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A cylindrical structure used in a space launch vehicle should endure the compressive load and it must satisfy the requirement of compressive strength. For the light-weight of the structure and improving the performance of launch vehicle, a cylindrical structure reinforced by composite lattice can be used. Therefore, a compressive strength prediction technique of the cylindrical composite lattice structure is required. In this paper, the failure criterion was proposed using the compression test of a composite lattice subelement and a simple finite element analysis for the subelement. The failure criterion was introduced using the effect of the out-of-plane and in-plane bending deformation of the rib constituting the grid of structure on the compressive strength. The subelement specimen was prepared from two different structures and the compression test was performed using several fixture jigs which can generate various deformation of the specimen. The test results and finite element model were used to examine the effect of out-of-plane and in-plane bending deformation of the rib on the compressive strength and the failure criterion which can predict the compressive strength was derived using the relationships between each parameter. The compressive failure load of the cylindrical composite lattice structure was predicted by using the proposed method and the validity and accuracy of this method were verified through a comparison of the predicted results with the test results. It was possible to predict the compressive strength within a 5% error of the experimental result. [ABSTRACT FROM AUTHOR]

An alternative method to reduce setup time is to simultaneously carry out fixture planning for several parts in one setup planning. This is possible due to the size of parts which are relatively small to the size of the machine work bed, typically found in a make-to-order industry. This research proposed a fixture planning method for multi-workpiece setup. The fixture planning method comprised two stages: 1) multi-workpiece layout and 2) 3-2-1 pin location. An example of multiple workpiece setup is illustrated in this paper to point out the method's applicability. Future research activity will integrate the proposed collaborative human-robot assembly design system method. [ABSTRACT FROM AUTHOR]

The effect of removing suction on energy consumption, displacement, and separation of particles with different sizes and densities in the jig was investigated by CFD-DEM coupling. Water velocity functions were categorized into four modes: normal sinusoidal, partial removal of suction, complete removal of suction, and optimal. Particles rise to a certain height in the normal sinusoidal mode, while their jump height increases in the case of partial or complete removal of suction. The jump was controlled by fluid and added (Hutch) water velocities. Increasing the maximum jump height of particles leads to a decrease in separation, an increase in operational costs, and heightened particle mixing and energy consumption. In both modes of partial or complete suction removal, the fluid velocity should be reduced. The extent of velocity reduction depends on the power required to move the particles. The simulation of coarse particles (7 and 8 mm) revealed that in the complete removal of suction, the velocity should be decreased to less than half of the normal sinusoidal mode, and the hutch water velocity should be equivalent to the velocity amplitude. The energy consumption for the optimal mode was significantly lower than that of the other modes. [ABSTRACT FROM AUTHOR]

While modern 5-axis computer numerical control (CNC) systems offer enhanced design flexibility and reduced production time, the dimensional accuracy of the workpiece is significantly compromised by geometric errors, thermal deformations, cutting forces, tool wear, and fixture-related factors. In-situ sensing, in conjunction with machine learning (ML), has recently been implemented on edge devices to synchronously acquire and agilely analyze high-frequency and multifaceted data for the prediction of workpiece quality. However, limited edge computational resources and lack of interpretability in ML models obscure the understanding of key quality-influencing signals. This research introduces InterpHD , a novel graph-based hyperdimensional computing framework that not only assesses workpiece quality in 5-axis CNC on edge, but also characterizes key signals vital for evaluating the quality from in-situ multichannel data. Specifically, a hierarchical graph structure is designed to represent the relationship between channels (e.g., spindle rotation, three linear axes movements, and the rotary A and C axes), parameters (e.g., torque, current, power, and tool speed), and the workpiece dimensional accuracy. Additionally, memory refinement, separability, and parameter significance are proposed to assess the interpretability of the framework. Experimental results on a hybrid 5-axis LASERTEC 65 DED CNC machine indicate that InterpHD not only achieves a 90.7% F1-Score in characterizing a 25.4 mm counterbore feature deviation but also surpasses other ML models with an F1-Score margin of up to 73.0%. The interpretability of the framework reveals that load and torque have 12 times greater impact than power and velocity feed forward for the characterization of geometrical dimensions. InterpHD offers the potential to facilitate causal discovery and provide insights into the relationships between process parameters and part quality in manufacturing. [ABSTRACT FROM AUTHOR]

