ISSN:0748-8017    

DOI:10.1002/qre.4680080202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe product selected for detailed study was a cored grey iron disc, cast in a five cavity mould, subject to rejection at a highly variable rate. The behaviour of process variables in the sub‐systems of green sand, core making, metal pouring and metallurgical composition was analysed to detect any statistically significant correlations with the incidence of blisters, which was the predominant cause of rejection.To supplement the recorded data and to separate causal factors from correlations, a series of direct experimental trials was conducted to trace a faulty casting to the cavity, mould box, pouring conditions, green sand, cores and metallurgical composition pertaining at the time of actual production.From a progressively accumulated database of some 100 hours of the specific product runs, built up over several months, the production variables and responses were analysed using regression, ANOVA, correlation and factorial experimentation techniques. Three major interventions involving a change in bentonite supply and two modifications to the runner system were accompanied by a reduction of some 60 per cent in the mean level of blister rejects with an improved dispersio

ISSN:0748-8017    

DOI:10.1002/qre.4680080203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractFailure analysis of semiconductor components should not only be considered as an ever increasing costly activity which is economically difficult to support, to develop, and to justify, because of the continuous technology evolution. Analytical techniques such as integrated circuit pin‐to‐pin electrical test, plastic package opening with the acid dropper, hot spot detection with liquid crystals, EBIC, voltage contrast in static and voltage coding modes, can be developed and applied in failure analysis laboratories with low‐cost equipment. Although they are not intended to replace some well‐known expensive and sophisticated analytical tools, they can provide efficient

ISSN:0748-8017    

DOI:10.1002/qre.4680080204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper presents a case study that was initaated by excessive monitor failures occurring during a simulated early‐life test. Statistical analysis of the failure data suggested that there should be no longterm resistor failure problem. Large increases in resistance of some metal film resistors led to many of the monitor failures. Corrosion of the resistive film by residual chlorine for a particular resistor vendor's cleaning process was responsible. The results led to process changes to reduce the contamination and the reliability testing of the ‘new’ product revealed that the process changes were successful. A statistical designed experiment indicated that the ‘old’ resistors were not all degraded in the same manner. As a result of this experiment, the failures were attributed to poor process

ISSN:0748-8017    

DOI:10.1002/qre.4680080205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractIn this paper we investigate the use of the average unit run length (AURL) as an important measure of the effectiveness of various quality control charting schemes. In particular we focus on its appropriateness for normally distributed processes that tend to produce units (or measurements) at slow rates. In our investigations with the standard ShewhartX̄andRcharts, as well as the CUSUM chart, AURL shows that a sample size ofn=1 can yield the fastest means of detecting shifts

ISSN:0748-8017    

DOI:10.1002/qre.4680080206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMany standard texts on SPC offer simple procedures for setting up control charts. Although the procedures work well in some situations, there are many instances where the procedures do not produce useful charts. The failure to sustain SPC initiatives is often due to an over simplistic model of process variability.This paper examines the widely used procedures for setting up control charts and illustrates how these may fail when the process variability has certain characteristics. A more robust alternative procedure is examined in some detail. This involves taking a closer look at process variability and incorporating this with control chart design.

ISSN:0748-8017    

DOI:10.1002/qre.4680080207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper reviews the derivation and application of the reverse arrangement test which is used to assess whether a system has improved or deteriorated in a reliability sense. Because the well‐known and published table of statistics for this test is erroneous, the prime objective of this paper is to provide the correct statistical table. A secondary aim, however, is to demonstrate how this table can be applied when there is a paucity of failure data for each individual system and to show how a more meaningful reliability assessment can be obtained by pooling results, from the reverse arrangement test, for several system

ISSN:0748-8017    

DOI:10.1002/qre.4680080208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractAn age model is proposed for modelling imperfect repairable systems operating under a non‐homogeneous Poisson framework. The imperfect repair model investigated here effectively includes good‐as‐new, imperfect repair and bad‐as‐old regimes that have appeared separately in reliability engineering literature. To incorporate the impact of the equipment's operating environment, proportional intensities assumptions are integrated into the age model. Maximum likeihood estimates are derived for the parameters of

ISSN:0748-8017    

DOI:10.1002/qre.4680080209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0748-8017    

DOI:10.1002/qre.4680080210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0748-8017    

DOI:10.1002/qre.4680080211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY