Technical Analysis:"Accuracy" is a variable, not a constant. At Justway, we distinguish between theoretical machine resolutions and real-world industrial tolerances.
Choosing the right 3D printing technology is a strategic decision that balances geometry, material behavior, and cost. Below are the primary industrial processes utilized at Justway:
Material extrusion, as the name suggests, means that the material is extruded through a nozzle. Usually, this material is a plastic filament, which is melted and extruded through a heated nozzle. The printer places the material on the build platform along the process path obtained through software. Then the filament cools and solidifies to form a solid object. This is the most common form of 3D printing. At first glance, this sounds simple, but considering the extruded material, which includes plastics, metals, concrete, bio-gels, and various foods, it actually forms a very broad category. This type of 3D printer ranges in price from $100 to several hundred thousand dollars.
● Subtypes of material extrusion: Fused Deposition Modeling (FDM), Architectural 3D Printing, Micro 3D Printing, Biomedical 3D Printing
● Materials: Plastic, Metal, Food, Concrete, etc.
● Dimensional accuracy: ±0.5% (lower limit ±0.5mm)
● Common applications: Prototypes, Electrical enclosures, Shape and fit testing, Jigs and fixtures, Molded casting models, Buildings, etc.
● Advantages: The lowest-cost 3D printing method with a wide range of materials
● Disadvantages: Usually with lower material properties (strength, durability, etc.), and often with poor dimensional accuracy
FDM parts can be manufactured on various 3D printers using either metal or plastic. The JUSTWay system currently only supports plastic, while metal parts require the SLM process.
FDM parts can be made on various 3D printers using either metal or plastic. The FDM 3D printer is a market worth billions of dollars, with thousands of machines ranging from basic models to the manufacturer's complex models. The FDM machine is called filament fusion (FFF), which is the exact same technology. Like all 3D printing technologies, FDM starts with a digital model and then converts it into a path that the 3D printer can follow. Using FDM, a single (or several at a time) filament on a spool is inserted into the 3D printer and then sent into the printer nozzle. The printer nozzle or multiple nozzles are heated to the required temperature, causing the filament to soften, thus allowing the continuous layers to connect and form a sturdy component.
When the printer moves the extrusion head along the specified coordinates on the XY plane, it will continue to lay down the first layer. Then the extrusion head rises to the next height (the Z plane), and repeats the process of printing the cross-section, layer by layer, to build the object completely until it is fully formed. Depending on the geometry of the object, sometimes support structures need to be added to support the model during printing, for example, if the model has steep overhanging parts. These supports are removed after printing. Some support structure materials can dissolve in water or another solution.
Bucket polymerization (also known as resin 3D printing) is a series of 3D printing processes that use light sources to selectively cure (or harden) photosensitive polymer resin in a bucket. In other words, the light precisely targets specific points or areas of the liquid plastic to cause it to harden. After the first layer is cured, the build platform moves up or down (depending on the printer) a small amount (usually between 0.01 and 0.05 millimeters), the next layer cures, and is connected to the previous layer. This process is repeated layer by layer until a 3D component is formed. After the 3D printing process is completed, the object is cleaned to remove the remaining liquid resin and undergoes post-curing (in sunlight or a UV chamber) to enhance the mechanical properties of the component.
The three most common forms of bucket aggregation are Stereolithography (SLA), Digital Light Processing (DLP), and Liquid Crystal Display (LCD), also known as Mask Stereolithography (MSLA). The fundamental difference among these types of 3D printing technologies lies in the light source and the way it is used to cure the resin.
● Types of 3D printing technology: Stereolithography (SLA), Liquid Crystal Display (LCD), Digital Light Processing (DLP), Micro Stereolithography (μSLA), etc.
● Materials: Photopolymer resins (pourable, transparent, industrial, biocompatible, etc.)
● Dimensional accuracy: ±0.5% (minimum limit is ±0.15 millimeters or 5 nanometers, using μSLA)
● Common applications: Injection-molded polymer prototypes and final-use components, jewelry casting, dental applications, consumer products
● Advantages: Smooth surface finish, fine feature details
Stereolithography (SLA) comes from the SLA 3D printing examples of JUSTWAY.
SLA is the world's first 3D printing technology. The stereolithography technique was invented by Chuck Hull in 1986. He applied for a patent for this technology and established 3D Systems Company to commercialize it. Nowadays, this technology is available for enthusiasts and professionals from numerous 3D printer manufacturers. SLA uses a focused laser beam to align with a bucket of resin, selectively curing the cross-sections of the object within the printing area, and building layer by layer. Most SLA printers use solid-state lasers to cure the components. One disadvantage of this bucket polymerization method is that, compared with our next method (DLP), the point laser may take longer to track the cross-sections of the object, and the latter will flash light to immediately harden the entire layer. However, lasers can generate stronger light, which is required by some engineering-grade resins.
△ The SLA 3D printer uses one or more lasers to trace and solidify a single layer of resin at a time.
Anycubic, Carbon and ETEC's DLP 3D printing components
DLP 3D printing uses a digital light projector (instead of a laser) to flash each layer of the image simultaneously on one layer or resin (or expose multiple layers for larger components). DLP (more common than SLA) is used to produce larger parts or parts with larger volumes in a single batch because regardless of how many parts are in the build, each layer exposure requires exactly the same amount of time, which is more efficient than the point laser method in SLA. Each layer's image is composed of square pixels, resulting in one layer being formed by small rectangular blocks called voxels. Light is projected onto the resin using an LED screen or UV light source (lamp), and the light is projected onto the build surface through a digital mirror device (DMD).
