Newer self-adhesive LSR grades are designed to bond directly to selected thermoplastics and metals during injection molding. For suitable material combinations, this can reduce secondary processing, support automated production and improve consistency in high-volume manufacturing.<\/p>\n\n\n\n
<\/p>\n\n\n\n
But self-adhesive does not mean that every LSR will bond to every substrate.<\/p>\n\n\n\n
Successful overmolding still depends on material compatibility, part design, molding temperature, surface condition and process parameters.<\/p>\n\n\n\n Self-adhesive LSR is a two-component liquid silicone rubber formulated to develop adhesion to specific substrate materials during the molding and curing process.<\/p>\n\n\n\n Traditional LSR typically has low surface energy and excellent release characteristics. These properties are useful for molding, but they also make silicone difficult to bond to many other materials.<\/p>\n\n\n\n Conventional silicone overmolding may therefore require:<\/p>\n\n\n\n Substrate cleaning \u2192 Surface treatment \u2192 Primer application \u2192 Drying \u2192 LSR molding \u2192 Post-curing \u2192 Inspection<\/strong><\/p>\n\n\n\n Self-adhesive LSR can potentially simplify the process to:<\/p>\n\n\n\n Substrate preparation \u2192 Insert\/2K molding \u2192 Inspection<\/strong><\/p>\n\n\n\n The actual process depends on the selected LSR and substrate.<\/p>\n\n\n\n Commercial self-adhesive LSR systems are already available for materials such as polycarbonate (PC), polyamide (PA), polybutylene terephthalate (PBT) and selected metals.<\/p>\n\n\n\n For example, current self-adhesive LSR technologies include grades designed to bond to PC without primer and other grades intended for PA and metal substrates.<\/p>\n\n\n\n The biggest advantage is not simply eliminating an adhesive.<\/p>\n\n\n\n The real value comes from reducing the number of manufacturing operations required to produce a finished multi-material component<\/strong>.<\/p>\n\n\n\n Traditional bonding processes may involve several manual or semi-automated steps.<\/p>\n\n\n\n Primer must be applied in the correct amount and location. It may then require drying or activation before molding. Every additional operation introduces labor, handling and process-control requirements.<\/p>\n\n\n\n When a compatible self-bonding LSR system is used, some of these operations may be eliminated.<\/p>\n\n\n\n This can make the manufacturing flow shorter and easier to automate.<\/p>\n\n\n\n Primer application introduces another variable into production.<\/p>\n\n\n\n Potential problems include:<\/p>\n\n\n\n Eliminating primer where technically appropriate removes one potential source of process variation.<\/p>\n\n\n\n Self-adhesive LSR is particularly attractive for high-volume two-component molding and insert molding<\/strong>.<\/p>\n\n\n\n A rigid thermoplastic component can be molded first and then transferred automatically into an LSR mold. The silicone is injected around the required sealing or functional areas and cured inside the mold.<\/p>\n\n\n\n With suitable equipment, this process can be integrated into an automated manufacturing cell.<\/p>\n\n\n\n Current self-adhesive LSR systems are specifically promoted for automated two-component injection molding applications.<\/p>\n\n\n\n Every secondary operation means parts must normally be transferred, stored or queued between manufacturing stages.<\/p>\n\n\n\n Reducing these operations can decrease:<\/p>\n\n\n\n For large production volumes, these savings can become more important than the raw-material price difference between conventional and self-adhesive LSR.<\/p>\n\n\n\n This is one of the most important questions during product development.<\/p>\n\n\n\n There is no universal self-adhesive LSR that should automatically be assumed to bond to every plastic or metal<\/strong>.<\/p>\n\n\n\n Typical substrate candidates include:<\/p>\n\n\n\n Actual adhesion must always be tested with the specific resin grade<\/strong>, not just the generic polymer family.<\/p>\n\n\n\n For example, two PA66 materials can behave differently because of glass-fiber reinforcement, flame retardants, lubricants, release agents or other additives.<\/p>\n\n\n\n This is why material compatibility testing should be performed before tooling is finalized.<\/p>\n\n\n\n The two approaches should not be viewed as simply \u201cnew technology versus old technology.\u201d<\/p>\n\n\n\n Each has suitable applications.<\/p>\n\n\n\n This approach can still be useful when:<\/p>\n\n\n\n This approach becomes particularly attractive when:<\/p>\n\n\n\n Therefore, material selection should consider the entire manufacturing process rather than only the silicone price per kilogram.