Lost-wax casting is the most accurate, fast and convenient way to manufacture jewelry and fashion accessories. For the jewelry industry, in particular, lost-wax casting is the most profitable solution because jewels with different weights, sizes and shapes can be replicated with the utmost precision.
It is a complex procedure, which requires state-of-the-art tools and innovative machinery to manage the whole production line in the most effective way and achieve the best results.
From the master to the rubber mold
The process starts with the prototyping of the sample to recreate. The 3D printer creates a master, the prototype of the wax mold. Once the prototype has been printed, we can make the rubber mold.
The rubber mold is crucial for a high-quality end product. For the goldsmith sector, that’s an absolute priority
As for the wax, Masterix has chosen vulcanized silicone. Our vulcanizers eliminate humidity and micro-bubbles and compact the filling material to perfection, making the internal surface smooth and glossy.
Vulcanized rubber maintains its properties over time and keeps a perfect rigidity. The excellent quality of the mold is key not only for the output of the end product, but also for the production optimization.
A high quality mold can be used many times, with no need to start all over again from the 3D printed prototype. As a result, the manufacturing process is streamlined and the costs are amortized.
From the injection to the removal of wax
The wax mold is the negative - the “vacuum” we could say - of the piece to be created. It is a sort of a box that opens up in the middle, with a small cavity to inject the molten wax.
Before injecting the molten wax, the injectors - we will see later the technical details of our machines - remove all the air inside the mold. Vacuum ensures that the wax mold is perfectly filled, without air bubbles or flaws.
Masterix mold coolers: shortest time, increased productivity
Once filled with wax, rubber molds are placed on the coolers. These tools are extremely advantageous in the lost-wax casting process because they shorten the time that the wax takes to harden. Less waiting time, more productivity.
Injectors make it possible to use the rubber mold for new injections without waiting the “natural” time the wax takes to solidify. Consequently, there is no need for a large production of rubber mold, because the same ones can be re-used in a short time, an additional economic advantage.
When the wax has got solid, the rubber mold is opened and the piece is removed. We are ready to step to the next phase.
From the tree to the semi-finished product
All the wax pieces are welded on wax “tree” in order to create at the same moment and in the shortest time as many pieces as possible.
All the wax pieces are attached to the load-bearing structure of the tree, which is dipped into a plaster solution to create the shell.
The plaster is placed into an oven and, with the heat, the wax inside it melts and runs out off the bottom base, which is left open just to allow the leakage of the molten wax.
We have, therefore, a tree-shaped plaster mold - the load-bearing structure - with all the different molds of the pieces to create attached.
A plaster barrel is used as a casing for the cast of molten metal.Obviously, the material must be extremely heat-resistant. Let’s keep in mind that gold has a melting point at 1.948° F, steel at about 2732° F.
The molten metal is poured inside the plaster barrel and fills both the structure of the tree and the different pieces attached to it. Then, the plaster barrel is opened and the gold, silver or steel molds in it are collected.
The tree is retrieved and reused for other castings. As we said, one of the advantages of the advanced lost-wax casting process is that it does not produce waste nor the loss of precious metal.
The pieces, once detached from the tree-shaped structure, are still semi-finished products. After mechanical processing or special finishing like galvanization or coating, they are ready to be delivered.
Masterix automatic injectors, the innovation in the sector
The wax model is the base of the whole microcasting process. Therefore, it must be manufactured to perfection.
Masterix injectors are engineered to achieve the highest quality standards
- Weights, dimensions and shapes of the wax models are perfectly replicable
- Before the wax injection, all the air inside the mold is removed
- The productivity is optimized, without affecting the technical quality
Automatic models are the evolution of the most common machines. They have
- a mold cooling system included
- a touch-screen for the process supervision
- an automatic device for loading and unloading the rubber molds
The lost-wax casting, in conclusion, is the most effective production system for jewelry, due to its extreme accuracy and reliability.
It optimizes time and costs: the state-of-the-art machines ensure massive production in minimum time, always with the utmost quality. The highest productivity, without compromise.