Manufacturing Signature for Tolerance Analysis

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Polini Wilma ◽  
Moroni Giovanni
Keyword(s):  
Sensitivity Analysis ◽  
Manufacturing Process ◽  
Tolerance Analysis ◽  
Variational Model ◽  
Form Tolerance ◽  
Systematic Pattern

Every manufacturing process leaves on the surface a signature, i.e., a systematic pattern that characterizes all the features machined with that process. The present work investigates the effects of considering the manufacturing signature in solving a tolerance stack-up function. A new variational model was developed that allows to deal with the form tolerance. It was used to solve a case study involving three parts with or without considering the correlation among the points of the same surface due to the manufacturing signature. A sensitivity analysis was developed by considering different values of the applied geometrical tolerances.

Process Signature Modeling for Tolerance Analysis

2010 ◽  
Vol 10 (2) ◽  
Author(s):  
R. Ascione ◽  
W. Polini ◽  
Q. Semeraro
Keyword(s):  
Concurrent Engineering ◽  
Manufacturing Process ◽  
Tolerance Analysis ◽  
Actual Surface ◽  
Contact Points ◽  
Geometric Tolerances ◽  
Systematic Pattern ◽  
Process Signature ◽  
Nominal Surface

Many well-known approaches exist in the literature for tolerance analysis. All the methods proposed in the literature consider the dimensional and the geometric tolerances applied to some critical points (contact points among profiles belonging to couples of parts) on the surface of the assembly components. These points are generally considered uncorrelated since the nominal surface is considered. Therefore, the methods proposed in the literature do not consider the actual surface due to a manufacturing process. Every manufacturing process leaves on the surface a signature, i.e., a systematic pattern that characterizes all the features machined with that process. The aim of the present work is to investigate the effects of considering the manufacturing signature in solving a tolerance stack-up function. A case study involving three parts has been defined and solved by means of a method of the literature, the variational method, with and without considering the correlation among the points of the same surface due to the manufacturing signature. This work represents a first step toward the integration of the design and the manufacturing in a concurrent engineering approach.

A Method for Integrating Form Errors Into Geometric Tolerance Analysis

2005 ◽  
Author(s):  
Robert Scott Pierce ◽  
David Rosen
Keyword(s):  
Manufacturing Process ◽  
High Speed ◽  
Tolerance Analysis ◽  
Analysis Model ◽  
Geometric Tolerance ◽  
Form Errors ◽  
Product Function ◽  
Component Models ◽  
Insight Into

In this research we describe a computer-aided approach to geometric tolerance analysis for assemblies and mechanisms. This new tolerance analysis method is based on the “generate-and-test” approach. A series of as-manufactured component models are generated within a NURBS-based solid modeling environment. These models reflect errors in component geometry that are characteristic of the manufacturing processes used to produce the components. The effects of different manufacturing process errors on product function is tested by simulating the assembly of these imperfect-form component models and measuring geometric attributes of the assembly that correspond to product functionality. A tolerance analysis model is constructed by generating-and-testing a sequence of component variants that represent a range of manufacturing process capabilities. The generate-and-test approach to tolerance analysis is demonstrated using a case study that is based on a high-speed stapling mechanism. As-manufactured models that correspond to two different levels of manufacturing precision are generated and assembly between groups of components with different precision levels is simulated. Misalignment angles that correspond to functionality of the stapling mechanism are measured at the end of each simulation. The results of these simulations are used to build a tolerance analysis model and to select a set of geometric form and orientation tolerances for the mechanism components. It is found that this generate-and-test approach yields insight into the interactions between individual surface tolerances that would not be gained using more traditional tolerance analysis methods.

scholarly journals To model bolted parts for tolerance analysis using variational model

2015 ◽  
Vol 4 (1) ◽  
pp. 139 ◽  
Author(s):  
Wilma Polini ◽  
Massimiliano Marziale
Keyword(s):  
Contact Surface ◽  
Tolerance Analysis ◽  
Variational Model ◽  
Solid Model ◽  
Functional Requirements ◽  
Form Errors ◽  
Proposed Model ◽  
Mechanical Products ◽  
Planar Contact

Mechanical products are usually made by assembling many parts. Among the different type of links, bolts are widely used to join the components of an assembly. In a bolting a clearance exists among the bolt and the holes of the parts to join. This clearance has to be modeled in order to define the possible movements agreed to the joined parts. The model of the clearance takes part to the global model that builds the stack-up functions by accumulating the tolerances applied to the assembly components. Then, the stack-up functions are solved to evaluate the influence of the tolerances assigned to the assembly components on the functional requirements of the assembly product.The aim of this work is to model the joining between two parts by a planar contact surface and two bolts inside the model that builds and solves the stack-up functions of the tolerance analysis. It adopts the variational solid model. The proposed model uses the simplified hypothesis that each surface maintains its nominal shape, i.e. the effects of the form errors are neglected. The proposed model has been applied to a case study where the holes have dimensional and positional tolerances in order to demonstrate its effectiveness.

