Applying polyurethane in precision potting of switches and connectors

MOLEX is an international company that manufactures electrical devices. Their factory is located in Sulecin, in the west of Poland.

Switches and connectors produced by MOLEX require potting to ensure resistance to weather and water, which has to be done in small shots. Due to difficult-to-reach areas, potting is carried out manually, as cables don’t permit automation.
 

Demanding mixing process

For this application, a two-component no VOC polyurethane resin is used. The mixing of this resin is difficult and is carried out with a static mixer, and exact, simultaneous pumping is extremely important. This makes the potting process in this application very demanding, as the product has a pot-life of only 5-7 minutes (theoretically 10 minutes) at room temperature.

In the beginning, manual mixing and potting were introduced. However, the result was a high amount of air entrapments, which resulted in very poor aesthetic joint. Also, the resin level control was difficult, as air was released a long time after the potting process, and the level of resin changed. The potential rejection of parts was considerable.

For their new potting process, Molex’s had requirements to save material and limit its consumption.

 

Putting the PR70 to the test

Local Graco distributor AMB TECHNIC, introduced the PR70™ to MOLEXS. The PR70 is a fixed ratio dispensing system that accurately meters, mixes and dispenses two-component medium to low-viscosity materials. ABM TECHNIC evaluated and tested the system on site. The PR70 was equipped with an electrically driven agitator in the tank to ensure no air could enter the resin, even at a low resin level. The quality of the mixing of the resin and aesthetic potting was proven with the PR70. 

 

Reliable and durable dispense system

MOLEX found the following features of the PR70 beneficial for their organisation:

• The PR70 is an accurate and affordable plural-component system.
• Mix ratio range fixed, but easily chosen from available pistons in typical sizes.
• Static mixing allowed good and stable quality of resin, without air entrapments.
• Easy to use and understand user control interface for their existing operators.
• Simple process to introduce.
• Small shots realised by syringe potting of small parts.
• No solvent cleaning on the production site.

More information

For more information about fixed ratio dispensing systems or the Graco PR70, fill in the form below.