797PCP-2K Progressive Cavity Pump and Static Mixers Improve Automotive Relay Production

Application Success Story

One common application we see in the automotive industry is applying epoxy to relay housings. Automotive relays are an integral part of a vehicle’s circuit design. Keeping heat and moisture out is required for proper function and to avoid contamination or corrosion. The epoxy works well as a sealant to fill voids. It provides reliable cooling, and environmental temperature, and humidity protection for sensitive automotive electronic circuits.

Recently we helped a machine builder develop a solution for a customer with this exact application. In this blog post, you’ll learn how Nordson EFD provided a total system solution. It took months of testing at one of our global application labs, but we were able to improve the customer’s current process and exceed expectations in terms of the application requirements.

Here are some details about this application:

Fluids Used

• 2-part epoxy

Application Requirements

• Dispense precise amounts of 2-part epoxy onto aluminum relay housings
• Dispense accurate, repeatable lines with a consistent cycle time
• Eliminate drooling and dripping

Previous Process

The previous setup used two 1/10 oz caulk tubes that fed into a pressurized system that was then attached to a robot with the epoxy dispensed out of a mixer.

Issues with Previous Process

The previous system setup led to dripping and drooling of the mixed material. The mixer was oriented vertically, which contributed to poor deposits due to the thick viscosity of the material. When a mixer is vertical, dead fluid has no where to go and ends up drooling excess material onto the part.

The previous process also lacked an important step, which was to degas the fluid prior to mixing. This caused air bubbles and pockets to stay in the fluid so when they were trying to dispense, the deposit accuracy suffered considerably.

Solution

• EV Series automated dispensing system
• 797PCP-2K progressive cavity pump
• ValveMate™ 7197PCP-2K controller
• Series 190 disposable spiral bayonet mixers
• Optimum 14 ga SmoothFlow tapered tips
• Optimum 20 oz cartridges

After testing, our fluid dispensing experts concluded that degassing the fluid prior to dispensing was essential for this application to ensure the most accurate dispense results. We transferred the epoxy into our Optimum 20 oz cartridges to use with pressurized retainers. The cartridges were then degassed to remove any entrapped air bubbles prior to mixing. Degassing can be done with a centrifuge.

To keep the process automated, we recommended our 3-axis EV Series robot that features vision-guided software to deliver precise fluid placement. Vision-guided dispensing robots use marks and fiducials to automatically offset the dispense program to compensate for slight shifts in part orientation or location. For example, if someone were to put the relay housing onto the robot in the wrong direction, the software would recognize this and automatically correct the dispense.

This helped to eliminate user error and provided the accurate, repeatable lines that this application required. Lastly, the robot’s vision system helped the machine builder detect the substrate more easily, which allowed for simple set up and programming.

Since dispense weight accuracy and repeatability were a significant part of the application requirements, we recommended our 797PCP-2K progressive cavity pump. The pumps are designed to precisely meter accurate ratios of part A and part B materials through static mixers for highly repeatable dispensing with fluid deposit accuracy at ± 1% regardless of variation in material viscosity over time. When paired with our ValveMate 7197PCP-2K volumetric pump controller, adjusting controls of meter mix dispensing parameters were made easy with the intuitive touchscreen interface.

The next product we highly recommended were our mixers. Having the correct static mixer can make or break your application. It’s important to look at the material properties of both parts A and B and pick the mixer with the right number of elements and diameter to achieve the proper bonding properties. In this case, our Series 190 disposable plastic spiral bayonet mixers were the best fit and a key to the success of this application because they ensured that the materials were 100% mixed by the time they left the mixer.

The implementation of our 797PCP-2K Y shutoff valve was also critical for this application. It eliminated the dripping and drooling issues caused by the previous process by aligning the mixer in a diagonal versus a vertical position, thus eliminating the dead fluid volume. In addition, the shutoff valve works to stop the flow of the material and provide a clean, drip-free cutoff of material flow.

Lastly, choosing the right tip is an important part of an application because choosing the wrong one could lead to rejects, rework, and affect cycle rates. Since we were working with mixed 2-part epoxy with a very thick viscosity, we suggested our Optimum 14 ga SmoothFlow tapered tip that attached to the shutoff valve.

Our tapered tips work perfectly when applying thick viscosity fluids because of their large diameter that makes it easier to push material through them. They’re also designed with unrestricted flow, unlike other tips that have a choke point. This is important for thick epoxies because any restriction can cause a build-up of pressure and affect the accuracy of the dispense.

Results

In the end, the machine builder benefited from our overall expertise to provide them with a complete dispense solution that included automation, dispense pumps, controllers, cartridges, retainers, mixers, and tips.

Our total system solution was able to meet their application requirements by delivering precise amounts of 2-part epoxy, dispensing accurate and repeatable lines of material, and eliminating the drooling/dripping issue they were having with their previous process. Offering the total system led to faster, easier set up and programming since our products work harmoniously with one another.

If you would like to discuss your dispensing project with an experienced fluid dispensing expert, don’t hesitate to email us at [email protected].

Lori Labonte

Lori Labonte is a Sales Representative at Nordson EFD. She helps manufacturers throughout Indiana, Kentucky, Tennessee, and Virginia find the best possible dispensing solutions for their fluid applications. Lori has more than 12 years of fluid dispensing expertise. She joined Nordson EFD in 2008.