Part Program Generation Research Articles

Automated Coordinate Measuring Machine Inspection Planning Knowledge Capture and Formalization

Capturing the strategy followed during a coordinate measuring machine (CMM) inspection planning session has been an extremely challenging issue due to the time-consuming nature of traditional methods, such as interviewing experts and technical documents data mining. This paper presents a methodology demonstrating how a motion capture-based system can facilitate direct and nonintrusive CMM operator logging for capturing planning strategies and representing in knowledge formats. With the use of recorded motion data, embedded knowledge and expertise can be captured automatically and formalized in various formats such as motion trajectory graphs, inspection plans, integrated definition (IDEF) model diagrams, and other representations. Additionally, a part program can be generated for driving a CMM to execute component measurement. The system's outputs can be used to help understand how a CMM inspection strategy is planned, as well as training aids for inexperienced operators and the rapid generation of part programs.

Generic software tool for counteracting the dynamics effects of optical beam delivery systems

Laser micro-machining is a promising manufacturing solution for fabricating complex micro-engineering products in wide range of materials that incorporate different multi-scale functional features. Optical beam deflector systems are key components in laser micro-machining systems, and they are one of the main factors determining the processing speed and hence machining throughput. However, their performance is speed dependent and the negative dynamics effects have a direct impact on the laser micro-machining accuracy, repeatability and reproducibility. This article presents a generic software solution for minimising these negative dynamics effects, thus improving significantly the laser machining performance across the full range of available processing speeds. In particular, these improvements are achieved by introducing machine-specific compensations in machining vectors to counteract beam deflectors’ inertia regardless of their directions, length and set process speed. An empirical model was developed to obtain data about the actual dynamic response of the beam deflection system across the full range of available processing speeds, and then based on these data, the proposed generic software was implemented into a stand-alone ‘adaptive’ postprocessor. The generation of machine executable part programs is automated, and it is only necessary for the user to enter the selected scanning speeds and beam diameters. Experimental validation was conducted to demonstrate the capability of the proposed software tool. The results demonstrate that substantial improvements can be obtained in machining quality by maintaining a constant pulse distance throughout the machining operations, while the dimensional accuracy is maintained across the available processing speeds without sacrificing the machining efficiency.

An investigation on swarm intelligence methods for the optimization of complex part programs in CNC turning

Automation of engineering procedures for the development of new manufacturing processes is of great importance in modern competitive conditions. For example, metalworking companies would greatly benefit from the development of methods for automatic generation, testing and optimization of part programs for machining operations. Indeed, the generation of part programs—even by using CAM software—does still require strong human interven- tion and it is basically a best guess approach with minimum optimization. Moreover, further refinement and correction of the part program on the machine tool is often necessary. Machining operations are generally based on a large number of parameters and therefore optimization strategies should be able to deal with high-dimensional spaces and disjoint domains. In this paper, two swarm intelligence optimiza- tion algorithms—particle swarm optimization (PSO) and artificial bee colony (ABC)—have been applied for opti- mizating the part program of a complex turning part. The optimizers were implemented in a framework for automatic part program generation, realistic simulation, and feasibil- ity analysis. The results evidenced that both approaches were capable of optimizing efficiently the part program, and that the optimization time of the PSO approach on modern computers may be suitable for application in production.

An innovative approach for automatic generation, verification and optimization of part programs in turning

Continuous innovation of products and optimization of manufacturing processes are of fundamental importance for preserving competitiveness. In the last decades, several approaches based on analytic models for optimization of basic machining operations such as cylindrical turning and face milling have been developed. However, the analytic approaches may not be adequate for real industrial applications, since they are based on average cutting parameters and thus they are not capable of taking into account the effect of complex geometries and instantaneous cutting conditions. In this paper, an innovative integrated system for automatic generation of optimized part programs in turning based on realistic machining simulation is proposed. The system components are described in detail and the machining simulator is validated by comparison with the results of real cutting tests. Then, the optimization approach is applied to a simple case study. The results show that the behavior of the cost function is rather complex, even for simple workpieces. Moreover, the simulator can detect unfeasible combinations of cutting parameters and thus reduce inline part program refinement and optimization. The optimal combination of cutting parameters determined by the new system was competitive with the solutions derived from tool specifications or proposed by a machining expert.

Automatic CNC Part Programming for through Hole Drilling

This paper describes a novel method for automatic generation of process plans and numerical control (NC) part programs from STEP data files. Using proposed system, it is possible to achieve fully automation of recognition of through hole features, generation of process plans and NC part programs. Thus, it becomes possible to go from neutral file to finished product in a fully automated fashion. The algorithms have been implemented on mini-computer to process product data, and display recognized hole features, process plans and creates output files containing NC part programs. These NC part programs are tested through BMV45TC24 CNC Vertical Machining Centers. The results are satisfactory.