<\/p>\n\n\n\n Electronics increasingly require integrated waterproof structures.<\/p>\n\n\n\n Instead of assembling a separate silicone gasket into a plastic housing, silicone can potentially be molded directly onto the housing.<\/p>\n\n\n\n Applications include:<\/p>\n\n\n\n Integrated sealing structures can also reduce the risk of gasket displacement during final assembly.<\/p>\n\n\n\n Automotive components frequently combine rigid engineering plastics, metal terminals and flexible sealing elements.<\/p>\n\n\n\n LSR overmolding can be used for:<\/p>\n\n\n\n Self-adhesive LSR can be especially useful where production volume and automation requirements are high.<\/p>\n\n\n\n LSR is widely used for medical and healthcare products because suitable grades can provide flexibility, temperature resistance and biocompatibility.<\/p>\n\n\n\n Potential multi-material applications include:<\/p>\n\n\n\n However, medical applications require additional consideration of material certification, sterilization compatibility, extractables and regulatory requirements.<\/p>\n\n\n\n Some self-adhesive LSR grades are available for applications requiring food-contact compliance.<\/p>\n\n\n\n Typical applications can include:<\/p>\n\n\n\n The exact regulatory requirements should always be confirmed for the target market and final application.<\/p>\n\n\n\n Changing from conventional LSR to self-adhesive LSR does not eliminate the need for good mechanical design.<\/p>\n\n\n\n Several factors should be evaluated during DFM.<\/p>\n\n\n\n Increasing the effective bonding area can improve the robustness of a silicone-to-substrate interface.<\/p>\n\n\n\n Very narrow bonding surfaces may produce less reliable results, particularly when the component experiences peeling forces.<\/p>\n\n\n\n Even when chemical adhesion is available, mechanical interlocking features can provide additional security.<\/p>\n\n\n\n Possible structures include:<\/p>\n\n\n\n For safety-critical components, combining chemical adhesion with mechanical retention may provide a more robust design.<\/p>\n\n\n\n Bonded interfaces generally perform better under shear or compression than under continuous peeling.<\/p>\n\n\n\n Product geometry should therefore minimize forces that repeatedly peel the silicone away from the rigid substrate.<\/p>\n\n\n\n LSR has very low viscosity before curing and can enter extremely small gaps.<\/p>\n\n\n\n Parting lines, shut-off surfaces and insert tolerances must therefore be carefully designed.<\/p>\n\n\n\n This is particularly important around electrical contacts, sealing surfaces and cosmetic areas.<\/p>\n\n\n\n Adhesion development can depend strongly on molding temperature and the temperature of the inserted substrate.<\/p>\n\n\n\n A process that works during laboratory testing may behave differently when inserts enter the mold at different temperatures during mass production.<\/p>\n\n\n\n Process validation should therefore include realistic production conditions.<\/p>\n\n\n\n No.<\/p>\n\n\n\n This depends on the specific LSR formulation and the application.<\/p>\n\n\n\n Some commercial self-adhesive LSR grades are specifically formulated so that post-curing is not required under their recommended processing conditions. Other formulations may benefit from additional heat treatment to improve bonding or achieve application-specific properties.<\/p>\n\n\n\n For example, some self-bonding systems can develop stronger adhesion after subsequent heat treatment or storage.<\/p>\n\n\n\n Therefore, manufacturers should not assume that \u201cself-adhesive LSR\u201d automatically means \u201czero post-cure.\u201d<\/p>\n\n\n\n The correct process should be established from the material supplier’s technical data and actual validation testing.<\/p>\n\n\n\n Before building production tooling, we recommend evaluating at least the following information:<\/p>\n\n\n\n 1. Substrate material<\/strong><\/p>\n\n\n\n Provide the exact plastic or metal specification whenever possible.<\/p>\n\n\n\n For plastics, the exact resin grade is preferable to simply specifying \u201cPC,\u201d \u201cPBT\u201d or \u201cNylon.\u201d<\/p>\n\n\n\n 2. LSR requirements<\/strong><\/p>\n\n\n\n Define:<\/p>\n\n\n\n 3. Bonding requirement<\/strong><\/p>\n\n\n\n Determine whether the interface needs to withstand:<\/p>\n\n\n\n 4. Operating environment<\/strong><\/p>\n\n\n\n A bond that performs well at room temperature may behave differently after repeated exposure to heat, humidity or chemicals.<\/p>\n\n\n\n Environmental testing should reflect the actual application.