ISO 22514-8:2014 过程管理中的统计方法 能力和性能 第8部分：多状态生产过程的机械性能

标准编号：ISO 22514-8:2014

中文名称：过程管理中的统计方法 能力和性能 第8部分：多状态生产过程的机械性能

英文名称：Statistical methods in process management — Capability and performance — Part 8: Machine performance of a multi-state production process

发布日期：2014-06

标准范围

This part of ISO 22514 aims to define the evaluation method to quantify the short-term capabilityof a production process (capacity of the production tool, widely termed capability), i.e. the machineperformance index, to ensure compliance to a toleranced measurable product characteristic, when saidprocess does not feature any kind of sorting system.If the production process integrates a sorting system, then this one (clearing away nonconforming parts)should be analysed independently.This part of ISO 22514 does not aim to define evaluation methods of the capability of a production processthat is gauged through long-term observation (capability process or performance process indices).This part of ISO 22514 defines— the principles guiding the development of indicators for quantifying capability, and— the statistical methods to be employed.The characteristics used to evaluate production process capability have statistical distributions, and itis presumed, a priori, that at least one of these distributions is multi-modal. A distribution is presumedto be multimodal if it results from the marked effect of at least one cause inducing a significant differencebetween the produced items.This part of ISO 22514 applies, for example, to characteristics generated by processes such as thefollowing:— multi-cavity casting: simultaneously producing several identical parts from a mould featuringseveral cavities.Since each cavity has its own geometry and its own position in the mould architecture, it can createa systemic difference on the output result;— multi-fixture machining: a part produced at the same time, but the produced parts are positioned inrelation to the production tool by different fixture systems.Since each fixture has its own geometry, mount clamps, etc., it can create a systematic difference onthe output result;— batch load treatments: heat treatment applied at the same time on a set of identical parts (the batchload), distributed within a pre-defined space of furnace. The position of an item of the batch relativeto the furnace can influence the output result.Each cavity, fixture, or position in the batch load corresponds to a different state. The multi-stateprocess can be understood as the result of the combination of different states within the same process(e.g. cavity, fixture, position in the batch load).NOTE It needs to be ensured that such systematic differences, if any, constitute only a very small proportionof permissible error so that their impact is harmless and do not affect the capabilities of the process.

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