Metering, mixing and dispensing

Highly reactive adhesives are more difficult to mix and apply because of their short working life, resulting in inaccuracies and material waste. Automated metering, mixing, and dispensing equipment may be required. 

FIGURE 17.6 Operating schematic of an automatic metering, mixing, and dispensing machine for adhesive systems.6... 

Because many acrylic adhesives cure very rapidly with a significant exotherm, manufacturers generally recommend that quantities greater than a pint (ca. 0.47 L) should not be mixed at one time. As a consequence of the rapid exothermic cure of many acrylic adhesives, the use of dual component cartridges is often ideal. Most products can be purchased in ready-to-use cartridges. For large continuous operations, various automated types of meter-mix-and-dispense equipment are marketed by a number of engineering companies. 

The motionless or static mixer has found significant advantages in mixing two or more resinous components. This device is used in many modem automatic meter-mix-and-dispense systems. (See motionless mixer). 

Each of these can be complex. Adhesive placement may be as complicated as an independently monitored automated metering, mixing and dispensing system fitted with a pot-life guard - but it could be as simple as manual dispensing from a purpose-made bottle. 

Composite Integration, http //www.composite-integration.co.uk Magnum Venus Plastech Limited, http //www.plastech.co.uk Liquid Control Corp., 7576 Freedom Ave. N.W., P.O. Box 2747, North Canton, Ohio 44720. Web page www.liquidcontrol.com. Meter, Mix and Dispense Equipment Engineering Handbook, 1996. 

Examples of Complete Systems for Metering, Mixing and Dispensing Two-Component Adhesives/Sealants... 

Suppliers of metering, mixing and dispensing equipment for the two-component adhesives ... 

Although the material cost is relatively low, some adhesive systems may require metering, mixing, and dispensing equipment as weU as curing fixtures, ovens, and presses. Capital equipment investment must be included in any economic evaluation. The following items contribute to a hidden cost of using adhesives, and they also could lead to serious production difficulties ... 

For a large-scale bonding operation, hand mixing is costly, messy, and slow, and repeatability is entirely dependent on the operator. Equipment is available that can meter, mix, and dispense multicomponent adhesives on a continuous or shot basis. 

The most popular meter, mix and dispensing machines have been designed around gear pumps and pistons, or a combination of both. This chapter will explain how both systems function, their strengths and weaknesses. 

In conclusion, the methods of dispensing reactive materials are varied. We are seeing the meter, mix, and dispense machine being integrated into computer controlled production lines. Dispensers are working successfully with... 

Table 1 shows suppliers of equipment for metering, mixing and dispensing, as well as spray equipment. 

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