What Are The Working Principles Of Internal And External Plastic Parts in Home Appliances?

Basic Molding Principles
Injection Molding: Plastic pellets are fed into a heating chamber and melted into a fluid; a screw then injects the material under pressure into a custom mold cavity. After cooling and solidifying, the part is demolded to form the finished product. This is the most common manufacturing method for appliance plastic parts, suitable for the vast majority of structural components such as casings, handles, and drawers.
Thermoforming (Vacuum Forming): Rigid plastic sheets are heated until soft and then drawn onto the mold surface via vacuum suction; after cooling, they are trimmed to shape. This process is frequently used for large-surface, thin-walled components like refrigerator liners and door liners.
Other Auxiliary Processes:Blow molding is used for hollow parts such as drain pipes and cold accumulators; extrusion is used for the continuous production of long items like door gaskets and profiles; and reaction foaming is used for the thermal insulation layers in refrigerator cabinets and doors.

 

Functional Principles of External Plastic Parts
Insulation and Protection: Leveraging the excellent electrical insulation properties of modified plastics, these parts prevent internal electrical leakage and protect users from electric shock upon contact with the casing. They also feature appropriate flame-retardant properties to slow the spread of fire in the event of abnormal overheating.
Aesthetics and Structural Support: Taking advantage of the high plasticity of plastics, complex curved surfaces and angular shapes can be formed in a single piece. Glass-fiber reinforcement provides sufficient impact strength, ensuring resistance to cracking or deformation from everyday bumps. Additionally, surfaces can be directly colored or laminated to achieve distinctive visual designs.
Thermal Insulation and Anti-Scalding: Plastics have a much lower thermal conductivity than metals, effectively blocking the transfer of heat from internal heating elements to the exterior. This prevents users from being burned when touching the casing, making the material ideal for small heating appliances such as rice cookers and toasters.