Green Sand vs Resin Sand vs Lost-foam
湿砂型 vs 树脂砂 vs 消失模
标签：选型, 湿砂, 树脂砂, 消失模, 对比
湿砂型用膨润土+水粘结，最便宜、可手工捣实，适合小批量与教学，但强度低、易塌箱。树脂砂（呋喃/酚醛冷固）强度高、尺寸好，适合复杂件与量产，但有气味与固化时间窗。消失模用 EPS 泡沫做"永久模"，埋砂后浇入金属使泡沫气化，无需起模，适合一体成型的大件；缺点是发气量大、易皱皮。选型：教学/小件→湿砂；精尺寸→树脂砂；一体大件→消失模。
Green sand (bentonite+water) is cheapest and hand-rammable, good for small batches and teaching, but weak and prone to collapse. Resin sand (furan/phenolic cold-set) is strong and dimensionally stable, ideal for complex/production parts, but has odor and a cure window. Lost-foam uses an EPS foam "permanent" pattern buried in sand; metal vaporizes the foam, so no draw is needed — great for one-piece large parts, but high gas generation risks folds. Pick: teaching/small → green; precise → resin; one-piece large → lost-foam. ---