C.S.P. Rao

A CAD system for extraction of mating features in an assembly

Purpose – The information and knowledge about a product and its assembly are necessary to generate all feasible assembly sequences of that product. Assemblies contain a very large amount of information and complex relationships. Identifying assembled parts as well as their contact surfaces is very important in design and manufacturing since this information is essential. The problem is to not only make the information available but also use the relevant information for making decisions, especially determination of the optimum assembly sequence. This paper aims to address these issues.Design/methodology/approach – This paper describes a system for processing assembly models and extracting assembly related data using application programming interface (API) of the computer‐aided design (CAD) software. These data are used to identify the relationships between different components of an assembly thus encouraging generation of feasible assembly sequences.Findings – Instead of total human interpretation of the a...

A Novel Method of Using API to Generate Liaison Relationships from an Assembly

A mechanical assembly is a composition of interrelated parts. Assembly data base stores the geometric models of indi-vidual parts, the spatial positions and orientations of the parts in the assembly, and the relationships between parts. An assembly of parts can be represented by its liaison which has a description of its relationships between the various parts in the assembly. The problem is to not only make the information available but also use the relevant information for making decisions, especially determination of the assembly sequence plan. The method described in this paper ex-tracts the feature based assembly information from CAD models of products and build up liaisons to facilitate assembly planning applications. The system works on the assumption that the designer explicitly defines joints and mating condi-tions. Further, a computer representation of mechanical assemblies in the form of liaisons is necessary in order to automate the generation of assembly plans. A novel method of extracting the assembly information and representing them in the form of liaisons is presented in this paper.

Mechanical and dry sliding wear behavior of Al7075 alloy-reinforced with SiC particles

In this article, the experimental results of the mechanical and tribological properties of Al7075–SiC composites are presented. The composites of Al7075 containing 2–6 wt% SiC were fabricated by liquid metallurgy route. The experimental results showed that the density of the composites increase with increased SiC contents and are in line with the values obtained by the rule of mixtures. The hardness and tensile strength of the Al7075–SiC composites are found to be increased by increased volume percentage of ceramic phase at the cost of reduced ductility. The wear properties of the composites containing SiC exhibited the superior wear-resistance properties.

A heuristic for priority-based scheduling in a turbine manufacturing job-shop

The increasing importance of make-to-order manufacturing, inventory reduction and resource optimisation have placed further emphasis on the growing role of scheduling in the current global business environment. Often there has been a problem of applying the mathematically rich concepts of scheduling theory to solve the real-time industrial problems – in particular the problem of job-shop scheduling. In this context, in our current work, we develop a priority-based heuristic for minimising the makespan for a turbine manufacturing industry. This heuristic gives the optimal schedule based on the dynamic priorities of the customer work orders. We also propose bounds for makespan in job-shop scheduling environment. There are a host of issues addressed by the job shop scheduling system, like resource break-down, reentrance of the jobs on the resources that are already visited by the job. Our research helps in connecting the academic theory with real-time industrial scheduling problem to get better quality results.

Consignment stock policy with controllable lead time for effective inventory management in supply chains

In this paper, we develop an inventory model where the replenishment lead time is assumed to be dependent because at the time of contract with a manufacturer retailer may intend to reduce the lead time for which he pay an additional cost to accomplish the increased production rate. We provide a solution procedure to obtain the efficient ordering strategy in Hills inventory model in particularly Consignment Stock (CS) policy of Supply Chain Management (SCM) for a single vendor–single buyer under the stochastic nature. The lead time of CS strategy has been controlled to minimise Joint Total Expected Cost (JTEC) and simultaneously optimised other decision variables such as quantity transported, lead time, the number of transport operations and delay deliveries under stochastic environment so as to gain a competitive advantage in the business strategy. Numerical examples are presented to illustrate the solution procedure.

Consignment stock policy using genetic algorithm for effective inventory management in supply chains

In this paper, we consider single-vendor?multi-buyer Consignment Stock Policy (CSP) inventory model which is a distinctive flavour of Vendor Managed Inventory (VMI). Four different models have been formulated using Genetic Algorithm (GA) to minimise joint total expected cost of vendor and buyer and simultaneously optimise other decision variables such as quantity transported, number of transport operations, delay deliveries and buyer maximum and minimum stocks under stochastic environment. Numerical examples are presented to illustrate the proposed models, and the effects of changes on the cost and system parameters on the inventory are studied by using sensitivity analysis. To solve the iterative procedure involved, the GA is coded in VC++.

Optimisation of supply chains for single vendor?multibuyer consignment stock policy under controllable lead time using genetic algorithm

In this article, we develop a controllable-lead-time inventory model where the lead time is assumed to be dependent because at the time of contract with a manufacturer, the retailer may intend to reduce the lead time, for which he will pay an additional cost to accomplish an increased production rate. The lead time of Consignment Stock (CS) strategy has been controlled to minimise Joint Total Expected Cost (JTEC), and other decision variables such as quantity transported, lead time, number of transport operations and delay deliveries under stochastic environment have been simultaneously optimised so as to gain competitive advantage in the business strategy. Numerical examples and sensitivity analysis are presented to illustrate the solution procedure.

Generation of optimum sequence of operations using ant colony algorithm

Computer-aided process planning (CAPP) forms an important interface between computer-aided design (CAD) and computer-aided manufacturing (CAM). It is concerned with determining the sequence of individual manufacturing operations required to produce a product as per technical specifications given in the part drawing. In this paper the process planning is modelled as a combinatorial optimisation problem with constraints, and an ant colony optimisation (ACO) approach has been used to solve it. This is a newly developed metaheuristic algorithm used as a global search technique for the quick identification of the optimal operations sequence by considering various feasibility constraints.

A robust process optimisation for fused deposition modelling

Rapid Prototyping (RP) technology is being widely used in diverse areas including mould manufacturing. However, the quality of RP parts is significantly affected by the process parameters of the RP machine. This work presents an experimental design technique for determining the optimal quality of a part build by the Fused Deposition Modelling (FDM) process with ABS plastic material. The design investigates (L9 Taguchi array) the effect of the parameters, contour width, raster width, raster angle and air gap on the dimensional accuracy, form features and surface finish. The experimental results are analysed by using the Analysis of Variance (ANOVA) method.

Optimisation of cam-follower motion using B-splines

This paper proposes design of cam-follower velocity curve by using B-spline polynomials. B-spline polynomials are smooth curves defined by control points. Curve shape can be modified by changing the control points. The traditional design method for improving the motion characteristics of the follower is to find an optimum displacement curve for which follower velocity, acceleration curves to be continuous and their peak values as small as possible (i.e. minimum jerk). B-spline polynomials of degree three and six control points are used in design of follower velocity curve. The B-spline curve is used to approximate the various basic curves which have better motion characteristics. A computer-aided design and computer-aided manufacturing (CAD/CAM) system is developed which generates follower motion curves, i.e. displacement, velocity, acceleration, jerk and cam profiles. An analysis is carried out on B-splines with basic curves for maximum accelerations to select the best cam follower motion. It also provides cam profile coordinates to manufacture a cam on computer numerical control (CNC) machines.