In the conditions of the increase in the range of products in the automobile and aircraft industry, there is a tendency to increase the scope of application of flexible fixtures. Thus, in the current article, it was proposed to consider a new concept of a flexible fixture for location parts of a complex shape. The stress and deflection of the steering knuckle elements were calculated using finite element modeling. During the experiment on the static loading, the deflection of the steering knuckle elements was measured, and the results of finite element modeling were validated. It was determined that the stiffness of the proposed flexible fixture ensures compliance with the tolerances of the mutual location of the surfaces of the part, making it reasonable for feature research the novel flexible fixture design during milling. [ABSTRACT FROM AUTHOR]

In this paper, we focus on the development of a machine for manufacturing needle probes used in the electrical testing of printed circuit board (PCB) in-circuit-test fixtures. Currently, the manufacturing process for needle probes involves manual tasks such as wire threading, soldering, heat shrink tubing application, heat shrink tubing heating, and placing cylindrical terminals into a needle disc. Owing to the time-consuming nature of this production process, automation is proposed for improvement. The system development involves programmable logic controller (PLC) control and pneumatic cylinder mechanisms to replicate the manual wire threading process. Pneumatic grippers are used to position cylindrical terminals and heat shrink tubing. Two stepper motors drive plastic rollers for copper wire extension by a rolling process along V-shaped groove straightening guides, reaching the wire insertion holes on the PCB. A YZ-axis servo stage with clamping fixtures secures the PCB and moves it to the wire insertion holes. Once the copper wire extends through the cylindrical terminal, the threading action for that PCB hole is completed. Subsequently, laser welding joins the cylindrical terminal with the copper wire, and a hot air blower fuses the heat shrink tubing with the cylindrical terminal. Pneumatic grippers grasp the threaded cylindrical terminals. Simultaneously, an XY-axis servo stage with clamping fixtures places the disc into the clamping fixture, moves it beneath the pneumatic grippers, and inserts the cylindrical terminals into the disc. After completion, a few centimeters of copper wire in front of the rollers are cut, marking the completion of the needle placement for that hole on the disc. The combination of PCB hole wire threading and disc hole needle placement constitutes one cycle of the wire threading fixture. The machine repeats this automated sequence until the entire needle probe fixture is produced. [ABSTRACT FROM AUTHOR]

CubeSats, known for their compact size and cost effectiveness, have gained significant popularity. However, their limited size imposes restrictions on the optical aperture and, consequently, the Ground Resolution Distance in Earth Observation missions. To overcome this limitation, the concept of deployable optical payloads with segmented primary mirrors which can unfold like petals has emerged, enabling larger synthetic apertures and enhanced spatial resolution. This study explores the potential benefits of leveraging Additive Manufacturing (AM) and Topology Optimization (TO) in the realm of ultra-precision machining, specifically single-point diamond machining. The goal is to reduce fixture weight while improving stiffness to minimize deformations caused by rotational and cutting forces which compromise optical performance. Through Finite Element Analysis, this research compares conventionally machined fixtures with those produced using AM and TO techniques. The results reveal that concept designs created via TO can achieve a remarkable 68% reduction in weight. This reduction makes the assembly, including the machining fixture and 12 U deployable segments, manageable by a single operator without the need for specialized lifting equipment. Moreover, these innovative designs lead to substantial reductions of up to 86% and 51% in deformation induced by rotational and cutting forces, respectively. [ABSTRACT FROM AUTHOR]

