Last week, Resin Designs discussed the gel seal application process. Today we will be reviewing the various connector types. Gels provide sealing on multiple types of connectors.
In the connector market, there are numerous special cases. Below you will find some of the more common cases. Typically, in these special cases, connectors are not as compatible with gels than more standard connector designs.
Connectors with Mixed Contact Sizes
A mixture of contact sizes should be accommodated by a single gel grommet seal. In turn, the biggest contact size and pitch will determine the gel configuration. Most of the small contacts could have gels which are over-designated due to the large contacts in the connector.
This situation commonly occurs in electronic interfaces where a small amount of contacts are required and a majority of the interface is low level signals. The connector should then be segmented to isolate the larger contacts and allow different sealing solutions to optimize the system. Connectors using a mix of 1.5mm and .6mm contacts can be efficiently and economically sealed with Resin Designs brand gel grommets.
Modular connectors contain an outer housing that accepts a variety of individual contact inserts. This will allow the connector configuration to be altered by changing wafers instead of retooling the whole connector.
Inserts can be either factory installed or user installed. The connector leaves the factory completely during the factory design. When the inserts are completely installed, the connector looks similar to a standard connector. Gel grommet design is complex in order to ensure that a single overall design will work with the full range of modularity designed into the connector. Now, the only major difference between grommets for different configurations is the placement of the contact slits. In order to attain a single overall design, it’s best to design for the largest contact.
In the case of the modular connector, the harness shop loads the contacts into the insert and then the insert into the housing. A “standard” application of gel grommets is generally not possible because of space constraints. However, there is an alternate approach to sealing with gels.
IDCs (Insulation Displacement Connectors) for flat ribbon cables come with pre-installed contacts in the connector. In many instances, IDCs of fixed contact designs are incorporated in two-piece connector type designs. New design connectors can also be sealed with gels.
Pull to Seat Designs
In pull to seat designs, the terminated contact is assembled from the front instead of the rear of the connector. Two variations have been viewed.
In a few assemblies, the contact is terminated to the wire and the wire is then fed through the connector. Next, the contact is seated into the connector from the front. This does work with a gel grommet but it implies that the entire length of the wires is pulled through the gel. This leaves a film of gel on the full length of the wire.
A second method includes shooting the un-terminated wire through the seal and the connector body, cut, strip and terminate the wire and then pull it back into the connector to seal. Gel grommets are compatible with this type of assembly.
In some instances, two wires are terminated to a single contact. Typical rubber seals (individual wire seals or monoblocks) cannot seal to twinned wires.
While significant work has been accomplished in this area, gels still have not displayed an ability to reliably seal to twinned wires.