如何对树脂 3D 打印件进行后固化

如果您使用的是立体光固化 (SLA) 3D 打印机，那么了解如何后固化您的树脂 3D 打印件十分重要。后固化过程能够尽可能提高部件强度并增强部件稳定性。但每种树脂在后固化后的性能略有差异，需要采用不同的时间和温度才能达到材料的最佳性能。

请下载我们的树脂打印件后固化指南，了解后固化的基本知识及其对各种 Formlabs 树脂的影响

Any resin used in SLA 3D printing can be thought of as a highly cross-linked macromolecule, or a continuous network of polymer chains (monomers and oligomers). Within that macromolecule, there are still some reactive groups that can further cross-link the polymer network when exposed to light and heat.

As more cross-links form, material properties, such as modulus and tensile strength, improve. The objective of post-curing is to link as many of these unreacted groups as possible to bring a part to its maximum material properties.

Once optimal material properties are reached, further post-curing of certain resins can sometimes cause brittleness or warping. The post-curing protocol must therefore be specific for both time and temperature in order to avoid curing too much, and will be unique to each resin and part geometry.

Optimal post-curing starts with heat. Rising temperatures increase the energy, and therefore mobility, in the polymer network. This gives reactive groups a higher probability of finding each other and creating more connections. Formlabs post-curing machines, the Form Cure and the Form Cure L, both use a heater to help the curing chamber quickly reach the desired temperature and then maintain it throughout the postcure.

Once the desired temperature is reached, light is introduced. Photons of light activate remaining photoinitiators, causing nearby reactive groups to form bonds and finish the cross-linking process. With each new cross-link the polymer network becomes more securely linked together and material properties improve.

As more cross-links form in the resin, the network slightly densifies, resulting in some minor shrinkage of the whole part. This is normal for any parts produced with a resin 3D printer. PreForm, Formlabs’ free print file preparation software, automatically compensates for this shrinkage to ensure your post-cured prints are dimensionally accurate to your original CAD designs.

理想的后固化设置会在最佳时间内实现您所需要的性能。对于 Formlabs 通用树脂，您可以使用 Form Cure V2 进行一分钟的快速固化。在需要强度、固化和耐高温的应用中，Formlabs 工程树脂的后固化时间可长达 120 分钟，具体取决于所使用的后固化硬件。

Formlabs 通过在内部开展后固化研究，确定了每种 Formlabs 树脂的最优设置。我们的材料科学家使用 ASTM 方法测试了每种材料在不同温度下的各项机械性能。

有关 Form Cure V2、Form Cure V1、Form Cure L V2 或 Form Cure L V1 的最新后固化设置建议，请访问我们的网站。您还可在网站上下载材料数据表，其中包含执行建议的后固化操作后部件的具体机械性能。

As more dental and medical professionals adopt 3D printing in their workflows, 3D printing companies have to ensure that the entire process is controlled to consistently manufacture high performing parts with biocompatible safety for the end user. Biocompatibility requirements require careful adherence to these pre-approved processes, and this applies to the post-cure step of the printing process as well.

Formlabs technology has been validated in FDA-cleared workflows, which means that for each resin intended for use in a biocompatible application, there are certain printing, washing, and curing steps that must be followed without deviation in order for the final part to be considered a biocompatible device.

The Form Cure and Form Cure L are important parts of these workflows. After careful testing and a thorough regulatory process, the validated settings for post-cure times ensure that each printed part for biocompatible applications has optimal mechanical properties and is consistently safe for use.

Find specific post-curing recommendations for each material in the Manufacturing Guide for each material.

An ideal post-cure setting achieves the properties you need in optimal time. Formlabs developed an in-house post-cure study to identify optimized settings for each individual Formlabs Resin. Using the ASTM method, our materials scientists tested a variety of mechanical properties at various temperatures for each material.

