Geometrical Product Specification Research Articles

Overview of Principles and Rules of Geometrical Product Specifications According to the Current ISO Standards

The article provides an overview of the philosophy of geometrical product specifications (GPS), which are, in addition to material specifications, a key component of effective planning and production of mechanical products as well as communication between partners in these processes. The principles and basic rules for precise and unambiguous specification of all requirements are embodied in a series of ISO GPS standards. It includes standards that describe the required accuracy of geometrical features of size and geometrical tolerances. An overview of the fundamental principles and rules imposed by the current ISO GPS standards and their content was carried out. This includes a description of the organization of the ISO GPS system and a summary of the content of the more relevant standards, which have recently undergone multiple revisions. The ISO GPS standards are based on the duality principle of specification and verification. In the present research, we focused primarily on geometrical specifications, while omitting the parallel pillar of verification, which, according to the ISO GPS matrix model, contains an even greater number of standards that define this area in more detail.

GPS-navigator: an advanced search engine to gather information and navigate through standards in the field of geometrical product specification

GPS-navigator: an advanced search engine to gather information and navigate through standards in the field of geometrical product specification

Handling the Functional Features of Accelerator Components Using ISO GPS Situation Features

The building blocks of a scientific facility based on particle beams comprise magnets and electro-magnetic devices. The optical design usually imposes a demanding accuracy with respect to their theoretically exact position and orientation. It happens that the functional features are either not clearly defined – what is the « axis » of a magnet –, or not explicitly used along their lifecycle. Improving how to handle these functional features would contribute to meeting demanding challenges. The European Spallation Source (ESS) is aiming at providing a powerful proton linear accelerator and a target system to produce pulsed neutrons. The challenging complex design and integration yielded to introducing a tool shared in common by all stakeholders along the lifecycle: the “situation features”, as defined in ISO GPS (Geometrical Product Specifications) standards. They are here developed, and extended to beyond-mechanics use cases. Two examples of fiducialization and installation phases are presented for neutron beam guides and quadrupole magnets. Perspectives of generic use are also highlighted.

Evaluation of Students’ Measuring Capability in the Dimensional Control Laboratory Using R&R Procedure by Variables

Abstract The curriculum of technical bachelor programs often focuses on various theories in order to emphase understanding but there is also an actual need to provide the students with specific technical skills. This paper presents an effective means to evaluate the students’ capability to measure geometrical product specifications namely the procedure of Repeatability and Reproducibility by variables. The measurement results were processed using MINITAB statistical software with its module called Gage R&R Study. The conclusion was that the analyzed measurement system is excellent.

Optimization of 3D Tolerance Design Based on Cost–Quality–Sensitivity Analysis to the Deviation Domain

Under the new geometric product specification (GPS), a two-dimensional chain cannot completely guarantee quality of the product. To optimize the allocation of three-dimensional tolerances in the conceptual design stage, the geometric variations of the tolerance zone to the deviation domain will be mapped in this paper. The deviation-processing cost, deviation-quality loss cost, and deviation-sensitivity cost function relationships combined with the tolerance zone described by the small displacement torsor theory are discussed. Then, synchronous constraint of the function structure and tolerance is realized. Finally, an improved bat algorithm is used to solve the established three-dimensional tolerance mathematical model. A case study in the optimization of three-part tolerance design is used to illustrate the proposed model and algorithms. The performance and advantage of the proposed method are discussed in the end.

Perpendicularity assessment and uncertainty estimation using coordinate measuring machine

The validation of the conformity of parts according to the ISO 98-4 standard, cannot be achieved without an accurate estimation of the measurement uncertainty, which can become difficult when it comes to a complex measurement strategy to control a geometrical specification of a mechanical part using a Coordinate Measuring Machine (CMM). The purpose of the study in this paper is to analyze the measurement strategy following the Geometric Product Specification (GPS) Standard, to estimate the associated uncertainty of the different parameters of each step, to be able to achieve the uncertainty of the measurement of a given specification (perpendicularity error in our study) using the Guide to the expression of uncertainty in measurement (GUM). This uncertainty will be thereafter validated by a Monte Carlo simulation, and an interlaboratory comparison will be conducted to compare the obtained results according to the ISO 13528 standard. Our contribution is based on a more accurate estimation of the measurement strategy's parameters uncertainties. This approach can also be used by accredited calibration laboratories (ISO 17025) or in the general case in the control of perpendicularity specification of mechanical parts using a coordinate measuring machine. A case study has been conducted, controlling a perpendicularity specification with a tolerance limit of 15 µm, after the calibration of the CMM to obtain the variance-covariance matrices. The mechanical part perpendicularity error (12.55 µm) was below the limit, however, was judged “not conform” when considering the estimated uncertainty (4.06 µm) and the interlaboratory comparison was satisfactory despite the difference of the acceptance criterion.

