Recent lma_codef items

A Review of Burr Formation in Machining

Wed, 19 Jan 2011 00:00:00 +0000

One of the major concerns in deburring technology is centered on how to predict the size and shape of burrs to insure uniform removal and, if this is possible, how to design the process or product in advance to minimize or control the burr size. This paper reviews some of the research done over the past several years on this important topic. The paper includes a discussion of burrs in conventional machining, process planning for burr minimization as well as micromachining applications.

Burrs—Analysis, control and removal

Wed, 19 Jan 2011 00:00:00 +0000

Increasing demands on function and performance call for burr-free workpiece edges after machining. Since deburring is a costly and non-value-added operation, the understanding and control of burr formation is a research topic with high relevance to industrial applications. Following a review of burr classifications along with the corresponding measurement technologies, burr formation mechanisms in machining are described. Deburring and burr control are two possible ways to deal with burrs. For both, an insight into current research results are presented. Finally, a number of case studies on burr formation, control and deburring along with their economic implications are presented.

2D Accessibility Analysis for Water Jet Cleaning

Thu, 26 Nov 2009 00:00:00 +0000

Effective cleaning with high pressure waterjets requires direct impact of jets and sufficiently high impact pressure. The objective of this research is to find all such cleanable regions, given a CAD model of a workpiece, by means of geometric accessibility analysis. We use a configuration space (C-space) approach for addressing the problems of both optimum surface proximity for effective cleaning and collision avoidance between the cleaning lance and the workpiece. Minkowski sums are used to compute the C-spaces and cleanable regions are then found by visibility analysis. Implementations and results for 2D examples are shown to validate the approach.

Investigation of Internal Cleaning Effects in Two-Phase Gas-Liquid Flows

Sun, 28 Jun 2009 00:00:00 +0000

In the past few years, cleanability of mechanical components became a new engineering constraint in the automotive and aerospace industry due to a rapid increase in the complexity of engines, transmissions, suspension components, etc. Cleaning processes currently used in industry are quite inefficient as they incur significant energy and consumable costs and, in many cases, cannot achieve the degree of cleanliness necessary to meet performance and service life requirements of the components. There is a good amount of scope to improve the existing technology with analytical and computational tools that can help predict and control cleaning effect at design and process planning stages. On the other hand, an improvement in the understanding of the mechanics of chip cleanability which involves interactions between the cleaning fluid and the chip critical and workpiece bottleneck dimensions can help us investigate the development of new technologies that enhance the phenomenon that...

Formulation of the Chip Cleanability Mechanics from Fluid Transport

Thu, 2 Apr 2009 00:00:00 +0000

The presence of solid particle contaminant chips in high performance and complex automotive components like cylinder heads of internal combustion engines is a source of major concern for the automotive industry. Current industrial cleaning technologies, simply relying on the fluid transport energy of high pressure or intermittent high impulse jets discharged at the water jacket inlets of the cylinder head, fail to capture the dynamics of interaction between the chip morphology and the complex workpiece landscape. This work provides a preliminary insight into an experimental investigation of the mechanics of chip transport at play, and how it can be used to build an effective chip optimization model that significantly aids in improving the cleanability of contaminant chips. The objective is to relate the mechanics of chip transport with the chip form parameters as much as possible, which makes the objective and constraints in the optimization model quantifiable. The end objective...

Cleanability of Mechanical Components

Thu, 22 Jan 2009 00:00:00 +0000

We developed computer-aided planning tools for waterjet cleaning processes incorporating experimental results. We designed experiments to determine the influence of key waterjet parameters on cleaning effect and devised a computer-aided visualization and optimization scheme incorporating these parameters. In addition, we developed a particle dynamics model to simulate local waterjet interaction with target surfaces. Finally, we developed a model to predict water traps inside the workpieces based on layered volume segmentation. Our tools will aid designers and process planners in achieving efficient cleaning of geometrically complex workpieces in a high volume manufacturing environment.

Modeling of Inter-Layer Gap Formation in Drilling of a Multi-Layered Material

Wed, 27 Jun 2007 00:00:00 +0000

With increases in the use of multi-layered material in the aerospace industry to reduce weight while still meeting strength requirements, studying inter-layer burr formation in drilling of a multi-layered material becomes more important. Inter-layer gap formation due to material bending by drilling thrust force has significant effect on inter-layer burr formation. A finite element model for inter-layer gap formation in a multi-layered material was proposed. A gap formation was initiated by initial difference in elastic bending of layers and developed by plastic deformation of the first layer. Influence of clamping location on gap size was also investigated.

