RCA analüüs tootmises tootekvaliteedi tagamiseks Ericsson Eesti AS näitel

Töö eesmärgina püstitatud kvaliteetse tootmise tagamine läbi toote defektide eemaldamisega, tänu millele tagati efektiivne tootmine (Lean mõtteviis). Efektiivsuse tagamiseks ja defektide eemaldamisel sai kasutatud selliseid meetmeid nagu: analüütilis-, monitoorimis,-komponentide ja tarne infot sisaldavaid arvuti programme. Lisaks aitasid probleeme lahendada sellised mõõteseadmed nagu: vektorsiduanalüsaator, toote testjaamad, multimeeter, MUST tester (jootmiskvaliteedi määrmiseks) jpm. Mis andsid tulemuseks, esiteks, SMA komponendi jootmisprobleemi puhul, et mägumisanalüüsi labori katsetuse tõestusena tarnija poolse mittevastavuse. Teiseks selgus signaali kao probleemi puhul, et toote endi testjaamade limiitide muutuse sisseviimine lahendab kõrvalekalde. Kolmanda juhtumi puhul on koaksiaal adapteri defektide tekkimine tootmisliini kahes asukohas, milles selgus, et esimeses asukohas tuli PA testri kaablitele installeerida otsakud kaitsmaks adaptereid pooltoote testimise ühendamisel ja pooltoote testilt eemaldamise ajal. Teine koht oli kahe pooltoote integreerimisel, kus ühe pooltoote sees olevad juhttihvtid said kahjustada, kuna nende silindrilise kuju tõttu toimus pooltoodete üksteisest kõrvale suunamine ja omakorda said ka adapterid kahjusatada. Seega tihvtid ei tätnud oma ülesannet ja lahendusena tehti silindrilise kujuga tihvtid koonuseliseks. Kõigi eelpool mainitud lahenduste ja kasutatud vahendite tulemuste abil sai saavutatud kvaliteetne tootmine, mis on tähtis eelkõige ESST klientidele ja Ericssonile endile kui ka tema tarnijatele, tagamaks efektiivse ja kvaliteetse tootmise ja läbi selle sai autorgi hea väljaõppe. Siinkohal hea edaspidine koordineerimine on väga vajalik, ühtlasi on sellel positiivne külg, loob osakondade vahel teadlikust ja koostöö valmidust, kaotab ära nö. „telgid“, tagamaks läbipaistvuse olukorra seisust (Jidoka üks osa). Töö aitas ka tõestada, et DMAIC töötab hästi ja on igati efektiivne, huvigruppidena ei olnud küll määratud spetsiaalset eraldi meeskonda, aga nendeks olid teiste osakondade töötajad (insenerid, vealeidjad jne). Seega sai selgeks ja need probleemid aitasid tõestada, et kõik parendustegevused ei pea ilmtingimata läbima DMAIC mudelit, lihtsalt need probleemid kas ei ole piisavalt keerukad või saab kasutada nende lahendamiseks ka lihtsamaid vahendeid (ning alati tuleks eelistada lihtsamaid vahendeid).

Thesis “RCA analyses in production to ensure product quality based on Ericsson Eesti AS” is describing product quality improvements in Ericsson Eesti As by finding, defining and solving the deviations found in radio modules produced by Ericsson. Radio module is one of the equipments found in RBS (radio base station- also manufactured by Ericsson) which helps along with other equipment inside it to provide to consumers any kind of mobile telecommunication services and technologies (like 2G, 3,5G, of course LTE aka 4G.). There are represented various defects like by SMA, workmanship issues, electronic functional faults, and also issues related to design. Through removing those deviations it gives benefits to not only to Ericsson itself but to its suppliers (to which most faults are related to) and of course through this improvement flow ensures customer satisfaction (which is the primary target of removing deviations). Product improvement in Ericsson is supported by RCA, consisting the technical RCA (which finds technical root cause) and also process RCA (which prevents reoccurrences). Improvement in company is based on DMAIC (define, measure, analyze, improve, control) system. And additionally to explanation of what is DMAIC, RCA, how it works the autohor solved three quality problems. Creation of this thesis has given good and interesting training for author. Created awareness of what parameters, characteristics can be measured using various equipment, some equipment used was: MUST tester (for solderability wetting test), teststations, VNA (vector network analyzer for measuring signal loss) etc. Like previously mentioned there are deviations described and solved in such areas like: SMA; final assembly, incoming inspection (supplier quality) and even design technical issues. SMA deviation example is based on one capacitor of its solder issue, plus it is described the wetting balance analyze which helped to prove that the capacitor solder issue was indeed caused by supplier. And therefore 8D report was created by the supplier to remove such defect in the future. Secondly there is return loss (signal loss) which can be expressed by S-parameter measurement (by VNA), which is followed by little explanation how it is done, solution was to relax the limit of the test station (software) because the same cable and SMA components (same by spec.) worked on lower frequency band products and S11 parameter for measured samples not all of them had deviation. Thirdly is described coaxial adapter damage caused in two places: PAU test station (power amplifier unit) test and second place was during integration of two half products (PAU+TRX), in this act there was situation where due to guiding pins design issue the pins missed the holes where they were supposed to go and due to this misalignment the adapters were damaged. Solution: for PAU teststation was introduced plastic covers, which covers the testing cables which are mounted on coaxial adapters during testing. About during integration part, there was implemented new guiding pins shape (change was from cylindrical shape to conical), then during integration the guiding pins actually helped to guide one half product to another. Thesis also helped to prove that based on those product deviations that not all improvement actions has to follow strictly DMAIC system, simply because those problems are not complicated enough or they can be solved by simpler tools (and always easier methods should be preferred).