Lear more about 3D Printing 

Learn more about 3D printing

3D printing or additive manufacturing is a process of making three dimensional solid objects from a digital file.

The creation of a 3D printed object is achieved using additive processes. In an additive process an object is created by laying down successive layers of material until the object is created. Each of these layers can be seen as a thinly sliced horizontal cross-section of the eventual object.

3D printing is the opposite of subtractive manufacturing which is cutting out / hollowing out a piece of metal or plastic with for instance a milling machine.

3D printing enables you to produce complex shapes using less material than traditional manufacturing methods.

The term “fused deposition modeling” and its FDM abbreviation are terms trademarked by the developer of the process. Therefore, the term fused filament fabrication, or FFF, is also used as an exact synonym for this type of printing. Both abbreviations and terms are used here. Some also call the process fused filament printing.

Several types of 3D printing have been developed or are in development, but FDM printing remains the most common and cost-effective.

What is FDM 3D Printing?

Fused deposition modeling, or FDM, is an innovative type of printing that uses additive manufacturing technology to produce 3D objects. Common applications include prototyping, small-batch manufacturing and hobbyist use.

The term “fused deposition modeling” and its FDM abbreviation are terms trademarked by the developer of the process. Therefore, the term fused filament fabrication, or FFF, is also used as an exact synonym for this type of printing. Both abbreviations and terms are used here. Some also call the process fused filament printing.

Several types of 3D printing have been developed or are in development, but FDM printing remains the most common and cost-effective.

Additive deposits are printed in an x-y-z rectilinear, three-dimensional design with x as vertical and y as horizontal. As 2D layers are added on top of each other, the z axis providing depth to create 3D takes shape. During the process, bracing or scaffolding might be required for support of the object being manufactured based on its design. This additional material is typically printed as part of the entire FFF print process and then removed mechanically when printing is completed.

Infill Percentage

3D printing is used to manufacture objects ranging in density from hollow to solid. How closely to one another the roads of material are deposited determines the infill percentage which then determines density and strength of the object. Common infill percentages for 3D printers are 0, 5, 10, 15, 20, 25, 50, 75 and 100 percent.

Types of FDM Printed Materials

A wide range of materials can be used in fused filament fabrication 3D printing.

Thermoplastics are the most common type, and several thermoplastics are popular. They include:

  • ABS: Most entry-level and home 3D printers use ABS plastic to create a wide range of items from tools to toys. The filament form of ABS is employed for FDM printing. The pros of ABS include the many colors it is available in and its excellent strength. It is an affordable material as well, as it is produced in many non-proprietary forms.
  • PLA: This is a biodegradable plastic that is becoming more popular as an ecofriendly alternative to traditional plastics. The downside is that it is not as durable or flexible as ABS plastic. PLA filament is used in FDM/FFF printing while PLA resin is used in other types of 3D printing. Transparent and colored PLA is available.
  • Nylon, aka Polyamide: Nylon filament is a popular choice in FFF printing due to its many advantages. It is flexible, strong and durable. Nylon is easily colored prior to or after printing, but is used in its natural white too, so is often referred to as white plastic. Interlocking and moveable parts can be fabricated with nylon.
  • PET flexible plastic: Polyethylene terephthalate (PET) is used commercially in many applications including plastic bottles and carpet fibers. PET is hard, light and flexible, so it is a good choice for lightweight objects that don’t need to be very strong.

These are the most commonly used plastics in 3D printers, but not the only thermoplastics available. The list includes:

  • Polycarbonate (PC) – strong, resistant to heat and impact. It has high tensile strength and is used in the automotive and aerospace industries.
  • TPE (NinjaFlex) – thermoplastic elastomer (TEP) is a top choice when elasticity is vital to the design, and it offers smooth feeding and good build platform adhesion.
  • PETT or T-glase (tough glass) – offers biocompatibility and is FDA-approved for food containers.

How to Design for FDM 3D Printing

The process begins with a using CAD software to produce your design. When designing, keep these tips for3D printing in mind.

  • Make walls the proper thickness: The general rule of thumb is that vertical wall thickness should be four times the thickness of the slices being used in layering. For example, if the slice thickness is 0.010 inches, the wall should be a minimum of 0.040 inches thick. This creates far better stability and will prevent the wall from buckling and delaminating.
  • Avoid warp: Thin-walled sections of your model might be prone to warping, so consider adding ribs in those sections to improve strength and eliminate the warp risk.
  • Use rounded threads: When threading a part, designs with rounded roots and crests operate more smoothly than those with sharp edges. Choose a “dog point” head design of 1/32″ minimum. This will make it far easier to get the threading started.
  • Follow these parts sectioning guidelines:
    • Design parts in sections when the part is too large for the build space
    • Don’t overdo support material
    • Consider building overhanging parts separately to be fused after printing
    • Design thin and fragile pieces separately to be fused after printing
  • Support angles: When your design features angles greater than 45 degrees, supports should be included in the design that can be easily remove once the object is printed.
  • Space parts properly: When you’re producing a batch of assembly parts, space them far enough away from each other to prevent them from fusing during the print process. The rule of thumb for assemblies being produced fully assembled is to provide a clearance on the z axis of the thickness of one slice. Additionally, the XY clearance should be the extrusion width, at minimum.
  • Use minimum suggested text sizes: 16-point boldface type is suggested for the top and bottom of your FFF model; 10-point boldface is the minimum suggested size for vertical surfaces.
  • Combine files for small parts into a single file: Make sure they all have the same starting height, so they will all touch the build plate. Also, leave 2mm between parts to avoid them fusing together.
  • Limit your polycount where possible: Where it won’t reduce product integrity or aesthetics, lower polycount will create smaller files.
  • Consider post-printing options: Thermoplastics can be drilled, cut, turned and tapped after production. Making these alterations after printing might reduce the difficulty of designing the piece.
  • Design in one of these file types: STL, OBJ, ZIP, STEP, STP, IGES, IGS, 3DS and WRL files are supported by most 3D printers.