Jigs and fixtures are essential tools for modern manufacturing and machining processes. They contribute to precision, efficiency, cost-effectiveness, and safety in various industries, ultimately impacting the quality and competitiveness of products in the market. This course improves the visualization, imagination and drawing skill of the students which are helpful to them to draw their ideas clearly and rapidly, to read the drawing drawn by others and to create successful design. Manufacturing process course includes Jigs and fixture topic in this topic it is expected to imagine, visualize and develop the engineering drawing as per given requirements which includes orthographic projections in which imagining 3D objects are required to convert in 2D drawing. The students of second year mechanical engineering find this task difficult due to no prior basic knowledge, poor imagination and visualization skill. These skills are improved by experiential learning. Hence the attainment of the course learning outcome related to these topics is recorded low. To overcome this problem, a experiential learning approach implemented along with classroom teaching in order to enhance the, visualization, imagination and technical drawing skill of second year engineering students. In this article, the author has presented the efforts taken to improve the visualization, imagination and drawing skill through active engagement of students for learning in the classroom and outside of classroom. Due to systematic implementation of experiential learning, student's engagement towards learning, attainment of the course outcomes (COs) and overall exam result of the course have been improved [ABSTRACT FROM AUTHOR]

A solution method based on the ant colony optimization (ACO) algorithm is established for the hybrid flow shop scheduling problem with the objective of minimizing the maximum completion time and the number of fixtures. By using the linear weighting method, the dual-objective optimization problem can be effectively converted into a single-objective optimization. Taking the scheduling problem of an automated production line of precision parts as an example, the feasibility of the proposed algorithm is verified, and the integrated optimization of fixture resource allocation and production scheduling is realized. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to develop a special modular fixture system for machining and drilling parts that hold pneumatic jacks componets. This family of parts is usually made in various dimensions and sizes but with a specific geometric shape. The design requirements of the restrictions, the way of the construction process is considered as the design inputs of this system. Positioning and clamping system have been designed, modeled and simulated for the mass production of a family of these parts with minimal changes in the manufacturing process. The results obtained from the idea of designing such restraints in machining processes show that with its help, it is possible to reduce the design and manufacturing costs of restraints for a group of parts that are similar in appearance but different in size and dimensions. It will significantly reduce and minimize the time of adjusting these equipments during the production process and will increase the productivity and circulation of products. [ABSTRACT FROM AUTHOR]

Studying the effects of cutting parameters on cutting force and energy consumption in the core removal and slicing process of crab‐apple can provide the theoretical basis for the design and optimization of crab‐apple core removal and slicing equipment. In this study, the single‐factor tests were carried out on a special fixture and microcomputer‐controlled electronic universal testing machine to study the effect of slicing speed, blade oblique angle, and blade‐edge shape in the slicing process and core removal tool wall thickness and speed in the core removal process on the cutting force and energy consumption. The test results showed that the peak force and energy consumption can be reduced by adopting the concave type blade compared to the convex type blade. Slicing speed and blade oblique angle have significant effects on the cutting performance of crab‐apple in the slicing process. When blade oblique angle and cutting speed increase, the cutting force and energy consumption both show a decreasing trend. For the core removal process, reducing the core removal tool wall thickness and increasing the core removal speed can reduce the cutting force and energy consumption and improve the processing quality. [ABSTRACT FROM AUTHOR]

Metal forming process is one of the most important manufacturing processes that translate the sheet and bulk metal to the final product with simple punch and. Single point incremental forming (SPIF) process is considered as a modern flexible manufacturing techniques that is use a simple tool and non-specific fixture die to complete the forming, this method is used in prototype manufacturing system due to the time consuming during the forming. The advantage of this process is low cost and simple equipment. However, some limitation was founded including poor geometric accuracy, non- uniform thickness distribution, dimple and high forming time. Multi-point forming (MPF) is another modern forming method that is used in industrial applications due to its advantage such as uniform thickness distribution with low forming time consuming. This method used matrix of simple tools to deform the sheet metal to the desired shape. Wrinkle and dimple due to small contact area between tool and blank under high forming force are considered the main limitation of using MPF process. To take the advantages of this processes with reduced the limitations a hybrid forming (HF) process of both MPF and SPIF are used. The experimental work was applied to produce a hemi-spherical product of brass blank using the SPIF, MPF, and HF processes. Satisfac- tory results are obtained using a hybrid forming process with free of defects products and reduction in production as compared to the SPIF. A high improve in microstructure including refinements in grain size with twins effects. The sample produced with SPIF process showed a high microhardness as compared to the sample produced using MPF process, however, the hybrid MPF and SPIF forming process showed slightly improving in microhardness as comparing to the as received materials, reflecting the microstructure development of the processed samples. [ABSTRACT FROM AUTHOR]

