Machine Elements in Mechanical Design Prepared by: Misrty Dipen

Introduction Mechanical Systems or Devices are designed to transmit power and accomplish specific patterns of motion. Mechanical Components – Gears, Bearings, Shafts, Keys, Couplings, Seals, etc.

Design Process (Section 1-4) Identify Customer Requirements Define functions of the device State design requirements Define evaluation criteria Propose several alternative design concepts Evaluate each proposed alternative Rate each alternative against each evaluation criteria Select the optimum design concept Complete detailed design of the selected concept

Application How are customer requirements identified? Functions are “high level” requirements that tell what a device is supposed to do. Design requirements are detailed, specific, quantitative data expanding the functions. What evaluation criteria would be important? What does the “detailed design” look like? What next?

Text Example – Speed Reducer

Functions To receive power from the tractor’s engine through a rotating shaft To transmit the power through machine elements that reduce the rotational speed to a desired value. To deliver the power at the lower speed to an output shaft that ultimately drives the wheels of the tractor.

Design Requirements

Integration of Design Speed Reducer Assembly: One Housing Four Gears Three Shafts Six Bearings Several Keys and Seals Etc.

Design Skills Required Technical Drawing Computer-Aided Engineering (CAE) Manufacturing Processes Statics, Dynamics, and Strengths of Materials Kinematics and Mechanisms Verbal and Written Communication

Design Presentation Develop a specification set that communicates effectively all manufacturing information, safety information, usage information, etc. Specifications sets include: CAD Models Drawings (Assembly, Detail, Stress Reports) Bills-of-Material Instructions: Manufacturing Assembly Maintenance Usage

The Engineering Method Recognize and understand the problem Accumulate data and verify accuracy Select the appropriate theory or principle Make necessary assumptions Solve the problem Verify and check results

Problem Presentation Problem Statement Diagram Theory Assumptions Solution steps Identify results and verify accuracy