△ Digital Light Processing (DLP) resin 3D printers come in both amateur hobby versions and fully functional manufacturing machines. Modern DLP projectors typically have thousands of micrometer-sized LEDs as the light source. Their on-off states are individually controlled, which can enhance the XY resolution. Not all DLP 3D printers are the same. The power of the light source, the lens it passes through, the quality of the DMD, and many other components that make up a $300 machine vary greatly from those of a machine costing over $200,000.
Powder bed fusion (PBF) is a 3D printing process in which a heat source selectively melts the powder particles (plastic, metal or ceramic) within the build area to create a solid object layer by layer. A powder bed fusion 3D printer spreads a thin layer of powder material on the printing bed, typically using a blade, roller or wipe. The energy from the laser fuses the specific points on the powder layer, then deposits another powder layer and fuses it to the previous layer. This process is repeated until the entire object is manufactured, and the final product is encapsulated and supported by the unfused powder.
● Types of 3D printing technology: Selective Laser Sintering (SLS), Laser Powder Bed Fusion (LPBF), Electron Beam Melting (EBM)
● Materials: Plastic powder, metal powder, ceramic powder
● Dimensional accuracy: ±0.3% (lower limit ±0.3mm)
● Common applications: Functional components, complex pipes (with hollow design), small batch component production
● Advantages: Functional components, excellent mechanical properties, complex geometries
● Disadvantages: High machine cost, usually high-cost materials, slow construction speed
△ Justway's SLS 3D printed components
Selective Laser Sintering (SLS) uses a laser to create objects from plastic powder. First, a box of polymer powder is heated to a temperature just below the melting point of the polymer. Then, a re-coating blade or eraser is used to deposit a very thin layer of powder material (usually 0.1 millimeters thick) onto the build platform. The laser begins to scan the surface according to the pattern arranged in the digital model. The laser selectively sinters the powder and solidifies the cross-section of the object. When the entire cross-section is scanned, the build platform moves down by one layer thickness. The re-coating blade deposits a new layer of powder on the most recently scanned layer, and the laser bonds the next cross-section of the object onto the previously solidified cross-section.
△ The SLS 3D printed components can be manually or automatically descaled and cleaned.
Repeat these steps until all the objects are manufactured. The un-sintered powder remains in its original position to support the objects, which reduces or eliminates the need for a supporting structure. After removing the parts from the powder bed and cleaning them, no other necessary post-processing steps are required. The parts can be polished, coated or colored. There are many differences among SLS 3D printers, not only in their sizes, but also in the power and quantity of the laser, the size of the laser spot, the time and method of heating the bed, and the distribution of the powder, etc. The most common materials used in SLS 3D printing are nylon (PA6, PA12), but TPU and other materials can also be used to print flexible components.
Among all 3D printing technologies, this one has the most aliases. The official name of this metal 3D printing method is Laser Powder Bed Fusion (LPBF), which is also widely known as Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM). In the early stages of this technology's development, machine manufacturers created their own names for the same process, and these names have been used ever since. It should be particularly noted that these three terms refer to the same process, even though there are some differences in certain mechanical details.
△ The Justway Metal test piece used to demonstrate the SLM accuracy (Source: Justway Metal)
Among all 3D printing technologies, this one has the most aliases. The official name of this metal 3D printing method is Laser Powder Bed Fusion (LPBF), which is also widely known as Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM). In the early stages of this technology's development, machine manufacturers created their own names for the same process, and these names have been used ever since. It should be particularly noted that these three terms refer to the same process, even though there are some differences in certain mechanical details.
As a subtype of powder bed fusion, LPBF uses a metal powder bed and one or more (up to 12) high-power lasers. The LPBF 3D printer uses lasers to selectively fuse the metal powder together layer by layer at the molecular level until the model is completed. LPBF is a highly precise 3D printing method, typically used to create complex metal parts for aerospace, medical, and industrial applications.
△justway's LPBF metal 3D printing is similar to SLS.
The LPBF 3D printer starts from a sliced digital model. The printer fills the build chamber with powder and then uses a scraper (like a windshield wiper) or a roller to spread the powder in thin layers on the build plate. The laser traces the layers onto the powder. Then the build platform moves down, and another layer of powder is applied and fused with the first layer until the entire object is built. The build chamber is closed and sealed, and in many cases, it is filled with inert gases such as nitrogen or argon mixtures to ensure that the metal does not oxidize during the melting process and to help remove debris during the melting process. After printing, the parts are removed from the powder bed, cleaned, and often undergo secondary heat treatment to eliminate stress. The remaining powder is recycled and reused.
Material choice dictates the part’s longevity and performance.
Precision in 3D printing is not absolute; it is influenced by equipment optics, part orientation, and environmental variables. To manage engineering expectations, Justway adheres to the following internal dimensional accuracy standards for parts under 100mm:
Technical Note: While machines have "nominal" specs, our Z-axis accuracy may vary slightly due to optical compensation and mechanical layering (standard layer thickness is typically 0.1mm).
SLA & DLP: Vat photopolymerization. Optimized for ±0.1mm - ±0.2mm precision. Best for aesthetic masters and fit-testing.
SLS (Nylon): Powder-bed fusion. Offers high structural integrity with a ±0.25mm tolerance. No support structures required, allowing for complex internal channels.
SLM (Metal): Full-melt laser technology. Capable of producing dense mechanical parts in Titanium or Aluminum with ±0.25mm industrial accuracy.
Beyond simple accuracy, three specific parameters dictate the quality and "sharpness" of your final part:
Understanding that 3D printing is a "layer-by-layer" additive process is crucial. Issues like dimensional deviation or structural feature loss often stem from a mismatch between the design's requirements and the chosen process's physical limits. By establishing these $\pm$0.2mm benchmarks, Justway ensures that your assembly fits on the first try, every time.
Return to Index:
Justway Technical Resource Center: 3D Printing Quality Standards & Troubleshooting Guide
