Blaine Lilly

Estimation of tool wear in orthogonal cutting using the finite element analysis

Abstract In metal cutting, tool wear on the tool–chip and tool–workpiece interfaces (i.e. flank wear and crater wear) is strongly influenced by the cutting temperature, contact stresses, and relative sliding velocity at the interface. These process variables depend on tool and workpiece materials, tool geometry and coatings, cutting conditions, and use of coolant for the given application. Based on temperatures and stresses on the tool face predicted by the finite element analysis (FEA) simulation, tool wear may be estimated with acceptable accuracy using an empirical wear model. The overall objective of this study is to develop a methodology to predict the tool wear evolution and tool life in orthogonal cutting using FEM simulations. To approach this goal, the methodology proposed has three different parts. In the first part, a tool wear model for the specified tool–workpiece pair is developed via a calibration set of tool wear cutting tests in conjunction with cutting simulations. In the second part, modifications are made to the commercial FEM code used to allow tool wear calculation and tool geometry updating. The last part includes the experimental validation of the developed methodology. The focus of this paper is on the modifications made to the commercial FEM code in order to make reasonable tool wear estimates.

Manufacturing of Dies and Molds

Abstract The design and manufacturing of dies and molds represent a significant link in the entire production chain because nearly all mass produced discrete parts are formed using production processes that employ dies and molds. Thus, the quality, cost and lead times of dies and molds affect the economics of producing a very large number of components, subassemblies and assemblies, especially in the automotive industry. Therefore, die and mold makers are forced to develop and implement the latest technology in: part and process design including process modeling, rapid prototyping, rapid tooling, optimized tool path generation for high speed cutting and hard machining, machinery and cutting tools, surface coating and repair as well as in EDM and ECM. This paper, prepared with input from many CIRP colleagues, attempts to review the significant advances and practical applications in this field.

Advanced Techniques for Die and Mold Manufacturing

Summary Die and mold manufacturing represents a significant area of production technology since it influences the feasibility and economics of producing a very large number of discrete components. Modern die manufacturing includes just about all aspects of manufacturing: part design, geometry handling and transfer, die design, process modeling, prototype production, control of dimensional and surface quality as well as advanced mechanical, electrical, and electrochemical machining methods. This paper, prepared with input from various CIRP colleagues, attempts to review the latest advances and practical applications in the field.

Simultaneous Optimization of Mold Design and Processing Conditions in Injection Molding

Injection molding (IM) is considered the foremost process for mass-producing plastic products. One of the biggest challenges facing injection molders today is to determine the proper settings for the IM process variables. Selecting the proper settings for an IM process is crucial because the behavior of the polymeric material during shaping is highly influenced by the process variables. Consequently, the process variables govern the quality of the part produced. The difficulty of optimizing an IM process is that the performance measures (PMs), such as surface quality or cycle time, that characterize the adequacy of part, process, or machine to intended purposes, usually show conflicting behavior. Therefore, a compromise must be found between all of the PMs of interest. In the past, we have shown a method comprised of Computer Aided Engineering, Artificial Neural Networks, and Data Envelopment Analysis (DEA) that can be used to find the best compromises between several performance measures. The analyses presented in this paper are geared to make informed decisions on the compromises of several performance measures. These analyses also allow for the identification of robust variable settings that might help to define a starting point for negotiation between multiple decision makers. Future work will include adding information about the variability of PMs on the DEA analysis and the determination of process windows with efficiency considerations. This paper discusses the application of this method to IM and how to exploit the results to determine robust process and design settings.

Experimental determination of friction coefficients between thermoplastics and rapid tooled injection mold materials

Purpose – To determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection molding process using rapid‐tooled mold inserts.Design/methodology/approach – Static coefficients of friction were determined for semi‐crystalline high‐density polyethylene (HDPE) and amorphous high‐impact polystyrene (HIPS) against two rapid tooling materials, sintered steel with bronze (LaserForm ST‐100) and stereolithography resin (SL5170), and against P‐20 mold steel. Friction tests, using the ASTM D 1894 standard, were run for all material pairs at room temperature, at typical part ejection temperatures, and at ejection temperatures preceded by processing temperatures. The tests at high temperature were designed to simulate injection molding process conditions.Findings – The friction coefficients for HDPE were similar on P‐20 Steel, LaserForm ST‐100, and SL5170 Resin at all temperature conditions. The HIPS coefficients, howev...

Modelling and verification of ejection forces in thermoplastic injection moulding

Reducing cycle times in the field of injection moulding demands that parts be ejected as soon as they are dimensionally stable. It is, therefore, imperative that the ejection forces be balanced and adequate so as to reduce the probability of part deformation. In this paper, we estimate ejection forces for moulded parts that have been used by the industry, and compare these models to simulation and experimental results for a simple cylindrical sleeve.

