Mechanical and Aeronautical Engineering Graphical Communication (MGC 110) Study Notes

Manufacturing Principles and Operations

• CNC Advantages: Computer Numerical Controlled machines minimize human error during production.

• Bending Mechanics: "Bottoming" is a technique used to permanently deform all material within the bend during operation.

• Hole Operations:     * Reaming: Used for finishing and accurate sizing, not for center-locating (unlike center drilling).     * Boring: Vertical boring machines are utilized for large diameter work (> 30\,mm).

• Turning Optimization: Surface finish is improved by slowing the feed rate of the cutting tool.

• Threading: During M10 external thread tapping on a lathe, operators must keep the tool feed rate and spindle speed constant.

Engineering Formulas and Calculations

• Drill Tip Allowance ($A$): For a drill bit with tip angle $\theta$ and diameter $D$:     * $A = 0.5D \tan(90 - \theta/2)$

• Bending Force ($F$):     * General formula: $F = K_{bf} \frac{TS \times w \times t^2}{D}$     * Edge-bending constant: $K_{bf} = 0.33$     * $V$-bending constant: $K_{bf} = 1.33$

• Machining Time ($T_m$):     * $T_m = \frac{d}{f_r}$     * Rotational feed rate: $f_r = N \times f$

• Material Removal Rate (MRR):     * $MRR = \frac{\pi D^2 f_r}{4}$

• Bend Allowance ($BA$):     * $BA = \frac{2\pi A}{360} (R + K_{ba} t)$     * For R < 2t, $K_{ba} = 0.33$. For $R \ge 2t$, $K_{ba} = 0.5$.

Standard Components and Material Handling

• Workholding on Lathes: Suitable tools include 3-jaw chucks, collets, and dog plates; vice clamps are typically not used.

• Torque and Movement Connection:     * Keys and Keyways: Essential for efficient torque transmission and providing a positive drive connection between rotating parts.     * Circlips: Used specifically to prevent axial movement of components.     * Bearings/Bushings: Reduced noise and vibration by ensuring smooth rotational motion.

• Standard Parts: Standard components include bolts, screws, and nuts. Custom parts like a "Base Plate" are generally not categorized as standard components.

CAD Software Fundamentals (SolidWorks)

• Feature Tools: The "Rib" tool is located in the Features tab.

• View Tools: The "Auxiliary View" tool is found under the Drawing tab.

• Assembly Mates:     * Coincident Mate: Constrains two planar surfaces to be flush or in contact with each other.     * Component Initialization: In SolidWorks, the first component added to an assembly is mechanically "Fixed" in space by default.

Assembly Drawing: Rope Guide

• Application: A Rope Guide assembly changes rope direction from vertical lifting to horizontal pulling.

• Key Components:     * Base plate with M12 and M6 mounting points.     * Pulley with outer diameter $\Phi 80$ and lubrication hole $\Phi 5$.     * Shaft ($\Phi 16$) and Bushing ($\Phi 20$ exterior, $\Phi 16$ interior).

• Required Views:     * External main view.     * Full section right view through the shaft center.