Finite Element Modeling of Burr Formation in Metal Cutting

Wed, 27 Jun 2007 00:00:00 +0000

In order to advance understanding of the burr formation process, a series of finite element models are introduced. First a finite element model of the burr formation of two-dimensional orthogonal cutting is introduced and validated with experimental observations. A detailed and thorough examination of the drilling burr forming process is undertaken. This information is then used in the construction of an analytical model and, leads to development of a three-dimensional finite element model of drilling burr formation. Using the model as a template, related burr formation problems that have not been physically examined can be simulated and the results used to control process planning resulting in the reduction of burr formation. We highlight this process by discussing current areas of research at the University of California in collaboration with the Consortium on Deburring and Edge Finishing (CODEF).

Tool Path Planning Generation For Finish Machining of Freeform Surfaces in the Cybercut Process Planning Pipeline

Wed, 2 May 2007 00:00:00 +0000

The research describes part of a "Pipeline of De-sign and Manufacturing Tools" for product de-signers who are driven by short delivery-times. The overall project has been called CyberCut be-cause the modules can interoperate in a distrib-uted, Internet-based environment. This particular paper focuses on tool path generation of sculp-tured surfaces using 3-axis CNC machines. Im-portance is given to generating cutter location points that will meet the tolerance requirement while maintaining a certain surface finish. Sec-tions of the paper describe: a) the offset-generation method, b) the tool path generation scheme and c) the tool holder collision detection algorithm. The algorithms that have been devel-oped are used to machine sample parts.

Advancing Cutting Technology

Thu, 5 Apr 2007 00:00:00 +0000

This paper reviews some of the main developments in cutting technology since the foundation of CIRP over fifty years ago. Material removal processes can take place at considerably higher performance levels in the range up to Qw = 150 - 1500 cm3/min for most workpiece materials at cutting speeds up to some 8.000 m/min. Dry or near dry cutting is finding widespread application. The superhard cutting tool materi- als embody hardness levels in the range 3000 – 9000 HV with toughness levels exceeding 1000 MPa. Coated tool materials offer the opportunity to fine tune the cutting tool to the material being machined. Machining accuracies down to 10 ?m can now be achieved for conventional cutting processes with CNC machine tools, whilst ultraprecision cutting can operate in the range < 0.1?m. The main technological developments associated with the cutting tool and tool materials, the workpiece materials, the machine tool, the process conditions and the manufacturing environment...

Efficient Tool Paths and Part Orientation for Face Milling

Thu, 5 Apr 2007 00:00:00 +0000

High speed machining is pushing the limits of feeds and speeds. A different approach for high throughput is described here. The focus is on the maximum feed that can be obtained for a segment; the feed rate losses due to sharp changes in tool path are minimized. The interdependency of individual axis drive speeds for a tool path segment are analyzed. There exists an optimum work angle relative to the axes that reduces losses and increases allowable feeds for particular segments, saving valuable cycle time and balancing feed drive loads. Face milling and roughing steps of end milling are the most attractive application areas.

A Wireless Sensor for Tool Temperature Measurement and its Integration within a Manufacturing System

Thu, 5 Apr 2007 00:00:00 +0000

This is a systems-oriented paper that begins with a specific description of a wireless sensor that was developed to measure cutting tool tempera- tures in milling. Resistive Temperature Detectors (RTDs) were installed on the backside of end-mill inserts and a wireless platform transmitted data. The goal of this new work was to design a wire- less sensor system with a high degree of minia- turization, together with the ability to measure temperatures in real-time. As a result, the new system could be used within an Open Architec- ture Controller (OAC) as part of a closed loop monitoring system based on a desired “operating set-point temperature.” The second part of the paper describes a broader use of wireless sen- sors that can be integrated into factory-wide Wire- less Sensor Networks (WSNs). Such networks are an underlying technology that can further broaden the effectiveness of Computer Integrated Manufacturing (CIM) Systems. The final section of the...

