Shell Mould Casting

Better dimensional accuracy for small to medium custom parts with high precision.

SIYUAN Shell Mould Casting Foundry

Shell mold casting is used for products with more complex cavities.
Shell molding casting is also called pre-coated resin sand casting process, hot shell molding casting or core casting process.
The shell mould casting components have a little higher costs than sand casting. However, it owns many advantages such as tighter dimensional tolerance, good surface quality and less casting defects.
Before making the mould and core. the coated sand have been covered with a solid resin fim on the surface of the sand particles. The coated sand is also called shell (core) sand. The technological process is to mechanically mix powdered thermosetting phenolic tree with raw sand and solidify when heated. it has been developed into coated sand by using thermoplastic phenolic resin plus latent curing agent (such as urotropine) and lubricant (such as calcium stearate) througha certain coating process.
When the coated sand is heated, the resin coated on the surface of the sand particles melts. Under the action of the methylene group decomposed by the Maltropine, the molten resin rapidly transforms from a linear structure to an infusible body structure so that the coated sand is solidifed and formed. in addition to the general dry granular form of coated sand.there are also wet and viscous coated sand.
After mixing the original sand (or reclaimed sand), liquid resin and liquid catalyst evenly, and filing them into the core box(or sand box), and then tighten it to harden into a mold or mold in the core box (or sand box) at room temperature. The casting mould or casting core were formed, which is called self-hardening cold-core box modeling (core), or self-hardening method (core). The self-hardening method can be divided into acid-catalyzed furan resin and phenolic resins and self-hardening method, urethane resin sand self-hardening method and phenolic monoester self hardening method

Shell Mould Casting Capability

At Si YUAN shell mold casting foundry,
we could provide the design service according to your drawings, requirements, or just your samples. The customized casting parts produced by shell casting are serving in diverse industries such as trains, heavy-duty trucks, farm machinery, pumps and valves, and construction machinery. In the following, you will find a short introduction to what we could achieve by shell mold casting

Max Size: 1,000 mm x 800 mm x 500 mm.
Weight Range: 0.5 kg -100 kg.
Annual Capacity: 2,000 tons.
Tolerances: according to customers’ requests, if parts need to be machined, our machining workshop is in-house.

What material we can use by Shell mold casting

Gray Cast lron, Ductile Cast lron, Cast Carbon Steel, Cast Steel Alloys, Cast Stainless Steel. Cast Aluminium Alloys, Brass & Copper and Other Materials and Standards on request.

Metal &Alloys	Popular Grade
Gray Cast Iron	GG10,GG15,GG20,GG25,GG30,GG35 GG40;EN-GJL-100,EN-GJL-150,EN-GJL-200,EN-GJL-250,EN-GJL-300,EN-GJL-350; HT100,HT150,HT200,HT250,HT300,HT350;ASTM A48 Gray Iron Grades Class 20,Class 25,Class 30,Class 35,Class 40, Class 45,Class 50,Class 55,Class 60.
Ductile (Nodular)Cast Iron	GGG40,GGG45,GGG50,GGG55,GGG60,GGG70,GGG80;EN-GJS-400-18,EN-GJS-40-15,EN-GJS-450-10,EN-GJS-500-7,EN- GJS-600-3,EN-GJS-700-2,EN-GJS-800-2;ASTM A536 Ductile Iron Grades 60-40-18,65-45-12,70-50-05,80-60-03,100-70-03, 120-90-02.
Austempered Ductile Iron(ADI)	EN-GJS-800-8,EN-GJS-1000-5,EN-GJS-1200-2
Cast Carbon Steel	C20,C25,C30,C45
Cast Alloy Steel	20Mn,45Mn,ZG20Cr,40Cr,20Mn5,16CrMo4,42CrMo, 40CrV,20CrNiMo,GCr15,9Mn2V
Cast Stainless Steel	Ferritic Stainless Steel,Martensitic Stainless Steel,Austenitic Stainless Steel,PrecipitationHardening Stainless Steel,Duplex Stainless Steel
Aluminium Alloys	ASTM A356,ASTM A413,ASTM A360
Brass /Copper-based Alloys	C21000,C23000,C27000,C34500,C37710,C86500,C87600, C87400,C87800,C52100,C51100
Standard:ASTM,SAE,AISI,GOST,DIN,EN,ISO,and GB

Advantages of Shell Mold Casting

lit has suitable Complex cavity products. it can meet the requirements for high-strength shell core sand, medium-strengthhot-box sand, and low-strength non-ferrous alloy sand.
Excellent fluidity, good mold ability of the sand core and clear outline, which can produce the most complex sand cores,such as water jacket sand cores such as cylinder heads and machine bodies.
The surface quality of the sand core is good, compact and not loose. Even if less or no coating is applied, better surface quality to castings can be obtained. the dimensional accuracy of castings can reach grade ranging CT 7 – CT 8 and the surface roughness Ra can reach 6.3 – 12.5 um.this is better than with sand casting because a finer sand is used. The resin also assists in forming a very smooth surface.
Good collapsibility, which is conducive to casting cleaning and improving product performance
The sand core is not easy to absorb moisture, and the strength of long-term storage is not easy to decrease, which is conductive to storage,transportation and use

Shell Mould Casting Process

A two-piece metal pattern is created in the shape of the desired part, typically from iron or steel. Other materials are sometimes used, such as aluminum for low volume production or graphite for casting reactive materials.
Mould creation: Each pattern half is heated to 175-370 °C (350-700 °F) and coated with a lubricant to facilitate removal. The heated pattern is clamped to a dump box, which contains a mixture of fine silica sand and a thermosetting phenolic resin binder. The dump box is inverted, allowing this sand-resin mixture to coat the pattern. The heated pattern partially cures the mixture, which forms a shell around the pattern. Depending on the time and temperature of the pattern, the thickness of the shell is 10 to 20 mm. Each pattern half and surrounding shell is cured to completion in an oven giving it a tensile strength of 350 to 450 psi (2.4 to 3.1 MPa), and then the shell is ejected from the pattern.
Mould assembly: The two shell halves are joined together and securely clamped to form the complete shell mould. If any cores are required, they are inserted prior to closing the mould.
The shell mould is then placed into a flask and supported by a backing material.
Pouring: The mould is securely clamped together while molten metal is poured from a ladle into the gating system to fill the mould cavity.
Cooling: After the mould has been filled, the molten metal is allowed to cool and solidify into the shape of the final casting.
Casting removal: After the molten metal has cooled, the mould can be broken and the casting removed. Trimming and cleaning processes are required to remove any excess metal from the feed system and any sand remaining from the mould.