design guide 01 - design for assembly

It is very important for a machine designer to consider a lot of things when building a component. Whether it's able to be processed (design for manufacture); able to assembled easily (design for assembly); and even sometimes whether our machine can be repaired easily (design for maintenance).
Manufacturing process done in the machining workshop, the assembly would be done by assembly workshop. It is very important for a design engineer to know what's happening on the process. At least little by little information we gather will certainly help a lot for the next possible project.

What does it means to use "design for assembly" consideration? It means that every part is designed and modified well to ease the assembly process. As we all know, assembly is very important process that must be done correctly in order to obtain the desired shape (and often, includes obtaining functionality too)


In terms of assembly, that are matching, inserting, and grouping some components altogether, the most important factor is to consider how our components would be put into unity. Every surface contact is important to review as well as every jointed connection

There are several highlighted characteristic of products :
> Component's size
Very small components and very large components are very hard to deal, therefore the design must consider first whether the component can be "pick and placed" only by using hand.

> Component's symmetrical shape
Symmetric components are prone to be misplaced in the wrong direction. Therefore a design must consider giving an assembly guide in the technical drawing.

  > Component's material property and surface
A slippery or a flexible component must be well taken care, especially when it comes to surface defect caused by falling, or fracture on a flexible part due to excessive load.

> Probability of component getting tangled, nested, or stuck
A good assembly design must consider the placement and the guidance to keep the components in place


> Alignment between parts
Holding down a part for alignment can be done, but take too much effort, furthermore by using a guiding interface for self-locating , we can assemble with ease and a proper result will be guaranteed

> Inserting force
A part must be designed so that it can be matched and inserted using as little force as possible, of course still considering the tolerance and fit between parts

> Obstructed access
This refers to an assembly that are not able to be fixated due to obstructed placement of joining elements such as bolt or rivets


DESIGN RULES FOR ASSEMBLY EASE
The rules of designing to help assembly ease :
* Reduce part count and part types
* Strive to eliminate adjustment
* Design parts to be self-aligning and self-locating
* Ensure adequate access and unrestricted vision
* Ensure the ease of handling of parts from bulk
* Minimize the need for reorientations during assembly
* Design parts that cannot be installed incorrectly
* Maximize part symmetry if possible or make parts obviously asymmetrical

An assembly that can be easily assembled, usually makes it easier when maintenance or service, therefore, DFA is deeply related to DFS (design for service)

If you can't mate two parts, use a bigger hammer