What is FDM 3D Printing

Fused Deposition Modeling (FDM) is an additive manufacturing method that belongs to the material extrusion household.

In the pattern of FDM, an object is developed by uniquely transferring melted material in a pre-determined path layer-by-layer. The materials used are thermoplastic polymers and also come in a filament type.

There’s another name for FDM is fused filament fabrication (FFF), but the term “fused deposition modeling” and the abbreviated “FDM” were trademarked by Stratasys in 1991, creating the need for a second name.

FDM is the most commonly made use of 3D Printing innovation: it stands for the biggest setup base of FDM 3D printers globally and also is commonly the initial modern technology individuals are exposed to.

In this article, the standard principles, as well as the vital facets of the innovation, are presented.

A developer needs to remember the capabilities and also limitations of the innovation when producing a get rid of FDM, as this will certainly help him accomplish the best result.

How does FDM work?

I. A spool of thermoplastic filament is first loaded into the printer. Once the nozzle has reached the desired temperature, the filament is fed to the extrusion head and in the nozzle where it melts.

II. The extrusion head is attached to a 3-axis system that allows it to move in the X, Y, and Z directions. The melted material is extruded in thin strands and is deposited layer-by-layer in predetermined locations, where it cools and solidifies. Sometimes the cooling of the material is accelerated through the use of cooling fans attached to the extrusion head.

III. To fill an area, multiple passes are required (similar to coloring a rectangle with a marker).

When a layer is finished, the build platform moves down (or in other machine setups, the extrusion head moves up) and a new layer is deposited. This process is repeated until the part is complete.

Below is how the FDM construction process functions: 

1. A roll of polycarbonate filament is first loaded into the printer. When the nozzle has reached the wanted temperature, the filament is fed to the extrusion head and in the nozzle where it thaws.

2. The extrusion head is affixed to a 3-axis system that allows it to move in the X, Y, and also Z directions. The melted product is squeezed out in thin strands and is transferred layer-by-layer in established locations, where it cools and also strengthens. Often the air conditioning of the product is sped up via using cooling fans attached to the extrusion head.

3. To fill an area, numerous passes are needed (similar to tinting a rectangular shape with a marker). When a layer is completed, the develop platform actions down (or in various other device setups, the extrusion head goes up), as well as a new layer, is transferred. This procedure is duplicated up until the part is complete.

FDM 3D Printing 

Variations in Design and Capability

Variations in the extrusion system of fused deposition modeling 3D printers include, but are not restricted to Filament extruders, one of the most usual and functional variations which use reels of thermoplastic filament, Pellet extruders, exchanging the filament for granules of plastic, Chocolate extruders (whoopee!).

Paste extruders, where any type of paste can be squeezed out. Usual uses are with ceramics and also food.

Paste extrusion is sometimes left in its very own classification, as the paste is not necessarily a polycarbonate material.

The common theme with all of these variants is that a substance is being squeezed out through a nozzle onto a build plate and/or fusing through the warm or material bond to a previous layer in specific patterns to create a form, which is the basis of an FDM 3D printer.

Various other variations in FDM 3D printing include the systems of movement for all 3 axes on a printer.

Both main variants are Cartesian 3D printers-- like the RepRap/Prusa i3 or the CoreXY layouts-- and delta 3D printers. Each has advantages over the others, yet they all utilize the exact same general technique of printing. For a contrast of layouts, see this post.

Characteristics of FDM

Printer Parameters

Many FDM systems allow the adjustment of a number of process criteria, including the temperature level of both the nozzle and also the construct system, the development speed, the layer elevation, and also the speed of the air conditioning follower.

These are typically established by the operator, so they need to be of little worry to the designer.

What is necessary from a designer's viewpoint is to develop dimension and layer height:

The available developed dimension of a desktop computer 3D printer is typically 200 x 200 x 200 mm, while for industrial machines this can be as large as 1000 x 1000 x 1000 mm.

If a desktop computer machine is preferred (for instance for decreasing the expense) a large design can be burglarized into smaller parts and afterward set up.