Towards a Definition of “Geometric Verification Specifications” Within the ISO GPS System

The primary scope of tolerancing is to ensure functional requirements will be met by specifying geometrical tolerances. The duality principle, described within the ISO Geometrical Product Specification (GPS) standards, presents a perspective where the verification conceptually mirrors the specification. While this is a valuable model, further refinement is required to accommodate the different aims of inspection in support of the manufacturing process. This work aims to elaborate on the concept of a "geometrical verification specification" that is subordinate to the functional and/or manufacturing specifications. This verification specification may evolve as additional knowledge of the manufacturing process and inspection resources becomes available. A well-formed geometric verification specification should facilitate an appropriate inspection by any qualified operator, which in turn assures comparable measurement results across multiple instruments and facilities.

Estimation of parallelism measurement uncertainty according to the Geometrical Product Specifications standard using coordinate measuring machine

The dimensional and geometrical specifications control of a mechanical part is commonly done using a coordinate measuring machine. Collecting and processing measurement data through a probe, it allows measuring the conformity of the part according to specific tolerances. An accurate estimation of the uncertainty of measurement is critical; it is within this framework that our study is oriented; we aim to estimate the measurement uncertainty of parallelism error using the Guide to the Expression of Measurement Uncertainty (GUM), then we will proceed to a Monte Carlo simulation to compare the obtained uncertainty, we will then proceed to an inter-laboratory comparison to validate our model. Our contribution is based on a more detailed and precise estimation of the uncertainties of the measurement process taking into accounts the calibration of the machine and the propagation of uncertainties.

Use of geometrical product specifications in the structural design of second generation bearing hub unit

The article discusses selected issues of the application of ISO GPS standards and their use in defining the specifications of designed products. Their importance in meeting the functional requirements specified by the designer and expected by the user is highlighted. This was presented on the example of a comparative analysis of the design of a second-generation composite bearing hub, which is a modification of a double-race angular contact ball bearing. A comparison of the ways in which the requirements of the more important dimensions are specified was made according to ISO 492:2002 and ISO 492:2014. Verification of the requirements description according to the GPS will be carried out during the manufacturing process of the bearing hub unit.

Virtual task-specific measurement uncertainty determination for laser scanning

The framework of the Geometrical Product Specification defines the nominal geometry of the components and the characteristic tolerances. Various ISO standards describe the nine defined geometrical properties per characteristic of a workpiece. To prove conformance to the task specific tolerances according ISO 14253–1, the uncertainty budget needs to be determined. This paper presents a digital twin of an optical measurement system as a holistic concept to perform the task specific uncertainty determination. Different measurement strategies are applied to illustrate their effect on the measurement uncertainty of geometrical properties. Not all geometrical properties are relevant for an optical measurement system. Therefore, the discussed properties as a function of the optical measurement strategy in this paper are: size, distance, form and orientation.

Tolerance analysis method considering multifactor coupling based on the Jacobian–torsor model

Assembly quality affects the performance of mechanical products and reasonable tolerance designs are central to assembly quality. Unreasonable tolerance design leads to the mechanical equipment performance degradation under complex operating conditions. This study developed a novel tolerance analysis method that considers the influence of temperature, load, and other environmental factors based on the Jacobian–torsor and skin models. First, the deformation caused by multifactor coupling was analyzed using the finite element method, and the feature surface of deformation is extracted. Second, the deformation extraction and tolerance conversion based on the new generation geometrical product specification theory was used to convert the deformation of the feature into the dimension, orientation, and form tolerance. Third, the modified Jacobian–torsor model considering multifactor coupling was constructed by superimposing the converted tolerance with the design tolerances. Finally, the abrasion problem of the airborne actuator was considered as an example to verify the effectiveness and accuracy of the novel method. Through the accurate calculation of tolerances, it accurately analyzes the assembly state of the product under the influence of environmental factors, and provides more accurate guidance for the design and optimization of product tolerance in complex working conditions.

