Widely used in manufacturing, fixtures have a direct impact upon product manufacturing quality, productivity and cost, so much attention has already been paid to the research of computer aided fixture design (CAFD) and many achievements in this field have been reported. In this paper, a literature survey of computer aided fixture design and automation over the past decade is proposed. First, an introduction is given on the fixture applications in industry. Then, significant works done in the CAFD field, including their approaches, requirements and working principles are discussed. Finally, some prospective research trends are also discussed.

Computer aided fixture design: Recent research and trends

A key characteristic of the modern market place is the consumer demand for variety. To respond effectively to this demand, manufacturers need to ensure that their manufacturing practices are sufficiently flexible to allow them to achieve rapid product development. Fixturing, which involves using fixtures to secure workpieces during machining so that they can be transformed into parts that meet required design specifications, is a significant contributing factor towards achieving manufacturing flexibility. To enable flexible fixturing, considerable levels of research effort have been devoted to supporting the process of fixture design through the development of computer-aided fixture design (CAFD) tools and approaches. This paper contains a review of these research efforts. Over seventy-five CAFD tools and approaches are reviewed in terms of the fixture design phases they support and the underlying technology upon which they are based. The primary conclusion of the review is that while significant advances have been made in supporting fixture design, there are primarily two research issues that require further effort. The first of these is that current CAFD research is segmented in nature and there remains a need to provide more cohesive fixture design support. Secondly, a greater focus is required on supporting the detailed design of a fixture's physical structure.

Review: A review and analysis of current computer-aided fixture design approaches

In manufacturing engineering, localization accuracy is a key concern in the design of a fixture to specify a locating scheme and tolerance allocation. This paper presents a general analysis methodology that is able to characterize the effects of localization source errors based on the position and orientation of the workpiece. From this methodology, a fixture model is formulated by taking into account the overall errors among the system consisting of the workpiece and the fixture in the design of the fixture locating scheme. With this model, the locating principle and a criterion of the robust optimal design are then proposed to improve the localization quality of the fixture. Some examples are provided and allow for a detailed discussion about how to carry out the optimal design of the locating scheme. A comparative study is also made between the optimal solution and the empirical one. Finally, an experiment is made to validate the fixture locating scheme for a cylindrical workpiece. We conclude that this robust design method effectively achieves stable machining precision in workpieces.

A mathematical approach to analysis and optimal design of a fixture locating scheme

In any machining fixture, the workpiece elastic deformation caused during machining influences the dimensional and form errors of the workpiece. Placing each locator and clamp in an optimal place can minimize the elastic deformation of the workpiece, which in turn minimizes the dimensional and form errors of the workpiece. Design of fixture configuration (layout) is a procedure to establish the workpiece–fixture contact through optimal positioning of clamping and locating elements. In this paper, an ant colony algorithm (ACA) based discrete and continuous optimization methods are applied for optimizing the machining fixture layout so that the workpiece elastic deformation is minimized. The finite element method (FEM) is used for determining the dynamic response of the workpiece caused due to machining and clamping forces. The dynamic response of the workpiece is simulated for all ACA runs. This paper proves that the ACA-based continuous fixture layout optimization method exhibits the better results than that of ACA-based discrete fixture layout optimization method.

Machining fixture layout design using ant colony algorithm based continuous optimization method.

This paper presents a case-based reasoning (CBR) method for welding fixture design, a critical issue in the manufacturing of large and complicated equipment. However, previous fixture design research has mainly focused on machining fixtures rather than welding fixtures. In this paper, an approach of data abstraction for fixture design information representation is proposed, first to systemize and manage myriads of fixture related resources, e.g., past fixture design solutions, fixture units depository. Based on this approach, a multi-level CBR method for welding fixture design is then presented. This method could help designers, by referencing previous design cases, to make a conceptual fixturing solution quickly and, finally, finish the detailed solution of fixture design.

Case based reasoning method for computer aided welding fixture design

Computer‐aided fixture design (CAFD) techniques have been advanced so rapidly that computers can now generate fixture configurations automatically, for both modular fixtures and dedicated fixtures. Computer‐aided fixture design verification (CAFDV) is the techniques for verifying and improving existing fixture designs. It verifies the followings: geometric constraining ability, achieved tolerance, fixturing stability, and fixturing accessibility. Two models – one geometric and one kinematic – are created for the verification.

https://digital.wpi.edu/downloads/05741r744

Computer‐aided fixture design verification

Computer-aided fixture design (CAFD) techniques have been advanced rapidly so that fixture configurations can be generated automatically, for both modular fixtures and dedicated fixtures. Computer-aided fixture design verification (CAFDV) is the technique for verifying and improving existing fixture designs. In this paper, the framework of CAFDV is introduced based on two models, i.e., geometric and kinematic models. The fixturing tolerance and stability verification will be presented in separate papers.

Computer-Aided Fixture Design Verification. Part 1. The Framework and Modelling

Tolerance analysis is the most important issue in computer-aided fixture design (CAFD), and it is an important part of computer-aided fixture design verification (CAFDV). This study presents a new approach for fixture tolerance analysis that is more generalised and can be used to assign locator tolerances based on machining surface tolerance requirements. The tolerance analysis is also generalised to handle any type of fixture design, workpiece, datum feature, and machining feature tolerance. Locator tolerance assignment distributes tolerances to locators based on a sensitivity analysis.

Computer-aided fixture design verification. Part 2. Tolerance analysis

In fixture design, a workpiece is required to remain stable throughout the fixturing and machining processes in order to achieve safety and machining accuracy This requirement is verified by a function of the computer-aided fixture design verification (CAFDV) system This paper presents the methodologies of fixturing stability analysis in CAFDV A kinetic fixture model is created to formulate the stability problem, and a fixture stiffness matrix (FSM) is derived to solve the problem This approach not only verifies fixturing stability, but also finds the minimum clamping forces, fixture deformation, and fixture reaction forces The clamping sequence can also be verified with this approach

Computer-Aided Fixture Design Verification. Part 3. Stability Analysis

Computer-aided fixture design (CAFD) techniques have been advanced rapidly that fixture configurations can be generated automatically, for both modular fixtures and dedicated fixtures. Computer-aided fixture design verification (CAFDV) is the technique for verifying and improving existing fixture designs. In this paper, the framework of CAFDV is introduced with two based on two models, geometric and kinematic models. The fixturing tolerance and stability verification will be presented in separated papers.Copyright © 2002 by ASME

Y. Kang

Papers

Computer‐aided fixture design verification

Computer-Aided Fixture Design Verification. Part 1. The Framework and Modelling

Computer-aided fixture design verification. Part 2. Tolerance analysis

Computer-Aided Fixture Design Verification. Part 3. Stability Analysis

Computer-Aided Fixture Design Verification: Part 1 — The Framework and Modeling