Influence of Exit Surface Angle on Drilling Burr Formation

Wed, 4 Apr 2007 00:00:00 +0000

The influence of an exit surface angle on drilling burr formation was analyzed. The experimental research found that a burr forms on only a certain portion of a hole when an exit surface is not perpendicular to a drill path. An effective interaction angle was newly defined and the concept of degree of plastic deformation was introduced in order to explain this phenomenon. The burr forming location predicted from the effective interac- tion angle was verified with experimental results

Manufacturing — Its Evolution and Future

Wed, 4 Apr 2007 00:00:00 +0000

The paper highlights events of manufacturing’s evolution and metamorphosis over a period of 60 years (as noted by the first author) and offers some observations on key developments and activities. It includes the reflections of professional activities of the first author and discussions of how manufacturing is evolving to accommodate the current and expected trends in manufacturing technology. Three specific software environments relative to developments in the design-to-manufacturing cycle are described. These lead into a perspective of what may now lie ahead, relative to enterprise issues, human system interactions, and the fully integrated “digital factory.”

Development of an Analytical Model for Drilling Burr Formation in Ductile Materials

Wed, 4 Apr 2007 00:00:00 +0000

An analytical model for drilling burr formation was developed. The model holds for ductile materials that do not show catastrophic fracture during the plastic deformation of workpiece material for burr formation. The proposed burr formation mechanism was based on the observation of behavior of workpiece materials during drilling of low alloy steel. The model was based on the principle of energy conservation and metal cutting theory. Experimental validation was done, and the results showed good agreement with the model. Based on the model, the effects of several important parameters on burr formation was investigated.

Design and Manufacturing for Cleanability in High Performance Cutting

Sat, 10 Feb 2007 00:00:00 +0000

Control of surface contamination in the form of small particles is becoming a major priority in conventional manufacturing processes, due to the higher sensitivity of mechanical assemblies to contamination-related failures. At the same time, the complexity of workpieces is increasing, making the removal of contaminants more difficult. Thus there is a critical need to facilitate cleaning in order to reduce the high costs and expenditure of natural resources required for cleaning operations. The objective of this paper is to present strategies to reduce or prevent solid particle contamination by manufacturing by-products throughout the product development and manufacturing chain, via cleaning-conscious design feedback to product developers in the context of Design for Cleanability (DFC) and improved process planning for manufacturing. We also show preliminary results on the effect of cutting parameters on chip size and morphology when machining cast aluminium silicon alloy,...

An Experimental Investigation on the Influence of Process Parameters During Chip Formation

Sat, 10 Feb 2007 00:00:00 +0000

As machines and products increase in productivity while shrinking in size, issues of contamination related failures become a greater risk. Previously, common contaminants such as sand from sand casting, dust from the air, or chips from machining, were within generally allowable product tolerances. The semiconductor industry was first to encounter contamination related problems from dust on their micro sized features. Now, the automo- tive industry is discovering millimeter sized chips blocking lubrication valves and scoring precision surfaces. This report details an experimental investigation of how chip related contamination may be controlled by varying milling and drilling cutting parameters such as feed, speed, depth of cut, and lubrication. Based on the assumptions of this paper, where the optimal chip is likely short, lightweight, with a large wavelength, and few rota- tions, it is found that the optimal milling chip is produced with increased speed, increased...

Review of Geometric Solutions for Milling Burr Prediction and Minimization

Wed, 7 Feb 2007 00:00:00 +0000

In this paper a review of various methodologies for burr prediction and minimization in face milling is presented. In particular, the authors look into the geometric solutions employed, which typically consist of understanding and modifying tool engagement conditions. The extent of applicability of various approaches is discussed and the possible direction for future research is indicated.

Strategies for Burr Minimization and Cleanability in Aerospace and Automotive Manufacturing

Sat, 15 Jul 2006 00:00:00 +0000

The quality of machined components in the aerospace and automotive industries has become increasingly critical in the past years because of greater complexity of the workpieces, miniaturization, usage of new composite materials, and tighter tolerances. This trend has put continual pressure not only on improvements in machining operations, but also on the optimization of the cleanability of parts. The paper reviews recent work done in these areas at the University of California-Berkeley. This includes: Finite element modeling of burr formation in stacked drilling; development of drill geometries for burr minimization in curved-surface drilling; development of a enhanced drilling burr control chart; study of tool path planning in face-milling; and cleanability of components and cleanliness metrics.