The regular layer height utilized in FDM ranges 50 as well as 400 microns as well as can be identified upon placing an order.

A smaller layer elevation generates smoother parts and catches curved geometries extra properly, while a larger elevation produces components quicker and at a reduced cost. A layer height of 200 microns is most typically used.

A post reviewing the influence of layer elevation in a 3D printed component can be located right here.

Warping

Warping is among one of the most common flaws in FDM. When the extruded product cools down during solidification, its dimensions decrease.

As various sections of the print cool at different prices, their dimensions likewise transform at various speeds. Differential air conditioning triggers the accumulation of interior anxieties that draw the underlying layer upwards, creating it to warp, as seen in number 3.

From a modern technology standpoint, bending can be stopped by closer monitoring of the temperature level of the FDM system (e.g. of the construct system and the chamber) as well as by boosting the adhesion between the part and the build platform.

The choices of the developer can likewise minimize the possibility of warping:

Huge level locations (think of a rectangular box) are much more vulnerable to bending and also need to be avoided when possible.

Slim sticking out features (think of the prongs of a fork) are likewise prone to bending. In this case, warping can stay clear by adding some sacrificial products besides the thin attribute (for instance a 200 microns thick rectangular shape) to increase the area that touches the construct system.

Sharp edges are buckling regularly than spherical shapes, so adding fillets to your design is a good practice.

Different materials are much more prone to warping: ABDOMINAL is normally much more sensitive to contorting compared to PLA or PETG, due to its higher glass change temperature level and also a relatively high coefficient of thermal development.

Layer Adhesion 

A good bond between the deposited layers is extremely vital for an FDM part. When the molten thermoplastic is extruded via the nozzle, it is pushed against the previous layer.

The heat as well as the stress re-melts the surface area of the previous layer and also allows the bonding of the new layer with the formerly published part.

The bond strength between the different layers is always lower than the base strength of the material.

This implies that FDM parts are inherently anisotropic: their stamina in the Z-axis is constantly smaller sized than their stamina in the XY-plane. For this reason, it is important to maintain a component orientation mind when developing parts for FDM.

For example, tensile examination pieces published horizontally in ABS at 50% infill were compared to check pieces printed up and down and were found to have virtually 4 times greater tensile toughness in the X, Y print instructions compared to the Z instructions (17.0 MPa compared to 4.4 Mpa) and also extended almost 10 times a lot more prior to breaking (4.8% compared to 0.5%).

Furthermore, given that the molten product is pushed against the previous layer, its shape is flawed to an oval.

This indicates that FDM parts will certainly constantly have a curly surface, also for low layer height, which small attributes, such as tiny holes or threads may need to be post-processed after printing.

Support Structure

The assistance structure is crucial for producing geometries with overhangs in FDM. The melted polycarbonate can not be transferred into thin air.

Because of this, some geometries require a support structure. An in-depth write-up describing making use of the support framework can be located right here.

Surfaces printed on support will usually be of reduced surface top quality than the rest of the part. Therefore, it is recommended that the component is developed in such a way as to reduce the demand for support.

Support is normally published in the very same product as the part. Support materials that liquify in fluid likewise exist, however they are made use of mostly in a premium desktop computer or industrial FDM 3D printers.

Printing on dissolvable sustains boosts substantially the surface area high quality of the component, yet boosts the overall cost of a print, as a professional device (with twin extrusion) is required as well as because the expense of the dissolvable product is fairly high.

Infill & Shell Thickness

FDM components are usually not printed solid to minimize the print time as well as save material. Rather, the external boundary is mapped making use of a number of passes, called the covering, and the inside is filled with an interior, low-density structure called the infill.

Infill and also shell thickness influence substantially the toughness of a part. An overview for selecting the most effective covering and also infill criteria for FDM 3D Printing can be located below.

For desktop computer FDM printers, the default setting is 25% infill thickness as well as 1 mm shell density, which is a great compromise between stamina as well as a rate for quick prints.