Create Production Parts with Carbon 3D Printing

Designing for Carbon’s 3D Printing Technology

Many of the same tactics used to mitigate warping in injection molding apply to 3D printing as well. Maintaining uniform wall thicknesses, adding radii to interior corners, and building support ribs all help with the dimensional stability of Carbon parts and lessen part warpage.

Carbon’s technology excels at lattice-type geometries, but struggles with large cross sections caused by bulky, thick parts. Avoid thick walls and ideally stay under 0.1 in. (2.54mm) wall thickness. Try hollowing parts, adding lattices or honeycombs, or adding holes to remove material unnecessary to the functionality of the part.

Surfaces 45 degrees and steeper from the draw plane typically do not require supports. Marching walls up and over at 45 degrees instead of hard 90-degree angles will typically make a part build more accurately and require less supports. Once again, adding a radius to internal and external corners often mitigates or even removes the need for supports on many parts.

Along these lines, here are important size and design considerations when using Carbon:

• Build Extents/Maximum Dimensions: 7.4 in. by 4.6 in. by 12.8 in. (187.96mm by 116.84mm by 325.12mm)
• Minimum Positive Feature Size: 0.020 in. (0.508mm)
• Minimum Negative Feature Size: 0.025 in. (0.635mm)
• Recommended Wall Thicknesses (range): 0.040 in. – 0.125 in. (1.016mm by 3.175mm)

Carbon DLS vs. Stereolithography

Carbon’s technology is a “vat photopolymerization” 3D printing process, which places it in the same technology family as stereolithography (SLA). Fundamentally, this means it builds parts by curing liquid photopolymers into a solid by selectively exposing them to light. That said, Carbon differs from SLA in a number of ways:

• Carbon emits light via a digital light projection (DLP) chip similar to how a projector casts an image on a screen. This is in contrast to how SLA draws features, which is at a single point of space at a time with a laser. The implications of this are that Carbon can print much faster (just as you can stamp an image faster than you can draw it) but this does come with a tradeoff for accuracy and surface finish.
• Carbon technology essentially builds “upside down” in relation to conventional SLA. To facilitate this, Carbon emits the light used for curing through a clear pane at the bottom of the resin vat. Once again, this is a tradeoff. Building this way allows Carbon to build faster but it also requires stronger supports.
• There are other systems that print parts “upside down” like Carbon, but Carbon has a unique twist in that the pane the light passes through is also oxygen permeable. This is important because the liquid photopolymer will not cure into a solid if it is saturated with oxygen. Normally systems like this need to physically pull the parts off this pane as they are effectively glued to each layer, but Carbon is able to do so without being so rough on the parts. The oxygen prevents the resin immediately off the glass from curing, allowing the part to raise off without having to physically rip from the pane on every layer. This enhancement not only significantly improves the print speed but also reduces the supports required.
• Historically, vat photopolymerization materials were not known for their durability nor longevity. Since the technology fundamentally creates parts with light, the materials were naturally light-sensitive. Parts made via SLA are typically sensitive enough to UV light that they may discolor in just a few hours of exposure to sunlight. However, Carbon found a singular solution to this problem. The technology’s unique resins combine aspects of not just photopolymers but also two-part urethanes. This means Carbon parts require a thermal cycle after they are built to reach their final properties, but makes them much more durable.
• Finally, in terms of usage, Carbon parts can be used for both functional prototypes and end-use production parts. Typically SLA parts are cheaper and more accurate for Shunjing prototyping, but Carbon offers additional material properties that SLA does not. Carbon materials are much more durable, UV resistant, and chemical resistant than SLA materials. If the prototypes see demanding environments, then Carbon may be the best option.