Week 12: Product Development 2 - 3D Printing

After a few weeks break we continued on where we left on in week 7 which is CADD and 3D printing. For Week 12 we learnt about stuff like Digital Fabrication, which enables one to quickly make what you need and when you will need it. It is flexible and is able to conform to a person's individual needs.

During this week, we adopted a peer teaching approach, where one group of students are to do research on a certain topic and hence teach the rest on the class the topic they researched about. For my group we had to research about slicer software and how it affect quality.

Slicer in a nutshell is a program that "chops" the model into thousands of different layers in which the 3D printer would follow to "print" out your item. There are many settings that affect the quality of a print that can be adjusted manually. These settings includes: Layer Height, Print Speed, Part Orientation, Bed Adhesion, Supports and Retraction.

Layer Height

Layer height as the name implies is the height of each layer and it is affected by settings like time, detail and strength. In general the longer the time and the finer the details may compromise material strength. To get the optimal layer height, a software called "magic number theory" can be used. This "magic number theory" will help to get the optimal balance of all 3 settings to get a high quality print.

Print Speed

As the name implies as well it affects how fast the printing go. Too slow of a print will deform the shape as the hot nozzle maintains on the plastic for too long, whilst fast printing will also deform due to insufficient cooling of the plastic. Some secondary settings that affect print speed includes: Outer and Inner shell speed, Infill speed and Top/ Bottom speed. Generally by decreasing the speed of each of these secondary settings, a higher quality print can be achieved.

Part Orientation

Part orientation is how the print is orientated with respect to the base plate.

This difference in Orientation can and will affect the quality of the print. Rules of thumb to get a high quality print is to orientate cylindrical objects vertically for a smooth outer finish and to consider the direction of the loading when choosing part orientation of a functioning part.

Bed Adhesion

Bed Adhesion refers to how the 3D print were to stick to the base plate. Non stick 3D prints can deform whilst printing and hence is to be avoided. Some factors to consider for Bed Adhesion includes the thermal expansion of the plastic and the ability for plastic to "wet" the base plate. For a high quality print, a base plate that is not too sticky is to be preferred for each removal of the print after it is completed.

Supports

Supports are as the name implies are supports for parts of the print that stick out to the sides of the print. These supports are then easily removed using pliers after the print is done. These supports are to be there for a high quality print. However not all extrusions to the sides needs supports as there are factors to consider such as the angle of the extrusion with respect to the main body.

Retraction

Retraction is that after a print is done, the nozzle will suck back some filament left to prevent any molten plastic from dripping. This Retraction is further expended into 2 different settings which are: Retraction Speed and Retraction Length. Bad Retraction will cause "hairs" to form within the print which is not desirable for a high quality print.

However, Retraction is not the only factor that can cause the "hairs' to occur as the temperature of the nozzle also affects this.

Written by: Pedro Tay