Automatic Feature Extraction and CNC Code Generation in a CAPP System for Micromachining

Feature extraction from a part model and Computer Numerical Control (CNC) code generation for machine tool control are the two extreme activities of a typical CAPP system. The present work discusses about a new methodology for automatic part feature extraction and CNC code generation for the invention of micro features in tool based micromachining processes. It has two main components; the first one deals with Extensible Mark-up Language (XML) based feature extraction from feature based model and interactive feature recognition. The second one deals with autonomous CNC code generation based on manufacturing features using various mathematical logic. Feature extraction through XML files avoids complex feature extraction process and automation of CNC code generation avoids human expertise and compatibility issues. The developed system integrated with micromachine tool through RS 232 communication interface. Hence for the given micro features, CNC code generation take place automatically and transferred to the micromachine tool in online with minimal user interface. The application of the proposed system verified with a case study. The developed system is limited to the parts having micro external step and drill features. Incorporation of more micro features, consideration of various other process planning activities and its part program generation ensures a complete CAPP system for micromachining.

Natural language manual programming for pulsed fiber laser micromachining

This paper proposes the use of voice commands expressed in natural language for part program generation for pulsed fiber laser micromachining. Traditionally, according to ISO G-code, a part program is an ordered list of program blocks in an ASCII formatted computer file. Each block identifies a machine operation and defines its parameters, following a predefined syntax. Under the proposed approach, such a file is replaced by natural language voice commands without any particular syntax constraints. Such an approach has the potential to facilitate the generation of part programs in domains (laser micromanufacturing, rapid prototyping, desktop computer numerical control) where traditional ISO G-code programming seems inappropriate, and the adoption and implementation of complex solutions such as STEP-NC or CAD/CAM systems could be unjustified. The input system is responsible for the recognition and interpretation of voice commands according to a statistical knowledge base learnt from examples. The proposed approach has been implemented in a prototype computer system, named smart programming system that has been validated by an application to the programming of pulsed fiber laser micromachining.

Simulated verification of NC part programs from 2D images

This paper describes a new approach to extract information from the 2D-drawing image files to determine turning features existing on rotational parts to be machined on turning centres; and later utilise this information to generate process plans and numerical control (NC) part programs. The software package is developed using ‘Java’ language incorporating the advanced features of Java Advanced Image (JAI) package. With the developed software package, one can achieve full automation of all aspects of the process plan, including sequence of operations, selection of tools, machining parameter selection and NC part program generation, etc. Thus, it becomes possible to go from image to NC part program in a fully automated fashion. This package is menu-driven and needs no programming skills to prepare NC part program for machining the parts. The paper includes an illustration of the procedure for extracting turned features, generating process plans and NC part programs from the image. The results are verified through CNC train simulation package and are satisfactory.

Automated generation of NC part programs for turned parts based on 2-D drawing image files

This paper describes a novel method for automated generation of process plans and numerical control (NC) part programs from 2D drawing image files. Four algorithms are introduced in this paper. First algorithm deals with extraction of geometrical data, second algorithm used to recognise turned features from the extracted geometrical data base. Recognised features are then passed to third and fourth algorithms for generation of process plans and NC part programs respectively. Using proposed system, it is possible to achieve fully automation of recognition of turned features, generation of process plans and NC part programs. Thus, it becomes possible to go from scanned image to finished product in a fully automated fashion. These algorithms have been implemented on mini-computer to process image data, and display recognised turned features, process plans and creates output files containing NC part programs. These NC part programs are verified through CNC train simulation package. The results are satisfactory.

A new software platform to support feature-based process planning for interoperable STEP-NC manufacture

Computer numerical control (CNC) manufacturing has evolved with the use of faster, more precise and more capable CNC controllers and machine tools. The enhancements in machine tools however have not been integrated under a common platform to support computer aided design (CAD)/computer aided manufacturing (CAM)/CNC software interoperability and as a result a plethora of standards are being used for these systems. ISO 10303 (STEP) and ISO 14649 (STEP-NC) seek to eliminate the barriers in the exchange of information in the CNC manufacturing chain and enable interoperability throughout the manufacturing software domain. With the progress on standardization and implementation, computer systems in the manufacturing process chain require evolution to support the STEP-compliant planning and manufacture. The current paper introduces a novel software platform entitled the Integrated Platform for Process Planning and Control (IP3AC) to support STEP-NC compliant process planning (computer aided process planning (CAPP)/CAM). A prototype process planning system (PPS) based on the platform is then presented as a sample application in the light of future interoperable planning and manufacture. The PPS has been developed with the application of a two-stage strategy for STEP-NC part program generation, namely general workplan generation and specific workplan generation. The work is verified through the use of case study components.

