Components Margins through the Product Lifecycle

In complex products the values of parameters are rarely exactly the required values, rather they often have a margin that might be designed in deliberately or be the incidental results of other design decisions. These margins play a critical role in design processes in managing engineering change and iteration. While engineers often talk about margins informally, designers and researchers also use other terms for specific margin concepts. This paper reviews the existing literature on related concepts and defines margins formally. It discusses the role margins play in handling uncertainty by distinguishing between buffer and excess. Buffer deals with uncertainty and excess with the remaining overcapacity of the design. Buffer can transition into excess of the design solution if the uncertainty can be reduced. The concepts are applied to the temperature margins of several candidate materials for a non-rotary jet engine component. This shows that a clear understanding of margins can help a company to select design alternatives.

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“…Eckert et al. (2012) argue that margins therefore lie in the relationship of these three elements. De Neufville et al.…”

Section: Related Concepts In the Literaturementioning

confidence: 99%

“…In Eckert et al. (2012) a design margin is defined as ‘the extent to which a parameter value exceeds what it needs to meet its functional requirements regardless of the motivation for which the margin was included’.…”

Section: Definition Of Marginsmentioning

confidence: 99%

Design margins: a hidden issue in industry

2019

Self Cite

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“…Design margins is an overarching term that is used to describe the multiple contingencies added to the design or the design requirement during the design process to provide flexibility, resilience and safety (Eckert and Isaksson, 2017). Different terms, such as safety factor, excess or buffer are used to use to denote different purposes for the element of a design that exceeds the functional requirements (Eckert et al, 2013). While the term 'margin' is often used within companies in a number of industry sectors, particularly in the aerospace or ship building industry (Stratmann, 2006), it has so far not been formally defined.…”

Section: An Overview Of Design Marginsmentioning

confidence: 99%

Empowering Decision Makers to Avoid the Oversizing of Building Service Systems

Jones¹,

Eckert²

2019

Proc. Int. Conf. Eng. Des.

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Oversizing of building service systems has a direct impact on building efficiency and operational costs. The research of this paper highlights several major contributors to the issue of oversizing. A key factor is the excessive and uncoordinated application of design margins applied during the multiple stages of a building services project; others include, a lack of communication and transparency across the various stakeholder groups, and the use of vague or unreliable data upon which initial project requirements are based. The impact of these factors on system performance and cost, and how these can impede on a building's ability to meet energy efficiency targets are analysed and discussed.The paper emphasises the need to develop robust processes that capture the scope and rationale for the margins applied, and to communicate this knowledge in a clear and unambiguous format, to all project stakeholders. The development of flexible and alternative design solutions that apply diversity principles, such as different backup systems to provide resilience rather than the traditional ‘like-for- like’ redundancy solutions, are also explored.

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“…A useful definition of a design margin is: "the extent to which a parameter value exceeds what it needs to meet its functional requirements regardless of the motivation for which the margin was included" (Eckert et al, 2013), which are added by different stakeholders for a variety of reasons. In the context of mechanical engineering, design margins are added to provide flexibility; flexibility itself being defined as providing "functionality, performance, and capacity" each of which "consists of many attributes, which can also be thought of as requirements" (Banerjee and de Weck, 2004).…”

Section: Design Marginsmentioning

confidence: 99%

Margins Leading to Over-Capacity

Jones¹,

Eckert²,

Gericke³

2018

Design Conference Proceedings

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This paper categorises and describes the design stages, stakeholders and decision processes of an overcapacity boiler upgrade that came about from the excessive use of design margins. Using a hospital case study, the reason behind the overcapacity and excessive margins is explored using semi-structured interviews, document analysis and process modelling. Design margins arise from a lack of systemic thinking during the design and installation phases. It is likely that margins are added as a matter of habit with no real thought to their applicability, calling into question the design process.

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Components Margins through the Product Lifecycle

Cited by 13 publications

References 20 publications

Design margins: a hidden issue in industry

Design margins: a hidden issue in industry

Empowering Decision Makers to Avoid the Oversizing of Building Service Systems

Margins Leading to Over-Capacity

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