Liquid Silicone Rubber Materials, LSR For Molding
Stockwell Elastomerics is a leading producer of liquid silicone rubber (LSR) based merchandise using its extensive in-home silicone rubber molding operations. LSR is a versatile elastomer that can be molded into sheets and forged into steady rolls for die reducing or waterjet cutting.
Stockwell Elastomerics applies acrylic stress sensitive adhesives onto LSR sheets and rolls for adhesive backed gaskets. One in every of Stockwell Elastomerics’ specialties is making use of film supported acrylic adhesives, corresponding to 3M 9415 or Adchem 256M and 3M 467 switch movie adhesive onto .010″ and .020″ thick cast liquid silicone rubber for display gaskets and similar functions requiring a very thin gasket.
Stockwell Elastomerics also injection molds custom 3D elements per customer specifications. LSRs have a wide temperature vary (-58°F to 392°F) and can be made in vast durometer vary (10 – eighty Shore A) without plasticizers. Silicone’s excellent rebound, UV and ozone resistance makes it supreme for out of doors sealing and may be use for submerged gaskets (IP67 and NEMA 6). Stockwell Elastomerics maintains in-home stock of silicone sheet, silicone rolls and molding compounds to be injection molded for quick response occasions.
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Rubber Touch Brochure
Includes small samples of cured LSR supplies to contact and really feel.
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What’s Liquid Silicone Rubber?
Liquid silicone rubber (LSR) may be very low viscosity silicone that can be injection molded or forged into silicone rubber sheets. “Liquid” is express in the title to differentiate LSRs from high consistency gum based mostly silicone merchandise. LSRs are addition cure / platinum cure systems in distinction with most gum based mostly silicones which are peroxide cured. In its uncooked uncured kind, LSR is 2 components liquid which might be mixed together (mixing of Half A and Half B begins the curing) and heated to accelerate the curing process. Raw gum primarily based silicones appear and feel just like clay. LSRs are typically injection molded or cast while gum based mostly silicones are sometimes compression molded. Note that injection molding of liquid silicone rubber is the inverse of molding thermoplastics; room temperature liquid silicone compound is injected into and cured in a scorching mold vs. plastic pellets melted into scorching liquid and forced into a cooled mold.
Silicone Supplies Choice Information
Why Specify Liquid Silicone Rubber?
Efficiency properties and fast cure cycles make liquid silicone rubber – Resource, a great selection for small molded elements. Not like most thermoplastic elastomers (TPRs and TPEs), LSR stays flexible and elastic down to -58°F and retains its properties as much as 392°F. Liquid silicone rubber is an effective candidate for gaskets, seals and cushioning pads in portable communications, knowledge acquisition devices and ruggedized electronic devices the place outside situations are demanding. The cure cycles in liquid injection molding allow for a 1 or 2 cavity mold to out-produce a compression mold with the next cavity count.
Past the mechanical, chemical, and thermal properties of LSR, there are quite a few other reasons to specify this type of fabric. From a manufacturability standpoint, a couple of key factors stand out. One among the largest causes that clients may find yourself going with LSR material is geometry. Any form of 3D shape that cannot be fabricated in a flat configuration would require a molding process – usually with parts like this, a excessive manufacturing quantity level justifies the added price of tooling that’s related to LSR molding.
Additionally, some prospects may have flat gaskets, but with very tight thickness tolerance needs. In these circumstances, Stockwell Elastomerics can leverage its sheet molding capabilities to hold tighter tolerances in small sheets, which might then be used to die-cut or waterjet minimize flat gaskets and pads.
Transitioning from Flat Prototypes to Molded Manufacturing Elements
Now and silicone products again, customers want to transition from flat cut elements to molded elements. As prospects work via small prototype runs of initial designs, Stockwell Elastomerics helps this alteration with quick flip waterjet cut gaskets using molded LSR sheets. As designs develop and molding is required, the same materials could be utilized. This eliminates re-testing and re-validation, since the fabric is the very same for the prototypes and manufacturing parts.
For parts with none form of 3D geometry, molding can be a really cost effective solution at high amount production, as traditional die-reducing and waterjet cutting have wasted materials cost. For example, a small window gasket may be fairly price effective to offer in small quantities as a waterjet reduce part, but as production quantities enhance, the mixed value of the wasted window cutout can add up. In cases like this, paying to instrument-up a production LSR mold creates a way more cost-efficient resolution trimmed piece value down the line.
Cure Catalysts – Tin vs. Platinum
In LSR supplies, a catalyst is required as a part of the curing course of. Frequent cure catalysts are tin (also called condensation cure) and platinum (often known as addition cure). All of Stockwell Elastomerics’ LSR merchandise are platinum-cured.
Platinum-cured LSR is typically “cleaner” than tin-cured LSR – this is why many of Stockwell Elastomerics’ LSR merchandise are appropriate to be used within the medical system business. Platinum-cured LSR is commonly capable of assembly FDA and USP Class VI certifications. Platinum-cured LSR can even survive higher temperatures when compared to tin-cured options.
Tin-cured LSR is usually present in consumer and inventor-grade material. This materials can cure utilizing condensation from the air and does not require heat. Tin-cured LSR is often not FDA grade and isn’t used in additional demanding applications.
While tin-cured LSR is extra accessible for hobby-grade and varied consumer purposes, it doesn’t supply some of the distinct advantages and high-performance traits of platinum-cured LSR. For this reason platinum-cured LSRs used exclusively – these materials finest serve customers in core industries served by Stockwell Elastomerics.
Liquid Silicone Durometer Range
LSR is available in a hardness vary of 10 to 80 durometer Shore A. 10 durometer LSR may be very tender like chewing gum and might feel softer than some additional firm silicone foam and silicone sponge merchandise. 80 durometer LSR is more durable than a heel of a shoe and is as firm as many thermoplastic elastomer products. Most functions for LSR are specified in the 20 to 60 durometer Shore A range.
Stockwell Elastomerics’ Liquid Silicone Rubber Touch Brochure can assist with choice of material hardness for particular purposes. The tensile, elongation and tear resistance properties of liquid silicones have improved since the preliminary commercialization of LSR.
Liquid Silicone Rubber Availability
Stockwell Elastomerics presents off-the-shelf LSR sheets (12″ x 12″) and steady solid rolls with or with out movie supported acrylic or acrylic switch movie adhesive options. The 12″ x 12″ molded sheets can be found from .032″ to .125″ thick. Stockwell Elastomerics’ on-site molding facility provides molded and cryogenically deflashed, custom liquid silicone gaskets and quite a lot of custom elements.