What is SLA 3D Printing?

SLA 3D printing is shorthand for stereolithography (SL), a 3D printing technology that has been in used for four decades in various forms of development. The process was first patented in 1986 by Charles Hull, the co-founder of 3D systems, but early technology can be traced to Japan as well.

Along with FDM 3D printing (fused deposition modeling) and SLS 3D printing (selective laser sintering), SLA is becoming more accessible to small businesses, entrepreneurs and other individuals as it becomes more affordable. You might here it referred to by additional terms including rapid prototyping, optical fabrication and resin printing, terms that roughly apply to SLS 3D and FDM 3D printing too.

Stereolithography is often chosen for creating prototypes and models because it produces clean, crisp forms with layering that is difficult to see or feel.

Here’s are the main steps in SLA printing, though there is some variation between printers and techniques:

  • It starts with a vat of liquefied photopolymer resin, meaning that the resin reacts to light. The resin is heated a specific, consistent temperature ideal for curing.
  • Inside the vat is a build platform that starts out at the top of the vat. In most printers, the platform is coated with resin material by a blade or armature that sweeps across it.
  • An ultraviolet (UV) laser, guided by computer-aided software and a file uploaded for the specific object to be built, is directed into the surface of the vat using two actuated mirrors known as galvanometers. The liquefied photosensitive polymer resins are cured by the laser as it “draws” the preprogrammed design, one layer at a time.
  • The platform is lowered incrementally a distance equal to one layer of cured resin as each layer of the prototype or product is drawn onto its surface. Each cured layer becomes part of the piece.
  • For many pieces, support structures are required to eliminate deflection caused by gravity and to support the piece laterally as well. The supports are printed along with the product/prototype, often attached to the build platform.
  • Once the SLA 3D object is finished, it is gently peeled from the print platform, also called a bed. It is immersed in a chemical solution that removes excess resin.
  • Next, the entire piece and its supports is placed in an ultraviolet curing oven.
  • Finally, any support structures are trimmed from the piece, and it is complete.

Uses for SLA 3D Printing

Here is how stereolithography is being used.

  • Prototyping: Also known as rapid prototyping, creating prototypes was the original purpose of this process. Manufacturing prototypes of parts in a wide range of fields continues to be a popular use for stereolithography. The advantage of this process is that the prototype can be made at far less expense than by using more traditional means. The prototypes are accurate and detailed, even when non-conventional shaping is required. They can be machined and used in the design of master patterns for injection molding, metal casting and thermoforming, among other production methods. The prototypes can then be used to assess the performance of the design, and they are often used in marketing campaigns for the object once production has begun.
  • Medical and dental modeling and prosthetic production: Accurate 3D models of anatomical parts such as bone structures and organs are created with this technology. The models are used in training. They can also be customized for individual patients using the data gained from testing such as an MRI or three-dimensional CT scan. Medical and dental models aid in planning for operative procedures and in the manufacturing of implants and prosthetics.
  • Manufacturing: While SLA 3D printing is not a cost-effective means of mass production, it is an inexpensive way to create one or a few customized products that are unique. For example, designs are used in branding, logo creation, publicity and custom gift making.

How to Design for SLA 3D Printing

How to Design for SLA 3D Printing
Computer-aided manufacturing (CAM) and computer-aided design (CAD) software is essential to the process of all 3D printing including stereolithography. The software is used to produce computerized models out of mere ideas. The models can be changed and tested; now, they can also be printed. Before printing, the CAD model must be sliced/layered to print one layer at a time.

To be used in 3D printing, the CAD/CAM files are translated into a file type the 3D printer can read. The most common language used in SLA printing is STL, or Standard Tessellation Language.

These tips improve SLA design:
Maintain minimal thicknesses: Features no less than .030″ for standard SLA and 0.015″ for high-resolution SLA are required, including knife-edge and thinning features, curvy sections of the design and raised lettering on logos and other texts
Control edge-to-edge distance: Creating edge-to-edge distances between faces of less than 0.20″ will produce objects with a smoother face
Choose watertight design: To avoid non-binding surfaces in the object, use watertight settings in CAD
Space multiple parts: Design clearance of at least 0.015″ between parts being printed on a parts tree
Check your measurement units: Be sure to save designs in the appropriate units, either inches or mm

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