<\/p>\n\n\n\n 5. Production volume<\/strong><\/p>\n\n\n\n Annual volume strongly influences whether manual insert molding, automated insert molding or full two-component molding is economically appropriate.<\/p>\n\n\n\n For a new silicone overmolding project, adhesion should be verified experimentally.<\/p>\n\n\n\n Typical evaluation can include:<\/p>\n\n\n\n The exact test method depends on the final application.<\/p>\n\n\n\n One useful failure-analysis question is:<\/p>\n\n\n\n Where does the failure occur?<\/strong><\/p>\n\n\n\n If the silicone cleanly separates from the substrate, the interface may be the weak point.<\/p>\n\n\n\n If the silicone tears while material remains bonded to the substrate, the interface may be stronger than the silicone itself.<\/p>\n\n\n\n This type of observation can provide valuable information during material and process optimization.<\/p>\n\n\n\n The material itself may cost more than a conventional general-purpose LSR.<\/p>\n\n\n\n But raw-material cost alone does not determine the final component cost.<\/p>\n\n\n\n A better calculation is:<\/p>\n\n\n\n Total Part Cost = Material + Molding + Surface Treatment + Primer + Labor + Secondary Processing + Inspection + Scrap + Logistics<\/strong><\/p>\n\n\n\n If self-adhesive LSR removes two or three downstream operations, the total manufacturing cost may decrease even when the LSR itself is more expensive.<\/p>\n\n\n\n The economic advantage generally becomes more significant as production volume increases.<\/p>\n\n\n\n One of the important developments in silicone manufacturing is the move from producing isolated rubber components toward producing integrated multi-material assemblies<\/strong>.<\/p>\n\n\n\n Instead of manufacturing:<\/p>\n\n\n\n Plastic housing + separate silicone gasket + manual assembly<\/strong><\/p>\n\n\n\n manufacturers increasingly evaluate:<\/p>\n\n\n\n Plastic housing + directly overmolded silicone sealing structure<\/strong><\/p>\n\n\n\n This approach can reduce part count, simplify assembly and support automated manufacturing.<\/p>\n\n\n\n Advances in self-adhesive LSR make this approach practical for a growing range of engineering plastics and metals.<\/p>\n\n\n\n However, the best results come from considering the silicone material, rigid substrate, mold structure and final product requirements together at the beginning of the project.<\/p>\n\n\n\n If you are developing a component that combines LSR with plastic or metal<\/strong>, material compatibility should ideally be evaluated before production tooling is finalized.<\/p>\n\n\n\n MadeForSilicone supports custom LSR injection molding, insert molding and silicone overmolding projects for electronic, automotive, medical, industrial and consumer applications.<\/p>\n\n\n\n Send us your:<\/p>\n\n\n\n Our team can evaluate the part structure, material combination, tooling concept and manufacturing process to help determine whether self-adhesive LSR, conventional LSR with surface treatment, or another overmolding solution<\/strong> is more appropriate for your project.<\/p>\n\n\n\n What is self-adhesive LSR?<\/strong><\/p>\n\n\n\n Self-adhesive LSR is a liquid silicone rubber formulated to develop adhesion to selected plastics or metals during molding. Depending on the material combination, it can reduce or eliminate the need for separate primer or adhesive application.<\/p>\n\n\n\n Can self-adhesive LSR bond directly to plastic?<\/strong><\/p>\n\n\n\n Yes, selected grades can bond to engineering plastics such as PC, PA and PBT. However, adhesion depends on the exact resin grade, additives, surface condition and molding parameters, so testing is recommended.<\/p>\n\n\n\n Can LSR be overmolded onto metal?<\/strong><\/p>\n\n\n\n Yes. Certain self-adhesive LSR grades are designed for metal bonding. The metal type, coating, surface cleanliness and process conditions must be evaluated before mass production.<\/p>\n\n\n\n Does self-adhesive LSR require primer?<\/strong><\/p>\n\n\n\n Compatible self-adhesive grades can eliminate primer for specified substrates. This should not be assumed for every LSR\/substrate combination.<\/p>\n\n\n\n Is post-curing required for self-adhesive LSR?<\/strong><\/p>\n\n\n\n Not always. Some commercial grades are designed for no post-cure processing, while other materials or applications may require or benefit from additional heat treatment. Follow the selected material’s technical requirements.<\/p>\n\n\n\n What information is needed for an LSR overmolding quotation?<\/strong><\/p>\n\n\n\n A 2D\/3D drawing, substrate material, silicone hardness, expected quantity, application, operating temperature and bonding\/sealing requirements are normally the most useful starting information.