Design for Manufacture and Assembly

Unit 1

Design Impact on Cost, Design for “X” - DFM approach, DFM Framework, Material and Process Evaluation, General DFM Guidelines, Machining and Casting Guidelines and Examples, Minimize Finishing Requirements. Computer applications for DFMA.

Design features to facilitate machining: datum features - functional and manufacturing. Component design - machining considerations, redesign for manufacture, examples. Form design of castings and weldments.

Unit 2

Tolerance Analysis: Process capability, process capability metrics, Tolerance - cost aspects, feature tolerances, geometric tolerances, relationship between attainable tolerance grades and different machining process. Cumulative effect of tolerances - sure fit law, normal law and truncated normal law.

Interchangeable part manufacture and selective assembly - control of axial play - introducing secondary machining operations, laminated shims - examples.

Unit 3

Datum Systems: Degrees of freedom, grouped datum systems - computation of translational and rotational accuracy - geometric analysis and applications.

True Position Theory: Co-ordinate and conventional method of feature location, tolerance and true position tolerance, virtual size concept, floating and fixed fasteners, projected tolerance zone, assembly with gasket, zero true position tolerance, functional gauges, paper layout gauging - examples.

Principles of Design for Assembly, Minimize Part Count, Standardization and Minimize Part Variety, Design guidelines for manual assembly, DFA analysis, DFA index, Design for Automated Assembly. Introduction to usage of DFMA software.