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Common Defects in UV 3D Printing (Part 2)

Release time:

2026-07-24 16:47

Common Defects in UV 3D Printing (Part 2)

Among the various defects in UV‑based 3D printing, interlayer adhesion issues directly affect the overall strength and integrity of the printed model. Delamination manifests as cracks between layers or separation of upper and lower layers, while partially cured “soft layers” result in localized weakness. These problems can, at best, degrade the model’s surface quality and, at worst, render the entire print scrap. The causes of interlayer adhesion failures span multiple factors, including exposure settings, resin condition, equipment performance, and model design. Understanding the symptoms and root causes of these issues is essential for troubleshooting and improving print quality.

I. Stratification

Layer separation manifests as cracks between layers, with the upper layer detaching from the lower layer, and is particularly common in high‑resolution models or those with complex structures.

Insufficient interlayer curing is a major cause of delamination. When the resin in each layer fails to cure completely within the exposure time, the chemical bonding between layers becomes inadequate, resulting in insufficient interfacial adhesion. This typically stems from an excessively short single-layer exposure time, which prevents the resin from attaining a sufficient crosslinking density, thereby reducing interlayer adhesion. If the bottom layer is underexposed, the substrate lacks adequate strength, leaving subsequent layers without a stable adhesive foundation and making delamination more likely.

Excessive adhesion of the release film can also lead to delamination. In equipment that employs a bottom‑up exposure process, each layer must be peeled off the release film after curing. If the release film’s adhesion is too strong, the tensile forces generated during peeling may pull down or tear the previously cured underlying layer, resulting in interlayer separation.

An improperly designed model structure can also lead to delamination. When the upper layers are large and heavy, while the lower layers lack sufficient support or have too small a contact area, the print may delaminate and fracture at weak points due to uneven stress distribution. Similarly, insufficient support in overhanging areas can cause the same issue.

II. Soft Layers Caused by Incomplete Curing

Incomplete curing in certain areas can result in insufficient interlayer adhesion, leading to localized delamination or blistering, as well as the presence of uncured liquid resin within the structure.

When resin degrades, expires, or becomes contaminated, its chemical reactivity diminishes, preventing complete photopolymerization in certain areas. During storage, the resin may absorb moisture or undergo partial pre‑polymerization, resulting in insufficient curing during printing and the formation of soft layers.

Another common cause is the attenuation of light source energy. Over time, the output power of UV lamps or LED light sources gradually declines; when the intensity falls below the threshold required for resin curing, the resin cannot achieve complete crosslinking. Similarly, a reduction in the transmittance of the LCD screen can result in insufficient effective light energy reaching the resin surface, leading to incomplete local curing.

Screen malfunctions or obstructions in the light path can also prevent certain areas from receiving sufficient curing energy. When the screen develops dead pixels or experiences localized degradation, the resin in the corresponding regions fails to receive adequate illumination, resulting in under‑cured soft layers.

III. Conclusion

Interlayer adhesion defects are a critical factor affecting the strength and integrity of UV‑3D‑printed parts. Delamination typically arises from insufficient interlayer curing, excessive release‑film tack, or an inadequately designed model geometry; soft layers caused by incomplete curing are often linked to resin degradation, reduced light‑source energy, or screen malfunctions. When troubleshooting, begin with the exposure settings, verifying that both the single‑layer and base‑layer exposure times are adequate; next, assess the resin condition and ensure the light source’s output power is within specification; finally, evaluate whether the model design requires optimization of the support structure. Through systematic diagnostics, interlayer adhesion issues can be effectively mitigated, leading to a marked improvement in the printed part’s structural integrity and mechanical performance.

Disclaimer: The above content has been compiled from publicly available sources and is provided for reference only. If any infringement occurs, please contact us, and we will address it promptly.

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Common Defects in UV 3D Printing (Part 3)

Common Defects in UV 3D Printing (Part 1)