To see how post-curing influences mechanical properties, this guide looks at changes in the tensile modulus, which shows a change in stiffness of a part, for each resin over time in Form Cure or Form Cure L. An object with a higher tensile modulus will have a greater resistance to changing shape under stress. Modulus of elasticity is closely related to how completely crosslinked photopolymer chains are within the part, which is why Formlabs uses modulus to represent overall completeness of post-curing.

The “green” shape of a model is formed by laser-curing the resin during printing, but some potential polymer connections remain unbonded. Cross-linking the remaining polymer proportionally improves strength, stiffness, and temperature resistance. Post-curing also causes some part shrinkage. Formlabs measures accuracy and mechanical properties based on a standard post-cure of parts, and material settings are tuned to account for shrinkage under the same conditions.

The following graphs will help you understand how Formlabs materials respond to post-curing, viewed as a percentage increase in tensile modulus. Familiarity with post-curing behavior saves time and improves accuracy when post-curing parts for your particular application.

In this example, Rigid 4000 Resin exhibits a sharp rise in modulus of elasticity over the first 15 minutes of post-curing, increasing by 116%. After 15 minutes, no further improvements are observed. 

Rigid 4000 Resin is a glass-filled composite material designed for parts requiring high stiffness and strength, as well as low deformation under load. Post-cure directly increases strength and stiffness by further crosslinking the polymer matrix surrounding microparticles of glass, holding them rigidly in place. Post-cure of Rigid 4000 Resin is substantially impacted by temperature. At higher temperatures, a large improvement in modulus of elasticity is gained over a short period of time. Post-curing beyond 15 minutes will not affect properties but will begin to cause cosmetic yellowing, and is not recommended. For most applications of Rigid 4000 Resin, post-cure for 15 minutes at 80 °C in Form Cure.

The most common issues encountered when post-curing parts are under-curing and warping. If parts seem weaker or less rigid than expected, they may be insufficiently post-cured. Undercuring can occur when a part is particularly thick or large, as larger parts take longer to heat. Light alone cannot post-cure much beyond the surface of a part, which is why Form Cure and Form Cure L apply both heat and light. If a part is significantly larger or thicker than Formlabs’ test geometries, it may require a longer post-curing time or higher temperatures to reach a full internal post-cure.

Warping during post-cure may occur if a part is especially thin, and is not equally exposed to light on all sides. Form Cure and Form Cure L help prevent warp by rotating the part on a turntable during post-curing, and by exposing the part to light from all directions — including underneath the turntable.

Post-cured parts also tend to be more brittle than green parts. Typically, as modulus increases elongation will decrease; because of this, over-cured parts can be undesirably brittle.

后固化有很多方法，包括简单的光固化（自然光、紫外线美甲灯、紫外线固化站、DIY 紫外线固化箱等）以及同时使用光和热等。热处理能够加速这一过程并形成更完整的键合，从而提高材料性能，这是仅通过光固化无法实现的。

Formlabs 提供两种后固化解决方案，分别为适用于桌面级 SLA 3D 打印机的 Form Cure 和适用于大幅面专业级 SLA 3D 打印机的 Form Cure L，旨在快速一致地对使用 Formlabs 树脂打印的部件进行后固化。Form Cure 和 Form Cure L 可以利用精准波长的光照，以不同的温度和时长对 SLA 3D 打印部件进行后固化。

Form Cure uses a 405 nm light source, which was determined through an extensive internal testing process to be the most effective at creating the best modulus and tensile strength in parts printed on Formlabs printers. In comparison, when the time and temperature were the same, but a 365 nm light source was used, the modulus reaches only 67% as that of the 405 nm samples. There is a significant difference in the post-cured properties at each wavelength, especially so at shorter post-cure times.

阅读 Formlabs 后固化指南，了解后固化对每种 Formlabs 树脂主要性能的影响，并为您的应用确定最佳后固化方案。

下载指南以了解：

• 后固化对每种 Formlabs 材料主要性能的影响
• 针对特定材料应用的最佳后固化建议
• 避免常见后固化问题的策略