A Geometric Model for Tolerance Analysis with Manufacturing Signature and Operating Conditions

2019 ◽  
Vol 9 (3) ◽  
pp. 1-13
Author(s):  
Wilma Polini ◽  
Andrea Corrado
Keyword(s):  
Concurrent Engineering ◽  
Manufacturing Process ◽  
Geometric Model ◽  
Tolerance Analysis ◽  
Operating Conditions ◽  
Geometric Reasoning ◽  
Assembly Sequence ◽  
Turning Process ◽  
Engineering Approach

In this work, a geometric model for tolerance analysis has been carried out. Geometric reasoning has been implemented in the model to simulate the manufacturing process and, then, the assembly sequence. The proposed geometric model has been applied to a case study consisting of two circular profiles due to the turning process, and a hollow rectangular box. The two circular profiles have been assembled inside the box by considering the gravity, and the friction among the parts and the actual points of contact with and without using the manufacturing signature. Matlab® software has been used to implement the geometric model for tolerance analysis. The results have been compared with those obtained by using a literature model with and without considering the manufacturing signature. This work aims to be a first step towards the integration of the design and the manufacturing in a concurrent engineering approach.

scholarly journals Sensitivity analysis for interpretation of machine learning based segmentation models in cardiac MRI

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Markus J. Ankenbrand ◽  
Liliia Shainberg ◽  
Michael Hock ◽  
David Lohr ◽  
Laura M. Schreiber
Keyword(s):  
Neural Networks ◽  
Sensitivity Analysis ◽  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Cardiac Mri ◽  
Magnetic Resonance Images ◽  
Model Interpretation ◽  
First Case ◽  
Segmentation Models

Abstract Background Image segmentation is a common task in medical imaging e.g., for volumetry analysis in cardiac MRI. Artificial neural networks are used to automate this task with performance similar to manual operators. However, this performance is only achieved in the narrow tasks networks are trained on. Performance drops dramatically when data characteristics differ from the training set properties. Moreover, neural networks are commonly considered black boxes, because it is hard to understand how they make decisions and why they fail. Therefore, it is also hard to predict whether they will generalize and work well with new data. Here we present a generic method for segmentation model interpretation. Sensitivity analysis is an approach where model input is modified in a controlled manner and the effect of these modifications on the model output is evaluated. This method yields insights into the sensitivity of the model to these alterations and therefore to the importance of certain features on segmentation performance. Results We present an open-source Python library (misas), that facilitates the use of sensitivity analysis with arbitrary data and models. We show that this method is a suitable approach to answer practical questions regarding use and functionality of segmentation models. We demonstrate this in two case studies on cardiac magnetic resonance imaging. The first case study explores the suitability of a published network for use on a public dataset the network has not been trained on. The second case study demonstrates how sensitivity analysis can be used to evaluate the robustness of a newly trained model. Conclusions Sensitivity analysis is a useful tool for deep learning developers as well as users such as clinicians. It extends their toolbox, enabling and improving interpretability of segmentation models. Enhancing our understanding of neural networks through sensitivity analysis also assists in decision making. Although demonstrated only on cardiac magnetic resonance images this approach and software are much more broadly applicable.

scholarly journals Sensitivity Analysis of Fuzzy Activity-Based Life Cycle Costing

2018 ◽  
Vol 225 ◽  
pp. 05002
Author(s):  
Freselam Mulubrhan ◽  
Ainul Akmar Mokhtar ◽  
Masdi Muhammad
Keyword(s):  
Sensitivity Analysis ◽  
Life Cycle ◽  
Interest Rate ◽  
Life Cycle Costing ◽  
High Impact ◽  
Final Output ◽  
Left And Right ◽  
The Interest Rate ◽  
Operation Cost

A sensitivity analysis is typically conducted to identify how sensitive the output is to changes in the input. In this paper, the use of sensitivity analysis in the fuzzy activity based life cycle costing (LCC) is shown. LCC is the most frequently used economic model for decision making that considers all costs in the life of a system or equipment. The sensitivity analysis is done by varying the interest rate and time 15% and 45%, respectively, to the left and right, and varying 25% of the maintenance and operation cost. It is found that the operation cost and the interest rate give a high impact on the final output of the LCC. A case study of pumps is used in this study.

Improving Casthouse Throughput Using Discrete-Event Modelling

2011 ◽  
Vol 693 ◽  
pp. 3-9 ◽  
Author(s):  
Bruce Gunn ◽  
Yakov Frayman
Keyword(s):  
Sensitivity Analysis ◽  
Discrete Event ◽  
Casting Machine ◽  
Production Data ◽  
Model Output ◽  
Arrival Times ◽  
Event Simulation ◽  
Modelling System ◽  
Key Parameter

The scheduling of metal to different casters in a casthouse is a complicated problem, attempting to find the balance between pot-line, crucible carrier, furnace and casting machine capacity. In this paper, a description will be given of a casthouse modelling system designed to test different scenarios for casthouse design and operation. Using discrete-event simulation, the casthouse model incorporates variable arrival times of metal carriers, crucible movements, caster operation and furnace conditions. Each part of the system is individually modelled and synchronised using a series of signals or semaphores. In addition, an easy to operate user interface allows for the modification of key parameters, and analysis of model output. Results from the model will be presented for a case study, which highlights the effect different parameters have on overall casthouse performance. The case study uses past production data from a casthouse to validate the model outputs, with the aim to perform a sensitivity analysis on the overall system. Along with metal preparation times and caster strip-down/setup, the temperature evolution within the furnaces is one key parameter in determining casthouse performance.

scholarly journals Waste reduction of polypropylene bag manufacturing process using Six Sigma DMAIC approach: A case study

2021 ◽  
Vol 8 (1) ◽  
pp. 1896419
Author(s):  
Muhammad Hamad Sajjad ◽  
Khawar Naeem ◽  
Muhammad Zubair ◽  
Qazi Muhammad Usman Jan ◽  
Sikandar Bilal Khattak ◽  
...  
Keyword(s):  
Six Sigma ◽  
Manufacturing Process ◽  
Waste Reduction
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