<\/p>","protected":false},"excerpt":{"rendered":" Liquid silicone rubber (LSR) overmolding is widely used to combine the flexibility, sealing performance and temperature resistance of silicone with the structural strength of engineering plastics or metals. […]<\/p>\n","protected":false},"author":1,"featured_media":2596,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[2834,2846,2839,2833,2840,2838,2841,2842,2837,2843,2845,2836,2835,2844],"class_list":["post-2595","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-2k-molding","tag-custom-lsr-molding","tag-custom-silicone-parts","tag-liquid-silicone-rubber","tag-lsr-insert-molding","tag-lsr-overmolding","tag-self-adhesive-lsr","tag-self-bonding-lsr","tag-silicone-injection-molding","tag-silicone-overmolding","tag-silicone-seals","tag-silicone-to-metal-bonding","tag-silicone-to-plastic-bonding","tag-two-component-molding"],"_links":{"self":[{"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/posts\/2595","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/comments?post=2595"}],"version-history":[{"count":1,"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/posts\/2595\/revisions"}],"predecessor-version":[{"id":2597,"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/posts\/2595\/revisions\/2597"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/media\/2596"}],"wp:attachment":[{"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/media?parent=2595"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/categories?post=2595"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madeforsilicone.com\/fr\/wp-json\/wp\/v2\/tags?post=2595"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/www.madeforsilicone.com\/wp-content\/uploads\/2026\/09\/01_self_adhesive_lsr_overmolding.png\")
<\/figure>\n\n\n\nWhat Is Self-Adhesive LSR?<\/h2>\n\n\n\n
Why Is Self-Adhesive LSR Important for Overmolding?<\/h2>\n\n\n\n
1. Fewer Secondary Operations<\/h3>\n\n\n\n
2. Lower Risk of Primer-Related Variation<\/h3>\n\n\n\n
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3. Better Potential for Automated Production<\/h3>\n\n\n\n
4. Reduced Work-in-Process<\/h3>\n\n\n\n
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Which Materials Can Self-Adhesive LSR Bond To?<\/h2>\n\n\n\n
Substrate<\/th> Potential for Self-Adhesive LSR Overmolding<\/th> Applications typiques<\/th><\/tr> PC<\/td> Good with compatible grades<\/td> Transparent housings, electronics, medical components<\/td><\/tr> PA \/ Nylon<\/td> Available with selected grades<\/td> Automotive connectors, structural components<\/td><\/tr> PBT<\/td> Common engineering substrate<\/td> Electrical connectors, sensor housings<\/td><\/tr> Metal<\/td> Grade-dependent<\/td> Inserts, frames, electrical components<\/td><\/tr> PPS<\/td> Requires validation<\/td> High-temperature electrical parts<\/td><\/tr> ABS<\/td> Grade\/process dependent<\/td> Consumer products and housings<\/td><\/tr> PP<\/td> More challenging<\/td> Consumer and fluid-handling components<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Self-Adhesive LSR vs Traditional LSR Overmolding<\/h2>\n\n\n\n
Traditional LSR + Primer<\/h3>\n\n\n\n
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Self-Adhesive LSR<\/h3>\n\n\n\n
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Common Applications for Self-Adhesive LSR<\/h2>\n\n\n\n
Electronic Waterproof Seals<\/h3>\n\n\n\n
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Automotive Connectors and Sensors<\/h3>\n\n\n\n
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Medical and Healthcare Components<\/h3>\n\n\n\n
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Food and Household Products<\/h3>\n\n\n\n
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Design Considerations for Self-Adhesive LSR Overmolding<\/h2>\n\n\n\n
Bonding Area<\/h3>\n\n\n\n
Mechanical Interlocks<\/h3>\n\n\n\n
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Avoid Peel Loading<\/h3>\n\n\n\n
Control Flash Areas<\/h3>\n\n\n\n
Consider Substrate Temperature<\/h3>\n\n\n\n
Does Self-Adhesive LSR Always Eliminate Post-Curing?<\/h2>\n\n\n\n
How to Evaluate a Self-Adhesive LSR Project<\/h2>\n\n\n\n
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Prototype Testing Before Mass Production<\/h2>\n\n\n\n
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Is Self-Adhesive LSR More Expensive?<\/h2>\n\n\n\n
The 2026 Direction: From Silicone Parts to Integrated Components<\/h2>\n\n\n\n
Need Help Evaluating an LSR Overmolding Project?<\/h2>\n\n\n\n
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FAQ<\/h3>\n\n\n\n