{"id":29115,"date":"2026-05-28T18:50:30","date_gmt":"2026-05-28T18:50:30","guid":{"rendered":"https:\/\/leweiprecision.com\/"},"modified":"2026-05-30T18:58:40","modified_gmt":"2026-05-30T18:58:40","slug":"what-is-vacuum-casting-guide","status":"publish","type":"post","link":"https:\/\/leweiprecision.com\/zh\/what-is-vacuum-casting-guide\/","title":{"rendered":"What Is Vacuum Casting? A Complete Guide for Product Developers"},"content":{"rendered":"

Vacuum casting sits in a manufacturing gap that most product developers do not know exists. It is not as fast as \u4e09\u7ef4\u6253\u5370<\/a>, not as precise as \u6570\u63a7\u52a0\u5de5<\/a>, and not as cost-effective at high volume as injection molding \u2014 but it produces something none of those processes can: injection-molded quality surface finish, in production-equivalent materials, at prototype quantities and lead times.<\/p>\n\n\n\n

For product developers who need functional prototypes, pre-production samples, or low-volume production parts that look and feel like the final injection-molded product, vacuum casting is often the right answer \u2014 and this guide explains exactly what it is, how it works, and when to use it.<\/p>\n\n\n\n

How Vacuum Casting Works \u2014 Step by Step<\/strong><\/strong><\/h2>\n\n\n\n

Vacuum casting (also called polyurethane casting or PU casting) uses a silicone mold to produce parts from two-component polyurethane resins. The process unfolds in these stages:<\/p>\n\n\n\n

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  1. Master pattern creation: A high-quality master \u2014 typically CNC machined or SLA 3D printed \u2014 is produced in the final part geometry. Surface quality on the master transfers directly to the castings, so the master finish is important.<\/li>\n\n\n\n
  2. Silicone mold making: The master is suspended in a frame and liquid silicone is poured around it. The silicone is cured and then cut open to remove the master, leaving a cavity in the exact negative of the master geometry.<\/li>\n\n\n\n
  3. Vacuum casting: Two-component polyurethane resin is mixed and placed in a vacuum chamber. The vacuum removes air bubbles from the resin. The silicone mold is placed in the chamber, the resin is poured or injected under vacuum, and the chamber returns to atmospheric pressure \u2014 pressing the resin into every surface detail of the mold.<\/li>\n\n\n\n
  4. Curing and demolding: The filled mold is cured at 40\u201370\u00b0C for 1\u20134 hours. After curing, the silicone mold is opened and the casting is removed. Secondary operations (painting, primer, hardware insertion) can follow.<\/li>\n\n\n\n
  5. Repetition: One silicone mold typically produces 15 to 25 castings before the mold degrades. Multiple molds can be made from one master to scale output.<\/li>\n<\/ol>\n\n\n\n

    Vacuum Casting vs CNC Machining vs Injection Molding<\/strong><\/strong><\/h2>\n\n\n\n
    FACTOR<\/strong><\/td>VACUUM CASTING<\/strong><\/td><\/tr>
    Tooling cost<\/strong><\/td>Low ($200\u2013$1,500 per mold)<\/td><\/tr>
    Parts per tool<\/strong><\/td>15\u201325 parts per silicone mold<\/td><\/tr>
    Lead time (first part)<\/strong><\/td>3-7 \u5929<\/td><\/tr>
    Achievable tolerance<\/strong><\/td>\u00b10.3\u20130.5mm<\/td><\/tr>
    Surface finish<\/strong><\/td>Excellent \u2014 replicates master surface<\/td><\/tr>
    Material range<\/strong><\/td>Rigid & flexible PU, silicone, ABS-like, PP-like<\/td><\/tr>
    Best volume range<\/strong><\/td>1-100 \u4e2a\u90e8\u4ef6<\/td><\/tr>
    Internal features<\/strong><\/td>Limited \u2014 must extract from mold<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    Vacuum Casting Materials \u2014 What You Can and Cannot Do<\/strong><\/strong><\/h2>\n\n\n\n

    Vacuum casting uses two-component polyurethane systems that are formulated to simulate the properties of thermoplastic materials used in production \u6ce8\u5851<\/a>. Common options include:<\/p>\n\n\n\n