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2-Part Epoxy Dispensing: Fluid Dispenser vs. Meter Mix System

Pros and Cons to Consider

27 June 2018

By Tom Muccino

Dispensing epoxy adhesives, primers, sealants, and coatings in electronics, medical devices, and other manufacturing processes can be a challenge, especially when the material is a 2-part epoxy with a set working time or pot life. The working time affects how long the epoxy can be dispensed before it becomes unusable.

In general, there are two types of dispensing solutions to consider: one-component fluid dispensers or meter mix systems. Your decision will likely depend on the working life of the material, shot-size volume, budget, and the level of accuracy and repeatability required. In this article, we’ll discuss the pros and cons and provide some application examples to get you started.

Option #1. Fluid Dispenser

With air-powered (i.e. pneumatic) fluid dispensers you can achieve precise, controlled amounts of epoxy down to 0.15 mm with a 32-gauge dispensing tip. Often this requires pre-mixing part A and part B and pouring it into a syringe barrel. It is imperative to mix the two components according to the fluid manufacturer’s instructions, otherwise the performance of the material will be compromised. If the material comes pre-mixed and frozen in the syringe it will need to be thawed according to the fluid manufacturer’s instructions.

Once the fluid is ready to be dispensed, an operator can use the fluid dispenser to manually apply the material to the workpiece or the syringe barrel can be mounted onto an automated dispensing robot for high-volume production.

The syringe barrel contains the epoxy, often with a piston inserted for the most accurate results. An operator programs the fluid dispenser to apply air pressure to the piston to push the epoxy through the dispensing tip affixed to the end of the syringe barrel. The higher the pressure and the longer it is applied, the greater the amount of fluid is dispensed.

    Recommended Dispensing Tips and Needles: SmoothFlow™ tapered tips provide the best dispensing results for thick epoxies. For epoxies with a tendency to string, try using a smaller gauge tip and increase the air pressure. General purpose tips can also be used. Oval tips are useful when a flat ribbon of thick epoxy is required.

    Recommended Pistons: Most materials work well with white Optimum® general purpose pistons. However, if you see too much piston bounce with stringy epoxies, switch to the orange flat-walled piston. For bounce issues with thicker material, specify the Clear Flex piston.

One con of using benchtop fluid dispensers is that you need to consider the working time of the material more closely than you do when using a meter mix system since the two components are not mixed at the point of dispense.

If you completely fill a syringe barrel with a pre-mixed epoxy that has a short pot life, you risk wasting more fluid than necessary.

    Recommended Practice: It’s best to pre-mix just enough to produce as many parts possible for the pot life of the epoxy. For example, if you’re working with a 30-minute pot life, only premix what you will use for 20 minutes. This will ensure you use all the epoxy in the syringe barrel and throw out an empty syringe, which will lower costs associated with fluid waste.

Another factor to consider when using fluid dispensers is that the epoxy will thicken over time. As the viscosity changes, the deposit size changes. If the dispensing parameters remain fixed during the working time of the material, the deposits will get smaller as the material thickens.

    Recommended Fluid Dispenser: Nordson EFD recommends the Ultimus™ V High Precision Dispenser for epoxies with a viscosity that changes over time. Most air-powered fluid dispensers use the same initial dispense parameter settings when dispensing the entire contents of a syringe barrel. With the Ultimus V, you can program a profile for the length of time it takes to dispense all the material in your syringe.

    For example, if your epoxy has a 45-minute working time, you can program the pressure to change as the viscosity of your material thickens. Once you “teach” the Ultimus V the different dispensing parameters your fluid requires over time, the dispenser automatically makes the incremental pressure changes as you’re dispensing the next time you run the program. You can program the Ultimus V based on the visual appearance of the deposits or the weight of the deposits over time.

For 2-part epoxies that come pre-packaged in 50mL Side x Side cartridges, the Equalizer™ dispensing tool can be used in manual applications or mounted to an automated dispensing system. The tool works with 1:1, 2:1, and 4:1 mix ratios. A variety of static mixers and dispense tips can be used to provide precise, repeatable epoxy deposits. And since the mixing happens at the point of dispensing, it lessens the consideration required for the epoxy’s pot life.