As an important component of the machining system, the influence of fixtures on the machining deformation of the workpiece cannot be ignored. By controlling the clamping force during the machining process is an effective means to suppress or improve the machining deformation. However, due to the dynamic coupling of part geometry, clamping method, manufacturing process and time-varying cutting forces, it is difficult to obtain accurate clamping forces, which hinders the realization of fixture-based deformation control. In this paper, the variation of clamping force is considered as the response of the joint action of cutting force and other working conditions in spatial and temporal terms, and a clamping force prediction method based on deep spatio-temporal network is proposed. The part geometry model is first parameterized based on voxels, after which the cutting forces are dynamically correlated with the clamping forces in spatial and temporal terms. Then, a convolutional network was designed to capture the spatial correlation between the working conditions such as cutting force and clamping force, and a gated recurrent cell network to capture the temporal correlation to predict the clamping force during machining. Finally, an experiment of milling a cylindrical thin-walled part illustrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a work undertaken in a pipe line manufacturing company which welds (butt joints) different diameter of pipes which are used for manufacturing of boiler. In order to weld two separate pipes, initially both of them has to be aligned and dimensionally checked to reproduce the data in the Engineering drawing. It takes up a lots of time and man power. And also, to make sure that the pipes do not lose its orientation, after the aligning bridge pieces are tag welded with the pipes to arrest all the degrees of freedom of the pipes and thereby immobilizing it. Our project gives the alternative for welding of bridge pieces in pipes for butt joints. By implementing the suggestion of carrying out the process by using fixture, we can reduce the total welding and fit-up time to 75% of the actual time. It also neglect other major problems such as, welding of brittle materials like P91, unnecessary reworks, human efforts, reduction of defects on parent material. [ABSTRACT FROM AUTHOR]

Fixture layout design (FLD) determines the specific position of locators and clamps to position and support the workpiece with respect to a machine tool. The FLD approaches that use Finite Element Analysis (FEA) are widely used in previous works, and it becomes computationally expensive and specific to a particular problem. Further, the FLD and clamping force optimization were often performed separately, ignoring their interdependence. In the present work, to maximize the dimensional and form quality of the part, the reaction forces of the locators are made uniformly distributed by suitably varying the fixture layout and clamping force. The parametric rigid body model is used to depict the behaviour of the workpiece-fixture system, and it is incorporated with the genetic algorithm to optimize the design variables. A prismatic workpiece with slot milling operation is considered to validate the proposed methodology. Stability criterion and tool-fixture interference are considered constraints. Subsequently, FEA is used to verify the integrity of the proposed approach. The results infer that the uniformity in distribution of maximum elastic deformation of the workpiece is achieved due to the uniform distribution of reaction forces. Further, the effects of cutting forces on fixture layout and clamping forces are studied. [ABSTRACT FROM AUTHOR]

