scholarly journals Three-Dimensional Synthesis of Manufacturing Tolerances Based on Analysis Using the Ascending Approach

Mathematics ◽  
2022 ◽  
Vol 10 (2) ◽  
pp. 203
Author(s):  
Badreddine Ayadi ◽  
Lotfi Ben Said ◽  
Mohamed Boujelbene ◽  
Sid Ali Betrouni
Keyword(s):  
Surface Defects ◽  
Three Dimensional ◽  
Tolerance Analysis ◽  
Machining Process ◽  
Dimensional Synthesis ◽  
Machining Processes ◽  
Machined Surface ◽  
Manufacturing Tolerances ◽  
Machining Fixtures ◽  
Set Up

The present paper develops a new approach for manufacturing tolerances synthesis to allow the distribution of these tolerances over the different phases concerned in machining processes using relationships written in the tolerance analysis phase that have been well developed in our previous works. The novelty of the proposed approach is that the treatment of non-conventional surfaces does not pose a particular problem, since the toleranced surface is discretized. Thus, it is possible to study the feasibility of a single critical requirement as an example. During the present approach, we only look for variables that influence the requirements and the others are noted F (Free). These variables can be perfectly identified on the machine, which can be applied for known and unknown machining fixtures; this can be the base for proposing a normalized ISO specification used in the different machining phases of a mechanical part. The synthesis of machining tolerances takes place in three steps: (1) Analysis of the relationship’s terms, which include the influence of three main defects; the deviation on the machined surface, defects in the machining set-up, and the influence of positioning dispersions; then (2) optimization of machining tolerance through a precise evaluation of these effects; and finally (3) the optimization of the precision of the workpiece fixture, which will give the dimensioning of the machining assembly for the tooling and will allow the machining assembly to be qualified. The approach used proved its efficiency in the end by presenting the optimal machining process drawing that explains the ordered phases needed to process the workpiece object of the case study.

scholarly journals Analysis of Forces in Vibro-Impact and Hot Vibro-Impact Turning of Advanced Alloys

2011 ◽  
Vol 70 ◽  
pp. 315-320 ◽  
Author(s):  
Riaz Muhammad ◽  
Agostino Maurotto ◽  
Anish Roy ◽  
Vadim V. Silberschmidt
Keyword(s):  
Finite Element ◽  
Cutting Forces ◽  
Three Dimensional ◽  
Element Model ◽  
Machining Process ◽  
Strain Rates ◽  
Machining Processes ◽  
Machined Surface ◽  
Cutting Zone

Analysis of the cutting process in machining of advanced alloys, which are typically difficult-to-machine materials, is a challenge that needs to be addressed. In a machining operation, cutting forces causes severe deformations in the proximity of the cutting edge, producing high stresses, strain, strain-rates and temperatures in the workpiece that ultimately affect the quality of the machined surface. In the present work, cutting forces generated in a vibro-impact and hot vibro-impact machining process of Ti-based alloy, using an in-house Ultrasonically Assisted Turning (UAT) setup, are studied. A three-dimensional, thermo-mechanically coupled, finite element model was developed to study the thermal and mechanical processes in the cutting zone for the various machining processes. Several advantages of ultrasonically assisted turning and hot ultrasonically assisted turning are demonstrated when compared to conventional turning.

The Set-Up-Map for Automating the Positioning of Castings and Weldments in Fixtures to Ensure Completely Machined Surfaces

2016 ◽  
Author(s):  
Nathan J. Kalish ◽  
Satchit Ramnath ◽  
Payam Haghighi ◽  
Joseph K. Davidson ◽  
Jami J. Shah ◽  
...  
Keyword(s):  
Dimensional Space ◽  
Small Body ◽  
Three Dimensional ◽  
Global Coordinate System ◽  
Tolerance Zone ◽  
Machined Surface ◽  
Cloud Data ◽  
Machining Fixtures ◽  
Set Up ◽  
Intersection Method

