When manufacturing injection-molded parts, you often hear terms like "structural part," "functional part," and "aesthetic part." What are differences between them? Different types of products have different quality requirements and evaluation standards. Below is an explanation of these three types:

1. Structural Parts
• Definition: Refers to parts in a product that primarily provide support, connection, fixation, and bear mechanical loads (such as tension, compression, impact, and torque). They are "skeleton" of product, determining its overall strength, rigidity, stability, and reliability.
• Design Focus: Mechanical properties and dimensional stability. Engineers are most concerned with whether it can withstand expected load without fracturing, deforming, or experiencing fatigue.
• Common Examples:
• Connecting parts: Screw posts, buckles, hinges, reinforcing ribs.
• Supporting frames: Internal brackets of mobile phones/laptops, outer shell frames of home appliances, bases of automotive interiors.
• Load-bearing components: Chair legs, tool casings, gears, bearing housings.

 

2. Functional Parts
• Definition: Refers to parts in a product that perform specific physical functions. They usually involve movement, conduction, sealing, insulation, etc., and their core is "function" rather than "support."
• Design Focus: Functionality and precision. Focus is on whether it can accurately and reliably complete specific task assigned by design.
• Common Examples:
• Moving parts: Gears, racks, sliders, buttons, switches.
• Conducting parts: Lenses, light guides, waveguides (used to conduct light or signals).
• Sealing/insulating parts: Seals, valves, insulating housings.
• Special functions: Breathable membranes, antibacterial components, conductive components.
3. Aesthetic Parts
• Definition: Refers to parts in a product that are directly visible to user and primarily affect product's visual appearance, tactile feel, and brand image. They are "skin" and "face" of product.
• Design Focus: Surface quality and aesthetic effect. Goal is to achieve a flawless surface, uniform color, and high-quality texture.
• Common Examples:
• Housings: Mobile phone front and back covers, TV panels, remote control casings, washing machine control panels.
• Decorative parts: Car grilles, logo badges, decorative strips.
• Parts that come into contact with people: Handles, button surfaces.

 

The key to differentiating these three lies in judging them from four dimensions: design objectives, inspection standards, materials, and process requirements.

In actual products, a single part often possesses multiple attributes, requiring identification of its primary attribute.
Example Analysis:
1. Laptop A-shell (screen back cover)
• Primary attribute is aesthetic part: Because it determines the first impression of computer, requiring perfect color, texture, and logo.
• Secondary attribute is structural part: It also needs a certain strength and rigidity to protect the screen, and will have reinforcing ribs designed internally.
• How to differentiate? If it breaks during a drop test, it's a structural problem; if there are scratches or color differences on the surface, it's an aesthetic problem. Its primary task is to "look good," so it is classified as an aesthetic part.
2. Power tool casing
• Primary attribute is structural part: It must be strong enough to withstand impact and vibration, to house internal motor and gears.
• Secondary attributes are aesthetic and functional parts: It also has a brand logo and texture (aesthetic), and is designed with an ergonomically comfortable grip area (functional).
• How to differentiate? If grip area breaks, it's a fatal structural failure; if anti-slip texture on the grip area is uncomfortable, it's a functional/aesthetic problem. Its primary task is to be "sturdy," so it is a structural part.
3. Transparent water lid of a coffee machine
• Primary attribute is functional part: It needs to achieve a sealed and leak-proof function.
• Secondary attribute is aesthetic part: It is transparent, requiring high transparency and no defects.
• How to differentiate? If it leaks water, it's a functional failure; if it looks cloudy or has bubbles, it's an aesthetic problem. Its primary task is to "seal," so it is a functional part.

 

• Structural components: Question is, "Is it strong and durable?" - Core concern is mechanical performance.
• Functional components: Question is, "Does it work properly?" - Core concern is functionality.
• Aesthetic components: Question is, "Does it look good?" - Core concern is surface quality.
When differentiating between these types of parts, focus on their primary purpose. Focus and standards for these three types of components are completely different in design, manufacturing, and quality inspection stages. Understanding these differences is fundamental to developing high-quality products.