The manufacturing of composite parts and assemblies requires various kinds of tools, which determine the accuracy, performance, and cost of the end component. Additive manufacturing (AM), also known as 3D printing technology, has a direct impact on the manufacturing the of composite structures by offering rapid production of molds. 3D printing of molds, jigs and fixtures for composites manufacturing increases flexibility and design opportunities and reduces costs and lead time. Large-format AM systems, that can create an object larger than 1 m3, are the only systems that are suitable for rapid production of molds. Most of these systems are based on single-screw thermoplastic pellet extruders. Massivit 3D has developed a unique technology called Cast-In-Motion (CIM) and a designated system, the Massivit 10000, for direct digital printing of tools and molds, made of a proprietary epoxy-based, Thermoset casting material, CIM 500. The technology consists of printing a double-wall shell made of a proprietary UVcured Water Breakable (WB) material, Dimengel 50, followed by casting a calculated amount of CIM 500. The WB printing process and the thermoset-casting processes operate intermittently to create a near net shape, thermoset mold encapsulated by the WB shell. After the encapsulated mold is cured to optimize its mechanical properties at elevated temperatures, it is immersed in a water bath which causes the shell to crumble away and can be post finished to obtain the desired surface finish and geometry for the mold. The system can also be used for the printing of geometric cores and soluble mandrels for the composites industry by utilizing the printing of the WB and other various acrylic base UV cured materials without the conjunction of the CIM 500. This paper presents the advancements in CIM technology with its proprietary materials to enable direct manufacturing of complex finished molds. It also presents various applications from the design phase through printing to post finishing that meet customers' requirements. [ABSTRACT FROM AUTHOR]

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This research aims to improve J-type Anchor bolt installation in the column structure process. Determining the impact of the joining process on those Anchor bolts and column bases, the work was concerned with the Overall Equipment Effectiveness (OEE) data. Three major process indicators corresponded to the scale of OEE; Availability, Performance, and Quality rate. The use of jig and fixture has been a well-established approach to control the column base within the standard position. All of the control points have been measured on the 3D axis, as 2D in the support plane and the vertical level of the column base. Consequently, the problem of downtime loss due to the adjustment of column base position was decreased. Complete one job installation of a column with 36 CM2 cross-section and 20m of the height, took an averaged-cycle time of 22 minutes. Also, the before and after improvement of the process were compared resulting to an increase in the rate of the first right job by 45 percent. Availability increased by 4%, Performance increased by 5%, Quality rate increased by 4%. resulting in an overall equipment effectiveness increase of 11%, and the Process Capability Index (CP) was increased from 1.14 to 2.22 leading to suitable operating costs. [ABSTRACT FROM AUTHOR]

Fixture layout for machining thin-walled structures plays an important role in fixture performance. This work focuses on the optimization design of machining fixture layout including clamp layout and the layout of support heads. A universal optimization methodology that can automatically generate the optimal machining fixture layout is proposed. The optimization of fixture layout is implemented based on the criteria of minimizing maximum deflection of the thin-walled workpiece while remain relatively small torque caused by the clamping tables. An evolutionary algorithm is employed to solve the fixture layout optimization for the optimal solution. The optimal position of the support heads and the layout of clamping tables obtained from this work vary along with the change of cutting force. To validate the proposed optimization methodology, a fixture layout design for a typical thin-walled structure is optimized as an example. The case study demonstrates the application of the proposed approach in the fixture layout design for thin-walled structures, which is beneficial to design an optimal fixture layout. [ABSTRACT FROM AUTHOR]

The rapid development of manufacturing in recent years has led to a significant expansion of the technological capabilities of modern metal-cutting equipment. Therefore, the modern approach to intensifying production requires an advanced fixture design. Design and manufacture of flexible fixtures capable of machining similar shapes and sizes of complex geometry parts reduce setup time. The article aims to design flexible fixtures for parts such as one-piece connecting rods under incomplete locating conditions. The advantages are the minimum number of parts and tool availability for multi-axis machining connecting rods in one setup. This approach, combined with up-to-date machining centers and industrial robots, can increase the production efficiency of manufacturing non-removable connecting rods. This effectiveness is in a decrease in the number of operations by 5–7 times, fixtures—by 3–4 times, and machine tools—by 3–5 times, depending on the type of a non-removable connecting rod and its design features. The numerical simulation results of the proposed fixture design confirmed the comprehensive technological capabilities and dynamic characteristics. Particularly, a decrease in displacements and oscillation amplitudes up to 7% compared to the full-basing locating chart was provided. It is determined that the system "fixture–workpiece" entirely meets all the strength, accuracy, and rigidity parameters, which allows you to perform machining with intensive cutting modes. The amplitudes of oscillations do not exceed the tolerances on the dimensions of these surfaces, established by requirements for non-removable connecting rods, and all displacements are elastic. During numerical simulation, the workpiece position remained stable at all machining steps. [ABSTRACT FROM AUTHOR]

