The prototypes resulting from this technology come from the creation of a silicone mold resulting from a master model made in Stereolithography.
The impression of the tooling is then filled with Polyurethane resin, using a specific vacuum casting machine.
Tool life can range from 6 to 30 pieces; it depends on the geometry of your parts and the polymer used.
Elastomer: from 35 to 95 Shore
Rigid: close ABS, PA, PP, PC, HDPE
4 to 6 working days for tools, then 2 to 3 pieces per working day
Axis explains vacuum casting to you in but a few words
Axis uses vacuum casting to allow for more varied uses.
Vacuum casting enables the production of pieces which are flexible or rigid, and of different hardnesses, or transparent, or of different colours, with different textures when produced in small-scale, …
The different stages of this manufacturing method are outlined in more detail below.
How does it work?
When creating pieces in vacuum casting (or copying them), there are several stages:
Stage 1: First of all, you need to create a master model in stereolithography. For more details on the method for manufacturing such a piece, view the page “How does it work?” for stereolithography.
After your 3D file has been received, we will process it, then programme it to put it into production, applying shrinkage, or not, depending on the material used.
The launch of the production of the master model shall take place in accordance with the stereolithography procedure.
It is heated so as to be hardened.
The piece is cleaned and sanded. The necessary finishes shall be provided by our prototypists, since the appearance of the molding while resemble that of its master model (graining, transparency, …).
Our molders will stick a mark along the joint plane, to facilitate the opening of the silicone mold.
Stage 2: Creation of the mold
The master model created in stereolithography is installed (suspended) in a wooden box with the help of a plug (recycled feed plug, which will allow the material to circulate in the mold cavity) and vents (allowing for the evacuation of air from the material).
Once the piece has been installed, the silicone shall then be poured into the box, and the imprint will then be collected.
Once the silicone has hardened, our molders will open the wooden box along the joint plane.
After the full opening of the silicone mold, the master model obtained from stereolithography will be gently removed, so as not to damage the silicone.
Stage 3: Creation of a copy
The casting operator in charge of the project will carefully close the mold manually while ensuring that there is not left any space (at all) which could leak any polyurethane recently injected into the mold.
They will install it in the machine, prepare the two materials for mixing separately and place them in the machine (high position).
The machine is closed, then put under vacuum while mixing of material A (isocyanate) and material B (polyol) takes place. The two materials are, one after the other, incorporated under vacuum, then poured into the silicone mold courtesy of gravity.
When the material emerges from all the created vents, air shall be resupplied into the machine, and the filled mold shall be placed in a warm oven for several minutes until it hardens.
Once the material is sufficiently hard, the casting operator will unmold the mold and remove the molding.
Stage 4: Finish
The project manager will then proceed to the molding deburring stage.
They will include the inserts or transfers (if they are ordered), and provide any element corresponding to your specifications.