Mold design and silicone parts go hand in hand. One affects the other, which means resulting quality is highly dependent on how the other functions. In fact, mold design is one of the most important steps in the initial planning stages when it comes to the production of silicone rubber components and keypads.
Silicone molds are available in a variety of shapes and sizes, with each being made with unique purposes for different end results. At SiTECH, our highly skilled mold makers boast decades of experience in the liquid silicone injection molding process.
Our Process
Once we receive Released for Production 3D CAD files of a clients’ design, we can kick start the mold design process. Backed by SolidWorks 3D modeling software, our engineers are able to design all the mold parameters from start to finish according to unique specifications. During design, it’s important to take into account the behavior and qualities of liquid silicone rubber.
That’s because we know liquid silicone rubber molds fill rapidly due to its low viscosity, even when subjected to low injection pressures. Mold components will be considered during the schematics stage of the process.
We also consider the material and composition of the mold, of which there are many such as:
- Steel core and cavity sets: These are the longest lasting and highly durable when it comes to LSR molding production.
- Aluminum core and cavity sets: These are less expensive and lighter than steel. Also, after extended use and thermal cycling, aluminum can succumb to the annealing process. This can impact the hardness and ductility of the metal.
When deciding which material to use during LSR molding production, we also take into account the thickness of the parts being manufactured vs. the thickness of the mold and design intricacies.
One thing to note about silicone rubber molding is that LSR expands when heated. This means it can be expected to shrink by two to three percent when the part is actually extracted from the mold. This is part of the cooling process.
What affects shrinkage? Many things, such as tool temperature, cavity pressure, and part thickness (thicker parts tend not to shrink as much as thin parts) can affect shrinkage.
Because the silicone rubber part mirrors the surface of the mold, the surface’s finish is important to the resulting component.
When producing clear or transparent parts, for example, we use polished steel. The presence of a textured or eroded surface helps us to more easily remove the silicone mold rubber parts because there are reduced adhesion qualities between the mold and the silicone. We treat the mold surface with a titanium/nickel compound to boost the life expectancy of the mold.
Contact SiTECH
As you can see, there are many decisions that go into the design and mold manufacturing process when making silicone components. It’s our job to keep you apprised of the process and what to expect so you can get peace of mind. To learn more, call SiTECH Corporation today at 757-887-8488.
