Browsing by Subject "Subtractive Rapid Prototying"
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Item Advanced Process Planning for Subtractive Rapid Prototyping(University of Texas at Austin, 2009-09) Petrzelka, Joseph E.; Frank, Matthew C.This paper presents process planning methods for Subtractive Rapid Prototyping, which deals with multiple setup operations and the related issues of stock material management. Subtractive Rapid Prototyping (SRP) borrows from additive rapid prototyping technologies by using 2½D layer based toolpath processing; however, it is limited by tool accessibility. To counter the accessibility problem, SRP systems (such as desktop milling machines) employ a rotary fourth axis to provide more complete surface coverage. However, layer-based removal processing from different rotary positions can be inefficient due to double-coverage of certain volumes. This paper presents a method that employs STL models of the in-process stock material generated from slices of the part along the rotation axis. The developed algorithms intend to improve the efficiency and reliability of these multiple layer-based removal steps for rapid manufacturing.Item Creating Implants from Allograft Bone using Subtractive Rapid Prototyping(University of Texas at Austin, 2012) Frank, Matthew C.; Joshi, Ashish; Lei, Shuangyan; Anderson, Donald D.; Tochigi, Yuki; Brown, Thomas D.This research involves the development of rapid manufacturing for bone implants using human allograft bone in a Subtractive Rapid Prototyping process. Using CT-derived CAD models of missing bone due to high energy trauma or tumor resection, surgical reconstruction could be improved with custom rapid implants made from natural bone. The bone “stock” material is of arbitrary shape and material distribution in the form of frozen donated cadaveric bones. Each is unique in shape and has highly anisotropic material properties; likewise for each final bone implant geometry and its material distribution. This work utilizes a PLY input file, instead of the more common STL, using color texture information that can be utilized for advanced process planning depending on whether the surface is fracture, periosteal or articular in origin. Moreover, we present a new PLY assembly model, called the Matryoshka model, where successively nested PLY files are used to designate changing material distributions in the donated bone; a method that could also aid in the use of multi-material additive RP systems. Using color Matryoshka models and their subsequent color slice files; this work presents novel solution methods for the selection of implant harvesting sites and automated process planning for the physical rapid prototyping process. Early implementations using bone surrogate materials will be presented.Item Rapid Manufacturing in Biomedical Materials: Using Subtractive Rapid Prototyping for Bone Replacement(University of Texas at Austin, 2008-09-10) Frank, Matthew C.; Hunt, Christopher V.; Anderson, Donald D.; McKinley, Todd O.; Brown, Thomas D.This paper presents methods for the rapid manufacturing of replacement bone fragments using a Subtractive Rapid Prototyping process called CNC-RP. The geometry of segmental defects in bone, resulting from traumatic injury or cancerous tumor resection, can be reverse-engineered working from medical images (such as CT scans), and then accurate defect fillers can be automatically generated in advanced synthetic biomaterials and other bioactive/biocompatible materials. The research provides evidence that suitable bone geometries can be created using subtractive RP from a variety of materials including Trabecular Metal® (porous tantalum), polymers, ceramics, and actual bone allografts. The research has implications in the orthopaedic treatment of segmental bone defects, as custom prototyped bone fillers should aid in bone growth and improve recovery.