CNC Machining

What is Plastic Parts?Type,Production Process and Application in Industry?

Plastics are the most common materials for producing end-use parts and products, for everything from consumer products to medical devices. Plastics are a versatile category of materials, with thousands of polymer options, each with their own specific mechanical properties. But how are plastic parts made?

A variety of plastic manufacturing processes have been developed to cover a wide range of applications, part geometries, and types of plastics. For any designer and engineer working in product development, it is critical to be familiar with the manufacturing options available today and the new developments that signal how parts will be made tomorrow.

This guide provides an overview of the most common manufacturing processes for producing plastic parts and guidelines to help you select the best option for your application.

How to Choose the Right Plastic Manufacturing Process

Consider the following factors when selecting a manufacturing process for your product:

Form: Do your parts have complex internal features or tight tolerance requirements? Depending on the geometry of a design, manufacturing options may be limited, or they may require significant design for manufacturing (DFM) optimization to make them economical to produce.

Volume/cost: What’s the total or the annual volume of parts you’re planning to manufacture? Some manufacturing processes have high front costs for tooling and setup, but produce parts that are inexpensive on a per-part basis. In contrast, low volume manufacturing processes have low startup costs, but due to slower cycle times, less automation, and manual labor, cost per part remains constant or decreases only marginally when volume increases.

Lead time: How quickly do you need parts or finished goods produced? Some processes create first parts within 24 hours,

while tooling and setup for certain high volume production processes takes months.

Material: What stresses and strains will your product need to stand up to? The optimal material for a given application is determined by a number of factors. Cost must be balanced against functional and aesthetic requirements. Consider the ideal characteristics for your specific application and contrast them with the available choices in a given manufacturing processes.

Types of Plastics

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Plastics come in thousands of varieties with different base chemistries, derivatives, and additives that are formulated to cover a wide range of functional and aesthetic properties.

To simplify the process of finding the material best suited for a given part or product, let’s look first at the two main types of plastic: thermoplastics and thermosets.

Thermoplastics
Thermoplastics are the most commonly used type of plastic. The main feature that sets them apart from thermosets is their ability to go through numerous melt and solidification cycles without significant degradation. Thermoplastics are usually supplied in the form of small pellets or sheets that are heated and formed into the desired shape using various manufacturing processes. The process is completely reversible, as no chemical bonding takes place, which makes recycling or melting and reusing thermoplastics feasible.

Common types of thermoplastic materials:

Acrylic (PMMA)
Acrylonitrile butadiene styrene (ABS)
Polyamide (PA)
Polylactic acid (PLA)
Polycarbonate (PC)
Polyether ether ketone (PEEK)
Polyethylene (PE)
Polypropylene (PP)
Polyvinyl chloride (PVC)
Thermosetting Plastics
In contrast with thermoplastics, thermosetting plastics (also referred to as thermosets) remain in a permanent solid state after curing. Polymers in thermosetting materials cross-link during a curing process that is induced by heat, light, or suitable radiation. This curing process forms an irreversible chemical bond. Thermosetting plastics decompose when heated rather than melting, and will not reform upon cooling. Recycling thermosets or returning the material back into its base ingredients is not possible.

Common types of thermoplastic materials:

Cyanate ester
Epoxy
Polyester
Polyurethane
Silicone
Vulcanized rubber
Types of Manufacturing Processes
3D Printing
CNC Machining
Polymer Casting
Rotational Molding
Vacuum Forming
Injection Molding
Extrusion
Blow Molding

3D Printing
Professional 3D printers create three-dimensional parts directly from CAD models by building material layer by layer until a complete physical part is formed.

Types Of Plastic Materials Used In Part Manufacturing

Not all plastics are created equal. The material you choose impacts everything from part performance to production processes. Here are the main categories of plastics used in manufacturing:

Thermoplastics
Thermoplastics soften when heated and harden when cooled. This allows reheating and remolding repeatedly. Common thermoplastics include polyethylene, polypropylene, polystyrene and ABS. Advantages include versatility, recyclability and durability.
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Thermosets
Thermosets form permanent chemical bonds when heated, so they can’t be remolded after initial forming. Polyurethane, epoxy and phenolic resins are common thermosets. They provide enhanced mechanical properties and thermal resistance.

Elastomers
Elastomers exhibit rubber-like flexibility and resilience. Silicone rubber and thermoplastic elastomers like TPE are widely used for parts needing elasticity. Benefits include impact absorption and conformability.

Composites
Composites combine plastics with reinforcements like glass fibers or carbon nanotubes. This tailors properties like strength and abrasion resistance. Fiber-reinforced nylons are popular composite options.

Factors That Influence Plastic Part Design

Plastic part design requires balancing many interdependent factors. Here are key considerations before manufacturing:

Mechanical properties: Strength, ductility, impact resistance based on material choice and part geometry.
Dimensional accuracy: Maintaining precise tolerances and accounting for shrinkage.
Part weight: Thinner walls can reduce weight but compromise durability.
Aesthetics: Surface finish, textures, part consolidation, etc.
Assembly: Interlocking features for simplified assembly and fastening.
Keep these in mind early on to optimize manufacturability and performance.

Popular Plastic Molding Processes Explained
Choosing the right molding technique depends on production volumes, part design, plastic properties and precision needs. Here are the most common methods:

Injection Molding
uses high pressure to force molten plastic into a mold cavity, yielding complex parts with excellent consistency and detailed features. Ideal for mass production.

Blow Molding
heat softens plastic then inflates it inside a mold using compressed air. Enables hollow parts like bottles with thin, customizable walls.

Rotational Molding
uses biaxial rotation to evenly coat plastic powder onto a mold. Provides seamless, hollow parts like tanks and cargo containers. Minimal material waste.

Compression Molding
uses thermoset plastics, compressed with heat and pressure between male/female mold halves. Simple, high-volume process for small precision parts.

Thermoforming
heats thin thermoplastic sheets then vacuums/presses them onto a mold. Fast and economical for high-volume packaging and basic parts.

Latest Trends And Innovations
Plastic part manufacturing continues advancing through new technologies:

Multi-material molding combines hard and soft plastics for hybrid material properties.
Micro-molding produces intricately detailed micro-parts for medical and electronics applications.
3D printing enables rapid prototyping and low-volume production without molds.
Automation and IoT brings data-driven efficiency, quality control and supply chain integration.
Sustainable materials like bioplastics reduce environmental impact.
By harnessing such innovations, manufacturers can create better-performing plastic parts faster and more flexibly than ever before.

Essential Takeaways
Plastics offer unmatched versatility for fabricating diverse part geometries and material properties cost-effectively.
Optimal part design requires balancing factors like function, manufacturability and aesthetics.
Injection molding leads for high-volume production, but alternate processes serve other needs.
Ongoing advances are expanding the design possibilities and competitive edge of plastic parts.
With careful material selection and process expertise, nearly any plastic part can be produced efficiently. Work closely with your manufacturing partner to fully leverage plastics’ potential and bring your visions to life efficiently.

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