Multiple dependent state repetitive group sampling plan for Burr XII distribution

In material engineering application, the failure time of material due to weakness in material (fatigue) is usually caused by repeated variations of stress. The failure time is modeled by statistical distributions. In this article, an attribute multiple state repetitive group sampling plan is developed assuming that the life time follows the Burr Type XII distribution. The plan parameters are determined by considering two points on operating characteristic (OC) curve. Tables are given for the practical use. The advantages of the proposed plan are discussed over the single sampling plans. Examples are given to illustrate the proposed plan.     

The effects of inspection error on single sampling inspection plans

Acceptance sampling plans are designed under the assumption of perfect inspection. However, inspection tasks are not, even under ideal inspection conditions, free of error. In this paper we consider the effects of inspection error on probability of acceptance, average outgoing quality, and average total inspection. These measures are examined under both replacement and non -replacement assumptions. Also, a method is presented whereby an acceptance sampling plan may be designed which explicitly considers inspection error.     

A note on economic sampling inspection plans

The determination of economic sampling inspection plans is discussed. A computational procedure that allows beta prior information is outlined.     

Economic in-line inspection sampling strategy with learning effects

This paper presents an innovative approach to a wafer inspection strategy that incorporates learning dynamics in semiconductor manufacturing factories. Using the data from fabrication lines (fabs) we demonstrate algorithms for computing the sampling strategy in terms of the percentage of wafers to sample for a process in different phases of a product life cycle. The average selling price and wafer starts per weeks are considered in the model. The paper provides an optimal solution methodology and concludes that the learning benefits of quality control activities may achieve the most cost-effective operations.     

科学应用抽样检验标准

自关于抽样检验的国家标准ＧＢ２８２８～２８２９—８１发布实施后,目前已发布了２０多个有关抽样检验的国家标准,但科学地、正确地选用抽样检验标准,在实际运用中还存在一些问题。产品质量监督抽样检验标准的选用是其中典型的事例。根据有关法规赋予产品质量监督检验...     

浅谈家电产品监督抽查工作中的抽样环节

本文对监督抽查工作的定义及抽样要求进行介绍,通过对抽样环节中发现的问题进行分析,提出在新形势下做好抽样工作的建议。     

Automatic sampling for CMM inspection planning of free-form surfaces

Coordinate measuring machines (CMMs) are used to examine the conformity of the produced parts with the designer's intent. The inspection of free-form surfaces is a difficult process due to their complexity and irregularity. Many tasks are performed to ensure a reliable and efficient inspection using CMMs. Sampling is an essential and vital step in inspection planning. Efficient and reliable approaches to determine the locations of the points to be sampled from free-form surfaces using the CMM were developed. Four heuristic algorithms for sampling based on the NURBS features of free-form surfaces are presented. The sampling criteria are equiparametric, surface patch size and the surface patch mean curvature. An algorithm for automatic selection of sampling algorithms performs complexity checks on NURBS surfaces, including the surface curvature changes and surface patch size changes, and selects the suitable sampling algorithm. Extensive simulations were performed using the developed methodologies to evaluate their performance using free-form surfaces with different degrees of complexity and compared with the uniform sampling pattern. The CMM measurement errors and manufacturing form errors have been simulated in these studies. The developed algorithms provide a useful tool in selecting the effective sampling plans for the tactile CMM inspection planning of free-form surfaces.     

产品表面检测的变步长采样机制研究

针对产品表面缺陷检测系统中,由于定步长数据采集造成数据冗余量大、工作效率低的现象,提出变步长自适应的数据采集方式,以信号变化为采样依据实现调频。首先,基于采样步长的影响因素(乃奎斯特采样定理、识别尺寸、弧度畸变及空间畸变),推导出采样步长的函数关系表达式。其次,采用Matlab仿真平台,利用最小二乘法拟合,具体分析并验证被检产品各待检区域通过公式计算得到的采样步长均在95%的置信区间内。实验表明:推导出的采样步长公式为产品各待检区域旋转步长的合理选取提供理论依据;该模式可以根据不同信号实现频率自适应调节,可提高获取信息的利用率并减少数据冗余。     

Domain-specific Gaussian process-based intelligent sampling for inspection planning of complex surfaces

Precision measurement of complex surfaces requires intensive sampling for fully characterising the surface geometry and reducing the measurement uncertainty, which is, however, less efficient when the data are costly to acquire. This paper presents a Gaussian process (GP)-based intelligent sampling method for achieving well balance between the measurement efficiency and accuracy. The method makes use of GP to model the surface with domain-specific composite covariance kernel functions. The statistical nature of the GP makes it capable of giving credibility to the arbitrary prediction over the entire established model which can be used in a critical criterion to perform intelligent sampling of the surfaces. The method is independent from the coordinate frames, which makes the sampling plan easily utilised without accurate pre-positioning in actual measurement. The effectiveness of the method is verified through a series of comparison study and actual application in measuring a multi-scaled complex mould insert on coordinate measuring machine.     

A new inspection sampling plan under capacity constraints and multiple shifts

Various SPC models have been widely deployed in the quality control of different production systems. This paper considers a new design of SPC model with associated decision rules to control a process that produces items in finite lots and has a variance shift as well as a mean shift. Under both an inspection capacity constraint and a false alarm rate constraint, an inspection sampling plan that maximizes the yield of production is developed. Numerical examples are presented to illustrate and evaluate the approach. A semi-economic approach that computes the optimal quantity of inspection capacity is also presented.     

A resubmitted sampling scheme by variables inspection for controlling lot fraction nonconforming

The paper attempts to develop a resubmitted sampling scheme by variables inspection for controlling lot fraction nonconforming when the quality characteristic follows a normal distribution and has two-sided specification limits. In this paper, the plan parameters are determined by the classical two-point condition on the operating characteristic curve, which will satisfy the quality requirements and allowable risks by the producer and the consumer simultaneously. The behaviour of the proposed sampling plan is discussed and compared with the conventional single sampling plan by variables. The proposed plan requires smaller sample size for inspection with the same protection to the producer and the consumer especially when the quality of the submitted lot is good enough. Tables of the plan parameters under several selected quality requirements and risks are provided for practical applications, and the operating procedure is also presented and illustrated with an example.     

A successive sampling control chart using multiple dependent state sampling over two successive occasions

In this paper, successive sampling (SS) mean monitoring control chart is proposed for two successive occasions using multiple dependent state (MDS) sampling and characterized as MDS-SS control chart. The sample size is selected on the basis of SS for the control statistic in two pairs of the control limits. The average run length is evaluated, and the performance of the proposed concept over the existing SS control chart is presented using a real-life example. The SS monitoring chart concept is compiled with MDS, and it becomes more sophisticated in detection of warning signs.