Model Reduction Techniques with RBE2 and RBE3 Connection for Structural Results of Handling/Lifting Fixtures for Satellite Payloads

A fixture is design to hold, support and locate every component with accuracy. Fixture design is very important step for the setup-planning phase. The present work aims to get proper result with accurate connection of the fixture. In this work, two techniques are built for fixture analysis, give the comparison of structural results of full model, and reduce model with connection of RBE 2 and RBE 3. Design and analysis of fixture is done by using known softwares, inventor and hyperworks.

An automatic and optimal selection of parts orientation in additive manufacturing

Purpose In additive manufacturing processes such as stereolithography and fused deposition modeling, optimal part orientation is pivotal in improving the quality of the part. This paper aims to propose an automatic and optimal part orientation system to improve part quality/accuracy in additive manufacturing, which minimizes the production time and hence reduces the cost of product. Design/methodology/approach The developed system reads STEP AP 203 E2 file from CATIA V5 and generates data extraction output file by extracting the relevant geometrical and topological data using an object-oriented approach. Afterwards, the algorithms and rules are developed to extract and recognize feature faces along with their geometric properties such as face type, face area, parallelism and perpendicularity. The feature data obtained that are used to develop feasible part orientations depend on the maximization of G&DT for all part faces. The automatic slicing is then achieved by creating slicing file using CATVBA editor inside CATIA V5. Findings After slicing, output data are exported in Excel data sheet to calculate the total additive volume of the part. The building time of the part is then calculated on the basis of machine parameters, part geometry, part height, layer thickness and amount of support volume needed to build the part. The optimal orientation of the part is achieved by maximization of G&DT value and minimization of production time. The proposed methodology is tested using an illustrative example. Originality/value Although lot of approaches have been discussed in the literature, automation of setup planning/orientation of the part in additive manufacturing is not fully attained. Therefore, the article focuses on the automation of setup planning by adding automatic feature extraction and recognition module along with the automatic slicing during setup planning. Moreover, the significance of adding feature extraction and recognition module is to achieve best accuracy for form feature faces and hence reduction in post processing machining/finishing operations.

A hybrid optimization approach for setup planning with tolerance constraints

Computer-aided process planning (CAPP) plays an important role in integrated manufacturing system and it can serve as a bridge between CAD and CAM. As a crucial part of CAPP, setup planning is a multi-constraint problem, in which the precision takes priority over efficiency. However, instead of precision constraints, traditional optimization methods have paid much more attention to efficiency requirements. This leads to the reduction in the precision of the final parts. This paper develops an optimization approach for solving computer-aided setup planning problem, which takes into account various constraints, especially the precision requirements specified by designers. First, objective function of the optimization model is formulated and a series of constraints, including feature precedence, tool approaching direction (TAD), and precision requirements are systematically created. Next, the model is solved by using a hybrid particle swarm optimization algorithm. In order to overcome the local optimum trap, mutation and exchange operations are adopted from the genetic algorithm. Finally, a part is tested in the case study and the validation of this method is proved.

RULE-BASED PROCESS PLANNING AND SETUP PLANNING WITH CONSIDERATIONS OF GD&T REQUIREMENTS

Computer aided process planning is a critical link between design and manufacturing. The ready process plan in integration of design and manufacturing is always important to save manufacturing time, reduction of work in progress. This paper describes a rule based intelligent process planning system which selects necessary manufacturing processes features in the metal mechanical parts. Novel feature of this system is the use of detailed GD&T specification on both process selection and setup planning modules. Process selection module selects the necessary processes for manufacturing the hole feature that depends on feature dimensions, feature precedence, and specified geometric and dimensional tolerances. Setup planning module determines the sequences of the setups of the prismatic part on the machine tools that includes clustering and sequencing of the features in setups. This module uses rules for the following steps: tool approach direction definition, setup formation based on GD&T requirements, resolution of possible cyclic setups, setup sequencing and operation sequencing in setups. Rules can generate valid setups for both 3-axis and 4-axis milling machines. The procedures are illustrated on several examples.