13. MOLDING AND CASTING

Objectives

group assignment:review the safety data sheets for each of your molding and casting materials, then make and compare test casts with each of them. Compare mold making processes

individual assignment: design a mold around the process you'll be using, produce it with a smooth surface finish that does not show the production process toolpath, and use it to cast parts

— Types of Molding

TYPE OF MOLDING	DESCRIPTION
Injection Molding	Molten plastic is injected into a mold under pressure and cooled before ejection.
Blow Molding	Used for hollow plastic products such as bottles and containers.
Compression Molding	Material is placed in a heated cavity and compressed into shape.
Rotational Molding	Creates hollow parts by rotating a mold while resin coats the interior.
Extrusion Molding	Material is pushed through a die to create continuous profiles.
Thermoforming	Heated plastic sheet is shaped over a mold and cooled.
Casting	Liquid material is poured into a mold and solidified.
Die Casting	Molten metal is injected into a die under pressure.

— Materials Used for Molding

MATERIAL	DESCRIPTION
Plastics	Thermoplastics: PE, PP, PS, PVC can be melted and remolded. Thermosetting Plastics: Epoxy, phenolic and melamine become permanently set after molding.
Rubbers	Natural Rubber: High elasticity and resilience. Synthetic Rubbers: Silicone, neoprene, nitrile and EPDM for heat, oil and weather resistance.
Metals	Aluminum: Lightweight and corrosion resistant. Steel: Strong and wear resistant for molds. Zinc / Magnesium / Copper Alloys: Used in die casting for precision parts.
Ceramics	Porcelain: Heat resistant ceramic for specialized products. Alumina & Zirconia: Used where hardness and thermal stability are needed.
Composites	Fiber Reinforced Polymers (FRP): Fiberglass, carbon fiber and aramid composites with high strength-to-weight ratio.
Foams	Polyurethane Foam: Cushioning and insulation products. Polystyrene Foam: Used for packaging and insulation boards.
Glass	Borosilicate Glass: High thermal and chemical resistance for labware, optics and lighting components.

Silicone Molding

Silicone molding, also known as silicone rubber molding, is a type of molding process that uses silicone rubber as the molding material. This method is widely used for creating flexible and durable parts, often for prototypes, low-volume production, and intricate designs that are difficult to achieve with other molding processes.

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