A statistical approach in the FEM simulation analysis of geometrical product specification during the cold tube drawing process

The cold drawing process produces high-quality tubes with precise dimensions, good surface quality, and higher strength due to cold forming. The tube drawing is used to reduce the cross section of the produced tubes. Depending on the reduction size, the outer diameter and wall thickness of the final tube changes. Due to the fact that cold drawing of tubes is mostly the last operation of production, it is necessary to pay attention to the process parameters and geometry of the forming tools. This paper presents a statistical evaluation of the influence of the wall thickness of the pre-tube, die diameter, and pre-tube diameter on the measured responses, which were the outer diameter and wall thickness of final tube, after the FEM simulations of the drawing process. For these purposes, a factorial design with three input factors was implemented. The goal of using the simulations was also to investigate whether the single-pass type of tube drawing would guarantee useful statistical results that could lead to significant time and cost reductions. The FEM simulations were executed using DEFORM software of Scientific Forming Technologies Corporation with Design of Experiment application module of this software. A factorial design of experiment has been processed in Minitab v. 17 software. The results show that most of the factors significantly influenced the response variables.

GPS Application in the Design of Gearboxes

Abstract The integrated geometrical product specification (GPS) system for workpiece geometry specification and verification is an improved engineering tool for product development and production. The goal of the GPS system is to provide tools for cost-effective management of variability in products and processes. This can be achieved by using a more precise way of expressing the functional requirements of the workpiece, complete and well-defined specifications and integrated verification approaches. The intended function of the product is ensured by controlling the geometry and material properties of the workpiece parts, which make up the product. GPS is a language just for checking geometry, and further development is based on computational mathematics and correct, consistent logic using general sets of rules that can be applied to all types of specifications. This article deals with the application of GPS rules in the design of gearboxes.

Application of Geometric Product Specifications on gearbox component drawings

Technical documentation of individual gearbox components is an important part of the production process. For the development and production of these components, an improved engineering tool is used to specify and verify the geometry of the workpiece - Geometrical Product Specifications (GPS) system. This system is intended only for checking geometry and is based on computational mathematics and correct, consistent logic using general sets of rules. This paper is devoted to the application of geometric tolerances used in drawings to components of gearboxes, such as gearbox bodies, shafts, covers, and gears.

Discussion on Fast Calibration Method of Coordinate Measuring Machine

This article presents a novel design of a device with simple structure, convenient operation and stable performance for fast calibration of coordinate measuring machines (CMMs). The purpose of the design is aiming at the solving the problems of long timeconsuming, high cost and high requirements for calibration personnel during the traditional calibration process of CMMs. The technical specifications of the designed calibration device complies with ISO 10360-2-2009 Geometrical Product Specifications (GPS)-Acceptance and reverification tests for coordinate measuring machines (CMM)-Part 2: CMMs for measuring linear dimension and ISO 10360-5-2020 Geometrical Product Specifications (GPS)-Acceptance and reverification tests for coordinate measuring machines (CMM)-Part 5: Coordinate measuring machines (CMMs) using single and multiple stylus contacting probing systems using discrete point and/or scanning measuring mode. The device can complete the calibration of the CMMs quickly, obtain the size error and probing error of the CMM in a short time, and provide data support for users to determine whether the CMM meets the application requirements.

A Statistical Approach in the Analysis of Geometrical Product Specification during the Cold Tube Drawing Process

Cold tube drawing provides higher accuracy compared to hot approaches. The process can be used to reduce the dimensions of tubes, and depending on the reduction size, the wall thickness of these may be subject to changes. In the process, any form of variability provoked by external factors is highly sensitive, given that the resulting tubes are often the final step in tube production. This paper focused on the evaluation of the influence of pre-tube factors on key variables after the drawing process, i.e., the final roundness, outer diameter, and wall thickness of the tubes. For these purposes, a factorial design with fixed factors was implemented. It was also a goal to investigate if the single-pass type of drawing would guarantee good statistical results potentially leading to significant time and financial reductions. The measurements were executed in the machine ZEISS CenterMax. The statistical analysis took place on Minitab 19. The results prove that most factors, and their interactions, significantly impacted the response variables, leading the authors to understand that a single-pass approach would not properly work under the conditions defined for the experimentation. These results also allow for reflection on the causes and necessary measures related to lubrication, technological heritage, and quality that would impact the results themselves.

