THE 3D PRINT­ING PROCESS

HWM (Singapore) - - Learn -

3D print­ing is an ad­di­tive process, which means that the ob­ject is con­structed by adding ma­te­rial in lay­ers. This is in con­trast to “sub­trac­tive” man­u­fac­tur­ing, through which an ob­ject is con­structed by cut­ting or ma­chin­ing raw ma­te­rial into a de­sired shape.

Al­most all con­sumer 3D print­ers use a type of plas­tic to cre­ate ob­jects. The two most pop­u­lar plas­tics are Acry­loni­trile Bu­ta­di­ene Styrene (ABS), which is also used to make Lego and is chemical-based, and Poly­lac­tic Acid (PLA), which is de­rived from nat­u­ral sources, such as corn or sug­ar­cane. PLA tends to be stiffer than ABS. Whichever plas­tic the 3D printer uses – some can ac­tu­ally use both – the raw ma­te­rial comes in the form of fil­a­ment, usu­ally 1.75mm or 3mm in width, which is stored on a spool at­tached to the 3D printer.

When the fil­a­ment is at­tached to the printer, it is fed through the print head. The print head con­tains a heated tube that the fil­a­ment passes through, heat­ing it and liq­ue­fy­ing it be­fore it is ex­truded by the print noz­zle. The liq­uid plas­tic is then de­posited as ul­tra-fine lines gen­er­ally about 100 mi­crons thick, or roughly 0.1mm, which quickly so­lid­i­fies and fuses to build up lay­ers. Some print­ers can de­posit lay­ers as thin as 16 mi­crons, or 0.016mm.

To make the ob­ject 3D, the print head needs to be able to move in mul­ti­ple di­men­sions. Many print­ers use a gantry-type sys­tem where the print head is at­tached to a metal frame, let­ting it move both hor­i­zon­tally and ver­ti­cally. The print bed will then move up and down to add a third di­men­sion. In some print­ers the print head can move in all three di­men­sions. Print jobs can take min­utes, hours or even days for more com­pli­cated ob­jects.

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