Holly Ann Quinn September 28, 2010

1. RPI Masters Engineering ProjectAnalysis of Near Net Shape Forged Gears for Helicopter Transmissions Holly Ann Quinn September 28, 2010

2. Problem Statement • Is using Near Net Shape (NNS) Forging a better way to manufacture gears for helicopter transmissions? • Potential Benefits • Lower Cost • Minimal Waste of Raw Material • Streamlined Process • Decreased Manufacturing Time • Equal Strength, Hardness and Fatigue Properties • Potential Detractions • Higher cost of manufacturing tools, i.e. Forging Dies • May need to replace dies more frequently and at greater cost than cutting/grinding wheels • Unknowns • Can Hardness and Fatigue properties of gears manufactured with NNS forging match those of “traditionally” manufactured gears?

3. Horizontal Cutter “Traditional” Method of Gear Manufacturing • Cutting/Rough Machining Operations • Gear teeth can be generated in multiple ways, such as hobbing or a cutter (horizontal or vertical): • Material Processing • Carburization is a process performed at high temperatures during which carbon gas is infused into the coast and drive side of gear teeth to achieve adequate hardness levels. • Tempers are performed to toughen the material and increase ductility. • Heat Treatment often via Quenching is performed to harden the material by rearranging the microstructure to martensite. • Finish Machining and Grinding • Gear Teeth are ground to achieve accurate geometry, as well as remove any distorted material acquired during heat treat. • Bearing Journals, Diameters are machined to Blueprint dimensions. • Final Material Processing and Plating • Low Temperature Heat Treatment/Stress Relief Bake • Cadmium or Silver Plating to increase strength. • Shot Peening to increase strength.

4. Gear Manufacturing with Near Net Shape Forging • Method of Manufacturing with NNS Forging • The process begins with a billet or piece of forged material stock which is heated to some temperature and flattened into a “pancake” by a press. • Then, the stock is usually “punched” with a die into a mold so that the stock takes the form of the mold: • Characteristics of the Part • Close dimensional tolerances • Minimum post-forging machining necessary to achieve the desired geometry • Refined grain structure comprised of an organized orientation of the crystals • Improved the physical properties due to refined microstructure

5. Simulations • Plan to use DEFORM software to showcase improved microstructure achieved with NNS forging as compared to machined material • Improvements in microstructure should correlate with improved fatigue strength of gear.

6. Expectations • The main goal of this project is to research the gear manufacturing process that utilizes NNS forging methods and material processing techniques that create a gear with adequate case hardness and strength. • The hope is to produce a strong, durable gear at minimal costs and processing time. This would be the most important outcome of this project.

7. Deadlines 9/14/10 100 Word Write-up Due 9/21/10 Tentative Project Proposal Due 9/28/10 Final Engineering Project Proposal and Small Presentation Due 10/5/10 Literature Search and Carrying out Work: - Write about processing techniques for case hardness in gears (heat treat/carburization), including discussion about microstructure changes during these processes. 10/12/10 Literature Search and Carrying out Work - Start Discussion section, starting with the affect material processing performed on “traditionally” produced gears may have on gears that are produced with NNS forging methods. - Complete Literature Search - Edit and complete sections: Abstract, Introduction, and Methodology. 10/19/10 First Progress Report Due Analysis, Computation and Writing - Determine gear geometry and loading conditions - Begin analysis with DEFORM for a NNS forged specimen and compare to machined material. 10/26/10 Analysis, Computation and Writing - Continue analysis with DEFORM. Include heat treated/carburized material analysis

8. Deadlines 11/2/10 Analysis, Computation and Writing - Write about computational results including the effects of heat treatment on NNS forged gears 11/9/10 2nd Progress Report w/~6-12 slide Presentation of Progress Due Review, Assessment, Correction and further Analysis, Computation and Writing - Discuss results and comparison of gears resulting from two production methods. - Discuss different processing methods available to manufacture a gear that may better meet design criteria. 11/16/10 Review, Assessment, Correction and further Analysis, Computation and Writing - Complete and edit Analysis, Discussion & Results sections of project 11/23/10 Review, Assessment, Correction and further Analysis, Computation and Writing - Write Conclusions - Create final project presentation slides 11/30/10 Final Draft of Project Due Final Reviews, Wrap-up and Closure - Complete and Edit Conclusions - Edit presentation slides - Complete References and check citing is correct throughout document 12/7/10 Final Reviews, Wrap-up and Closure - Edit and review project documents - Include all reference documents including simulation models and results on RPI website. 12/14/10 Final Report Due - Write about design criteria and application for gear, including material properties