Tolerance Specification and Related Issues for Additively Manufactured Products

2015 ◽  
Author(s):  
Gaurav Ameta ◽  
Paul Witherell ◽  
Shawn Moylan ◽  
Robert Lipman
Keyword(s):  
Free Form ◽  
Complex Geometries ◽  
Geometric Accuracy ◽  
Current State ◽  
Manufactured Products ◽  
Internal Cavities ◽  
Tolerance Specification ◽  
Functional Features ◽  
Traditional Manufacturing ◽  
Am Processes

Additive manufacturing (AM) has gained increased attention in the last decade as a versatile manufacturing process for customized products. AM processes can create complex free-form shapes, introducing features such as internal cavities and lattices. These complex geometries are either not feasible or very costly with traditional manufacturing processes. This creates new challenges in maintaining and communicating dimensional and geometric accuracy of parts produced. In order to manufacture a product that meets functional needs, the specification of those needs through geometry, material and tolerances is necessary. This paper surveys the current state and needs of geometry related accuracy specification mechanisms for AM, including a review of specification standards such as ASME Y14.5 and ISO 1101. Emerging AM-related tolerancing challenges are identified, and a potential plan of action is put forth for addressing those challenges. Various issues highlighted in this paper are classified as (a) AM-driven specification issues and (b) specification issues highlighted by the versatility of AM processes. AM-driven specification issues include build direction, layer thickness, support structure related specification, and scan/track direction. Specification issues highlighted by the versatility of AM processes include, region-based tolerances for complex freeform surfaces, tolerancing internal functional features, tolerancing lattice and infills. Basic methods of solving these specification issues are also highlighted.

Investigating the Role of Geometric Dimensioning and Tolerancing in Additive Manufacturing

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Gaurav Ameta ◽  
Robert Lipman ◽  
Shawn Moylan ◽  
Paul Witherell
Keyword(s):  
Additive Manufacturing ◽  
Tolerance Analysis ◽  
Geometric Accuracy ◽  
Geometric Dimensioning And Tolerancing ◽  
Dimensioning And Tolerancing ◽  
Internal Cavities ◽  
Functional Features ◽  
Traditional Manufacturing ◽  
Am Processes

Additive manufacturing (AM) has increasingly gained attention in the last decade as a versatile manufacturing process for customized products. AM processes can create complex, freeform shapes while also introducing features, such as internal cavities and lattices. These complex geometries are either not feasible or very costly with traditional manufacturing processes. The geometric freedoms associated with AM create new challenges in maintaining and communicating dimensional and geometric accuracy of parts produced. This paper reviews the implications of AM processes on current geometric dimensioning and tolerancing (GD&T) practices, including specification standards, such as ASME Y14.5 and ISO 1101, and discusses challenges and possible solutions that lie ahead. Various issues highlighted in this paper are classified as (a) AM-driven specification issues and (b) specification issues highlighted by the capabilities of AM processes. AM-driven specification issues may include build direction, layer thickness, support structure related specification, and scan/track direction. Specification issues highlighted by the capabilities of AM processes may include region-based tolerances for complex freeform surfaces, tolerancing internal functional features, and tolerancing lattice and infills. We introduce methods to address these potential specification issues. Finally, we summarize potential impacts to upstream and downstream tolerancing steps, including tolerance analysis, tolerance transfer, and tolerance evaluation.

Towards Multiscale Topology Optimization for Additively Manufactured Components Using Implicit Slicing

2017 ◽  
Author(s):  
John C. Steuben ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Topology Optimization ◽  
Complex Geometries ◽  
Generate Functional ◽  
Hand Tool ◽  
Macro Scale ◽  
Functional Features ◽  
Future Work ◽  
Functional Components ◽  
Am Processes ◽  
Meso Scale

Additive Manufacturing (AM) encompasses a set of fabrication technologies that are being used with increasing frequency in a wide variety of scientific and industrial pursuits. These technologies, which operate by successive additions of material to a domain, enable the manufacture of highly complex geometries that would otherwise be unrealizable. However, the material micro and meso-structures generated by AM processes differ remarkably from those that arise from conventional techniques and occasionally introduce unwanted functional features; this has been an obstacle to the use of AM in some applications. In the present work, we propose a multiscale method that utilizes the unique meso-scale structuring capabilities of implicit slicers for AM, in conjunction with existing topology optimization tools for the macro-scale, in order to generate functional components. The use of this method is demonstrated on the example of a hand tool. We discuss the applications of this methodology, its current limitations, and the future work required to enable its widespread use.

