Industrial Adhesive Bonders for Glass, Medical, Metal, and Plastic Assembly

CHOOSING THE BEST ADHESIVE FOR YOUR MANUFACTURING PROCESS IN 6 EASY STEPS:

Step 1. DESIGN
Designing an adhesive into an application should be done with consideration for many different aspects of the adhesive process. Substrate selection, bond gap, dispensing patterns, failure modes, tensile requirements, environmental stresses, thermal events and transitions, and a host of other parameters all combine to play a part of the process. When designing for a light curable adhesive, it is also important to include substrate transmission, and to avoid shadowed areas in the bond area. The recommended bond gap: 0.002 to 0.006 inches, or 0.5 mm to 1.5 mm.

STEP 2. ADHESION
The first and most basic property that all adhesives must have is good adhesion to the substrates being bonded. Substrate selector guides are a good place to start for choosing candidates. When only one substrate material is to be bonded (for example, polycarbonate to polycarbonate) the process of selecting a group of adhesive candidates is straightforward. When two different substrates are to be bonded, i.e., acrylic to glass, a range of candidates should be evaluated. After a few adhesion tests, it will be obvious which substrate is more difficult to bond and adhesive choices can be optimized for that substrate.

STEP 3. PHYSICAL PROPERTIES
DYMAX supplies adhesives with a wide range of physical properties. Since bond and part performance are dependent on adhesive physical properties, it is critical that full consideration be given to the stresses that will be applied to your parts during their expected lifetime. Product Data Sheets (PDS) include an extensive list of product properties.

STEP 4. VISCOSITY
In choosing a viscosity, consideration should be given to how the adhesive must flow (or not flow) on the part after the adhesive is applied. Part geometry, process design, assembly speed and method should all be considered when selecting a viscosity. Viscosity is a material’s resistance to flow. Low-viscosity adhesives flow more readily than high-viscosity adhesives. Gels flow very slowly and are recommended when adhesive flow on a part after dispensing must be minimal. DYMAX adhesives are available in a variety of viscosities. An intuitive nomenclature is used to identify relative viscosities.

The identifiers appear as suffixes on product names:
VLV = Very Low Viscosity, LV = Low Viscosity, T = Thick, VT = Very Thick, Gel = GEL. Standard-viscosity products do not have a suffix. In general, all viscosity grades of a particular adhesive offer similar physical properties.

STEP 5. CURING EQUIPMENT
DYMAX light curing adhesives cure either with ultraviolet (UV) light only or with both UV and visible light. Those that cure with UV and visible light typically cure faster, deeper, and through transparent, but UV-blocked, substrates. All DYMAX UV-curing systems emit either UV, visible, or UV/visible light and are designed to cure all DYMAX UV and UV/Visible curing adhesives. In applications where the adhesive is exposed to air during the cure, higher-intensity lamps may be required to achieve a tack-free surface. As with any manufacturing process, a safety factor should be incorporated into the UV curing process.

STEP 6. FUNCTIONAL TESTING
Prior to production, actual parts (assembled with the candidate adhesive(s)) should be subjected to real-life stress conditions to ensure adequate performance. In addition, actual parts, assembled at the upper and lower limits of the dispensing and curing process should also be tested to ensure all parts produced meet the end-use performance criteria. In most cases, use testing should employ accelerated testing. DYMAX adhesives are used in many applications where parts must endure stressful conditions for long periods of time from years to even decades. Adhesive use testing should include stresses somewhat above those expected for assembled parts. The severity of this testing is best determined by part designers.