Experimental Investigation of the Influence of Machining Parameters on Chip Geometry for Enhanced Cleanability

Sat, 15 Jul 2006 00:00:00 +0000

When a part is manufactured, different processing steps can introduce contaminants to the workpiece. One common form of contamination is the chips produced by machining, which often lodge in the crevices and pathways of the workpiece causing problems for both the accuracy of subsequent machining operations, and the usability of the part. To avoid such problems, it is important to both optimize the type of chip produced so it can be most easily removed from the workpiece, and to minimize the number of chips that remain. By varying process parameters such as feed, speed, depth of cut, and lubrication, some insight is gained as to how these parameters affect chip geometry and size. The results for drilling were mostly inconclusive, while the results for milling provided an important first step towards optimizing the chip form.

Quantifying Edge Defects in Drilled FRP Composites

Sat, 8 Jul 2006 00:00:00 +0000

Fiber Reinforced Polymer (FRP) composites are being increasingly used as replacements for metals in engineering applications. Though these composites are manufactured in near-net shape, machining is often necessary for integration and assembly. The most common machining operation performed on these materials is drilling. A commonly observed defect in drilling is edge defects which include incomplete fiber cutting. This report discusses a model which estimates edge defects during FRP drilling. Results predicted by the model are compared to experimental observations and possible techniques to characterize defects in FRP drilling are discussed.

Automated Drill Modeling for Drilling Process Simulation

Sat, 8 Jul 2006 00:00:00 +0000

Accurate models of twist drills are needed for Finite Element simulations of the drilling process. Existing drill designing methods rely extensively on discretized analytical equations to describe the drill and different sets of equations need to be formulated as the drill design changes. This paper presents a method to create accurate models of two-flute conical twist drills using solid-modeling techniques which addresses some of these shortcomings. Boolean operations are used to mimic the drill manufacturing steps and generate the fully designed drill. The drills generated by this method have been used in Finite Element simulations to study the effect of drill point geometry on burr formation in drilling.

Finite Element Modeling of Drilling Using DEFORM

Fri, 16 Jun 2006 00:00:00 +0000

DEFORM-3D is a robust simulation tool that uses the finite element method (FEM) to model complex machining processes in three dimensions. One of the most recent processes that has been modeled in DEFORM is drilling. The program has many features that can be daunting and difficult to adjust for a new user. These features combine machining and the FE model to simulate drilling operations. Although this program can generate useful results, it can be very difficult to obtain these results consistently. This is because the code is often subject to crashing when the simulation parameters are not set properly. By recognizing the common errors and idiosyncrasies of DEFORM, a user can generate useful simulations quickly and efficiently. The background, application, troubleshooting, and analysis of DEFORM-3D are presented to showcase its capabilities while discussing its limitations in drilling.

Fabrication of Protruding Features in a Micro-Mold: a Planning Report

Fri, 16 Jun 2006 00:00:00 +0000

There exists an opportunity to study the manufacturing process of protruding features for the purpose of polymer mold fabrication at the micro-scale. An experiment is planned using Taguchi DOE methods to fabricate micro-scale positive features by varying size, spindle speed and spindle direction. Data will be collected on feature accuracy, and used to further refine the experiment in an effort to produce a precise, accurate, micro feature. Results and knowledge gained herein will be extended to features of greater complexity, requiring increasing degrees of precision.

Comparative Study of Finite Element Simulation Software

Wed, 20 Jul 2005 00:00:00 +0000

The choice of finite element software for machining analysis is an important factor in determining the quality and scope of analysis that can be performed. In this report, a comparative study is presented on three commercially available finite element analysis software packages detailing their applicability for performing machining simulations, specifically to study burr formation. The three packages presented are Deform, AdvantEdge and Abaqus. Each software package is discussed first and its advantages and disadvantages are presented. Then, the packages are compared and the suitable package for different scenarios is suggested.

