The How's & The Why's
The drawing's may be prepared and ready for manufacturing, but now the process must be decided from the options available to us at the University and bearing in mind that this is a product prototype and not a full scale production process.
Out of all the process' we have had training in and have the options of using, I decided the two best options for my product would be either:
# CNC Router or
# FDM (Rapid Prototyper)
This is down to the high level of detail within my design and the need for as little post CAM finishing as possible in a bid not to loose this detail.
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The Pro's and Con's of these Process'
CNC Router
My initial intention was to create my prototype using the CNC router as this will create my item out of a durable model board that will be hard wearing and will have an due to the shape of my item should have very little steps therefore creating an excellent surface finish with a small amount of finishing with wet and dry sand paper before painting.
However ... due to the very small nature and extra fine detail within my item there are restrictions of this process that makes it unsuitable for use for this item, as detailed below:
# tool can only cut rounded corners - as my item has squared corners and edges this alone makes it unsuitable.
#tool diameter governs the minimum width of detail - my item has details that exceed the minimum tool restrictions (see below).
Fused Deposition Modelling (FDM - Rapid Prototyping)
As the name suggests this is a relatively quick process, not much different to sending a document to an ink-jet printer. Once the .stl file has been created this is essentially printed using the FDM machine which builds the object in layers from ultra fine molten extruded thermoplastic as shown in the image below.
This process of manufacturing gives a high level of detail and is perfect for creating small delicate components such as a prototype USB memory stick.
It does have the drawback of not having as smooth of a finish as the CNC Miller, and with a product as small as mine with very fine and delicate detail, the ridges created by the layering process may be improbable to completely remove.
Despite this I believe this will be the best process for creating my prototype product as the detail is one of the most important aspects of my product, although I aim to achieve the best quality finish I can an extremely high quality finish would be achieved by injection moulding the product if it was to go into production.
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Production Process
.stl files are processed and sent to print.
FDM machine process' this data and 3D prints the objects, this took approximately 1.5 hours for my complete product.
The FDM creates the object with two parts:
# The thermoplastic model &
# The support material
This support material is a soluble starch based material that when soaked in an Alkaline tank (shown below) dissolves leaving a clean and undamaged model.
Below shows an assembled body section of my product, this unfinished model was created using the process and forms part of USB Stick Mark I
