From NOK to OK: STIWA optimizes the rework process

From NOK to OK: STIWA optimizes the rework process

September 8, 2021

By mak­ing data avail­able in a tar­get­ed man­ner, process­es can be kept sta­ble in the long term. In this way, out­liers can be detect­ed and cor­rect­ed at an ear­ly stage. How­ev­er, if errors occur in the pro­duc­tion process, STIWA has been enabling the inte­gra­tion of rework sta­tions in the STIWA con­trol sta­tion for many years. With AMS Analy­sis-CI Rework, com­pre­hen­sive analy­sis options are now avail­able live on the HMI.

Rework is a mea­sure to make non-con­form­ing prod­ucts (NOK) con­form again (OK) for deliv­ery to the cus­tomer by means of sub­se­quent pro­cess­ing. In prin­ci­ple, avoid­ing rework is the pri­ma­ry goal in pro­duc­tion. How­ev­er, this is becom­ing increas­ing­ly dif­fi­cult, explains Alexan­der Meisinger, Sales Man­u­fac­tur­ing Soft­ware at STIWA Group: “Tech­nol­o­gy lead­ers pro­duce at the lim­its of what is tech­ni­cal­ly fea­si­ble. The under­ly­ing process­es and depen­den­cies are becom­ing cor­re­spond­ing­ly more com­plex. Increas­ing cus­tomer require­ments for pre­ci­sion and accu­ra­cy increase the risk of defec­tive parts in the process. In order to avoid rejects or to save NOK parts and com­po­nents, pro­fes­sion­al, data-based rework is there­fore becom­ing increas­ing­ly impor­tant in addi­tion to struc­tured process analysis.”

 

STIWA opti­mizes rework

At STIWA, the rework sta­tion can be eas­i­ly inte­grat­ed into the STIWA AMS ZPoint-CI machine con­trol sta­tion. The con­fig­u­ra­tion of rework tar­gets, rework actions or spe­cial runs is there­by much eas­i­er. Rea­sons for defects, mea­sured val­ues, batch infor­ma­tion, process curves, etc. are auto­mat­i­cal­ly dis­played, enabling quick deci­sions in the selec­tion of rework actions. With the rework analy­sis, these records are linked direct­ly on the HMI with data from Analy­sis-CI. This can be used, for exam­ple, to answer the ques­tion of which rework actions have led to suc­cess for which defects, or which com­po­nents most fre­quent­ly require rework. Anoth­er analy­sis sce­nario is changes after dou­ble checks. They pro­vide infor­ma­tion about the reli­a­bil­i­ty of the test sta­tions, for example.

 

Sus­tain­able cost reduction

AMS Analy­sis-CI Rework increas­es the qual­i­ty of rework sus­tain­ably and in the long term. The sav­ings can also be eas­i­ly quan­ti­fied, accord­ing to Alexan­der Meisinger: “For a machine with 1 mil­lion parts pro­duced and a machine turnover of around 100 mil­lion euros per year, a reduc­tion in scrap includ­ing rework from 5 to 2 % means a sav­ing of around 4.5 % of the machine turnover already in the first year — tak­ing all pro­duc­tion costs into account.”

 

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