FEATURE-BASED PROCESS PLANNING FOR INTEROPERABLE STEP-NC MANUFACTURE

With the progress on STEP-NC standardization and implementation, STEP-NC-oriented computer systems in the process chain require evolution to support the STEP-compliant planning and manufacture. This paper explores process planning (CAPP/CAM) based on STEP-NC and presents a CAPP prototype system (PPS) in the light of future interoperable planning and manufacture. The PPS has been developed using STEP-NC features throughout the planning process and applies a two-stage strategy for STEP-NC part program generation, namely general workplan generation and specific workplan generation. The work is verified through use of case study components.

A prototyping and microfabrication CAD/CAM tool for the excimer laser micromachining process

A CAD/CAM tool for prototyping and small-scale production of micro-electro-mechanical systems (MEMS) devices based on the excimer laser ablation process has been developed. The system’s algorithms use the 3D geometry of a microstructure, defined as an STL file exported from a CAD model, and parameters that influence the process (laser fluence, pulse repetition frequency, number of shots per area, wall angle, stitching errors) to automatically generate a precise NC part program for the excimer laser machine. The performance of the system has been verified by NC part program generation for several 3D microstructures and subsequent machining trials. An initial stitching error of 23.4±2.2-μm wide and 3.4±1.5-μm high was observed when the overlap size between adjacent volumes was zero, when ablating 100×100-μm features in polycarbonate (PC) at a fluence of 0.5 J/cm2 using a workpiece-dragging technique. When the size of the overlap was optimised by a system based on optimal process parameters determined by the Taguchi design of experiment method (DOE), and incorporated in the mask design, the maximum stitching error was reduced to 13.4±2.2-μm wide and 1.4±0.9-μm high under the same conditions. By employing a hexagonal-shaped mask with incorporated size of the image overlap, reduced horizontal-stitching errors of 2.4±0.2-μm wide and 1.4±0.2-μm high were observed. The system simplifies part program creation and is useful for excimer laser operators who currently use a tedious trial and error process to create programs and complex masks to generate microstructure parts.

Making CNC machine tools more open, interoperable and intelligent—a review of the technologies

The aim of the next generation of computer numerically controlled (CNC) machines is to be portable, interoperable and adaptable. Over the years, G-codes (ISO 6983) have been extensively used by the CNC machine tools for part programming and are now considered as a bottleneck for developing next generation of CNC machines. A new standard known as STEP-NC is being developed as the data model for a new breed of CNC machine tools. The data model represents a common standard specifically aimed at the intelligent CNC manufacturing workstation, making the goal of a standardised CNC controller and NC code generation facility a reality. It is believed that CNC machines implementing STEP-NC will be the basis for a more open and adaptable architecture. This paper outlines a futuristic view of STEP-NC to support distributed interoperable intelligent manufacturing through global networking with autonomous manufacturing workstations with STEP compliant data interpretation, intelligent part program generation, diagnostics and maintenance, monitoring and job production scheduling.

A 3D-CAM system for quick prototyping and microfabrication using excimer laser micromachining

A 3D CAM tool for rapid prototyping and small-scale production of MEMS devices based on excimer laser ablation process has been developed. The system’s algorithms use the 3D geometry of a microstructure, defined in a CAD model, and parameters that influence the process (etch rate, wall angle, stitching errors, etc.) to automatically generate a precise NC part program for the excimer laser machine. The performance of the system has been verified by NC part program generation for several 3D microstructures and subsequent machining trials. Stitching errors of 23.4±2.2 μm wide and 3.4±1.5 μm height were observed when overlap size between adjacent volumes were zero, when ablating 100×100 μm features in PC at fluence of 0.9 J/cm2 using a workpiece dragging technique. When the size of the overlap was optimised by software based on optimal process parameters determined by Taguchi design of experiment method (DOE) and incorporated in the mask design the maximum stitching errors are reduced to 13.4±2.2 μm wide and 1.4±0.9 μm in height under the same conditions. Employing the hexagonal shaped mask with incorporated size of the image overlap, horizontal-stitching errors with width of 2.4±0.2 μm wide and 1.4±0.2 μm high were observed. The software simplifies part program creation and is useful for excimer laser operators who currently use a tedious trial and error process to generate microstructure parts.

Automatic generation of numerical control part programs using object-oriented software

This paper presents an automatic approach to the generation of numerical control (NC) part programs for a specified manufacturing process plan. Generation of NC part programs for a specified process plan is a tedious task, especially when there are repetitive sequences of operations. The interactive graphics software developed in the present work simultaneously generates manual part programs. Three modules of the present software separately create an interactive process plan and NC code for point-to-point operations, straight-cut operations and contouring operations. Outputs of the present software are shown with examples.

