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Slovenian Custom Liquid Silicone Molding: How We Turn Complex Designs Into Production-Ready Parts
Table des matières
When a “Simple” Silicone Seal Will Not Mold Cleanly
A common project begins with a small silicone seal that looks straightforward in CAD: thin walls, several sealing ribs, a narrow assembly groove, and no allowance for flash. The customer may need it for a medical device, fluid-control assembly, or consumer product that must be assembled without hand trimming. That is where custom liquid silicone molding becomes more than selecting an LSR grade and cutting a cavity. LSR flows easily into thin sections, but it also finds small gaps at the parting line. If air cannot leave the cavity at the right time, the last area to fill may trap gas, produce short shots, or create weak edges. Low-viscosity LSR makes venting and tool fit especially important because the same opening that releases air can also become a flash path.
The First Check Is Usually Not Material Selection
When a part flashes or fills unevenly, changing the silicone compound is often the wrong first move. The first question should be: where does the material enter, and where does the air go? In one recurring project pattern, a thin sealing rib filled inconsistently across a multi-cavity tool. Instead of raising injection pressure, the engineering review focused on gate position, flow length, cavity balance, and vent locations near the final fill areas. The tool also needed to account for post-molding shrinkage, which does not behave like a single fixed number. LSR shrinkage varies with material grade, wall thickness, mold temperature, cavity pressure, flow direction, and any post-cure process. A part can look acceptable immediately after molding but miss an assembly tolerance after it cools or goes through post-cure.
Why Tooling Details Decide Flash and Repeatability
Most flash problems start much earlier than people think. They begin with the parting line, insert interfaces, ejector-pin clearance, and the way the cavity vents. Increasing clamp force may reduce a symptom, but it does not correct a parting surface that does not seal consistently. For flash-free molding, the tool must let air escape without allowing silicone to pass into the vent. Some complex cavities also benefit from vacuum-assisted molding, which removes air before injection rather than forcing the material to compress it during filling. This approach is particularly useful for precision silicone parts with thin sections, deep ribs, or narrow sealing features. The production value is practical: less flash means less manual trimming, fewer handling steps, and a more repeatable part edge from cavity to cavity.
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When a Cold Runner Changes the Production Plan
For high-volume custom liquid silicone molding, runner waste can become a manufacturing problem of its own. A cold runner keeps the mixed LSR cool until it reaches the heated cavity, helping prevent premature curing in the feed system while reducing runner scrap. That sounds simple, but the tool must maintain a clear temperature separation between the cold runner and the hot curing zone. If heat moves into the runner, material can begin curing before it enters the cavity. The result may be restricted flow, unstable shot size, downtime, and a tool that must be cleaned before production can resume. At xflsrmolding, the decision to use a cold runner is normally tied to the part geometry, cavity count, expected production volume, and tolerance requirements—not treated as a standard feature for every silicone injection molding project.
FAQ: Questions Buyers Ask Before Tool Release
A production-ready silicone part is rarely created by changing one machine setting after another. It comes from checking material flow, temperature, venting, shrinkage, and demolding before those issues become expensive tool revisions.
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