In recent years, the growing need for reducing non-structural damage after earthquakes has stimulated a dedicated effort to develop innovative types of fasteners for anchoring non-structural components (NSCs) to reinforced concrete (RC) host-structures. To contribute to such need, and building on previous research, this paper presents the results of a series of uni-directional shake-table tests of simulated NSCs anchored to concrete via: (1) expansion, and (2) chemical anchors; post-installed into: (a) uncracked, and (b) cracked concrete. Considering different construction details, the experimental investigation focused on traditional anchorage systems, alternative solutions comprising mortar filling into the gap clearance, and a low-damage system relying on supplemental damping devices, capable of reducing the acceleration of the NSCs as well as the force of the anchorage during seismic shakings. The experimental tests provided significant evidence on the beneficial effects of a dissipative anchorage protecting both the non-structural component and the anchorage itself, even during strong earthquakes. Moreover, when construction details allow to close the fixture clearance with a mortar filling, this stiffer solution provide an additional reduction of NSCs seismic accelerations and forces. Therefore, suggestions for further improvements of the adopted low-damage solution are also proposed. [ABSTRACT FROM AUTHOR]

• Welding induced buckling was observed during thin plates butt welding with dissimilar materials. • Advanced TEP FE computation with large deformation was carried out to represent welding induced buckling. • Good agreement between computed result and measurement was observed with considering clamping effect. • Clamping can significantly reduce magnitude of out-of-plane welding distortion without change of deformed tendency. Welding induced buckling is generally considered as the most complicated type of out-of-plane welding distortion during thin plate section fabrication, which will significantly influence the fabrication accuracy and cost. Thin plates of 3 mm thickness with dissimilar materials were experimentally butt welded together beforehand, while clamping constraint by fixture jig and additional plate was employed. After cooling down and clamping release, out-of-plane welding distortions were measured, and characteristic of welding buckling behavior can be observed. Advanced thermal elastic plastic (TEP) FE computation with solid elements models of examined butt-welded joints were then carried out. Welding induced buckling can be represented without considering clamping constraint, while much larger difference between computed results and measurement data was obtained. When the influence of clamping constraint employed during welding experiment was considered, good agreement for both deformed tendency and magnitude of out-of-plane welding distortion can be represented. With the clarification of mechanism based on the comparison of longitudinal residual stress, plastic strain as well as shrinkage force, clamping can significantly reduce magnitude of out-of-plane welding distortion, which still could not avoid the occurrence of welding induced buckling, as well as the change of deformed shape pattern. [ABSTRACT FROM AUTHOR]

Composite structures in aeroplanes are often thin-walled and lightweight, resulting in significant compliance, which presents a handling and assembly challenge due to the associated part deformations. In order to counteract these deformations, the parts are held in their specified geometry using stiff and correspondingly heavy fixtures or jigs. Mobile industrial robots are very versatile and widely used in industrial volume production, but they are limited in their payload capacity. High-rate production of large aerospace modules requires highly automated flexible assembly processes. The approach presented in this paper is to combine mobile units with lightweight assembly jigs that have the capability of deformation compensation. The subject of the study is a high-rate assembly process for flap modules using an Autonomous Industrial Mobile Manipulator (AIMM) and a lightweight end effector. The end effector has a shape compensation function, implemented by an integrated Stewart platform, which enables the compensation of manufacturing tolerances as well as gravity effects. The compensation function is used in a closed loop and counteracts shape deviations by appropriate fixture shape adjustments. The paper reports on the conceptual design of the assembly scenario, the design of the end effector, its realization and the successful experimental demonstration at 1:1 scale. [ABSTRACT FROM AUTHOR]

