On Measurement and Interpretation of Toughness Behaviour of Carbide Tools

The actual significance of any definition of toughness behaviour of carbide tools depends on the existence of an interrelation between the quality as defined and the occurrence of chipping and premature failure in cutting. While at present there is no adequate analysis available and the existing classifications do not even provide a qualitative indication for tool choice, one first has to evaluate the behaviour of cemented carbides for simplified load conditions. Where fracture and chipping is a mechanical phenomenon, in the case of tools assisted or even dominated by thermo-mechanical effects, a logical first step for the evaluation of carbide grades would seem to determine the property profile of carbide tools in terms of toughness and resistance to thermal shock, but in such a way that a qualitative interpretation of the cutting conditions can be taken into account. This article deals with a tentative approach for the evaluation of toughness performance of throw-away carbide inserts with the aid of a four point bending test and the diagonal compression test, the latter also being used for measuring the relative resistance to thermal shock

The integration of process planning and machine loading in small batch part manufacturing

PART is a highly automated planning system in which both process and production planning functions are integrated. This paper discusses a method to improve machine tool selection in process planning by integration with loading. A method is presented to select the best process plan from a number of possible alternatives taking into account the limited availability of resources. Various aspects of the quality of a process plan are evaluated and expressed in the so-called evaluation time. To prevent redundant work, partly worked out process plans are considered as alternatives. The consequences of the different alternatives have to be estimated which includes the estimation of machining times. The loading problem is modelled as the minimization of the total evaluation time for a given order set, subjected to capacity constraints

Flowdrilling: a Preliminary Analysis of a New Bush-Making Operation

Flowdrilling is a bush-making operation applied to thin walled products for joint engagement. Fastenings exhibit mechanical properties which depend largely on the shear strength of the parent material and the area of engagement. Flowdrilling is specifically designed to increase the latter. Developments during the last six or seven years have resulted in a number of industrial usefull applications. Previous attempts to use “rotary plunging methods” failed due to low tool life and the inability to obtain an acceptable finish. The paper describes the different process variables and gives the results of a preliminary analysis of the different mechanical and physical aspects. Manufacturing properties like cycle time and tool life are also dealt with

The Integration of Process Planning and Shop Floor Scheduling in Small Batch Part Manufacturing

In this paper we explore possibilities to cut manufacturing leadtimes and to improve delivery performance in a small batch part manufacturing shop by integrating process planning and shop floor scheduling. Using a set of initial process plans (one for each order in the shop), we exploit a resource decomposition procedure to determine schedules to determine schedules which minimize the maximum lateness, given these process plans. If the resulting schedule is still unsatisfactory, a critical path analysis is performed to select jobs as candidates for alternative process plans. In this way, an excellent due date performance can be achieved, with a minimum of process planning and scheduling effort

Fixture Design with FIXES: the Automatic Selection of Positioning, Clamping and Support Features for Prismatic Parts

FIXES is a computer aided system for the automatic generation of set-ups and for fixture design for prismatic parts, to be used in an integrated process planning environment. The generation of set-ups having been described in a previous paper [9], this paper concentrates on fixture design, in particular the automatic selection of the faces for the positioning, clamping and support of workpieces. The selection procedures described are based on both the topology of the prismatic part and the geometric relations between the different part elements (features). The geometric relations are evaluated with the aid of a so-called Converted Tolerance Scheme

FIXES, a system for automatic selection of set-ups and design of fixtures

This paper reports on the development of a computer aided planning system for the selection of set-ups and the design of fixtures in part manufacturing. First, the bottlenecks in the present planning methods are indicated. A brief description is given of the CAPP environment PART, in which FIXES is incorporated. The planning procedure of FIXES consists of two parts: the selection of set-ups and the design of a fixture for each set-up. The automatic selection of set-ups is based on the comparison of the tolerances of the relations between the different shape elements of the part. A tolerance factor has been developed to be able to compare the different tolerances. The system automatically selects the positioning faces and supports the selection of tools for positioning, clamping and supporting the part. A prototype implementation of FIXES is discussed

Cost Decision Support in Product Design

The constraints addressed in decision making during product design, process planning and production planning determine the admissible solution space for the manufacture of products. The solution space determines largely the costs that are incurred in the production process. In order to be able to make economically sound decisions, costing data support must be integrated into the decision making processes. Regarding product design, the designer must be supplied with transparent costing data, that is ready for direct application. In this paper a functional architecture for costing data support during product design, as well as a corresponding data structure are presented