RESIN SHRINKAGE IN 3D PRINTED JEWELRY: EXPLORING THE PREDICAMENT OF PRECISION

Date: Aug 23, 2024 Category: 3D Printing for Jewelry

One important aspect that might compromise the precision and caliber of jewelry manufactured via 3D printing is resin shrinkage. To create exact, high-quality jewelry, jewelers must understand the reasons behind shrinking. The quality, accuracy, and overall integrity of the final product can be compromised by this phenomenon, making it a critical concern for those in the industry. 

RESIN SHRINKAGE IN 3D PRINTING: WHAT IS IT?

When liquid resin hardens during the curing process, it loses some of its volume, this is called resin shrinking. In stereolithography (SLA) and digital light processing (DLP) 3D printing, the resin is put in contact with a light source, usually UV light. This sets off a chemical reaction that hardens the resin. The molecular structure changes when something changes from a liquid to a solid, it causes the volume to decrease, known as shrinkage.

For jewelry makers, even a small amount of shrinking can lead to mistakes that make the pieces not fit right, not meet the specifications, or lack the detail that was wanted. The key to making high-quality 3D jewelry is to understand the things that cause resin to shrink. Every jewelry maker wonders about this when they print their 3D model. Firstly, they must know the possible types of shrinkage to determine the real reason.

HOW AND WHY DOES SHRINKING HAPPEN, AND WHAT KINDS OF SHRINKAGE MAKE 3D PRINTING CHALLENGING?

The polymerization process, which entails converting monomers—small molecules—into polymers—larger, bonded molecules—makes the entire 3D printing process feasible.

This reaction causes the molecules to pack more closely together, leading to a reduction in volume, which is perceived as shrinkage.

Post-Printing Shrinkage

The exothermic nature of the polymerization reaction, which results in the release of heat, can induce localized heating, hence causing additional alterations in material density and shrinkage. DAs the resin cools down, variations in thermal expansion across different sections of the object might lead to further deformation and shrinkage.

Solution: Apply Shrink Compensation in your slicing and supporting software according to the shrinkage rate of the specific resin.

Post-Curing Shrinkage

Some resins may undergo incomplete polymerization following the printing process. Post-UV curing is necessary for optimal results in jewelry casting, as using uncured resin could result in undesirable results.

Solution: Apply Shrink Compensation in your slicing and supporting software according to the shrinkage rate of the specific resin.

Continuous Shrinkage in Cast-able Resins

Some resins have inherent features of ongoing shrinkage even after printing. This means that they will continue to shrink over time. The only option to address this issue is to cast the resin within a specific time range after printing.

Solution: Study the shrinkage Rate of the Resin. Apply shrink compensation according to the time frame of the casting.

Shrinkage Caused by Alcohol 

Isopropyl or Ethyl alcohol is utilized to cleanse the 3D-printed components, offering certain advantages and drawbacks that can be easily reduced.

Isopropyl alcohol (IPA), functions as a solvent for resin that has not yet hardened. When a 3D printed component is submerged in alcohol, the liquid resin present on the surface and inside the tiny pores of the print is dissolved and eliminated. Unfortunately, the alcohol can also get into the partially cured resin and make it temporarily swell.

Once the component is separated from the alcohol and becomes dry, the alcohol that was absorbed is released through evaporation. This can cause the material to contract when the swollen polymer chains revert to their previous or even smaller size due to the solvent being lost, resulting in the portion shrinking overall.

Solution: Avoid prolonged immersion of the printed models in alcohol and promptly dry them with compressed air after washing. 

Shrinkage Caused by an Incorrect Printing Profile

Most jewelry models stay under-cured or uncured when there is less exposure in the printing profiles. This results in shrinkage from alcohol wash as well as shrinkage from exposure to UV radiation in the atmosphere. 

Solution: To determine the proper exposure time for your 3D resins, run test models on your 3D printers.

Shrinkage Caused by Inadequate Support

The region can stay under-cured if suitable supports are not provided to the Jewelry Models. This results in shrinkage from alcohol wash as well as shrinkage from exposure to UV radiation in the atmosphere.

Solution: Ensure that the printing profiles are in concurrence with the Resin. Also, ensure that suitable supports are applied and that all exposed sections and isolated areas are properly covered.

IMPACT OF RESIN SHRINKAGE IN 3D JEWELRY PRINTING

  • Design Distortion:
    • Design distortion can occur when there is even a small amount of resin shrinkage, which can negatively impact the aesthetics and functioning of jewelry designs.
  • Fit Issues:
    • Rings and other components may not fit properly owing to shrinkage, which might compromise the overall quality of the finished product.
  • Loss of Detail:
    • Elaborate designs may experience a reduction in their level of intricacy, and the settings for gemstones may become excessively tight or loose.
  • Heightened post-processing:
    • Additional time and effort may be required to rectify distortions, modify dimensions, and enhance intricacies, resulting in augmented production expenses and extended lead times.
  • Material Waste:
    • Excessive shrinkage can cause components to become worthless, leading to the wastage of materials and necessitating the reprinting process.
  • Quality Impact:
    • Jewelers rely on precision and accuracy, making it imperative to comprehend and address resin shrinkage to uphold superior craftsmanship.

METHODS TO MINIMIZE RESIN SHRINKAGE FOR ENHANCED MODEL ACCURACY

Here are some actions you should do to improve the accuracy of your 3D models and reduce the amount of resin shrinkage:

  • Material Selection: Choose low-shrinkage materials or specialized resins. Consistent outcomes require the use of high-quality and proven resins.
  • Optimizing Print Settings: Decreasing the print speed promotes more uniform curing, hence minimizing shrinkage. Ensure consistent printing temperatures and select suitable layer heights to achieve a balance between fine detail and printing duration.
  • Tolerance Compensation: Modify the tolerance parameters in your slicing software to account for possible shrinkage. 
  • Model Design Enhancements: Ensure consistent wall thickness and incorporate support structures as needed to prevent deformation.
  • Environmental Control: Maintain a consistent temperature and reduce humidity levels in the printing environment to decrease shrinkage.
  • Post-processing: Employ ultraviolet (UV) light to post-cure resin prints to achieve thorough curing and minimize deformity.
  • Slicing Software: Slicing software parameters can be modified to enhance the strength and stability of the model throughout the curing process.

In conclusion, the precise production of 3D-printed jewelry necessitates the consideration of resin shrinkage. Jewelers can reduce shrinkage by using low-shrink resins, fine-tuning print settings, making designs better, and keeping the surroundings under control. Jewelers can fully leverage the potential of 3D printing technology in their craft by selecting the appropriate materials, optimizing the curing process, and regulating environmental conditions to reduce the effects of shrinkage.