259 DfR SUPPLIER HANDBOOK
Guidelines for Ensuring Reliability requirement fulfilment
Important matters in supply chain management are for example:
* how to make contracts
* how to manage reliability, traceability etc. of multiple suppliers (alternative, second suppliers)
* change management (component changes, changes in production processes or location etc. – either for example due to improvements in design, cost issues or availability of components or obsolescence)
* technical management
* how to handle returns, complaints etc.
Production part approval process is a rather formal process applied in automotive industry to establish confidence in component suppliers and their production processes. Obtaining approval requires the supplier to provide sample parts and documentary evidence showing that:
1) The clients requirements have been understood
2) The product supplied meets those requirements
3) The process (including sub suppliers) is capable of producing conforming product
4) The production control plan and quality management system will prevent non-conforming product reaching the client or compromising the safety and reliability of finished vehicles
Challenges in change management include for example matters like:
* some companies do not have a documented process for change management leading to varying procedure,
* part and end product requirements may be conflicting, suppliers may make changes (component, manufacturing location etc.) without notice,
* second source supplier need same attention as the first one (audits, testing, verifications etc.)
* traceability along a long supply chain is important (changes, returns, feedback on reliability etc.)
Life cycle costs need to be address properly and cost of poor quality has to be taken into account. Evaluating life cycle costs is important and it will make it easier to ”sell” all the procedures that are needed to reach the reliability and performance targets. In analysing life cycle costs all the life cycle phases have to be covered: evaluation, design and development, production, transport and storage, installation, maintenance, handling of returns and damaged or incorrect deliveries as well as disposal and recycling.
Cultural differences themselves have not been observed having been the cause for poor quality or reliability. Instead we it appears that ”the culture of quality” varies significantly between different suppliers. So the most important thing is the supplier selection and quality verification process, not necessarily considering cultural differences at all.
Regular (monthly/quarterly) technical meetings with key-suppliers are recommended. These meetings can serve as follow-up meetings for actions to reach and maintain required reliability levels. Setting reliability requirements to suppliers and contractors using reliability experts is recommended. These experts are able to set the quality and reliability targets and specify the measures used. Selection of suppliers is carried out by procurement in close cooperation with technical specialists.
260 OPTIMIZING COST AND RELIABILITY THROUGHOUT PRODUCT LIFECYCLE (RECO)
This report briefly describes the ideas that emerged during the KOTEL 131: OPTIMIZING COST AND RELIABILITY THROUGHOUT PRODUCT LIFECYCLE project.
Cost cut actions might have negative impact to products reliability. On the other hand the reliability has also clear impact to product life cycle costs. To avoid expensive cost cut actions products whole life cycle costs should be analysed when changes are considered. Other reason why the evaluation of the life cycle costs is important is that otherwise it is not easy to “sell reliability to the management”.
Participant companies use Design for reliability methods to ensure product reliability. Used methods were presented during the project and these methods are briefly described.
In analysing life cycle costs all the life cycle phases have to be covered: research and development, production, installation, operation, maintenance and disposal. Also software costs should be analysed. Several LCC estimation techniques exist and some software packages are available to estimation. It seems that the estimation techniques are in many cases too complicated to use and it is recommended to use the LCC estimations to comparison purposes. Many readily available reliability software have capability to do comparative analyses by utilising for example the Reliability Block Diagrams (RBD).
It is also possible to calculate the value of reliability by using existing warranty data. By this method it is possible to found out the relation between cost and MTBF. This kind of information of company’s own products might be useful when selling reliability investment to management.
Some cost cut actions were evaluated and ranked to best and worst actions based on their likelihood and possible impact to reliability. The likelihood and impact to reliability was evaluated by the participant companies and are then subjective opinions. It was found out that “positive cost cuts” are typically such that companies should improve the existing processes. Whereas “negative cost cuts” are typically immediate cost cuts (low-cost components, material, etc.).
