Toward cost-efficient tolerancing of 3D-printed parts: a novel methodology for the development of tolerance-cost models for fused layer modeling

Martin Roth,Andreas Giesert,Paul Schaechtl,Benjamin Schleich,Sandro Wartzack

doi:10.1007/s00170-021-08488-z

Abstract

Tolerance allocation methods significantly contribute to the qualification of Additive Manufacturing (AM) for (small-)series production ensuring high performance and efficiency. However, their usage prerequisites the availability of quantitative, reliable information on the impact of the assigned tolerances on the resulting manufacturing costs. The given article proposes a novel methodology for the systematic development of tolerance-cost curves for a cost-efficient tolerancing of 3D-printed parts. The proposed structured workflow aims at serving as a general guideline for both researchers and practitioners, while the exemplarily chosen perspective from Fused Layer Modeling (FLM) illustrates its adaption to a specific AM technology. The indirect, non-apparent interrelations between tolerances and resulting costs are modelled with the aid of an activity-based cost model, whereas the individual costs elements are mapped as function of the values for the machine-specific process parameters for AM, e.g., layer height or printing speed, which are required to achieve the assigned design tolerances. The total procedure covers all relevant steps, viz. the identification and quantification of the single cost items, the design of benchmark artifacts, adapted to given manufacturing and measuring techniques, the empirical determination of data on cost and geometrical accuracy by design of experiments and tolerance-cost curves. Its exemplary application to an academic use case shows its general applicability and benefits, but also its current limitations.

Highlights

Driven by the revolutionary idea of a manufacturing process that can rapidly produce any individualized part of unlimited geometrical complexity, the primary focus of Additive Manufacturing (AM) was initially on its application for industrial prototyping [1, 2]
The lack of current and accessible tolerance-cost data, serving as the basis to predict the effects of tolerance allocation on the resulting manufacturing costs by suitable cost models for AM, is critically recognized in literature [6, 7]
Access and availability to up-to-date tolerance-cost data are essential for an optimization-based allocation of costefficient tolerance values

Summary

Introduction

Driven by the revolutionary idea of a manufacturing process that can rapidly produce any individualized part of unlimited geometrical complexity, the primary focus of Additive Manufacturing (AM) was initially on its application for industrial prototyping [1, 2]. As a consequence of the continuous development and improvement of AM in terms of manufacturing techniques, machines and materials, its increased applicability nowadays enables the direct digital manufacturing of end use parts [2, 3]. The availability of quantitative, reliable information about the impact of the assigned tolerances on the resulting manufacturing costs is hereby a prerequisite for costefficient tolerancing [6]. A major obstacle in setting up reliable cost models for AM can be seen in the lack of structured approaches guiding the tolerance engineer through the various, interdisciplinary steps

Methods

Discussion

Conclusion