Dispensing Dynamics -Fluid Types
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I&J Fisnar Inc. Dispensing Dynamics - Part 2 - Fluids Cyanoacrylate Dispensing Bond Conditions Cyanoacrylate is an “instant” adhesive with three (3) principal chemical components, namely: methyl, ethyl, and butyl. Cyanoacrylate is generally a clear liquid with a viscosity from 3 cps to 2000 cps. The higher viscosity cyanoacrylates are described as “gap- filling”. There is also a cyanoacrylate, called Black-Max, with a rubber component to provide elasticity. Bonding strength is 15 Kg per cm². Polymerization The polymerization of cyanoacrylate is a reaction which occurs when the adhesive comes into contact with humidity. Polymerization reaction starts at the surface of the adhesive toward the center of the deposit. In order to have good adhesion (bond) between two substrates, the thickness of the cyanoacrylate must be thin. Example: If a large glob of glue is dispensed on a flat service, it will stay in liquid form because only a very thin layer of adhesive contacts the surface and will polymerize. Blooming Blooming may occur when a large amount of cyanoacrylate remains in liquid form. Some of the liquid material may vaporize and react with humidity. The result is a polymerization, which appears as a white dusty marking on the surface near the adhesive. To solve (or reduce) blooming: - Ventilate to eliminate vapor - Use an “activator” to polymerize at a faster rate An “activator” is generally a liquid which is volatile and can be applied before or after the assembly of the two parts being joined. When using an “activator”, the total polymerization process occurs in seconds and not over a longer period if relying on humidity alone to propagate the polymerization. The negative effect when using an activator is that it slightly reduces the strength and adhesion of the “bond”. Other conditions that can affect the bond strength and rate of polymerization are:

Too great a clearance between the two pieces requiring an excessive amount of material: Solution - use “gap-filling” material or “activator” An acidic surface which may affect humidity An irregular surface, which provides limited surface contact between the two parts being joined - Solution - use a higher viscosity or gel-type cyanoacrylate Room air is too dry - Solution - control the level of humidity or use an “activator” The materials to be bonded can influence polymerization. Since Teflon is a material that “repels” humidity on its surface, it cannot be glued with cyanoacrylate. This is...

- Dispense directly from a bottle using a PP300-GL-A (Glass) fluid reservoir or a peristaltic pump - Use a 700PTPCW pinch pen for manual control - Use a 710PTNM pinch tube valve for timed control The choice is made depending upon the material packaging and how it is to be dispensed. Since cyanoacrylate reacts with moisture and “metal- ions,” it is important to use dry compressed air (or nitrogen) and non- metallic wetted parts. Example 1: A PP300-GL-A fluid reservoir is a good solution, as the plastic bottle package containing the cyanoacrylate can be placed directly into the pressure...

The “blooming” residue can be easily cleaned with a solvent or with Loctite: DECAPLOCK 55. When using an I&J Fisnar Inc. DSPE501A and or JBE1113 liquid dispenser with a dispensing syringe to dispense cyanoacrylate, dripping may be prevented by using their suck-back features. However, caution must be exercised to avoid increasing the vacuum so that the material is drawn into the controller solenoid, voiding the warranty and incurring an expensive repair. When dispensing cyanoacrylates, a polyethylene piston is recommended as a barrier to the fluid in a syringe, but the barrier will prevent...

Because the curing time is long, the fluid has sufficient time to permeate surfaces and threads, including any irregular surfaces, thus providing an excellent sealing material. Mechanical Characteristics of Anaerobic Resins Anaerobic fluids are suitable for the following: - Screw locking Assembly of 2 cylindrical parts, e.g., bearings Sealing two parts of an assembly forming a liquid gasket Screws and bearing assemblies may require disassembly for maintenance or for other reasons, hence 3 different strength formulations are available : High (300 KG-CM), Medium (200 KG-CM) and Low (60...

- If a piston is not used in a syringe it is important to use an in- line fluid filter-trap to protect the dispenser. - 250 gram bottles can be placed directly inside an I&J2601-107 reservoir or a glass chamber reservoir PP300-GL-A. Regulated air pressure will feed the fluid to a pinch tube pen or valve such as model 700PTPCW or model 710PTNM valve. - When a timed control of shot size is required, a model DSPE501A or JBE1113 time/pressure dispenser will control shot size by pressure and time. This system can be used with a syringe or a reservoir feeding a 710PTNM pinch tube valve, a DV509...

size. To compensate for these phenomena, the operator could increase the pressure or increase the time to maintain a correct shot size. UV Cure Dispensing UV Cure Resin Properties UV cure fluids are a diversified range of products. They are not a family of products but a system of cure. They perform three principal functions: Bonding, Coating, and Sealing. UV light can be used to secure an assembly and a further process run to complete polymerization, such as an anaerobic or a heat treatment process. For many UV cure resins, polymerization can only be achieved by exposure to UV light. A...

3. – UV cure resin + solvent : In a possible coating and sealing application, the solvent is present to reduce the viscosity so as to have a self- leveling effect. Notes: There are silicones which polymerize with UV; in these instances the silicone should be treated with the same dispensing requirements as silicon. Some plastics which are used for outdoor products are clear but include some anti-UV, for example, polycarbonate. Some UV cure resins are also anaerobic and are sensitive to metal contact, not sufficient to polymerize but enough to gel. Storage and Packaging Packaging is...