The Genres Of Myth, Legend And Narration’s Historical Destiny

2020 ◽  
Vol 02 (11) ◽  
pp. 301-308
Author(s):  
Bakhodir Mamajanovich Rakhmanov ◽  
Keyword(s):  
Current State ◽  
Functional Features ◽  
Performance Character

The article analyzes the current state and functional features of the genres of myth, legend and narrative in post folklore. Small genres of folk oral epic creation, such as myths, legends, and narratives, serve the function of providing artistic information to the listener. They do not have a special artistic form. In addition, these genres have a broad mass performance character and do not have special performers. Because myths, legends, and narratives are dominated by exaggerated fiction, exaggerated interpretation, real reality does not fit their imaginative capabilities.

scholarly journals Investigation of microstructure and hardness of a rib geometry produced by metal forming and wire-arc additive manufacturing

2018 ◽  
Vol 190 ◽  
pp. 02005 ◽  
Author(s):  
Markus Hirtler ◽  
Angelika Jedynak ◽  
Benjamin Sydow ◽  
Alexander Sviridov ◽  
Markus Bambach
Keyword(s):  
Additive Manufacturing ◽  
Metal Forming ◽  
Batch Size ◽  
Unit Costs ◽  
Batch Sizes ◽  
Traditional Manufacturing ◽  
Manufacturing Technologies ◽  
Forming Tools ◽  
Wire Arc Additive Manufacturing ◽  
Am Processes

Within the scope of consumer-oriented production, individuality and cost-effectiveness are two essential aspects, which can barely be met by traditional manufacturing technologies. Conventional metal forming techniques are suitable for large batch sizes. If variants or individualized components have to be formed, the unit costs rise due to the inevitable tooling costs. For such applications, additive manufacturing (AM) processes, which do not require tooling, are more suitable. Due to the low production rates and limited build space of AM machines, the manufacturing costs are highly dependent on part size and batch size. Hence, a combination of both manufacturing technologies i.e. conventional metal forming and additive manufacturing seems expedient for a number of applications. The current study develops a process chain combining forming and additive manufacturing. First, a semi-finished product is formed with forming tools of reduced complexity and then finished by additive manufacturing. This research investigates the addition of features using AlSi12 created by Wire Arc Additive Manufacturing (WAAM) on formed EN-AW 6082 preforms. By forming, the strength of the material was increased, while this effect was partly reduced by the heat input of the WAAM process.

Computation of Voxel Maps Containing Tool Access Directions for Machining Free-Form Shapes

1996 ◽  
Author(s):  
Johan W. H. Tangelder ◽  
Joris S. M. Vergeest ◽  
Mark H. Overmars
Keyword(s):  
Free Form ◽  
Geometric Accuracy ◽  
Surface Sampling ◽  
B Spline ◽  
Spline Surface ◽  
Surface Data

Abstract An algorithm that derives tool access directions for machining free-form shapes is presented. A free-form shape to be machined is given by a preliminary B-spline model. We allow that the B-spline surface data are as inaccurate as the user-selected geometric accuracy of the prototype to be machined. Using surface sampling a visibility voxel map is obtained. From this map a voxel map is derived that contains per voxel a set of tool access directions. From the obtained voxel map regions can be selected that can be machined with a fixed tool access direction per region.

scholarly journals Design Right Once for Additive Manufacturing

2018 ◽  
Vol 188 ◽  
pp. 03020
Author(s):  
Antonios Tsakiris ◽  
Christos Salpistis ◽  
Athanassios Mihailidis
Keyword(s):  
Additive Manufacturing ◽  
Weight Reduction ◽  
Variable Density ◽  
Free Form ◽  
Structure Generation ◽  
Innovative Design ◽  
Key Factor ◽  
Traditional Manufacturing ◽  
Manufacturing Technologies ◽  
Free Form Surfaces

Additive Manufacturing (AM) has been widely considered a key factor for innovative design. However, the utilization of AM has not been as high as expected, although the technology offers key innovative design capabilities, weight reduction, parts count and assembly consolidation as well as material saving. This low utilization is attributed to the lack of AM understanding, mature CAE/CAM software tools addressing AM specific issues such as design support structure generation and removal, residual stresses, surface quality. In most cases, Design for AM (DfAM) is a crucial requisite for a “Design Right Once” approach. Such an approach is shown in the current study using three parts as example: an arthropod’s leg, a gearshift drum and an electric motor mounting frame. The implementation of geometrical conformal lattice structures and lattices with variable density are discussed. A structured design approach is presented and design dilemmas are solved in terms of a DfAM approach. Primary design optimizations are evaluated. Weight reduction is considered throughout the design and free form surfaces are being used. “Freedom to Design” principle is also portrayed and assembly parts consolidation occurs as a natural process of DfAM in comparison with previous design practices. It is concluded that, even from the primary design phase the design engineer can reveal his creativity because of the absence of constraints set by the traditional manufacturing technologies.

