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Revisiting the Liquid Silicone Molding Process and Its Benefits

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Many different processes can be used in the manufacturing industry to create products. One of the recent and more popular methods is silicone molding. This process allows for the creation of complex shapes and designs that would otherwise be difficult or impossible to create using traditional methods. If you want to learn more about silicone molding applications, read on!

What is Liquid Silicone Molding?

The primary material in liquid silicone molding is liquid silicone rubber or LSR. This material is versatile and spans a variety of applications across different industries. Some of its uses are electric connectors, seals, kitchen tools, and baby products.

Due to its ability to reject water and preserve its mechanical qualities in various temperatures, from cold to extremely hot, silicone has found widespread use. A liquid silicone rubber part is created using a method like that used to create thermoplastic parts.

Significant Properties of Liquid Rubber Silicone

Liquid silicone rubber offers various features that make it the appropriate material for various objects. It is incredibly resilient and temperature tolerant. For instance, silicone is sometimes used to make cupcake molds because it resists melting in a hot oven. Because silicone can withstand the cold of a freezer, it is also utilized for ice trays.

Silicone liquid rubber is resistant to water, oxidation, acids, and alkalis. It is very flexible, has a high tear and tensile strength, and has good elongation. Since LSR is translucent, adding color is simple. It is a preferred material for medical-grade items since it is bacterial-resistant and sterile.

The Liquid Silicone Molding Process

Two major components are required in the liquid silicone molding process: the compound and the catalyst. These two materials, marked as Compound A and Compound B, are placed in separate barrels.

The curing process begins when Compound A and Compound B are mixed at a 1:1 rate, and the pigment is added. The molder will automatically adjust the settings on the injection molding machine to accommodate the LSR and the specifications of the finished product. Some of these adjustments include the shot size of the LSR along with temperature, cycle time, pressure, and injection rate.

The LSR injection molding machine forces the clamp while heating the mold. The LSR is then injected into the cavities of the mold. Next, the silicone liquid rubber is heated until it solidifies. Then, it is removed from the mold. After that, some finishing steps are applied, which could involve drying, inspection, de-flashing, and packaging.

Some of the Advantages of LSR in Injection Molding

In injection molding, varied materials are used, each with its challenges. However, for liquid silicone rubber, it is not a problem. Here are the reasons why this material ranks high in injection molding:

Zero by-products: Due to its distinct molecular structure and lack of by-products generated during the molding process, liquid silicone rubber (LSR) is suited for various applications. However, because of the molecular structure’s stronger bonds, it cannot be recycled. Furthermore, the strength of the link between silicon and oxygen prevents it from degrading at high temperatures. LSR can withstand the sterilizing procedure and is chemically inert. The best material for medical devices, food applications, and baby care goods is, therefore, this one.

More design flexibility: The design principles for liquid silicone rubber molding are comparable to thermoplastics. However, there are some specifics where there is more flexibility. As a result, engineers and designers have more flexibility while using LSR in their work.

Sink and Planes: To enable the milling of molds, plane features on the mold opening direction need the requisite drawings. To prevent scraping, the mold design calls for almost 1 degree of a draft in a 25mm mold depth. Liquid silicone rubber is so thin that it can readily move into narrow walls. This allows the creation of pieces with various thicknesses. Meanwhile, most materials cure before cooling down because liquid silicone rubber compounds harden as they are heated. The sink is not a problem while using LSR molding. According to designers and engineers, silicone may be used to create parts with thicker features than thermoplastics.

Undercuts: The significant distinction between thermoplastics and liquid silicone rubber in injection molding is how undercuts are handled. Due to the liquid silicone rubber materials’ considerable flexibility, undercut features are not as constrained. However, sophisticated techniques are needed for rigid thermoplastic polymers. For instance, use a side action to create an undercut feature, then remove the material before opening the mold.

Compress-ability: The significant distinction between thermoplastics and liquid silicone rubber in injection molding is how undercuts are handled. Due to the liquid silicone rubber materials’ considerable flexibility, undercut features are not as constrained. However, sophisticated techniques are needed for rigid thermoplastic polymers. For instance, use a side action to create an undercut feature, then remove the material before opening the mold.

However, liquid silicone rubber also has its flaws. The disadvantages of liquid silicone rubber are numerous:

  • LSR falls short of aerospace requirements. This is because LSR would require adding chemicals and fillers, producing poor flow. Manufacturers will provide compression molded LSR grades for aerospace projects to combat this.
  • LSR part tooling can be intricate and may result in increased costs.
  • Longer lead times may result in a more complicated mold being utilized for LSR.

Advantages of Liquid Silicone Molding

Extreme temperatures, water, ozone, germs, and more are not a problem for LSR. It is a valuable material for various applications due to its strength and flexibility. Since it is inherently translucent, a color may be applied to give it a specific appearance or to distinguish individual pieces.

It is a consistent molding material that minimizes waste and increases efficiency when used in an injection molding process with a closed-loop system. Since injection molding is a closed system process and highly automated, it requires little staffing and has lower labor costs. In addition, the whole thing happens quickly, usually in seconds instead of minutes.

Conclusion

Despite these few drawbacks, employing LSR has several advantages over alternatives. First, a consistent and cost-effective project will be ensured when used with an experienced manufacturer like (Company Name). Please call (Telephone Number) or send an email to (Email address) if you are interested in beginning a project that will involve liquid silicone molding.

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