Improving Quality & Efficiency When Using Adhesives

By Jon McMichael, Senior Product Engineer at Graco, Inc., Applied Fluid Technologies Division

The production of both insulating glass and curtain wall incorporates bonding and sealing steps that utilize adhesives with multiple components. The success of these bonding and sealing steps is dependent upon proper mixing and accurate, on-ratio dispensing of the adhesive components. While a variety of technologies can currently be found on the market and are in use in the industry, many of these widespread mixing and dispensing methods have serious drawbacks that can impact final product quality, material costs, and production time.

Recent additions to the proportioner market incorporate new technology that addresses many of these drawbacks. This new technology offers improved real-time ratio assurance, reduced material usage and enhanced tracking of key information. With these benefits, final product quality is improved and both material cost and production time are decreased.

Generally speaking, industrial equipment called a proportioner is commonly used to mix and dispense multiple component adhesives in insulating glass and curtain wall applications.  Adhesive and sealing proportioners, whether hydraulic or pneumatic, use mechanically linked pumps, rocker arms and gear pumps. These existing proportioner systems have many drawbacks with the main issues pertaining to adhesive dispense accuracy, operational difficulty, material waste, frequent maintenance and repair, high capital costs, and lengthy equipment lead times.

Adhesive and sealant manufacturers formulate their materials to be mixed at specific ratios for maximum performance. Current proportioner technologies that rely on mechanically linked pumps offer no real-time ratio control. This is a problem when mechanical malfunctions occur, as it is impossible to tell that dispensing ratios are off until after the adhesive has been placed on the glass. Deviations from manufacturer-recommended mixing ratios can result in products that do not adhere or fail to cure, creating a great deal of material waste, product rework and lost time.

Existing proportioner technologies offer many challenges for operators, especially as far as ratio settings are concerned. With current systems, operators must manually adjust ratio settings, with the smallest error leading to inaccurately mixed materials and the issues described above. Complex cleaning processes known as base purges, sensitive dispensing adjustments, and difficult material changeover procedures all present additional challenges for operators.

As an example, existing proportioner technologies can often be difficult to clean after a shift or during material changes. The base purge process can be highly complex and may waste a significant amount of material.

In addition to regular cleaning, other routine maintenance is required with any proportioner system, and it is important to limit the expense of maintenance in terms of both part costs and man-hours. Due to specialized wear parts and lengthy turnaround time on part orders, existing proportioner systems can be difficult to maintain and costly to repair. The challenge and expense of repairs is further compounded by many manufacturers’ lack of trained, local support.

Finally, many proportioners on the market today take weeks, if not months, to build and ship to the end user. This can be a challenge for companies who must add or replace a system quickly. Advanced planning is often necessary to ensure that the required systems are available to meet the end user’s timeline.

Proportioner technology has changed significantly in recent years, with advancements designed to address the weaknesses and drawbacks of previous generations. New proportioner systems are feature-rich and designed to provide more accurate dispensing, proper mixing, and streamlined user experiences. They address issues of ratio monitoring, material waste, high costs and more. The advancements in proportioner technology offer enhanced benefits to end users that result in reduced material costs, less product rework, and superior operator experiences. Taken together, all of these factors lead to an improved purchasing ROI over existing proportioner technologies.

Intuitive user interfaces allow operators to set up systems and make ratio changes with the touch of a button. Operators can make ratio changes during production, allowing production to continue even when material requirements vary. In addition, new proportioners can be programmed so that only those with proper authorization can make ratio changes.

Ratio assurance is a challenge on traditional proportioners, especially with the delicate manual ratio adjustments required by mechanical systems. New, digital systems change the way operators interact with the proportioner, and vastly improve control over the system. With a few touches of a button, the operator can change the system’s mixing ratio, verify the proper calibration and review material consumption information.

As previously described, when using multiple component sealants or adhesives, maintaining the proper mix ratio is vital to the final quality of the product. With recent advancements in proportioner technology, real-time ratio monitoring can be incorporated into the proportioner system with failsafe measures that automatically shut down the system if off-ratio conditions exist. This technology, pioneered by Graco in its ExactaBlend™ AGP product, prevents off-ratio material from being dispensed onto the curtain wall or insulating glass product. When material is correctly mixed and dispensed on-ratio as intended by the material manufacturers, the end results are not compromised, and glass manufacturers are more confident in the end quality of their products.

Ratio monitoring technology can be paired with other data tracking, allowing operators to monitor material usage, view error reports, and analyze other key data. Collectively, these technologies allow operators to severely reduce waste. Given that off-ratio mixing results in inferior products that must be deglazed or scrapped, the accuracy and reliability of new proportioners limits scrapped products by providing positive ratio assurance and on-ratio mixing.

New proportioner technology also affords waste reduction benefits due to a reduced amount of material lost in base purges. Existing proportioners require base purges as often as twice a day. The material lost in these base purges can add up to more than 3,500 pounds (1600 kg) annually. New proportioning systems significantly reduce the amount of material lost during base purges, leading to savings of up to $6,000 a year.

Improved mixing technology has also been incorporated into the latest proportioners. The Graco MD2 Valve and tri-Core mixer, for example, offer high pressure, high-flow mixing and dispensing of multiple component materials. While the proportioner systems provide variable ratios between 6:1 and 14:1, the applicators can perform at flow rates up to 4,000 grams per minute.

To avoid system downtime when running out of adhesive, new proportioners offer advanced notification to operators, allowing them to prepare to replace the adhesive supply ahead of time. This minimizes the amount of downtime, increasing production throughput and maximizing productivity. 

Finally, proven pump technology, specialized hoses and other improvements have increased the reliability of the newest proportioner systems. Standardized components have been incorporated in some systems, such as in the Graco ExactaBlend AGP, leading to shorter repair times and reduced expenses. Even with all of these advancements, proportioners like the Graco ExactaBlend AGP often cost far less in initial capital investment than proportioners of previous generations.  New proportioners cost less to operate and maintain, and they may also have shorter lead times for initial delivery than previous products, allowing more flexibility for operators who need new or additional systems in a short time frame.

New proportioner technology for the glass industry addresses many drawbacks of existing systems, such as adhesive dispense accuracy, operational difficulty, material waste, frequent maintenance and repair, high initial capital costs, and lengthy equipment lead times. From ratio assurance and proper mixing to material waste reduction, updated proportioner systems, like the Graco ExactaBlend AGP, offer many benefits to companies in the insulating glass and curtain wall production industry.