Falke A (2025)
Publication Language: English
Publication Type: Book chapter / Article in edited volumes
Publication year: 2025
Publisher: VDI Verlag
Edited Volumes: PIAE EUROPE 2025
Series: VDI-Berichte
City/Town: Düsseldorf
Book Volume: 2446
Pages Range: 575-618
ISBN: 978-3-18-092446-5
DOI: 10.51202/9783181024461-575
In the development process of any component, the permissible dimensional deviations from the nominal geometry are defined in the form of tolerances (functional limits) in order to ensure the functional fulfillment of the components despite unavoidable manufacturing deviations and inaccuracies. The smaller or narrower these defined tolerances are, the greater the manufacturing effort required to produce the component, e.g. due to more precise, time-consuming and cost-intensive manufacturing processes, increased inspection and reworking effort and the greater number of optimization loops until release for series production which lead to longer project lead times. It is therefore essential to strike a reasonable balance between reliable functional fulfillment and cost expenditure, in line with the motto "as precise as necessary and as imprecise as possible". It is a question of guaranteed functional fulfillment at minimum cost. In an analysis of 150 specifications for technical plastic components (technical drawings) produced by injection molding, the degree of accuracy of the required tolerances was determined using the plastics standard ISO 20457. It also classifies the manufacturing effort required to produce components with this degree of accuracy, while taking material and process influences into account. As a result of this requirements analysis, it was possible to quantify a high degree of accuracy and, in most cases, very tight tolerance requirements. The majority of the tolerance requirements can only be achieved with increased manufacturing effort in the injection-molding process. In addition, plastic-specific material properties (e.g. flexibility, shrinkage) are often not sufficiently taken into account when specifying technical components, with the result that tolerances are specified that are too tight and in some cases cannot be manufactured according to today's generally recognized state of the art. If plastic-specific properties such as flexibility (ISO 10579) are taken into account and a comprehensive functional analysis is carried out during the development process, such tight tolerances are often not even necessary for fulfillment of the function. From an economic point of view, the definition of appropriate tolerances has a decisive influence on the manufacturing costs of a plastic part. The analysis data obtained with such tight tolerance requirements, and the resulting high manufacturing effort and therefore high manufacturing costs, result in a gigantic savings potential for the production of all plastic molded parts. The aim is to identify and quantify this savings potential. A methodology is presented that can be used to determine the costs associated with increased precision requirements. An analysis of the entire design and manufacturing process of a plastic molded part is used to determine where costs occur due to tolerances and what are the major cost drivers associated with precision requirements. A procedure for collecting the cost data for various components is presented to quantify the cost of a toleranced dimension in a component specification and the potential savings from avoiding tight tolerances. Finally, a model for predicting the cost effects of tolerances on plastic components will be developed, which can with a small amount of input data determine a cost factor for the additional costs per higher accuracy class of the tolerance requirements. The model will be used to predict, at an early stage in the development process, how much more expensive the production of the component will be due to dimensions with excessively tight tolerances, and what additional costs will result from the resulting higher production and inspection costs.
APA:
Falke, A. (2025). Method for determining the cost impact of tolerances on plastic components – How much does accuracy cost? How much does precision cost in the injection-molding process? In VDI Wissensforum GmbH (Eds.), PIAE EUROPE 2025. (pp. 575-618). Düsseldorf: VDI Verlag.
MLA:
Falke, Anja. "Method for determining the cost impact of tolerances on plastic components – How much does accuracy cost? How much does precision cost in the injection-molding process?" PIAE EUROPE 2025. Ed. VDI Wissensforum GmbH, Düsseldorf: VDI Verlag, 2025. 575-618.
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