Stockwell Elastomerics is a number one manufacturer of liquid silicone rubber (LSR) based merchandise utilizing its extensive in-home silicone rubber molding operations. LSR is a versatile elastomer that can be molded into sheets and cast into continuous rolls for die cutting or waterjet slicing.
Stockwell Elastomerics applies acrylic pressure sensitive adhesives onto LSR sheets and rolls for adhesive backed gaskets. One in every of Stockwell Elastomerics’ specialties is applying film supported acrylic adhesives, such as 3M 9415 or Adchem 256M and 3M 467 transfer movie adhesive onto .010″ and .020″ thick cast liquid silicone rubber for display gaskets and similar functions requiring a very skinny gasket.
Stockwell Elastomerics also injection molds custom 3D components per customer specifications. LSRs have a large temperature range (-58°F to 392°F) and can be made in extensive durometer range (10 – 80 Shore A) with out plasticizers. Silicone’s wonderful rebound, UV and ozone resistance makes it superb for outdoor sealing and might be use for submerged gaskets (IP67 and NEMA 6). Stockwell Elastomerics maintains in-home inventory of silicone sheet, silicone rolls and molding compounds to be injection molded for fast response occasions.
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Rubber Contact Brochure
Contains small samples of cured LSR supplies to touch and feel.
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What is Liquid Silicone Rubber?
Liquid silicone rubber (LSR) is very low viscosity silicone products that may be injection molded or cast into silicone rubber sheets. “Liquid” is specific in the identify to differentiate LSRs from excessive consistency gum based mostly silicone products. LSRs are addition cure / platinum cure programs in distinction with most gum based silicones which can be peroxide cured. In its uncooked uncured form, LSR is 2 elements liquid which might be blended together (mixing of Half A and Half B starts the curing) and heated to accelerate the curing course of. Raw gum primarily based silicones feel and appear much like clay. LSRs are typically injection molded or cast while gum primarily based silicones are usually 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 sizzling liquid and compelled into a cooled mold.
Silicone Materials Selection Information
Why Specify Liquid Silicone Rubber?
Efficiency properties and quick cure cycles make liquid silicone rubber a very good choice for small molded elements. Not like most thermoplastic elastomers (TPRs and TPEs), LSR stays versatile and elastic right 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, information acquisition devices and ruggedized digital gadgets the place outside situations are demanding. The cure cycles in liquid injection molding enable for a 1 or 2 cavity mold to out-produce a compression mold with a higher cavity depend.
Beyond the mechanical, chemical, and thermal properties of LSR, there are numerous other reasons to specify this type of fabric. From a manufacturability standpoint, a couple of key factors stand out. One in every of the most important reasons that clients might end up going with LSR materials is geometry. Any sort of 3D shape that cannot be fabricated in a flat configuration would require a molding process – usually with elements like this, a excessive production amount stage justifies the added value of tooling that’s related to LSR molding.
Moreover, some prospects might have flat gaskets, however with very tight thickness tolerance needs. In these cases, Stockwell Elastomerics can leverage its sheet molding capabilities to hold tighter tolerances in small sheets, which might then be used to die-lower or waterjet reduce flat gaskets and pads.
Transitioning from Flat Prototypes to Molded Production Components
On occasion, customers wish to transition from flat reduce components to molded elements. As clients work through small prototype runs of initial designs, Stockwell Elastomerics helps this change with fast flip waterjet minimize gaskets utilizing molded LSR sheets. As designs develop and molding is required, the identical material will be utilized. This eliminates re-testing and re-validation, since the fabric is the very same for the prototypes and production components.
For parts with none sort of 3D geometry, molding will be a very cost efficient solution at excessive amount manufacturing, as conventional die-reducing and waterjet cutting have wasted material cost. For example, a small window gasket may be quite value efficient to offer in small portions as a waterjet cut part, however as production portions improve, the mixed cost of the wasted window cutout can add up. In circumstances like this, paying to device-up a production LSR mold creates a way more cost-efficient resolution trimmed piece price down the road.
Cure Catalysts – Tin vs. Platinum
In LSR materials, a catalyst is required as a part of the curing course of. Frequent cure catalysts are tin (also called condensation cure) and platinum (also called addition cure). All of Stockwell Elastomerics’ LSR merchandise are platinum-cured.
Platinum-cured LSR is usually “cleaner” than tin-cured LSR – for silicone rubber this reason a lot of Stockwell Elastomerics’ LSR merchandise are suitable to be used in the medical machine industry. Platinum-cured LSR is commonly capable of assembly FDA and USP Class VI certifications. Platinum-cured LSR can also survive greater temperatures when compared to tin-cured options.
Tin-cured LSR is often found in consumer and inventor-grade material. This material can cure using condensation from the air and does not require heat. Tin-cured LSR is typically not FDA grade and isn’t used in additional demanding applications.
While tin-cured LSR is extra accessible for passion-grade and numerous client functions, it does not provide some of the distinct benefits and high-performance characteristics of platinum-cured LSR. This is the reason platinum-cured LSRs used exclusively – these supplies finest serve customers in core industries served by Stockwell Elastomerics.
Liquid Silicone Durometer Range
LSR is obtainable in a hardness vary of 10 to 80 durometer Shore A. 10 durometer LSR could be very soft like chewing gum and might feel softer than some additional agency silicone foam and silicone sponge merchandise. Eighty durometer LSR is more durable than a heel of a shoe and is as firm as many thermoplastic elastomer merchandise. Most functions for LSR are specified in the 20 to 60 durometer Shore A range.
Stockwell Elastomerics’ Liquid Silicone Rubber Contact Brochure can help with choice of material hardness for specific 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 continuous solid rolls with or without movie supported acrylic or acrylic transfer film adhesive choices. The 12″ x 12″ molded sheets are available from .032″ to .125″ thick. Stockwell Elastomerics’ on-site molding facility provides molded and cryogenically deflashed, customized liquid silicone gaskets and a wide range of custom components.
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