Traditionally, Design for Assembly (DFA) aims to facilitate the assembly operations and to minimise the time and costs  involved in joining sub-systems to form a complex product [2, 3]. This means minimising the number of sub-parts and eliminating fasteners fabricated.
Additive Manufacturing technologies offer more processing flexibility than other more conventional manufacturing methods. For instance, it promotes the combined fabrication of parts traditionally built separately due to geometry limitations, material differentiation, or costs.
Integrated operational assembly
The use of layer-by-layer deposition and selective processing promotes geometrical flexibility so a certain extent. In operational mechanisms, two or more components must move with respect to one another: AM can build these components fully assembled. For instance, a five-fingered robotic hand prototype featuring fingers with four degree of freedom was fabricated by Selective Laser Sintering . One of the key parameters for performance is the joint clearance .
Some AM methods also facilitate the ability to embed functional parts such as electric motors, gears, silicon wafers, printed circuit boards, and strip sensors.
Multiple materials can be used concurrently in AM to increase components functionality such as with ultrasonic additive manufacturing or with functionally graded materials (FGM) [6–9] made by direct laser deposition.
Functionally graded rapid prototyping (FGRP) is a novel design approach and technological framework enabling the controlled spatial variation of material properties through continuous gradients in functional components [10-14].
For instance, design can combine structural, environmental, and corporeal performance by adapting elements such as thickness, cell density, stiffness, flexibility, and translucency to load, curvature,…
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