The exoskeletal structure and tensile loading behavior of an ant neck joint

Insects have evolved mechanical form and function over millions of years. Ants, in particular, can lift and carry heavy loads relative to their body mass. Loads are lifted with the mouthparts, transferred through the neck joint to the thorax, and distributed over six legs and tarsi (feet) that anchor to the supporting surface. While previous research has explored attachment mechanisms of the tarsi, little is known about the relation between the mechanical function and the structural design and material properties of the ant. This study focuses on the neck--the single joint that withstands the full load capacity. We combine mechanical testing, computed tomography (CT), scanning electron microscopy (SEM), and computational modeling to better understand the mechanical structure-function relation of the neck joint of the ant species Formica exsectoides (Allegheny mound ant). Our mechanical testing results show that the soft tissue forming the neck joint of F. exsectoides exhibits an elastic modulus of 230±140 MPa and can withstand ~5000 times the ants weight. We developed a 3-dimensional (3D) model of the structural components of the neck joint for simulation of mechanical behavior. Finite element (FE) simulations reveal the neck-to-head transition where the soft membrane material meets the hard exoskeleton as the critical point for failure of the neck joint, which is consistent with our experiments. Our results further indicate that the neck joint structure exhibits anisotropic mechanical behavior with the highest stiffness occurring when the load path is aligned with the axis of the neck.

Bridging design disciplines: preparing students for unpredictable challenges

The demands of the global economy, coupled with the necessity of finding sustainable design solutions for the environmental crises that confront us, will require designers with divergent educational backgrounds to work in close coordination. As faculty at one of the largest public universities in the USA, we find ourselves confronted with the demands of working around an institution whose size discourages cross-disciplinary collaboration. In this article, we present strategies for working around these obstacles, and three case studies of students working across disciplines on design-related problems.

A curriculum collaboration model. working with upper division students to inprove a first-year program

This paper presents an overview of a quarter-long design-build project in the Fundamentals of Engineering (FE) course sequence, which is part of the First-Year Engineering Program at The Ohio State University (OSU). The current design-build project is discussed along with a justification for the need to institute a replacement. The primary focus of this paper is a unique collaboration model which was developed to address this need. Faculty, staff, and graduate teaching associates from the First-Year Engineering Program joined with the Industrial, Welding and Systems Engineering (IWSE) Department to investigate possible solutions. The paper describes the curriculum research and design methods used by the curriculum team. The document also discusses the requirements and constraints of the project and presents a detailed timeline of the evaluation and feedback tools implemented. The evaluation and feedback tools used are explained along with sample worksheets. The results of the first quarter are discussed in light of the constraints and requirements of the FE program. Finally, the improvements from the second quarter trials are further explained. This paper will provide clear examples of the project’s various cycles, discussion of the planned implementation process, and examples of the final roller coaster design. The collaboration model is reviewed, with experiences gained and future plans presented. I. Introduction The Fundamentals of Engineering (FE) course sequence is part of the First-Year Engineering Program at OSU, and is mandatory for all students not enrolled in the Honors equivalent. The FE sequence consists of two courses (ENG 181 and ENG 183), in which students are exposed to Engineering drawing, MATLAB, Excel, hands-on labs, and a quarter-long design-build project involving different fields of engineering. Enrollment in these courses is approximately 1000 students. The current design-build project is entering its third year of full-scale use, and the need to institute a replacement was identified as the result of a curriculum analysis. With up to 162 student teams using lab space and materials in a given quarter, the challenge is to create a replacement that is intellectually challenging while at the same time makes wise and economical use of space and materials.

Developing an Effective Platform for Introducing Mechanical Engineering in a Large Public University

In conjunction with a shift from an academic calendar based on ten–week quarters to one based on semesters, the Department of Mechanical and Aerospace Engineering at The Ohio State University has completely re–designed the mechanical engineering curriculum. As a part of this re–design, the MAE department has added a new course for sophomores entering the department that will emphasize hands–on skills in machining and electronics while simultaneously giving students a broad introduction to the kinds of problems that mechanical engineers typically confront in industrial practice.This paper describes the evolution of our thinking as we created the teaching platform that is the heart of the course, a multi–cylinder compressed air motor. Lectures are structured to provide ‘just in time’ information to the students as they build and test this platform in the laboratory. It was crucial to create a device that would be complex enough to challenge the students and provide an opportunity to explore the widest possible range of mechanical engineering concepts. After a review of similar courses in other programs, we decided to employ a multi–cylinder compressed air motor, controlled by a commercially available microprocessor, as the teaching platform.Because the course will be required of all students entering the major, an overriding constraint on the design is that the device is simple enough for three hundred students a year, working in teams, to construct and test it. At the same time, the air motors must also be complex enough to support the learning objectives of this course and subsequent courses in the curriculum. Our final design is a direct–injection six–cylinder radial compressed air motor that is controlled by an Arduino© microprocessor. Students will spend five weeks machining and assembling the motors in the machine shop, another four weeks learning to program the Arduino© to control the motor, and the remainder of the term testing and analyzing the performance of the motors.The air motors allow us to introduce students to machine design, engine design, thermodynamics, fluid flow, vibrations, electronics, and controls. We have pilot tested this course twice, and find that the students quickly take ownership of the motors, and are quite interested in optimizing the design to improve performance.Copyright