Designing and installing jigs and fixtures for new products are very costly tasks. In order to rapidly respond to frequent product changes in a manufacturing system, we developed a transformable pin array fixture system including reconfiguration planning software that finds the optimal position for mounting an assembly part and automatically generates a pin height control code. We first classified main fixturing quality factors such as type of contact, distance between a pin and a joining point, and part shape. We then formulate the part positioning problem as an alignment problem between the joining point set and the pin point set in the xy plane in consideration of the fixturing quality factors. A car door trim assembly module was used to verify the proposed method. Finite-element analysis results showed that in a car door trim assembly process such as ultrasonic welding and screwing, relocating an assembly part at the optimal position reduces its deformation. Note to Practitioners—Jigs and fixture systems are the fundamental manufacturing elements that are used for ensuring assembly quality. Traditionally, manufacturers have produced a small variety of products in massive quantities using dedicated jig and fixture systems. However, these dedicated workholding systems do not fit for the Today’s rapidly changing market. In order to enhance the reconfigurability of these systems, we propose a transformable pin array-based part fixturing system including part position optimization. Due to the system complexity, the assembly quality can be lower using the transformable fixtures than the conventional fixtures. Therefore, it is further necessary to develop a cost-effective reconfigurable fixture while preserving the assembly quality for the better chance of its industrial implementation. [ABSTRACT FROM AUTHOR]

Supporting fixtures are essential to suppress vibration in thin-walled milling. The trial-and-error basis method is still popular to determine suitable positions for fixture placement. This paper proposes a method to estimate the frequency responses of a workpiece with a fixture. The receptance coupling method is extended to represent the dynamics of supporting fixtures. The method allows the compatible use of receptance of a fixture between workpieces. The proposed method is applied to a thin-walled tube. The estimation results agree with the hammer testing results. Cutting tests showed that the fixture placed based on the proposed method can suppress vibration. [ABSTRACT FROM AUTHOR]

The tolerances of a part influence both the operation of the assembly of which it is part and the technological manufacturing process. High tolerances can lead to an assembly that does not work at the designed parameters, and low tolerances require additional machining operations that increase the cost of the part. The manufacturing series is another factor that influences the technological process. Large series production requires special facilities in terms of processing and control equipment which are needed in the manufacturing process. The paper presents a case study on the influence of tolerances of a part being produced in large series on the construction of the orientation and clamping device used in machining. Starting from the dimensions indicated in the design drawing, a first version of the fixture is proposed in which the parts are fixed and the tolerance of the closing dimension of the assembly of parts is analysed using the Worst Case and Root-Sum-Square methods. Since the closure size tolerance is outside the recommended range, another variant of orientation and fixture is proposed. By re-analysing, the closing dimension tolerance by the two methods mentioned above it was confirmed the necessity of modifying the part width tolerance. The analysis of the tolerance of the closing quota is resumed by the two methods mentioned above and the result confirms that it is necessary to change the tolerance to the width of the piece. The tolerance verification of the closure dimension of the assembly formed by the parts fixed in the device is performed by Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

Conventional design of jigs and fixtures has become unsuitable given the requirements of modern technology and complexity and diversity in the production with the rapid update of products. Computer-aided design (CAD) of jigs and fixtures is an effective solution in this direction. The current paper focuses on a computer-aided design of the traditional jigs and fixtures and developed a system containing tailor-made software, created using the Visual Basic programming language and installed on it the viewer screen to show the part. The developed system has been built by connecting Visual Basic programming language to the SolidWorks software on which the part is drawn and saved as STEP AP-203 file format, and the system reads and extracts the data from the STEP AP-203 file. Heuristic rules of feature recognition are pre-prepared for checking the extracted geometric data and deciding which data shape will represent the machining feature; then, the system provides the optimum design of the traditional jigs and fixtures for a group of hollow cylindrical parts that contain a group of cross-holes on the cylinder body, whether perpendicular or offset from the cylinder's axis, (inclined or inclined offset, or blind or through, by applying pre-prepared heuristic rules for the design of traditional jigs and fixtures. [ABSTRACT FROM AUTHOR]