There is considerable geometric variability of raw castings and weldments before any machining of surfaces that assemble with other components. Consequently, considerable time often is spent identifying successful set-up adjustments at the machining fixtures for such parts in a way to ensure that every machined surface will be complete. The proposed Set-Up-Map© is a point-space subset of R6 where each of the six orthogonal coordinates correspond to one of the rigid-body displacements in three dimensional space: three translations and three rotations. Any point within the Set-Up-Map (S-Map) corresponds to a small body displacement (SBD) of the part that satisfies the condition that each feature will lie within its associated tolerance zone after machining. S-Maps are derived from previous work on Tolerance Maps© (T-Maps), which represent feature deviations allowed by a given tolerance zone. Each raw casting or weldment is scanned, and the point-cloud data fitted to individual features, to determine how much each to-be-machined (TBM) feature deviates from nominal specifications. Each local T-Map is formed from a library, then shifted to be centered on its corresponding scanned feature on each casting; it becomes a local S-Map primitive. Each of these local S-Maps is then transformed to a single global reference frame. The intersection of these S-Map primitives in the global frame gives the allowable small body displacements that satisfy the positioning requirements for all TBM features. Since T-Maps are convex objects, a half-space intersection method is used to generate an S-Map. Any point within the S-Map represents a viable small body displacement specific to the global coordinate system established on the part. In the case that as-cast or as-welded features deviate from what is acceptable, the S-Map will be the empty set. Consequently, in addition to reducing the time for setup in a fixture, S-Maps can serve as a valuable diagnostic to determine that a part should be either scrapped or reworked.

Investigations on the Application of Minimum Quantity Solid Lubrication in Turning

2017 ◽  
Author(s):  
Mayur A. Makhesana ◽  
Kaushik M. Patel
Keyword(s):  
Tool Wear ◽  
Cost Effective ◽  
Solid Lubricants ◽  
Cutting Fluid ◽  
Solid Lubrication ◽  
Machining Processes ◽  
Machined Surface ◽  
Minimum Quantity ◽  
Set Up ◽  
Experimental Findings

Machining is the manufacturing process, capable of producing required shape and size by material removal. In recent times industries are striving to enhance the performance of machining processes. One of the problem associated with machining is the amount of heat generation as a result of friction between tool and workpiece. Heat generated may affect the quality of machined surface and tool wear. In order to control it, cutting fluid is applied in large quantity. The problem arises with the use of cutting fluid is its effect on worker’s health and environment. The present investigation is an attempt to explore the use the solid lubricants in machining as an alternative to cutting fluid. The work involves development of minimum quantity solid lubrication set up. Turning experiments has been performed by applying solid lubricants mixed with cutting fluid in minimum quantity. The performance of minimum quantity solid lubrication has been assessed in form of obtained surface finish, power consumption and tool wear during turning. Experimental findings discovered the superiority of minimum quantity solid lubrication over conventional cutting fluid and can be considered as cost effective and sustainable lubrication method.

Experimental and Numerical Studies on Defect Characteristics During Milling of Aluminum Honeycomb Core

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Qinglong An ◽  
Jiaqiang Dang ◽  
Weiwei Ming ◽  
Kunxian Qiu ◽  
Ming Chen
Keyword(s):  
Cell Walls ◽  
Surface Defects ◽  
Tensile Deformation ◽  
Optimization Method ◽  
Cutting Process ◽  
Machining Process ◽  
Honeycomb Core ◽  
Machined Surface ◽  
Entrance Angle ◽  
Aluminum Honeycomb