Geometric deviation modeling for single surface tolerancing using Laplace-Beltrami Operator

ISO standards on geometrical product specifications and verification (GPS) categorize the geometrical features partitioned from shapes based on their kinematic invariance classes. As a key issue to achieve predictable and interchangeable shape, geometrical tolerancing defines the tolerance zone within which the partitioned features shall be contained for dimensional and geometrical accuracy. However, most of the current research activities consider the geometrical features as orientation and position deviations of substitute ideal surfaces and neglect form errors within the developed models. In order to enhance the tolerance analysis and simulation, the concept of Skin Model Shapes (SMS) is therefore proposed to represent surface deviations in accordance with random nature of geometric deviations. In this paper, a new approach based on spectral analysis is proposed for SMS generation on mechanical parts. The Eigen-system of Laplace-Beltrami Operator (LBO) enables shape analysis with an unambiguous mathematical language due to its invariance of the position and orientation. The SMS generation process is completed with LBO by developing a modeling methodology for geometric deviation representation and generation on single surfaces in the design process. The obtained spatial frequency LBO decomposition on the single surface of invariant class is used to represent the statistical characteristics of the deviations and further used to reproduce deviations with similar distributions. A comparison is presented in the paper to illustrate the difference between a conventional Discrete Cosine Transform (DCT) based method and the proposed LBO-based method. Another case study is investigated to explain the implementation of the proposed method on different types of single surfaces of invariant class generation based on SMS.

Evaluation of relations and accumulations of geometrical deviations in multi-stage manufacturing based on Skin Model Shapes

The inevitable existence of variations in manufacturing processes leads to deviations in the geometrical result of the manufactured products. As a result, every part produced is shaped uniquely regarding its geometrical properties and has both systematic and random deviations. In addition, local and global deformations can have a significant impact on product quality and lead to complex relationships between deviations. Furthermore, the deviation accumulations occurring in multi-stage manufacturing must be considered in the tolerance procedures. Existing methods, especially in manufacturing tolerancing, assume certain simplifications, so that comprehensive evaluation and integration, as well as their complete metrological verification are hindered.This paper presents a method that considers manufacturing variations separately for each process step and accumulates the resulting geometrical deviations, based on the extension of established methods for Skin Model Shapes. The relationship between deviations and their accumulation can be quantified, which provides essential knowledge especially for manufacturing tolerancing. In addition, it complies with Geometrical Product Specifications and Verification Standards, which offers considerable benefits for geometric variation management during the whole product life cycle. Finally, a case study is presented to illustrate the approach.

Towards a Mathematical Definition of Skin Model for Geometrical Product Specification and Verification and its Physical Interpretation

The concept of skin model is a foundation stone for ISO standards in Geometrical Product Specifications and Verification. At the conceptual level, it provides an abstraction of the physical part denoting the boundary which separates the part's physical shape from its environment. It conveys the designer's perception of potential defects and deviations from a nominal geometry, which can only be hypothesized. Considered as a surface on the boundary of a solid model of non-ideal geometry, which can only be imagined, the ‘skin’ can take an unrestricted variety of forms and representations at different scales. Despite its conceptual relevance, only a few research efforts have been devoted to a formal characterization of the skin model based on a sound mathematical definition supporting an appropriate and relevant physical interpretation. The work presented in this paper proposes new scientific foundations of the skin model based on the structure of solids as a compact packing of spheres characterized by Van der Waals radii. This physics-based description is extended and supported by mathematical models based on regular sets and morphological operations, which provide a set of conditions and properties that enable a physical interpretation in the context of mechanical parts and their measurements.

Data-driven deviation generation for non-ideal surfaces of Skin Model Shapes

The digitalization techniques enable quality control as well as performance simulation of mechanical products in the Digital Twin era. In the product design process, realistic models regarding surface geometrical deviations are essential for further functional analysis. In the context of ISO standards on geometrical product specifications and verification (GPS), the Skin Model Shapes (SMSs) concept stemmed from the Skin Models paradigm is put forward to represent deviations of mechanical parts in accordance with the nature of geometric deviations on the surfaces. Contributions have been made to generate SMSs by combining both systematic deviations and random deviations on the nominal model. However, the non-ideal surface generation process is limited by the reuse of geometric deviation’s knowledge. Existing geometric deviations that are predicted or observed on the parts cannot be applied for other SMSs generation without new parameter settings using different methods. In this paper, a framework for data-driven geometric deviation generation is proposed for non-ideal surface modeling in tolerancing. A database that contains a variety of deviations generated by different methods is constructed. Deviations that are classified as systematic and random types are represented and stored as samples in the dataset. Deviation pattern identification is addressed by transfer learning using AlexNet and it is used for different types of non-ideal surface generation. Different approaches regarding both prediction and observation stage within SMS schema are included for constructing the deviation samples. The mapping process for both systematic and random deviation samples are considered. Therefore, there is no need to re-design deviations with parameters for the surfaces. A case study is used to illustrate the non-ideal surface generation process by the propose method.