Background : Tapping is one of the processes that most requires attention in the industry, due to the stage in which it occurs and its characteristics. In the case of tapping, it is common to use components and equipment with less rigidity, which compromises the dynamic behavior in several situations and can lead to process distortion or failure. Purpose: The objective of this paper is to study the dynamic behavior of tapping in relation to several characteristics of the process. Methods : The dynamic behavior of the force signal was used to evaluate the process, varying the cutting parameters and the clamping system of the workpiece. Results: The experimental results indicate that the floating system did not present a good dynamic behavior at high cutting speeds, this greater application of vibration is due to the resonance due to the combination of oscillations under forced and natural vibration. Conclusions: The natural frequency of the floating fixture system influenced the behavior of the axial forces. The increase in cutting speed resulted in a direct increase in the axial force vibrations as its frequency came close to the natural frequency of the system. Through dynamic analysis of the axial force signal observed the dynamic characteristics of the process and the machine tool. This allowed the dynamic evaluation of the system through the measurement of force signals generated in the threading process. [ABSTRACT FROM AUTHOR]

The magnitude of reaction forces in locating points is considered as one of the basic parameters in the fixture planning and element design stages of the fixture design procedure. The magnitude of these forces depends on the intensity, position, and orientation of the transient clamping and active machining forces and torque. Analysis of the effect of machining force and torque on reaction forces is a complex process because the magnitude, position, and orientation of machining loads change at any given time. In this paper, an analytical model is presented to investigate the effect of machining loads on online values of reaction forces in the contact points between the workpiece and the fixturing elements. The magnitude and direction of machining forces and torque are calculated on the tool path and using these parameters as inputs to the analytical model, the reaction forces are calculated in each of the six locators at each moment. A finite element analysis is performed to validate the values predicted by the analytical model. For this purpose, the necessary subroutines are prepared and the values of the reaction forces obtained from the simulation are compared to their corresponding values from the analytical model. A three-dimensional workpiece with a 3-2-1 locating system was used as a case study to evaluate the performance of the proposed model. The maximum error in calculating the reaction forces was obtained as 10.85% from the proposed analytical model which indicates the accuracy of the theoretical predictions. [ABSTRACT FROM AUTHOR]

Modelling the dimensional variation propagation in multi-station machining processes (MMPs) has been studied intensively in the past decade to understand and reduce the variation of product quality characteristics. Among others, the Stream-of-Variation (SoV) model has been successfully applied in a variety of applications, such as fault diagnosis, process planning and process-oriented tolerancing. However, the current SoV model is limited to the MMPs where only fixtures with punctual locators are applied. Other types of fixtures, such as those based on locating surfaces, have not been investigated. In this paper, the derivation of the SoV model is extended to model the effect of fixture- and datum-induced variations when fixtures with locating surfaces are applied. Due to the hyperstatic nature of these fixtures, different workholding configurations can be adopted. This will increase the dimension of the SoV model exponentially and thus may make the model-based part quality prediction extremely complex. This paper presents a method of reducing the complexity of the SoV model when fixtures based on locating surfaces are applied and evaluates the worst-case approach of the resulting part quality. [ABSTRACT FROM AUTHOR]

Fixture errors are one of the error sources in machining operations. The fixture errors consist of positioning inaccuracies and errors due to workpiece and fixture deformations. Fixture locators’ height error causes incorrect positioning of the workpiece in the fixture and inaccuracy in machined surfaces which can be much more than the locators’ height error. For machining precise workpieces, it is necessary to eliminate these errors. This paper presents a method for modelling and compensating the fixture locators’ height error effect on workpiece machined surfaces. In this method, the planes of workpiece actual coordinate system (ACS) are mathematically modelled in the workpiece theoretical coordinate system (TCS). Using the model, required homogenous transformation matrix for coinciding ACS with TCS and modifying machining toolpath for compensating the errors is generated. The presented model is used to develop a post-processing fixture locator error compensation module, which can modify CNC machining codes to eliminate the effect of fixture locators’ height error on the workpiece machined surfaces. For verifying the presented method, machining simulations and cutting experiments have been performed in this work. The results show that the method can eliminate the effect of fixture locators’ height error on the workpiece machined surfaces considerably. [ABSTRACT FROM PUBLISHER]