The honeycomb sandwich structure has been widely used in the aerospace industry due to its high specific strength and stiffness. However, the machining defects of the aluminum honeycomb core (AHC) have become the key factor that restricts its application. In this paper, the defects' characteristics including the formation mechanism, distribution characteristic, and cutting process of honeycomb cell walls during AHC milling process were experimentally investigated. Furthermore, using normalized Cockcroft and Latham ductile fracture criterion and Johnson–Cook (JC) constitutive model, the numerical simulation of the AHC machining process was conducted concerning the entrance angle. It is indicated that six categories of milling defects are obtained and the quantity as well as distribution regularity of AHC milling defects are determined by the double effects of both the entrance angle and cutting force. Most of the surface defects of honeycomb materials were found concentrated in three regions, named by zones I–III, in which extruding, shear, and tensile deformation was mainly generated, respectively. Besides, the finite element simulation results also agree well with the experimental findings. Finally, a novel optimization method to avoid defects in the aforementioned regions by controlling the entrance angle of all the honeycomb walls during the cutting process was proposed in this paper. Meanwhile, the optimal control equations of the entrance angle for all cell walls were derived. This method was verified by milling experiments at last and the results showed that the optimization effect was obvious since the quality of the machined surface was greatly improved.

Preliminary Design of Two Dimensional Vibration Assisted Machining System for Multi-Axis Micro-Milling Application

2020 ◽  
Vol 846 ◽  
pp. 105-109
Author(s):  
Gandjar Kiswanto ◽  
Poly ◽  
Yolanda Rudy Johan ◽  
Tae Jo Ko
Keyword(s):  
Machining Process ◽  
Micro Milling ◽  
Machining Processes ◽  
Machined Surface ◽  
Planar Surfaces ◽  
Preliminary Model ◽  
Machined Surface Quality ◽  
Machining System ◽  
Linear Vibrations ◽  
Linear Movement

Vibration assisted machining (VAM) is a method that is widely used in improving the performance of machined products. External vibrations with high frequency to ultrasonic range along with an meso-micrometer amplitude are given to the cutting tool or workpiece. This will result in a periodic separation phenomenon, hence reducing the cutting force which has positive impacts on increasing tool life and machined surface quality. Among the high-precision machining processes, micro-milling which has the ability to produce complex components with 2D and 3D features, can also be applied with the vibration assisted method, known as vibration assisted micro-milling (VAMM). Based on the direction of vibration given in the machining process, there are 1D VAMM with linear vibrations and 2D VAMM with circular or elliptical trajectory vibrations. However to date, neither developed 1D nor 2D VAMM systems are still limited to the research of planar surfaces cutting using linear movement axes, meanwhile vibration assisted in inclination cutting of micro-milling using the rotational movement axes is still very rare. Therefore the purpose of this paper is to present the preliminary model in designing a 2D VAMM system for a 5-axis micro-milling machine. The system is powered using piezoelectric actuators as the vibration-producing actuators.

Fractal Precision Models of Lathe-Type Turning Machines

1993 ◽  
Author(s):  
Irem Y. Tumer ◽  
R. S. Srinivasan ◽  
Kristin L. Wood ◽  
Ilene Busch-Vishniac
Keyword(s):  
Fractal Analysis ◽  
Fractal Dimensions ◽  
Primary Objective ◽  
Machining Process ◽  
Design Parameters ◽  
Complete Model ◽  
Machining Processes ◽  
Machined Surface ◽  
Surface Models ◽  
Surface Profiles

Abstract The primary objective of this research is to develop surface models of machining processes to simulate machined surface profiles and analyze their structure. In this paper, fractal analysis is used to discover and characterize the variational pattern of turned surfaces. This analysis provides a means of explicitly stating the precision of a machining process. The results are used to further test the validity of the concept of fractal dimensions at tolerance scales and to establish a relation between surface models, experimental surfaces, and fractals. Based on these results, a more complete model of turning is available to designers for choosing process and design parameters and for comparing the precision between competing machining processes.

