Everything you need to know about Silicones for Advanced Molding & Printing Applications
Why is silicone a great molding material?
Silicones are the material of choice for molds to reproduce the finest details in many applications, from artwork to architecture, via the production of prototypes for industries as varied as transport, renewable energy and food production. Silicones are versatile, customizable, safe and easy to process and provide innovative and robust performance features. They are also cost-effective, due to their durability (high resistance to different resins and corrosive materials) and are capable of being adapted to very different processing techniques. Silicones also offer the convenience of Room Temperature Vulcanization (RTV) and variable viscosity and fluidity levels. This wide choice of features makes it possible to produce molds with different hardness levels and specific mechanical properties, with the possibility of using a wide range of catalysts to enable this customization. In short, compared to other materials, silicone molds guarantee the highest levels of accuracy, reliability and durability.
Does silicone contain BPA?
Silicones, whatever their formulations or applications, are completely BPA-free. This chemical substance, which stands for Bisphenol A, has been used since the 1950s to reinforce certain polycarbonate plastics and epoxy resins, particularly those used in food and beverage containers. Research has shown that it may affect human health, especially hormone levels and other vital processes such as reproduction, fetal development and growth. Many countries around the world have therefore strictly regulated or banned the use of BPA in food contact products. However, BPA is never used in silicone products of any sort and is therefore not a health hazard, either for people manufacturing silicone products or end-users.
Are release agents required for extracting the product from all silicone molds?
Release agents facilitate the separation between the mold and the object, but they are not always required, depending on the industrial process and materials being used, as well as the level of detail and the final use of the product. For example, in polyaddition silicones, there is generally no need for a release agent. However, in polycondensation silicones, a release agent is recommended, especially if several undercutting areas are present in the master-mold. Release agents facilitate the separation between mold and object by inhibiting adhesion and/or providing the necessary slip effect, enabling low extraction resistance and reducing stress on the molded article. When determining which release agent is best, it is necessary to specify which separation properties are required, a decision that often requires collaboration between manufacturers and silicone suppliers.
How can silicone molds be used for casting concrete objects or parts?
Casting concrete stone materials in silicone molds is a convenient and accurate means to reproduce detailed designs for the creation of stone columns, wall sidings, rendering patterns or other decorative and functional architectural elements. To ensure that your design is reproduced accurately each time, it is important to choose the right material for each type of mold. Silicone provides superior performance features for molding concrete fixtures because it can consistently withstand multiple castings, given that it is durable and inalterable. Also, compared to other commonly used materials, such as latex and polyurethane, silicone features low shrinkage, excellent release properties, dimensional stability, high elongation capacities and shorter curing times. To optimize the rubbery properties of silicone for concrete casting, it is recommended to make molds within a specific thickness range, from 0.6-0.9mm.
What is the purpose of rapid prototyping and how does it work?
Rapid prototyping is an important stage in the design, development and approval process leading up to serial manufacturing. Once new virtual models are produced in CAD, industrial customers often need to rapidly produce physical prototypes before ramping up production. In prototypes, new products come to life and can be tested for true performance.
Silicone has become the preferred material worldwide for fast prototype molding of tooling and parts because it delivers the right features:
- Full transparency to see the object in the mold, ideal for cut molds or two-part silicone tools
- Excellent clarity and easy coloring
- Outstanding mechanical properties, including tear resistance
- More parts reproduced per mold due to high chemical resistance to artificial resins (PU, Epoxy, PES)
- Accurate reproduction of details and easy mold release, including no shrinkage when cured
- Multiple catalyst systems, providing greater flexibility and choice.
What is Pad printing?
In the printing process, the pad is the part that physically transfers the ink from the cliché to the object. This pad is often made with silicone rubber, because it is flexible and can adapt to the different shapes and sizes of the printing surface. The pad is positioned on a wood, aluminum or plastic base and uses fasteners for insertion in different machines.
The silicone pad has valuable features, including:
- Excellent mechanical properties, such as tear resistance and elasticity, ensuring long pad life
- High chemical resistance to corrosive substances in solvents and inks
- Reusability for thousands of print runs of certain parts in many applications
- Adaptability, based on dilution with silicone oils, to any hardness required
All these features mean that silicone pads fully release the ink they contain and are therefore easy to clean, reducing maintenance needs and costs.
What are silicone Reusable Vacuum Bags (RVBs) and what are their main molding applications?
Manufacturers of molded Fiber Reinforced Polymer (FRP) composite parts are increasingly using Reusable Vacuum Bags (RVBs) in their processes. These membranes, made from silicone, increase productivity, reduce costs and improve the quality and consistency of parts, while reducing the use of consumables. FRP composites are used in a wide variety of industries: automotive, renewable energy, aerospace, marine, construction, etc. These materials are composed of various fibers, such as glass, carbon and aramid mixed into resins, including epoxies, unsaturated polyesters, vinyl esters, phenolics, polyurethane and hybrids. Traditionally, FRP composite and hybrid material molding has used disposable plastic bag sheets that are placed and manually assembled by highly-skilled operators, an expensive and time-consuming process that generates a great deal of waste. Silicone RVBs can be used several times and can be easily adapted to different industrial needs, ensuring accurate, consistent, more environmentally friendly and cost-effective FRP molding.