Architecture and implementation of a shop-floor programming system for STEP-compliant CNC

STEP-NC (formalized as ISO 14649 and ISO 10303 AP238) is a new interface (or language) standard for the CAD–CAM–CNC chain, currently under establishment by ISO TC184 SC1 and SC4. Upon completion, it will replace ISO 6983, so called M & G codes used for CNC since 1950s. As the new language is being established, a new CNC controller called STEP-CNC (STEP-compliant CNC), capable of carrying out various intelligent tasks using the new language as an input, receives worldwide attention. Shop-floor programming (SFP) system is a computer-assisted part programming system interfaced with STEP-CNC. Its primary function is to generate part program in ISO 14649 (or STEP AP238) to machine the part geometry given by STEP AP203 or AP224 file. In this paper, we first present an architecture for the SFP system, followed by implementation technology including: (1) STEP physical file interpretation, (2) feature recognition, (3) process planning, (4) part program generation, and (5) verification. The developed methodology was implemented in a prototype called PosSFP, and tested with Korea STEP-NC system.

Automatic generation of part programs for milling sculptured surfaces

In recent years, a large number of commercially available CAD/CAMCAE packages as well as computer numerically controlled machine tools have been imported into Iranian manufacturing industry. However, there has been no easy-to-use link or interface between the two. In this paper, an attempt is made to establish a simple but effective software to link CAD packages and CNC machine tools. To achieve this, a software package was developed capable of exploring Initial Graphics Exchange Specifications (IGES) files of simple or free-form surfaces created on any CAD package. The data extracted from IGES files is used to graphically simulate tool path due to centre and tip of a ball nose tool and a filleted cutter as well as tip of a flat end mill cutter. Depending on the size of created surfaces, various dimensions of cutting tools should be selected by the user. Other features included in this package are the ability to automatically detect the correct machining direction and correct machining side of surface, calculation of tool compensation and tool step. Obviously, its main feature is its ability to automatically generate part programs for machining sculptured surfaces. Number of such surfaces were created on CAD systems and the generated tool path were successfully simulated and a few are presented in this paper.

Reverse Engineering of Sculptured Surfaces by Four-Axis Non-Contacting Scanning

Reverse engineering can be divided into four steps: surface data extraction; extracted data processing; surface reconstruction; and CNC part program generation. The goal of this research is to deal with data extraction from complex sculptured surfaces, redundant data elimination, and surface reconstruction problems of reverse engineering. To deal with the complex-sculptured-surface data extraction problem, an efficient four-axis non-contacting surface data scanning system, which integrates a PC-based XYZ table, a laser displacement meter (LDM), and a personal computer is developed. In this four-axis system, an LDM, an XYZ table and a PC are used as a displacement sensor, sensor carrier and central controller, respectively. In extracted data processing, we apply the medium filter technique to smooth data points, and propose a simple algorithm to discard efficiently those redundant measured points according to the required degree of accuracy. While in the surface reconstruction, we first try to convert all eliminated column or row data into spline curves. Methods for 2D spline (u, v directions) curve construction are described. Non-meshed 2D spline curves are then blended to a spline surface in terms of a sparse matrix data structure. Experimental results show that the proposed four-axis surface data scanning machine can be programmed to measure most of the complex sculptured surfaces which is not possible using a three-axis machine. The proposed extracted data-processing method can reduce the surface reconstruction time substantially, for only the cost of a little extracting time and minor modelling errors.

An Integrated Steel Workshop for Shipbuilding: A Real Application of Automation

The paper describes the layout of an innovative automated steel workshop for the manufacturing of ship blocks, recently set up at Fincantieri's Monfalcone Shipyard. The system implements the results of a European EUREKA! research program called FASP -Flexible Automation in Ship Prefabrication. The various working areas of the shop are described; for each of the new technologies being applied, the level of automation and integration with the other areas is discussed; the advantages obtained are compared with the best typical standards of a traditional production workshop. Inside a fully automated workshop, the information support must have a high integration and flexibility level. The two main issues relevant to information technology are described, i.e., :the modular and integrated systems for the design, part program generation and transmission; andthe production programming, management and control system.

An integrated intelligent process planning system (IIPPS) for machining

A key component of computer integrated manufacturing (CIM) is computer aided process planning (CAPP). Process planning in machining involves the determination of the cutting operations and sequences, the selection of machine tools and cutting tools, the calculation of machining parameters, and the generation of CNC part programs. Industrial structures in Norway are defined as small and medium-sized companies. The important fact is how well these companies use high technologies and resources in order to improve their production efficiency, product quality, and company competition in international markets. The concept of an integrated intelligent system (IIS) is created for this purpose. A prototype system, the integrated intelligent process planning system (IIPPS), is described for machining; it was developed on the basis of an IIS and constructed using three levels of effort: (1) AutoCAD, (2) dBASE III and (3) KnowledgePro. The system may be utilized not only by a process plann ing engineer in a company, but also by students of mechanical or industrial engineering.