Master Model Making for a 3D Printer
By Jennifer Theokary, Manager of 3D Print at RIVA
A 3D printer is a multi-functional tool that cuts costs, labor and streamlines the sample making process, yet there are other ways to use them to boost efficiency within a jewelry factory.
The traditional role of a 3D printer may be to create resins or waxes for direct investment casting, but what if it was used to create a master model that could go direct to VLT, liquid silicone or a vulcanized rubber mold? Many 3D printing companies have come up with extreme high surface resolution resins that withstand molding temperatures from 90C to 180-200C. These resins have a hardness (Shore D) of 88-94, allowing for unique cuts whilst molding.
When creating a master model, one may use two routes, direct 3D print to investment casting, or CNC machining the model. With a direct 3D print to investment casting, production time slows down, which in turn costs money for the factory. A simple value stream map shows this process below:
3D Print—Post Processing of Resin—Investment Casting Process—Jewelry Cleaning/Bench work—Polishing—Rubber Molding
When directly printing a model, using an approved resin for rubber molding, the process looks much simpler, saving money:
3D Print—Post Processing of Resin—Rubber molding
By 3D printing a master model, production time, material, and labor costs have all been saved.
Direct CNC machining a master model can be costly. It may include secondary operations, multiple set ups, and valuable machine time. This can delay production, costing the factory more money for a singular master model.
In the long run, the customer wants a beautiful piece, done at a reasonable price that was created within in a timely fashion. Often the best bet for cutting time and cost, is to 3D print the master model.
By 3D printing master models, a factory can fast track the delivery date of multiple pieces. Production time goes from few weeks to a few days with less labor. Once a CAD design is finished and printed, it can go directly to the molding process. Design changes, or function limitations, are quick to assess, since it is possible to have a master model created in as little as 40 minutes, in some cases. If changes need to be made after inspection of the model, one can simply change the CAD and reprint. This allows for accuracy and faster production time. The fast printing speeds on today’s 3D printers allow for multiple and quick design iterations, which can be used to access design changes with a customer. Changes can be made on the spot, with reprints for faster production.
Material, Intricate Geometries and Surface Finish
Using 3D printing, a factory has the liberty to create complex patterns, organic shapes, multiple holes, milgrain, or small settings for master models. This is not always possible with traditional model making clean up, or CNC machining. With a 3D printed master model, the surface quality is already at high resolution, and some resins will come out of the printer with a polished surface finish. This is important for intricate parts that are hard for a jeweler to clean.
3D printing a master model also allows for multiple components in one mold, without soldering or bench work. The data in a CAD design will be directly printed as a model. The master model can also have the spru for injection already designed into its body, which saves the caster the time of spruing before molding. Most of the resins used for direct molding are relatively hard, can be removed easily from the rubber mold and can also be broken, allowing one to carry out difficult cuts that would be impossible with a metal model.
Master models from 3D printing allows for machine accuracy, which in turn improves casting output.
Shelf Life and Space
Molding a direct 3D printed master model allows for more shelf life, space, and less material usage. The digital file is kept on your desktop, cloud, network, or external hard drive. At any given time, one can reprint the master model and remold. This is notable in the case of rubber molds breaking down over time.
In conclusion, using your 3D printer to make master models makes the whole process less complicated, as the mold making process becomes ergonomical, faster, and customizable, allowing for elaborate geometries and retaining an extended shelf life.