{"id":7849,"date":"2026-10-03T13:50:59","date_gmt":"2026-10-03T13:50:59","guid":{"rendered":"https:\/\/chinametalfoundry.com\/?p=7849"},"modified":"2026-10-08T03:15:10","modified_gmt":"2026-10-08T03:15:10","slug":"centrifugal-casting","status":"publish","type":"post","link":"https:\/\/chinametalfoundry.com\/pt\/blog\/centrifugal-casting\/","title":{"rendered":"Fundi\u00e7\u00e3o centr\u00edfuga: tipos de processos, toler\u00e2ncias e volume de equil\u00edbrio"},"content":{"rendered":"
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Centrifugal casting is the one casting process where the mold does the pumping. Metal poured into a spinning die is thrown outward against the wall, so you get a dense, low-inclusion cylindrical wall with no riser and no gating system at all<\/strong>. For buyers sourcing cylinder liners, ductile iron pipe, bronze bushings, roll sleeves and ring blanks, that single fact changes both the price and the metallurgy.<\/p>\n<\/div>\n

It also comes with a trade-off most RFQs miss: the outside diameter is set by the mold, but the inside diameter is set by how much metal you pour<\/strong>. That asymmetry drives tolerances, machining allowance and break-even volume. This guide covers the three centrifugal casting variants, the G-factor math that fixes your spin speed, a real process window for iron, steel, bronze and aluminium, the tolerances you can hold, the ASTM and ISO standards to cite in an RFQ, and a worked break-even against sand casting and bar stock. For industry fundamentals see the American Foundry Society<\/a>, and for the wider process map our complete metal casting guide<\/a>.<\/p>\n

\"centrifugal
Centrifugal casting: the mold wall forms the outside diameter, the poured metal mass forms the bore.<\/figcaption><\/figure>\n

What Centrifugal Casting Actually Is<\/h2>\n

Centrifugal casting is a family of processes in which metal is poured into a mold rotating about an axis, and centrifugal force \u2014 measured as a G-factor, usually 40 to 120 times gravity \u2014 presses the liquid against the mold wall. Because the force is always directed outward, the denser metal fills the periphery first while slag, dross, gas bubbles and light inclusions are displaced to the bore. In true centrifugal casting that contaminated inner layer is not a defect to chase; it is designed-in material that gets bored out<\/strong>, which is precisely why spun castings show fewer sub-surface inclusions than static castings on the same section.<\/p>\n

The absence of risers also means no gating yield loss. A static casting of a hollow cylinder typically pours 60 to 70 % usable metal; a true centrifugal casting of the same part pours 90 to 95 %. That gap, not labour, is what makes centrifugal casting competitive at volume.<\/p>\n

The Three Variants \u2014 and Which One You Are Buying<\/h3>\n
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“Centrifugal casting” in a quotation can mean three different things. Ask which one before you compare prices, because tooling and tolerances differ by a factor of three.<\/p>\n\n\n\n\n\n\n\n
Variant<\/th>\nRotation axis<\/th>\nPart geometry<\/th>\nCore used<\/th>\nTypical parts<\/th>\n<\/tr>\n<\/thead>\n
True centrifugal<\/td>\nPart centreline<\/td>\nHollow cylinder, one wall<\/td>\nNo core \u2014 bore is free surface<\/td>\nPipe, liner, bushing, sleeve, roll<\/td>\n<\/tr>\n
Semicentrifugal<\/td>\nCentral sprue, part offset<\/td>\nDisc or wheel, plus hub bore<\/td>\nYes \u2014 sand core for bore\/holes<\/td>\nWheel hubs, sheaves, flanges<\/td>\n<\/tr>\n
Centrifuging (pressure casting)<\/td>\nCentral sprue, cavities around it<\/td>\nAny small part in a radial cavity<\/td>\nYes, per cavity<\/td>\nValve bodies, fittings, brackets<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Only the first variant gives you the no-riser, no-core, high-yield economics. If a supplier quotes “centrifugal casting” for a non-axisymmetric part, you are buying the centrifuging variant \u2014 useful for thin-wall small parts, but it does not carry the yield advantage. For non-rotational geometry, evaluated properly, sand casting versus investment casting<\/a> is the more honest comparison, and our sand casting line<\/a> covers that territory.<\/p>\n

\"centrifugal
Horizontal spin for long tubes, vertical spin for short rings and flanged parts.<\/figcaption><\/figure>\n

The G-Factor Math That Fixes Your Spin Speed<\/h2>\n

Spin speed is not a preference, it is a calculation. The G-factor is the radial acceleration expressed in multiples of gravity:<\/p>\n

G = \u03c9\u00b2r \/ g<\/strong>, where \u03c9 = 2\u03c0N \/ 60. Rearranged for a shop-floor set point, N = 9.549 \u00d7 \u221a(9.81G \/ r)<\/strong> rpm, with r in metres measured at the bore.<\/p>\n

Worked Example: Horizontal Spun Steel Tube<\/h3>\n
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Tube OD 220 mm, bore diameter 180 mm, so r = 0.09 m at the bore and 0.11 m at the mold wall. Targeting G = 60 at the mold wall:<\/p>\n