Optimization Method of Rotational Axis Motion in 5-Axis Controlled Machining to Keep Command Tool Feed Rate

2020 ◽  
Author(s):  
Takayuki Nakamura ◽  
Kohei Ichikawa ◽  
Masanobu Hasegawa ◽  
Jun'ichi Kaneko ◽  
Takeyuki Abe
Keyword(s):  
Surface Roughness ◽  
Feed Rate ◽  
Machining Process ◽  
Rotational Axis ◽  
Feed Speed ◽  
Machining Processes ◽  
Machining Time ◽  
Machined Surface ◽  
Lead Angle ◽  
Tool Posture

Abstract In recent machining processes, 5-axis controlled machine tool is widely used for machining complicated workpiece shape with curved surface. In such process, to achieve high productivity, planning method of cutting conditions to satisfy both following the commanded tool feed rate in machining process and realization of good surface roughness are required. In conventional study, it is known that lead angle of tool posture against local machined surface influence the surface roughness. Then, common commercial CAM systems have already functioned to avoid interference and control the lead angle in each cutter location. However, in the generated cutter locations by the conventional algorithms, when the tool posture changes rapidly, there is a problem that actual feed rate does not reach the command value and machining time becomes longer than expected. In this paper, we propose the new tool posture correction algorithm. In the proposed method, first, the rotational axis that causes the feed speed rate decline is specified by preliminary experiments. And, the jerk value that is the threshold for the feed speed decline is investigated. After that, for the NC program, the command value of the target axis is modified within a range where interference of cutting tool does not occur, thereby preventing a decline in the actual feed rate. This paper describes an outline of the proposed modification method and the effect of the modification of the target axis positions on the lead angle and the actual feed rate.

Three-Dimensional Micromachining Based on AFM

2006 ◽  
Vol 315-316 ◽  
pp. 800-804
Author(s):  
Z.J. Hu ◽  
S.G. Zhang ◽  
Xiu Hua Zheng ◽  
Yong Da Yan ◽  
T. Sun ◽  
...  
Keyword(s):  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Control Device ◽  
Machining Process ◽  
Nanometer Scale ◽  
Pid Algorithm ◽  
Atomic Force ◽  
Set Up ◽  
Diamond Probe ◽  
Special Control

With the development of science and technology, Atomic Force Microscope is widely applied to the field of machining process in nanometer scale. Due to the limitation of the inventive purpose of AFM, only height mode and deflection mode can be applied in AFM-tip micromachining. It can’t control the machining depth during the micromachining process at present. In this paper, a new micromachining system is set up, which composed of a high precision three-dimensional stage, an AFM, a diamond probe and a special control device. By utilizing variation parameters PID algorithm and controlling the machining depth directly, the micromachining system can resolve the problem mentioned above.

scholarly journals Improving the Surface Quality Through a Laser Scan and Machining Strategy Combining Powder Bed Fusion and Machining Processes

2021 ◽  
Author(s):  
Tatsuaki Furumoto ◽  
Satoshi Abe ◽  
Mitsugu Yamaguchi ◽  
Akira Hosokawa
Keyword(s):  
Surface Quality ◽  
Machining Process ◽  
Powder Bed Fusion ◽  
Rough Machining ◽  
Machining Processes ◽  
Machined Surface ◽  
Factors Affecting ◽  
Powder Bed ◽  
Machining Strategy ◽  
Subtractive Machining

Abstract This paper focuses on the unconventional laser powder bed fusion (LPBF) technique in which the LPBF and machining processes were executed alternately to fabricate higher quality parts compared to those obtained using subtractive machining processes. The additional machining process changed the stress distribution inside the built part, resulting in the deformation of the surface morphology in the final part. The phenomenon pertaining to the combined LPBF and machining process based fabrication was investigated, and the influence of the process parameters on the formation of the surplus part and deformation of the machined surface was evaluated. In addition, a laser scan and machining strategy was formulated to improve the surface quality of the built part. The surplus buildup at the edge of the fabricated part occurred owing to the difference in the thermal properties between the solidified part and deposited metal powder. The laser-irradiated position at the first layer buildup and energy density were the principal factors affecting the formation of the surplus part, and the surplus buildup could be reduced using the laser scan strategy, in which the laser-irradiated position was shifted inward. The peripheral face of the built part formed periodical steps, owing to the deformation induced by the change in the thermal distribution inside the built part. These steps could be reduced using the machining strategy combining the rough machining process with a finishing allowance and stepwise finishing process.

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