Option #2. Meter Mix System

The benefit of meter mix systems is that you don’t have to worry as much about the working life of the material because part A and part B stay separate until they meet at the static mixing nozzle. When the two materials begin to cure in the nozzle, you just remove the disposable, plastic mixing nozzle and replace it with a new one.

A con of meter mix systems is that they can be somewhat limited when very small, controlled deposits are required.

    Recommended Mixers: Most 2-part epoxies require a static mixer with 15-24 mixing elements. Your application may require more mixing elements if part A and B are two very different viscosities or are very wide in mix ratio (4:1 or greater). It’s always best to ask an experienced fluid application specialist for recommendations since there are so many variables to consider.

Nordson EFD offers several types of static mixers that work with epoxies, including spiral mixers Series 160, 160AA, 161N, 162, 190, and 260. In addition, several 2-part epoxies come pre-packaged in EFD Side x Side and Ratio-Pak® cartridges.

For more information about Nordson’s meter mix systems visit Nordson Sealant Equipment.

Epoxy Dispense Valves and Jet Valves

Technically, a two-part epoxy can be applied with a one-component fluid dispensing valve or jetting valve, however, the pot life of the material will determine the feasibility of this option. If the epoxy has a 30-minute pot life, for example, it would be extremely difficult to work with precision dispensing or jetting valves. An epoxy with a 4-hour pot life would be feasible with special maintenance requirements. Operators would need to purge the valve frequently to prevent the epoxy from curing inside the valve.

Epoxy Application Examples

Example #1. Bonding Large Components in Printed Circuit Board Assemblies

A defense device manufacturer needed a faster way to produce its PCB assemblies with less rework. Previously operators dispensed the 2-part epoxy manually with a dispensing syringe attached to a standard pneumatic fluid dispenser.

    Recommended Solution: Ultimus V fluid dispenser and a 4-axis R Series automated dispensing system. The combination of new dispensing equipment reduced the time it took to apply the epoxy by 70%. It reduced the amount of rework by 90%.

Example #2. Filling Application for GPS Units

An electronic equipment manufacturer needed to replace its current squeeze bottle method of dispensing a bead of 2-part epoxy around the perimeter of components within portable GPS devices. Getting a controlled amount was difficult due to hand fatigue as the day went on.

    Recommended Solution: Ultimus I fluid dispensers equipped with Equalizer dispensing tools mounted on 3-axis EV Series automated dispensing systems. The customer increased throughput with a more efficient process that produced less material waste. The solution freed two operators that could be utilized in other areas.

Example #3. Bonding a Lens to a Housing of a Medical Device

A medical device manufacturer needed a more consistent method for bonding a lens to the housing of one of its devices. The application required dispensing dots, lines, and circle patterns smaller than a dime. The previous method involved using an Ultimus I dispenser to manually apply the 2-part epoxy to parts under a microscope. Rejects and general part-to-part consistency were the main issues.

    Recommended Solution: Mounting the Ultimus I to a 3-axis EV Series automated dispensing robot improved the consistency and efficiency of the process while eliminating epoxy waste and rejects.

Example #4. Potting Flexible Circuits

An electronics manufacturing company needed a more consistent solution for potting the ends of its flexible circuits with 2-part epoxy. The manual process was too labor intensive.

    Recommended Solution: Performus fluid dispenser and a 3-axis EV Series automated dispensing system. The customer was impressed by how easy the EV Series was to program, and the “Step & Repeat” function for when they didn’t need to produce a full batch of parts.

It’s always a good idea to speak with an experienced fluid dispensing application specialist when trying to decide on the best possible dispensing solution. If you have any questions, don’t hesitate to email us at info@nordsonefd.com.

Tom MuccinoAbout Tom Muccino

Tom Muccino is a Zone Manager at Nordson EFD. He manages the sales team located in the Midwest to the West Coast of the U.S. and Canada. Tom has more than 30 years of fluid dispensing expertise. He joined Nordson EFD in 1987.


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