Grom­met

JÄGER Group seals con­duc­tor rails thanks to an opti­mal mate­r­i­al-form-mix

Exact require­ment pro­file

The experts of Jäger Gum­mi und Kun­st­stoff work togeth­er with SMA tech­ni­cians to cre­ate the pre­cise require­ments pro­file for the new grom­met. Where are these parts used? What spe­cif­ic con­di­tions pre­vail between ‑40 and +110 degrees Cel­sius for a desired suit­abil­i­ty in usage? What are the require­ments for the planned instal­la­tion of the grom­mets? Togeth­er with the tool­mak­er, Jäger employ­ees devel­op a strat­e­gy for the mold design.

The grom­met is pro­duced in Trans­fer Mold­ing ™. In order to avoid pos­si­ble errors in advance, the experts of both com­pa­nies, after care­ful
coor­di­na­tion, joint­ly sub­ject­ed their ideas to exten­sive draw­ing tests. This devel­op­ment time was nec­es­sary and sen­si­ble: The feed-through grom­met is suc­cess­ful­ly used in the cur­rent invert­er mod­el.

Suf­fi­cient pres­sure despite var­i­ous tol­er­ances?

The design of the grom­met, which the experts ulti­mate­ly decid­ed on, meets the high demands on tight­ness. The bel­lows on the feed-through grom­met com­pen­sates for the tol­er­ances that arise dur­ing the instal­la­tion of the con­duc­tor rails as well as those to the adja­cent com­po­nents.

This also applies to the adjust­ment of the con­duc­tor rails. Inside the grom­met, the engi­neers there­fore also design posi­tion domes on both sides and a cir­cum­fer­en­tial seal­ing bead that posi­tions the seal on the con­duc­tor rails. Snap­ping the posi­tion­ing domes into the holes in the rail ensures that the seal exerts suf­fi­cient pres­sure on the base plates, this guar­an­tees tight­ness. Like the oth­er sil­i­cone seals used in the invert­er, this ver­sion also com­plies with the inter­na­tion­al­ly required UL 94 HB fire stan­dard. This means that SMA can also sup­ply these invert­ers to the USA, for exam­ple, or facil­i­tate UL cer­ti­fi­ca­tion of the sys­tem.

Leak tight­ness in the test

Togeth­er the design­ers involved devel­op a pro­duc­tion tool for pro­to­types. For this pur­pose, they define opti­mum sep­a­ra­tion areas on the tool so that
any burrs on the seal are not placed in seal­ing areas. The test run results in opti­mum seal­ing: The pro­to­type of the grom­met leaves noth­ing to be desired in terms of seal­ing and assem­bly.

This meant that noth­ing more stood in the way of com­plet­ing the devel­op­ment phase. From the test-mold, Jäger can pro­duce the first seals and deliv­er them to SMA for the start of pro­duc­tion. At the same time, the man­u­fac­ture of the tool for series pro­duc­tion begins. In the future, Jäger will sup­ply the annu­al require­ment of 100,000 grom­mets for the con­duc­tor rails in the invert­er of the future — in reli­able qual­i­ty at sig­nif­i­cant­ly reduced costs.

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