Challenges in Modeling Machining of Multilayer Materials

Wed, 20 Jul 2005 00:00:00 +0000

Multilayer structural members are used extensively in aerospace applications and there is a critical need for accurately modeling their machining, especially drilling. Modeling the machining of multilayer materials is complex as it’s a 3D dynamic process with multiple interacting material domains. These models can be used to minimize edge imprecisions and increase workpiece accuracy in machining by optimizing the process and geometric parameters. This report discusses the challenges in modeling the machining of aerospace multilayered materials, which include metal-metal stackups and metal-composite stackups. The challenges composite materials specifically pose from a modeling perspective are also discussed. A brief review of existing work in composite machining and finite element modeling is also presented. Finally, a framework for solving this problem is suggested and a roadmap based on the framework is presented.

Tool Path Planning for Reconfigurable Machines

Wed, 20 Jul 2005 00:00:00 +0000

All process elements of a reconfigurable manufacturing system should accommodate future changes. This paper looks at one such process element, tool paths, with focus on face milling and pocket milling. Tool paths for the first part are designed to optimize the process outcomes for the initial constraints. Change in market conditions or part design leading to change in cycle time requirements, geometry or complexity of the part, are met using incremental tool paths. Changes in cycle time are achieved by changing the feedrate and tool diameter. Changes in part design are tackled by modifying tool path segments. This system would provide a quick turn around time, less testing and quicker ramp up.

Drilling Burr Control Chart -Adding a Material Property Axis

Wed, 20 Jul 2005 00:00:00 +0000

A 2-dimensional drilling burr control chart was developed by Jinsoo Kim (2000, 2001) which quantifies the effects of feed rate and speed on burr size; but, each chart is only useful for a specific type of material, and many materials have yet to be studied. What is needed is an understanding of how material properties and their dependence on temperature effect burr formation, to avoid the necessity of creating a burr control chart for every type of material. The goal is to use previous studies of material properties and burr formation to develop a third axis on the burr control chart. Ideally, one could create a dimensionless number that is a function of the material properties that most effect burr formation.

Exit Order Sequence Burr Prediction Algorithm Based on Rectangular Coordinates

Wed, 20 Jul 2005 00:00:00 +0000

The derivation and implementation of an algorithm that calculates exit order sequence (EOS) as a planar milling burr prediction tool is presented. EOS expresses the orientation of a cutter relative to the workpiece in terms of the exit order of three points describing the major and minor cutting edges. EOS calculations along the contours of a CAD model are based upon an instantaneous, Cartesian frame of reference centered on the tool spindle axis and oriented in the feed direction. The scheme provides accurate and robust EOS calculations and introduces a “worst-case” approach to select a unique EOS from overlapping tool exit conditions.

Micro-Burr Formation and Minimization Through Process Control

Mon, 4 Apr 2005 00:00:00 +0000

This paper presents an investigation on micro-burr formation in machining. Micro-cutting is compared with conventional cutting in terms of cutting process characteristic and cutting conditions. In this paper, tungsten–carbide micro-mills were used to cut holes (in a drilling-like process) to investigate top burr formation. The size and type of burr created in stainless steel 304 are studied as a function of machining variables, which are feed, cutting speed and cutting edge radius, to help illuminate the micro-burr formation mechanisms. A series of experiments was conducted to study tool life as a function of cutting conditions. Tool life, here, is defined as the number of holes created before a significant increase in burr height. Based on experimental results, contour charts for predicting burr formation as well as tool life are developed to minimize burr formation and to improve tool life. The model, which includes the effect of feed, cutting speed, and the interaction between...

Strategies for Preventing and Minimizing Burr Formation

Sat, 18 Dec 2004 00:00:00 +0000

The past years have seen emphasis on increasing the quality of machined workpieces while at the same time reducing the cost per piece. Accompanying this is the decreasing size and increasing complexity of workpieces. This has put continual pressure on improvements in the machining process in terms of new processes, new tooling and tool materials, and new machine tools. This often falls under the terminology of High Performance Cutting (HPC) — the theme of this conference. A recent CIRP keynote /1/ outlined and explained some of these drivers for enhancement in machining technology. Fundamental to this continual improvement is understanding edge finishing of machined components, specially burrs. Deburring, like inspection, is a non-productive operation and, as such, should be eliminated or minimized to the greatest extent possible. nderstanding of the fundamentals of burr formation leads us to procedures for preventing or, at least, minimizing, burr formation. This...

Influences on Burr Size During Face-Milling of Aluminum Alloys and Cast Iron