Manufacturing Practices (BT-106) - Important Questions

Explain the fundamental concepts of Computer Numerical Control (CNC) machining. In your answer describe the main components of a CNC machine, types of axes and motions, drive and feedback systems, and the primary advantages and limitations of CNC machining compared to conventional machining.

Write a part program in G-code to machine a rectangular pocket with specified dimensions. Include declaration of coordinate system, tool selection and offset, spindle speed, feed, safe rapid moves, and finishing passes. Explain each block of code briefly.

Explain the coordinate systems used in CNC machines. Differentiate between machine (absolute) coordinates, work coordinates, and tool coordinates, and explain how transformations between these systems are performed during programming and setup.

Describe the principles of additive manufacturing (3-D printing). Classify the major additive manufacturing processes and explain the basic working principle of each of the following: material extrusion (FDM), vat photopolymerization (SLA), powder bed fusion (SLS/SLM), binder jetting, and directed energy deposition.

Discuss the key process parameters in FDM and SLM additive manufacturing processes. For each process explain how parameters such as layer thickness, build orientation, print speed (or scan speed), hatch spacing, and energy input (e.g., laser power) affect dimensional accuracy, surface finish, mechanical properties, and build time.

Compare and contrast subtractive manufacturing and additive manufacturing. Discuss differences with respect to material utilization, geometric complexity capability, tolerances and surface finish, lead time and production cost, need for fixtures/jigs, and typical suitable applications for each approach.

Explain the common post-processing methods used for parts produced by additive manufacturing and justify why post-processing is often necessary. Include mechanical finishing, heat treatment, support removal, infiltration/coating, and dimensional inspection in your answer.

What is hybrid manufacturing? Discuss the concept of combining additive and subtractive processes in a single setup. Explain the advantages, typical challenges (e.g., fixturing, thermal effects, process planning), and example applications where hybrid manufacturing provides clear benefits.