液状シリコーンゴム (LSR) 射出成形, 液体射出成形とも呼ばれます (リム), is a thermoset method for producing flexible silicone components. Two compounds are combined, heated within the mold, and a platinum catalyst is used to speed up the curing process.
What is liquid silicone rubber?
液状シリコーンゴム (LSR) is a thick liquid polymer that is produced using a clean liquid injection molding technique to create components.
LSR mouldings are dependable and excellent for difficult applications because of their low compression set and resistance to severe temperatures. LSR elastomer provides great optical clarity, 靭性, and design flexibility while maintaining good mechanical qualities across a wide range of temperatures (-50oC to 250oC).
The most stable LSRs are two-part, platinum-cured polymers used in liquid injection molding. LSR that has been platinum-cured is received in drums A and B. The vulcanization or curing process starts when the A and B material components are pumped into the injection barrel of the molding machine. A third liquid containing the color pigment is also pumped into the barrel if colored parts are desired. When it is injected into the heated mold cavities, where it hardens and becomes the precise shape of the item, the curing process is hastened even further.
Benefits of LSR Injection Molding
The advantages of injection molding include:
- High-volume manufacturing
Complex liquid silicone injection molding parts may now be produced in great volumes and at a low cost thanks to advanced LSR materials.
- Low potential for contamination
In contrast to the labor-intensive compression molding of silicone rubber gum, the liquid injection molding technique uses automated molding equipment that minimize human contact with the material. With liquid injection molders that feature completely automated, hands-free manufacturing processes, the possibility of component contamination in LIM is significantly diminished. ISO-certified clean rooms offer an environmentally controlled manufacturing environment with stringent sanitary guidelines for goods with hygienic production needs.
- a short cycle time
The geometry of the component, the general vulcanization properties, the temperature of the mold, the material when it reaches the mold, and the chemistry of the curing substance all affect the cycle time for LSR components. Faster curing is possible with two-part, platinum-cured LSRs by preheating the injection barrel and cold runner to 40–80 degrees Celsius.
- reduces waste and flash
Material scrap is nearly eliminated since the molds work flashlessly and have few material runners.
- Enhanced safety
Operator entry into the molding area is not essential thanks to the automation possibilities. Robots, chutes, or conveyor belts are used to extract and transfer parts from the injection molding process, eliminating handling and the possibility of burns or other safety issues.
Disadvantages of Liquid silicone rubber
- LSR cannot be recycled since once it cures, it cannot be moulded again. LSR
- Long and expensive production times
- If left untreated, their sticky texture will cause them to gather dust and other debris.
- When exposed to certain substances like sulfur and latex, LSR will prevent their ability to cure, hence they are not suited for submerged applications in alcohol or gasoline.
- Limited options for materials used in the LIM process Silicone comes only a small range of grades.
LSR射出成形の種類
LSRの素材にはたくさんの種類があります. いくつか含まれています:
- 医療レベル
医療用途に抽出できる能力, 組織への干渉を防ぐための非常に繊細な基準があります, 後続のフェーズで LSR から削除されます. 抽出物を除去することで材料の強度も向上します。. 制限的な (インプラントの費用は以下のとおりです 30 日) これらのグレードの通常の分類は無制限です。 (以上のインプラント 30 日).
- 自己潤滑性:
互換性のない流体を部品と組み合わせることが可能. シリコーンが乾燥して硬化すると、この物質が表面にブルームして滑らかな表面を提供します。. それから, 消費者がフルードの開花を望むペースに応じて, 1.5 に 3 パーセントのフェニル流体がシリコーンに添加されます.
- 導電性:
LSRコンポーネントには導電性グレードのカーボンブラックを塗布. 金属粒子が詰まったシリコーンと比較して, これらのグレードは非常に高い機械的品質を備えており、体積抵抗率が 9 オーム-センチメートル.
- 自己融着:
接着促進剤の添加. プライマーなしでさまざまな表面に接着します。. この物質はポリスルホンによく接着します, ステンレス鋼, アルミニウム, ガラスフィラー入りナイロン. 複合シール用, 組み立て部品を削減したり、2 つの嵌合部品間のシールをさらに強化したりする理想的な手段を提供します。.
- ラジオ・オブスキュア
シリコーン成分をX線で確認できるようにするため, 硫酸バリウムが塗布されています. これは、カテーテルや創傷ドレーンなどの医療用途にうまく機能します。.
- 難燃性
何も追加せずに, LSR ゴムの大部分は UL を満たします。 94 HBグレード. 高学年, V1 や VO など, 水を分解して放出する化学薬品の必要性.
- クイックキュア:
LSR のメーカーは、材料内の硬化部位として追加される官能基の量を制御できます。, エチレンプロピレンと同じように, 二重結合を持つターポリマーが追加される場合, エラストマーの架橋度を調整するため. より高い反応性が得られます, これにより、シリコーン部品の大量生産のサイクル時間が非常に短くなります。.
The LSR manufacturing process
Some materials require an additional step of adding cures (which were left out to increase the shelf stability of the material). All those steps are eliminated by an LSR. Here is an overview of the LSR production process:
1. A 55-gallon drum or a 5-gallon pail are the typical containers for LSR A + B components. The buckets are compressed by a process-controlled pumping kit, which feeds the material into the static mixer and injection unit.
2. After that, pigment streams can be added and manipulated. Press material will be combined with a screw and pushed forward during the injection process to create a "shot" of material, or the quantity required to fill the mold.
3. The material will remain clamped together after being injected into the mold to cure the LSR. The cured product is then removed from the mold by a human or a machine, and the cycle is then repeated. It is a very quick and effective process that usually takes 30 seconds or less.
4. In contrast, making a part typically takes six minutes or longer when using organic materials or high consistency silicone. Even more time is required to cure materials using peroxide, typically nine minutes. Compared to a silicone material with a high consistency, LSR can result in significant labor cost savings.
5. Add-on procedures like post bake can help improve compression set and lower volatilities. Deflashing also eliminates unnecessary flashing. After being thoroughly cleaned of any foreign matter, it is then packaged for shipping.
Why Is Liquid Silicone Rubber Ideal For Injection Molding Applications?
Easy-to-mold (and demold) low or high viscosity rubber silicones are needed by manufacturers in a variety of industries, 自動車を含む, healthcare, general industry, infant care, consumer products, and electronics, to make components quickly and affordably.
The material of choice for injection molding applications is liquid silicone rubber (LSR). The repeating Si-O chains that make up the silicone backbone are very flexible and provide this chemical structure special qualities such a wide working temperature range, weatherability, hydrophobicity, bio-inertness, electrical insulation, and a long lifespan.