Se usi una stampante 3D stereolitografica (SLA), è fondamentale che tu sappia come eseguire la polimerizzazione post-stampa, un processo che consente alle parti di ottenere maggiore resistenza e stabilità. Tuttavia, ciascuna resina reagisce a questo tipo di polimerizzazione in modo diverso e richiede specifiche impostazioni di tempo e temperatura per raggiungere proprietà ottimali.
Scarica la nostra guida alla polimerizzazione post-stampa per apprendere nozioni di base su questo processo e scoprire di più sul comportamento di ciascuna resina Formlabs.
Perché eseguire la polimerizzazione delle stampe in resina?
Each Formlabs Resin is formulated with advanced, light-sensitive polymer chemistries. Formlabs stereolithography (SLA) 3D printers use 405 nm lasers to cure the liquid resin, producing a highly accurate solid part. When an SLA part finishes printing, it remains on the build platform in a “green state.” This means that while parts have reached their final form, polymerization is not yet fully completed and the part has yet to attain maximum mechanical properties. Post-curing with light and heat is key to unlocking this last mile of material properties for SLA 3D prints. For biocompatible materials, post- curing is necessary to achieve the safety standards determined by regulatory agencies.
Achieving optimal properties is especially essential when using functional or specialty resins. Form Cure and Form Cure L, the two post-curing solutions from Formlabs, are designed to post-cure parts printed in Formlabs Resins with speed and consistency. Our engineers developed Form Cure and Form Cure L specifically to work with Formlabs Resins, using the same 405 nm light as the lasers in Formlabs SLA 3D printers. Parts are heated and automatically rotated in the reflective chamber to ensure an even and consistent post-cure.
Introduction to Post-Curing Science
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.
Contatta il nostro team vendite
Siamo qui per aiutarti, sia per necessità di prototipazione rapida che per la produzione di parti per utilizzo finale. Il team vendite di Formlabs è composto da specialisti e specialiste che sanno bene come supportarti trovando soluzioni per la tua azienda.
Per quanto tempo è necessario eseguire la polimerizzazione delle stampe in resina?
Le impostazioni di polimerizzazione post-stampa ideali permettono di ottenere le proprietà desiderate ottimizzando i tempi. Per le resine standard per usi generici di Formlabs, la Form Cure V2 consente una polimerizzazione rapida di un minuto. Se hai bisogno di stabilità, rigidità e resistenza alle alte temperature, le resine ingegneristiche Formlabs possono essere sottoposte a polimerizzazione post-stampa fino a 120 minuti (in base alla macchina utilizzata) per ottimizzarne le proprietà.
Formlabs ha svolto studi interni sulla polimerizzazione post-stampa per identificare le impostazioni ottimali per ciascuna resina Formlabs. Utilizzando il metodo ASTM, il nostro team di ingegneria dei materiali ha testato una serie di proprietà meccaniche a diverse temperature per ciascun materiale.
Puoi trovare tutte le impostazioni consigliate aggiornate per la polimerizzazione post-stampa con la Form Cure V2, Form Cure V1, Form Cure L V2 e la Form Cure L V1 sul nostro sito Internet. Le schede tecniche dei materiali con le proprietà meccaniche specifiche delle parti ottenute a seguito della polimerizzazione post-stampa consigliata possono essere scaricate dal nostro sito Internet.
Grazie alla Form Cure L, Radio Flyer riesce a stampare prototipi accurati in meno tempo, comprese le parti di uno scooter.
Biocompatible Materials and Post-Curing
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.
Campioni di resine BioMed
Ogni campione realizzato con una resina BioMed presenta design goffrati e incisi, sezioni di taglio con spessori di 0,5-2,0 mm, nonché informazioni normative specifiche di tale resina.
Methodology
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.
Post-Cure Troubleshooting
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.
Attrezzatura per la polimerizzazione post-stampa
Esistono diversi metodi di polimerizzazione post-stampa: usando semplicemente la luce (luce naturale, lampada UV per unghie, postazioni di polimerizzazione UV, scatole di polimerizzazione UV fai da te, ecc.) o usando sia luce sia calore. Il calore accelera il processo e permette la formazione di legami più stabili; ciò offre un miglioramento delle proprietà dei materiali altrimenti impossibile da ottenere con la sola luce.
La Form Cure e la Form Cure L, le due soluzioni di Formlabs per la polimerizzazione post-stampa per le stampanti 3D SLA desktop e di grande formato, sono progettate per garantire una polimerizzazione post-stampa rapida e uniforme delle parti realizzate con le resine Formlabs. La Form Cure e la Form Cure L permettono di sottoporre le parti realizzate con la stampa 3D SLA a polimerizzazione post-stampa alla lunghezza d'onda più adatta e con impostazioni di temperatura e durata differenti.
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.
Though the Form Cure L has the size to post-cure large parts, it can also be used to efficiently post-cure many small parts for batch production. A dental lab may have five Form 4B 3D printers, but need only one Form Cure L to cure all their parts at once, saving time, space, and labor.
Inizia a eseguire la polimerizzazione post-stampa di stampe 3D SLA in resina
Leggi la guida alla polimerizzazione post-stampa di Formlabs per capire come questo processo agisce sulle proprietà di base di ciascuna delle resine Formlabs e decidere le impostazioni migliori per la tua applicazione.
Scarica la guida per scoprire:
- Come la polimerizzazione post-stampa agisce sulle proprietà di base di ciascuno dei materiali Formlabs
- I consigli per eseguire una polimerizzazione post-stampa ottimale a seconda dei materiali di applicazione
- Le strategie per evitare i problemi di polimerizzazione post-stampa più comuni
