Manufacturing Process Capability and Specification Limits

Möttönen, Merja; Belt, Pekka; Härkönen, Janne; Haapasalo, Harri; Kess, Pekka

doi:10.2174/1874152500801010029

Cited by 12 publications

(9 citation statements)

References 28 publications

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“…Process capability indices are used in the manufacturing industry to provide numerical measures on whether a process is capable of producing items within the predetermined specification limits [3]. The capability indices or process capability ratio is a statistical measure of process capability produce output within specification limits.…”

Section: Indices Of Capabilitiesmentioning

confidence: 99%

“…Data are plotted in time order. A control chart has a central line for the average, an upper line for the upper control limit (UCL) and a lower line for the lower control limit (LCL) [3]. In practice, specification limits USL and LSL are usually established by engineers and are not a function of the capabilities of the process.…”

Section: Control Chartsmentioning

confidence: 99%

“…The result is that it is impossible to make two completely identical products. In the production process are specified so called control limits [3]. Their overshoot may indicate an undesirable effect, which may result in a poor quality of product.…”

Section: Introductionmentioning

confidence: 99%

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Design of System for Evaluating and Sorting Products with Tools of Statistical Process Control

Hrehová¹,

Fechová²

2018

Proceedings of the 2nd EAI International Conference on Management of Manufacturing Systems

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An important aspect of the company's position on the market is its ability to declare and maintain the required level of production quality. The most widely used way of evaluating the achieved quality level is the tools and methods of statistical process control. The combination of these tools and current technologies to automated data collection enables a design of a system that would be able not only to graphically present the data of the monitored parameters but also to evaluate them. In the presented design of system is also considered a database block, whose task is to archive the results. Linking the database to the proposed system aims to assess the level of production quality achieved over the long term.

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Section: Indices Of Capabilitiesmentioning

confidence: 99%

Section: Control Chartsmentioning

confidence: 99%

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Design of System for Evaluating and Sorting Products with Tools of Statistical Process Control

Hrehová¹,

Fechová²

2018

Proceedings of the 2nd EAI International Conference on Management of Manufacturing Systems

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“…statistical process control (SPC) tools, measurement system analysis (MSA) tools, six sigma methods, Taguchi´s design of experiments [3].…”

Section: Process Variationmentioning

confidence: 99%

Capability studies, helpful tools in process quality improvement

Simion

2017

MATEC Web Conf.

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Abstract. Ability of processes to meet customer'quality requirements has become essential for providing competitive advantages such as cost savings, reducing the number of nonconfoming products or increasing customer satisfaction. This paper aims to conduct a capability study for a swaging process (that ensures an assembly dimension) of a key product characteristic (the outer diameter of a new part), related to the concept of capability and performance indices and how these metrics can be used and interpreted to become powerful tools for decision making. To achieve the goal of the paper, the following key aspects were analyzed: capability of the measurement system capability (gage R&R), production equipment (machine) capability and process capability/performance during the first serial production. The analysis was performed with Minitab® 17, the most commonly used software for quality improvement. Process variationAs a matter of fact, in any process, regardless of how well designed or carefully maintained it is, a certain amount of inherent or natural variability will always exist [1]. This type of variation is the cumulative effect of many small causes, named common, chance or random causes. These types of causes produce a consistent and predictable type of variation over time. A process that is operating with only common causes of variation present is said to be a stable process or in a state of statistical control. Sometimes, dominant sources of variation may appear, that are not part of the process and they are named as special or assignable causes. These types of causes are not predictable and are sporadic in nature.It is important to know what type of variation is present in a process, because the action one takes for the process improvement depends on the type of variation. If special causes of variation are present, they should be first identified and then eliminated; the next step is to reduce common cause of variation.Competitive companies understand that satisfying the needs of customers and running a successful operation requires processes that are predictable and consistent. The variation which is present in a process (whether it is a business or a manufacturing process) is the main cause of the quality problems, so measuring variability and finding ways to reduce it, is essential for the success of any company.

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“…The variation constrained or bounded by the tolerances also directly affect product performance and robustness of the design and poorly performing products will eventually lose their place in the market. The possibility of minimizing failure cost of electronic production processes by adjusting acceptance limits of such resulting product of the operation was analysed through simulation in [9].…”

Section: Introductionmentioning

confidence: 99%

Process Capability Analysis of a Centre Lathe Turning Process

Erameh¹,

Raji²,

Durojaye³

et al. 2016

ENG

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A process capability study is performed for the turning process on a general purpose center lathe in order to verify the process performance and machine ability to perform within specified tolerance limit. The process and machine capability indices were measured to determine the process and machine adequacy for industrial application. The tolerance limits were obtained from the given nominal size of the shaft, using the basic hole system and 90 sample shafts were turned on the lathe machine to specification for varying spindle speed and feed rate of the lathe. Three (3) samples were randomly selected for the turning process of a combination of the spindle speed and feed rate as a subgroup size for a total subgroup of thirty (30). The diameters (representing the quality characteristics) were used to generate control charts and capability histogram for the process. The process is within statistical control but found incapable of meeting up to specification because the capability index (Cp) measured was less than 1 and the machine capability for industrial application is not adequate.

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Manufacturing Process Capability and Specification Limits

Cited by 12 publications

References 28 publications

Design of System for Evaluating and Sorting Products with Tools of Statistical Process Control

Design of System for Evaluating and Sorting Products with Tools of Statistical Process Control

Capability studies, helpful tools in process quality improvement

Process Capability Analysis of a Centre Lathe Turning Process

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