Pumping glue can be challenging because many adhesives tend to harden and solidify when exposed to air.
Water-Based Glues
Water-based glues, such as PVA glue, consist of natural or soluble synthetic polymers in powder form that are mixed with water to create a liquid adhesive. When applied to a permeable surface such as wood, the water evaporates and leaves a strong bond. This bond can be dissolved again by applying water. These glues are not only cost-effective but also environmentally friendly.
Solvent-Based Glues
Solvent-based glues are a mixture of polymer-based ingredients and solvent. Once the glue is applied and the solvent is exposed to air, it begins to evaporate until the adhesive cures and the bond reaches its maximum strength. This type of bond is more industrial in nature and is difficult to break once applied unless a chemical such as acetone is used. Solvent-based glues are very unforgiving and are also more harmful to the environment, so care must be taken during disposal.
What to Consider When Selecting a Pump for Glue
When pumping glue, several critical factors must be considered to ensure efficient operation, maintain product integrity, and extend equipment life. Key points include:
Hardening Properties: Determine whether the glue hardens when exposed to air. Some adhesives, such as cyanoacrylate (commonly known as super glue), polymerise rapidly on contact with air. For these adhesives, it is essential to minimise air exposure and ensure airtight storage and pumping systems to prevent premature hardening.
Cleaning Procedures: Consider how the pump and associated equipment will be cleaned. Glues often have adhesive properties that can stick to surfaces, leading to build-up and clogging if not properly cleaned. Choose pumps that are easy to disassemble and clean thoroughly to prevent cross-contamination and maintain operational efficiency.
Temperature Sensitivity: Assess how sensitive the glue is to temperature fluctuations. Some adhesives change viscosity with temperature, becoming thicker when cooled. This can affect pump performance and may require adjustments to flow rates or heating systems to maintain consistent viscosity and flow characteristics.
Material Compatibility: Ensure that the materials used in the pump construction are compatible with the glue being pumped. Certain adhesives may react with or degrade specific materials, leading to contamination or equipment damage. Choose pumps made from materials such as stainless steel, PTFE (polytetrafluoroethylene), or other chemically resistant materials such as EPDM that are suitable for handling the glue without adverse effects.
Flow Control and Precision: Consider the requirements for precise flow control and dispensing accuracy. Some applications demand accurate dosing and uniform application of adhesive, requiring pumps with adjustable flow rates, fine-tuned control mechanisms, and consistent dispensing capabilities to ensure optimal bonding performance.
Some pumps can be designed to pump from two containers at the same time. For example, where the adhesive is a two-part epoxy, the components can be pumped to a common manifold where the mixture reacts.
Maintenance and Downtime: Evaluate the maintenance requirements and potential downtime associated with the pump. Regular maintenance, including cleaning, lubrication, and component replacement, is essential to prevent malfunctions and extend equipment life. Choose pumps with robust design features, easy access to critical components, and reliable performance to minimise downtime and optimise productivity.
By addressing these considerations, you can select the appropriate pumping equipment and implement effective procedures for pumping glue, ensuring consistent performance, product quality, and operational efficiency in adhesive application processes.
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