261 RELIABILITY AND LIFETIME ESTIMATION OF FLEXIBLE CAPACITOR (REFLEX)
Komponenttivalmistajat ovat esitelleet erilaisia menetelmiä parantamaan keraamisten monikerroskondensaattoreiden luotettavuutta. Yksi menetelmä on lisätä kondensaattorin päätyrakenteeseen joustava polymeerikerros, joka lisää komponentin taivutuskestoa piirilevyn taipuessa mekaanisen rasituksen vuoksi.
Raportin alussa on state-of-the-art -osa, johon on kerätty tietoa eri komponenttivalmistajien käyttämistä joustavista päätyrakenteista ja jonkin verran tietoa näiden komponenttien käyttöön liittyvistä asioista. Valmistajien mukaan kondensaattoreiden sähköiset ominaisuudet eivät muutu joustavan päätyrakenteen vuoksi, eivätkä niiden käyttösäännöt esim. komponenttilevyjen valmistuksessa poikkea tavallisista keraamisista pintaliitoskondensaattoreista.
Toisessa osassa esitellään projektin aikana tehdyt testit ja niiden tulokset. Testeihin valittiin viideltä valmistajalta joustavarakenteinen 1210-tyypin kondensaattori. Komponenteissa oli kahta eri elektrodityyppiä, joissa toisessa oli nikkelielektrodit ja toisessa hopeapalladiumelektrodit. Vertailukomponentteina käytettiin normaalirakenteista kondensaattoria kahdelta valmistajalta. Testilevynä oli FR-4 materiaalista tehty piirilevy, jolle liitettiin seitsemän eri komponenttityyppiä SMD-pintaliitoslinjalla. Lisäksi käytettiin vertailulevyjä, joihin komponentit liitettiin käsin juottamalla.
Testeissä osalle komponenttilevyistä tehtiin taivutustesti, jossa levyä taivutettiin kolmipistetaivutuksella 25 mm asti. Toisen ryhmän levyille tehtiin ensin lämpökosteustesti ja sen jälkeen lämpövaihtelutesti.
Tulosten mukaan joustava päätyrakenne parantaa keraamisen kondensaattorin taivutuskestoa merkittävästi. Lämpökosteus- ja lämpövaihtelutestissä ei saatu merkittäviä luotettavuuseroja joustavarakenteisten ja normaalin kondensaattorin välille. Hopeaa elektrodeissa ja päätymetalloinnissa sisältävät komponentit ovat luotettavuusriski kosteuden ja jännitteen vaikutuksen alaisena. Käsin juotetut komponentit olivat testeissä huonompia kuin koneellisesti ladotut ja juotetut komponentit.
262 RELIABILITY OF POLYMER MATERIALS (PORE)
PORE project was initiated to collect information of different polymers and their longterm reliability and behaviour in different environments. The aim was to create guidelines for non-material specialists to help in selecting polymer materials for their designs. Due to limited project resources, only a limited number of polymer materials could be selected for this study.
This handbook is the outcome of the project and presents some of the test results and information gathered during the project. The handbook was written by the project steering group members. The ageing tests and material characterization analyses were conducted at Trelic Ltd. Trelic participated also in the writing and editing of the handbook.
Polymers in general and some of the important properties are presented in chapter 4. The usual additives in polymers as well as common degradation mechanisms of polymers are also presented. There are also some guidelines for the polymer material selection.
Tested materials and tests are presented in chapter 5. Five polymer materials and their properties are presented. The materials are polyamide, polycarbonate, polyurethane, polybutylene terephthalate and expanded polypropylene.
The participating companies provided case examples for this project. High temperature and high humidity test was selected for an ageing method to those case samples. Two test conditions were chosen. 85 ºC/85 % RH or 65 ºC/90 % conditions were used depending on the tested material. Test duration was 2000 hours.
Different material characterization methods were used after ageing tests to study ageing behaviour of the selected polymers. Only some of those test results are presented. Most of the case specific results are reserved for the project member companies only and are not published in this handbook.
Different ageing tests are listed in chapter 6. Guidelines for choosing suitable tests and material characterization methods for different polymer types are given.