Process For Production Of Parts Research Articles

Investigation into a new hybrid forming process: Incremental sheet forming combined with stretch forming

Asymmetric incremental sheet forming (AISF) is a process for the flexible production of sheet metal parts. In AISF, a part is obtained as the sum of localised plastic deformations induced by a simple forming tool that moves under CNC control. Three main problems exist in AISF: material thinning, geometric accuracy and the process duration. These limits restrict the range of applications of AISF. This paper focuses on a new hybrid process, the combination of AISF and stretch forming. First results are presented that show the positive impact of this hybrid process on the process limits.

A reference specimen for permeability measurements of fibrous reinforcements for RTM

The capability to simulate the flow of resin through a porous reinforcement by FE modelling has become very important for designing RTM production processes for high-performance composite parts. The key parameter in RTM flow simulations is the fibre reinforcement permeability. The measurement of this material parameter is still not standardized and many different set-ups have been proposed. Recently, a stereolithography technique was used to produce a textile-like solid specimen with anisotropic permeability, designed as a reference for calibration and comparison of permeability measurement set-ups and for validation of numerical permeability computation software. Unlike real textiles, the permeability properties of such reference specimens do not vary from test to test. Excellent repeatability of the experiments is achieved. When used for benchmarking, any discrepancy between different measurements on this specimen must be attributed to the set-up and data processing. This paper presents the first experimental measurements of the permeability of such reference specimens, obtained with a 2D central injection rig. The measured values, with principal components of the 2D permeability tensor of 2.47 ± 0.09 × 10 −9 m 2 and 5.44 ± 0.22 × 10 −9 m 2, are in good agreement with the values predicted using numerical permeability computation software. Statistics from a series of measurements using the same set-up show that the precision of the permeability identification depends on the data processing procedure. An approach which incorporates a numerical model that is also valid after the fluid reached an edge of the reinforcement performs significantly better than the approach, based on an analytical approximation, which was used before.

Process for Production of Ti Sintered Compacts Using the Injection Molding Method.

Pure Ti, which is used in the field of Metal Injection Molding (MIM), can be used to produce parts with complicated shapes. But, since oxidation, nitrogen and carbonization are generated during the debinding-sintering process, the mechanical properties of the sintered material cannot achieve the same level as those of the ingot material. Accordingly, we have studied the debinding and sintering methods by using various binder systems. This paper reports on the mechanical properties required by customers (0.2%proof stress of 216 MPa or more, tensile strength of 343 to 510 MPa, and elongation of 10% or more)and the development of the parts production process.

A mathematical programming model for system reconfiguration in a dynamic cellular manufacturing environment

In a dynamic manufacturing environment, manufacturing cell configurations based on current part mix and production process may need to be revised once the part mix or the production process has changed. However, machine and equipment moving costs make frequent reconfiguration uneconomical and sometimes impossible. Designing a sustainable cellular manufacturing system in a dynamic environment is studied in this paper. An integer programming model is developed to minimize material handling and machine costs as well as cell reconfiguration cost for a planning horizon of multiple time periods. Solving this integer programming problem is NP-complete. A decomposition approach is developed so that the decomposed subproblems can be solved with less computational effort. Dynamic programming is then employed to find a solution of the original problem. Numerical examples are presented to illustrate the model and the solution technique developed in this paper.

Advances in Manufacturing Algebra: Discrete-Event Dynamic Models of Production Processes

The paper presents a further original development of the Manufacturing Algebra aiming at describing the dynamics of the production procesess taking place in factories. Starting from the definition of events and event sequences, a theory of discrete-event dynamic systems is developed which is appropriate for modelling the time and space evolution of discrete (or by part) production processes, at any level of detail. The result is a set of state equations modellling the state evolution of the storage and production units of a factory under the action of a real-time production control.

Use of Monte Carlo simulation to select dimensions, tolerances, and precision for automated assembly

Abstract Design for assembly is a multifaceted problem that includes the determination of shape and size of mating parts and the selection of part production and assembly processes. An analytical method has been previously presented for selecting the dimensions and tolerances of mating parts and the precision of assembly equipment where the mating parts possess simple geometries such as lines and circles. This paper proposes a Monte Carlo modeling, simulation, and inferencing method to make the methodology applicable to the design of assemblies with irregular and complex cross sections. The method is implemented for the ellipse and convex polygon cross sections to illustrate the analytical and geometrical ideas involved. The ellipse model determines the effect of out-of-roundness on the mating of what would ideally be circular parts. The assembly performance of polygon shaped geometries is studied employing two alternative methods; fixed side ratios, and proportional clearances. Using the presented method, the noncontact and/or chamferless insertion of precision mechanical components can be analyzed and designed for high performance processing. Other applications of the method include aligning beams in material combining processes such as laser sintering, and placing a cutting edge or beam against a material in machining processes such as stamping and electrical discharge machining.

粉末鍛造法による急冷凝固アルミニウム合金部材の製造およびその評価

P/M forging of some rapidly solidified aluminum alloy powders was investigated in order to develop an inexpensive production process of high strength parts with complex shapes. The results of this study are summarized as follows:1. The investigation of several P/M forging process for Al-18%Si alloy powders showed that mechanical properties of this alloy produced by the rigid die hot coining, followed by the rigid die hot forging are as good as those produced by extrusion.2. Forging of Al-25%Si-3%Cu-1%Mg-1%Fe alloy and of Al-10%Fe-1.5%Mo-1%V alloy powders for production of wear resistance parts of and for heat resistance parts, respectively were investigated, the mechanical properties of those parts were as good as those produced by extrusion. In the case of production of complicated shape parts, the powder forging technique gives good production yield and cost savings in comparison with the powder extrusion, since the powder forging produces a part in its final form directly without machining step.

A survey of the perturbation analysis of discrete event dynamic systems

This paper introduces an analysis and optimization technique for discrete event dynamic systems, such as flexible manufacturing systems (FMSs), and other discrete part production processes. It can also be used for enhancement of the simulation results of, or the monitoring of the operations of such systems in real time. Extensive references are given where readers may pursue futher details.