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How com­pa­nies pre­vent assem­bly dam­age to rub­ber seals

21.11.2022   | Chris­t­ian Recht

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If a rub­ber seal is dam­aged dur­ing instal­la­tion, this affects its seal­ing per­for­mance. On the one hand, the ser­vice life of the seal is con­sid­er­ably reduced. On the oth­er hand, the risk of for­eign sub­stances or liq­uids pen­e­trat­ing the sealed object increases.

It is easy to blame the installer in such cas­es. How­ev­er, instal­la­tion dam­age is often the result of com­mu­ni­ca­tion errors or a design that does not suf­fi­cient­ly take into account the con­text of the installation.

For­ward-think­ing, easy-to-assem­ble design

Many design­ers come from the met­al sec­tor and have lit­tle expe­ri­ence with elas­tomers. There­fore, they can hard­ly assess how the mate­r­i­al behaves in prac­tice. This some­times leads to problems.

For exam­ple, the design some­times over­es­ti­mates the elas­tic­i­ty of rub­ber. It there­fore pro­vides too lit­tle space in the hous­ing for the seal (“When in doubt, the mate­r­i­al will give”). How­ev­er, this com­pres­sion expos­es the seal to per­ma­nent pres­sure, which leads to mate­r­i­al fatigue and fail­ure over time. The com­po­nent in which the seal is inte­grat­ed can also be dam­aged by the pres­sure, for exam­ple by bending.

Sim­i­lar prob­lems can occur with O‑rings if they are not the right size for the appli­ca­tion. For exam­ple, if the seal is too small and has dif­fi­cul­ty fit­ting over a pipe, it will be under per­ma­nent ten­sion. Rub­ber can stretch, but even­tu­al­ly the mate­r­i­al will fatigue and crack.

Anoth­er source of error is the pro­duc­tion-relat­ed tol­er­ances of elas­tomers. In prin­ci­ple, rub­ber can­not be man­u­fac­tured as pre­cise­ly as met­al. There are always small devi­a­tions from the tar­get val­ues, but these are sig­nif­i­cant­ly high­er than is usu­al in the met­al sec­tor. For this rea­son, design­ers should always allow for suf­fi­cient buffers when rub­ber mold­ed parts are to be installed. Oth­er­wise, seals that are at the upper end of the tol­er­ance range can be squeezed off.

Sharp edges also pose a risk. If a seal is stretched over such an edge, it can eas­i­ly be dam­aged. This applies both to assem­bly-relat­ed fric­tion effects (e.g. when the gas­ket is pushed into posi­tion) and to crush­ing that only occurs over time. Here, on the one hand, the design must coun­ter­act and avoid cor­re­spond­ing geome­tries or round off edges. On the oth­er hand, the assem­bly should take spe­cial care and watch out for pos­si­ble dam­age to the seal.

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Iso­lat­ed mold in production

Assem­bly teams need to be bet­ter educated

How­ev­er, pre­ven­tive mea­sures in con­struc­tion are not suf­fi­cient to effec­tive­ly pre­vent assem­bly dam­age. In addi­tion, the col­leagues on site need to be informed about the spe­cial fea­tures of the material.

In the rub­ber sec­tor, for exam­ple, resis­tance plays a major role. Every elas­tomer has sus­cep­ti­bil­i­ties or resis­tances to cer­tain sub­stances or influ­enc­ing fac­tors (tem­per­a­tures, UV light, etc.). For exam­ple, if rub­ber comes into con­tact with an acid to which it is not resis­tant, it decom­pos­es over time and los­es its mechan­i­cal prop­er­ties. This dis­tin­guish­es elas­tomers from met­als, which are nat­u­ral­ly resis­tant to most envi­ron­men­tal factors.

The assem­bly depart­ment must know for which oper­at­ing con­di­tions a rub­ber com­po­nent is approved or which sub­stances or tem­per­a­tures are to be avoid­ed. This does not only apply to per­ma­nent oper­a­tion. Even brief con­tact with the wrong chem­i­cal dur­ing assem­bly can cause per­ma­nent dam­age and impair the seal­ing per­for­mance of the com­po­nent. This could be, for exam­ple, clean­ing agents or sol­vents with which the seal comes into con­tact dur­ing installation.

Spe­cial atten­tion should be paid to stor­age con­di­tions. Rub­ber com­po­nents can only be stored for a lim­it­ed peri­od. After that, they lose their elas­tic prop­er­ties and become brit­tle. How long this takes depends on the mate­r­i­al as well as the envi­ron­men­tal fac­tors. Some elas­tomers can­not tol­er­ate heat or cold. Oth­ers are resis­tant to ozone or UV light and should not be stored outdoors.

It is impor­tant that the assem­bly knows and takes into account these lim­i­ta­tions. Oth­er­wise, the seal may be dam­aged even before installation.


You can look up the chem­i­cal resis­tances of the most com­mon elas­tomers in our resis­tance list.

More effec­tive com­mu­ni­ca­tion between design and assembly

Anoth­er impor­tant point is the com­mu­ni­ca­tion chan­nel between design and assem­bly. The com­mu­ni­ca­tion of infor­ma­tion should take into account the work process­es of the col­leagues on site, oth­er­wise it runs the risk of being lost. The assem­bly depart­ment usu­al­ly does not have the time to study pages and pages of tech­ni­cal doc­u­men­ta­tion before installing a rub­ber seal. They need the most impor­tant infor­ma­tion as briefly and com­pact­ly as possible.

It is a good idea, for exam­ple, to print rel­e­vant incon­sis­ten­cies in the form of haz­ard sym­bols on the pack­ag­ing or enclose them as a hand­out. If risk fac­tors are present, a note in the work instruc­tions is also con­ceiv­able. An online overview, in which the assem­bly depart­ment can look up resis­tances, has also proven its worth.


Instal­la­tion dam­age to rub­ber seals is not nec­es­sar­i­ly the fault of the col­league on site. In some cas­es, the design sim­ply did not take the con­text of the instal­la­tion suf­fi­cient­ly into account, so that dam­age occurs despite cor­rect instal­la­tion. Or the installers lack rel­e­vant infor­ma­tion, for exam­ple about resis­tance to cer­tain chem­i­cals. To avoid such prob­lems, for­ward plan­ning is need­ed that takes the instal­la­tion of the com­po­nent into account from the very begin­ning. To this end, it makes sense to uti­lize the know-how of sup­pli­ers and mate­r­i­al experts ear­ly in the devel­op­ment project. This is the most effi­cient way to devel­op assem­bly-friend­ly, durable components. 

Secure the Start of Production

Learn which fac­tors influ­ence your SOP!


Author: Chris­t­ian Recht

Chris­t­ian Recht is a sales rep­re­sen­ta­tive at Jäger in the office and in the field. The trained office admin­is­tra­tor has been in charge of pur­chas­ing and tech­nol­o­gy for the new devel­op­ment of rub­ber and plas­tic com­po­nents since 1991.

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