Shell Mold Casting

Resin Pre-coated Shell Mould Casting Foundry

Shell molding casting process is also called pre-coated resin sand casting process, hot shell molding castings or core casting process. The main molding material is the pre-coated phenolic resin sand, which is more expensive than green sand and furan resin sand. When the pre-coated sand is heated by the hot patterns, the sand will become strong shell to form the mold cavity, which will withstand the molten metal and alloys.

Coated sand is molding sand and core sand in which a solid resin film has already been coated on the surface of the sand particles before molding and core making; therefore, it is also called shell sand. The coating sand process involves mechanically mixing powdered thermosetting phenolic resin with the raw sand and then curing it upon heating.

Modern coated sand has evolved into a process using thermoplastic phenolic resin, a latent curing agent, and a lubricant, formulated through a specific coating process. When heated, the coated sand melts with the resin coating the sand grains. Under the action of the methylene groups released by the decomposition of hexamethylenetetramine (the latent curing agent), the molten resin rapidly transforms from a linear structure to an insoluble three-dimensional structure, thus allowing the coated sand to solidify and take shape.

The pre-coated sand can not be recycle used. The shell molding castings have higher costs than sand casting. However, the shell molding casting parts have many advantages such as tighter dimensional tolerance, good surface quality and less casting defects.

Shell Mold Casting Foundry

Pre-Coated Shell Mold

Capacities and Molten Metal for Shell Mold Castings

▶Ferrous and Non-Ferrous Metals for Shell Casting at RMC's Foundry

• Gray Cast Iron:  EN-GJL-100, EN-GJL-150, EN-GJL-200, EN-GJL-250, EN-GJL-300, EN-GJL-350
• Ducitle (Nodular, Spheroidal Graphite) Iron: 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
• Cast Aluminium and Their Alloys
• Alloy steel or carbon steel or other materials and standards on request
• Brass, Bronze and other Copper-based Alloys

• Max Size of Casting Molds: 1,500 mm × 1000 mm × 500 mm
• Weight Range of Shell Castings: 0.5 kg - 500 kg
• Annual Capacity of Shell Castings: 5,000 tons - 6,000 tons
• OEM Custom Services: Available
• Casting Tolerances: On Request.

Shell Mold Casting Foundry

How We Inspect Shell Mould Castings

Our Spectrometer checks 15 chemical elements and metallurgical microscope produces high-resolution images 1,000 times magnified, and our cleanliness meter determines particle size and quantity to ensure materials meet or exceed the international standard. RMC use ultrasonic detectors to discover flaws, and have X-ray machines and accelerators that can scan castings with 200 mm maximum wall thickness.

RMC has a full range of inspection capabilities in house, which include:

1.   - Spectrographic and manual quantitative analysis
2.   - Metallographic analysis
3.   - Brinell, Rockwell and Vickers hardness inspection
4.   - Mechanical property analysis
5.   - Low and normal temperature impact testing
6.   - Cleanliness inspection
7.   - UT, MT, PT and RT inspection

CMM

Shell Mould Casting Procedures

1- Design and Make Patterns.

The pre-coated resin sand needs to be heated in the patterns, so metal patterns are the necessary tooling to make shell molding casting

2- Make Pre-coated Sand Mold

After installing the metal patterns on the molding machine, the pre-coated resin sand will be shot into the patterns, and after heating, the resin coating will be molten, then the sand molds become solid sand shell and cores.

3- Melt the Cast Metal

Using induction furnaces, the materials would be melted into liquid, then the chemical compositions of the liquid iron should be analyzed to match the required numbers and percents.

4- Pouring Molten Metal

When the melted iron meet the requirements, then they will be poured into the shell molds. Based on different characters of the casting design, the shell molds will be buried into green sand or stacked up by layers.

5- Shot Blasting, Grinding and Cleaning

After the cooling and solidification of the castings, the risers, gates or additional iron should be cut off and removed. Then the iron castings will be cleaned by sand peening equipment or shot blasting machines. After grinding the gating head and parting lines, the finished casting parts would come, waiting for the further processes if needed.

Shell Mold

Pre-Coated Shell Mould

Shell Mould Casting Foundry Gallery

In RMC's foundry, we utilize the professional equipment to produce the patterns and form the casting shell mold. These highly organized equipment help us to produce the shell mold castings part of high quality and big volume. These equipment could produce diverse custom castings such as grey iron castings, ductile iron castings, carbon steel castings, alloy steel castings, stainless steel castings, aluminium castings and brass castings.

Applications of Shell Mould Casting Components

Shell mould castings could serve in many industries including gearboxes, industry valves, pumps, hydraulics, automotive, commercial truck, rail trains, logistics, agricultural machinery...etc. The castings mainly are used as gearbox housing, gearbox cover, pump housing, pump cover, cylinder heads, transmission box, brackets, wheel hub, connecting rods, axles and manifolds...etc.

Typical Shell Mold Castings

Value Added Services from Shell Mould Casting Foundry at RMC

Our services are varied and extensive. We offer material advisory service and development, as well as advice from our technical experts on design and casting with under the help of the software of 3D and CAD drawings and simulations software. From start to finish, we have you covered every step of the way.

• Sand Casting: Green Sand Casting with Handle and Automatic Molding Machine, Pre-Coated Shell Molding Casting, CNC Precision Machining and Metal Fabrications.
• Heat treatment: Quenching, Tempering, Normalizing, Annealing, Carburization, Nitration
• Surface treatment: Anodizing, Zinc-plating, Polising, GeoMet, Zintek, Electrophoresis....etc
• Testing Service: Chemical Composition, Mechanical Properties, Fluorescent or Magnetic Penetration Inspections (FPI, MPI), X-rays, Ultrasonic Testing, Dynamic and Static Balancing Testing

RMC offers a full range of metal forming and mechanical processing. If you would like to know more about our technology and manufacturing capabilities, contact us today.

Warehouse at RMC Sand Casting Foundry