-automatic or automatic, the dispensing equipment system specified will depend on the type of application and workplace conditions, such as dispense rate, parts per hour, operator availability and materials handling. Adhesive dispense systems are available for most production lines varying from bench-top applicators to fully automated robotic units with dispense times of <50 ms. 

The use of automated systems for application is already placing demands on the materials suppliers to provide consistent products, and this pressure is likely to increase. Controlled application is critical to the success of a bonded assembly. Additionally, the automation equipment will in itself become more sophisticated, and fully adaptive systems capable of monitoring and controlling flow rates will become available. These will enable the correct amount to be applied to the correct location without risk of either panel or fixture contamination. A comparison of manual and automatic dispensing system requirements is shown in Fig. 4.8. 

The choice of the adhesive determines the type of application equipment required. For most industrial applications, pump-operated applicator systems are used which are designed to pump the adhesive directly from bulk drums at relatively high working pressures. Systems for using hot-applied adhesives need to be equipped with heated follower plates, hoses and guns. For automated application, additional dispensing units are necessary to meter the exact quantity of adhesive required for each application. 

The introduction of robots to these applications has not been matched by any development by the dispensing equipment suppliers, the equipment being essentially automated versions of the manual system. 

Many small-volume users dispense adhesive directly from the manufacturer s bottles and tubes, which are specifically designed for this purpose, but when mechanical application is required the anaerobic nature of the adhesive demands equipment which will not cause spontaneous curing within the apparatus. This must be obtained from the adhesive manufacturer. However, it may be coupled with a variety of supplementary mechanisms ranging from simple guidance systems to fully automated, self-checking dispensers. The ingenious methods often used to apply these adhesives have led to the development of some of the sophisticated equipment to be found in the adhesives field. 

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