A Tool Path Modification Approach to Cutting Engagement Regulation for the Improvement of Machining Accuracy in 2D Milling With a Straight End Mill

2007 ◽  
Vol 129 (6) ◽  
pp. 1069-1079 ◽  
Author(s):  
M. Sharif Uddin ◽  
Soichi Ibaraki ◽  
Atsushi Matsubara ◽  
Susumu Nishida ◽  
Yoshiaki Kakino
Keyword(s):  
Cutting Force ◽  
Case Studies ◽  
Tool Path ◽  
Free Form ◽  
Geometric Accuracy ◽  
End Mill ◽  
Workpiece Surface ◽  
Engagement Angle ◽  
Path Modification ◽  
Tool Path Modification

In two-dimensional (2D) free-form contour machining by using a straight (flat) end mill, conventional contour parallel paths offer varying cutting engagement with workpiece, which inevitably causes the variation in cutting loads on the tool, resulting in geometric inaccuracy of the machined workpiece surface. This paper presents an algorithm to generate a new offset tool path, such that the cutting engagement is regulated at a desired level over the finishing path. The key idea of the proposed algorithm is that the semi-finish path, the path prior to the finishing path, is modified such that the workpiece surface generated by the semi-finish path gives the desired engagement angle over the finishing path. The expectation with the proposed algorithm is that by regulating the cutting engagement angle along the tool path trajectory, the cutting force can be controlled at any desirable value, which will potentially reduce variation of tool deflection, thus improving geometric accuracy of machined workpiece. In this study, two case studies for 2D contiguous end milling operations with a straight end mill are shown to demonstrate the capability of the proposed algorithm for tool path modification to regulate the cutting engagement. Machining results obtained in both case studies reveal far reduced variation of cutting force, and thus, the improved geometric accuracy of the machined workpiece contour.

Additive Manufacturing Processes for Infrastructure Construction: A Review

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Abhinav Bhardwaj ◽  
Scott Z. Jones ◽  
Negar Kalantar ◽  
Zhijian Pei ◽  
John Vickers ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Construction Industry ◽  
Manufacturing Sector ◽  
Manufacturing Processes ◽  
Current State ◽  
Industry Applications ◽  
Am Processes

Additive manufacturing (AM) has had an enormous impact on the manufacturing sector. Its role has evolved from printing prototypes to manufacturing functional parts for a variety of applications in the automotive, aerospace, and medical industries. Recently, AM processes have also been applied in the infrastructure construction industry. Applications of AM processes could bring in significant improvements in infrastructure construction, specifically in the areas of productivity and safety. It is desirable to have a review on the current state of emerging AM processes for infrastructure construction and existing gaps in this field. This paper reviews the AM processes in infrastructure construction. It discusses the process principle, application examples, and gaps for each of the AM processes.

Incorporating Manufacturing Constraints in Topology Optimization Methods: A Survey

2017 ◽  
Author(s):  
Alok Sutradhar ◽  
Jaejong Park ◽  
Payam Haghighi ◽  
Jacob Kresslein ◽  
Duane Detwiler ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Optimization Methods ◽  
Manufacturing Processes ◽  
Complex Geometries ◽  
Manufacturing Constraints ◽  
Post Processing ◽  
Optimization Framework ◽  
Manufacturing Methods ◽  
Traditional Manufacturing

Topology optimization provides optimized solutions with complex geometries which are often not suitable for direct manufacturing without further steps or post-processing by the designer. There has been a recent progression towards linking topology optimization with additive manufacturing, which is less restrictive than traditional manufacturing methods, but the technology is still in its infancy being costly, time-consuming, and energy inefficient. For applications in automotive or aerospace industries, the traditional manufacturing processes are still preferred and utilized to a far greater extent. Adding manufacturing constraints within the topology optimization framework eliminates the additional design steps of interpreting the topology optimization result and converting it to viable manufacturable parts. Furthermore, unintended but inevitable deviations that occur during manual conversion from the topology optimized result can be avoided. In this paper, we review recent advances to integrate (traditional) manufacturing constraints in the topology optimization process. The focus is on the methods that can create manufacturable and well-defined geometries. The survey will discuss the advantages, limitations, and related challenges of manufacturability in topology optimization.

scholarly journals A review of recently developed polymer composite materials for fused deposition modeling 3D printing

2021 ◽  
Author(s):  
Surendra Singh Dewada ◽  
Amit Telang
Keyword(s):  
Polymer Nanocomposites ◽  
Fused Deposition Modeling ◽  
Mechanical Performance ◽  
Electrical Performance ◽  
Fused Deposition ◽  
Current State ◽  
Nano Clay ◽  
Functional Part ◽  
Deposition Modeling ◽  
Traditional Manufacturing

Abstract Additive Manufacturing (AM) is a rapidly evolving technology due to its numerous advantages over traditional manufacturing processes. AM processable materials are limited and have poor mechanical performance, restraining the technology's potential for functional part manufacturing. Although FDM is the most popular and growing technique, the inferiority of the material limits its application to prototyping. Nanocomposite material improves the thermal, mechanical, and electrical performance of FDM objects. Mostly polymer nanocomposites are feasible to process and several researchers have reported enhanced performance with polymer nanocomposites. Carbon nanotubes, graphene nanoplatelets, nano clay, and carbon fiber are primary reinforcements to thermoplastics. The current state of the art relevant to advances in nanocomposites for the FDM process, as well as the influence of nanofillers on mechanical properties of the build object are reviewed in this paper.

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