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Home 9 Injection Molding 9 Best Material for Injection Molding: Which one Suits Your Needs?

Best Material for Injection Molding: Which one Suits Your Needs?

Author: Yaozu Deng
Published on: 2024-01-22

“The best material for injection molding is not a one-size-fits-all answer; it hinges on the part’s purpose, durability needs, and environmental exposure.”

Do you know injection molding can process hundreds of material types from plastic, metal, composite, and ceramics? However, there are some best materials for injection molding, which are used in most of the projects. For example, ABS, Nylon, Acrylic, Aluminum, and ceramic. Let’s discuss the best Injection Molding Materials their properties, applications, and in what scenario it is best.

 

Acrylonitrile Butadiene Styrene (ABS)

ABS is also known as a hard-to-break thermoplastic material. It holds excellent toughness, impact resistance, and thermal stability. Meanwhile, it is highly favored in injection molding due to its low melting point (221-240°C), robustness, smooth surface finish, and cost-effectiveness.

Table: Mechanical Properties of ABS Plastic. Source 

Property

Value

Elongation at Break

10 – 50 %

Flexibility (Flexural Modulus)

1.6 – 2.4 GPa

Stiffness (Flexural Modulus)

1.6 – 2.4 GPa

Tensile Strength

29.8 – 43 MPa

Toughness (Notched Izod Impact at Room Temperature)

200 – 215 J/m

Three main factors should be considered during ABS Injection Molding. First, ensure proper drying since it is more moisture-sensitive than some other thermoplastics. Second, ABS might exhibit a higher shrinkage rate during cooling and solidification. If so, adjust mold dimensions and processing parameters to counteract its shrinkage. 

Furthermore, ABS is the best material for the following injection molding application scenarios: 

  • Automotive: Dashboards, wheel covers, and interior trim due to its strength and heat resistance.
  • Medical Devices: Its non-toxic and sturdy nature makes it suitable for medical equipment casings and tools.
  • Consumer Electronics: ABS is ideal for housings for TVs, phones, and home appliances because of its protective and aesthetic qualities.
  • Toys: LEGO bricks, owing to its safety, colorability, and robustness.

 

Nylon Polyamide 

Nylon Polyamide or Nylong provides excellent toughness, heat resistance, wear and abrasion resistance, and fatigue resistance. Injection molding the Nylon means bringing these properties into application.

Injection molded nylon part 

Subsequently, it has three popular grades: Nylon 11, Nylon 12, and Nylon 46. Each of these grades has unique properties to offer. For instance, grade 11 is favorable for outdoor conditions, while injection molding parts of Nylon 46 are ideal in high-temperature applications. 

Nylon is the best-suited material for producing parts and products in the following areas;

Table: Best-suited applications of Nylong injection molding 

Industry

Applications

Reasons for Using Nylon

Automotive

Gears, bushings, bearings; Under-the-hood parts

Wear resistance,  strength, and durability

Electrical and Electronics

Insulators, connectors, parts of electrical appliances; Cable ties and housings

Excellent insulating properties and durability 

Packaging

Flexible food packaging

Strength and moisture resistance; Barrier properties for longer shelf life

Industrial Applications

Conveyor belts, hoses, tubes; Mechanical parts like screws and fasteners

Wear resistance, toughness, and strength 

 

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Polycarbonate(PC)

You can imagine how tough PC plastic is from the fact that it is nearly bulletproof. PC is highly resistant to impact, temperature, and shattering. Next, it is an optically clear transparent plastic. The injection molding method keeps intact these properties. So, we can solve similar manufacturing needs across industries. 

Table: Properties of Polycarbonate. Source

Properties Value 
Thermal Expansion (K⁻¹) 6.75 x 10⁻⁶
Ultimate Tensile Strength (MPa) 65.5
Yield Strength (MPa) 58.6
Flexural Strength (MPa) 93.1
Impact Strength-Izod notched (J/m) 641-854

Polycarbonate is the best material for components requiring high-impact resistance and clarity. Injection molding of PC plastic can create bulletproof glass, eyewear lenses, and other optical applications. Additionally, its lightweight nature makes it perfect for various protective applications.

 

Polycarbonate injection molding part

The heat resistance and electrical insulation properties make it suitable for electrical connectors and housings. Consequently, polycarbonate is a top choice for intricate components in the automotive and electronics industries, where durability and performance are critical. However, it is incompatible with food and chemical processing. 

 

Polypropylene(PP)

It is renowned as one of the best injection molding materials for food and chemical packaging applications. Polypropylene offers high hardness, chemical inertness, and resistance to high-temperature conditions. 

Custom polypropyle parts from injection molding

Custom polypropylene parts from injection molding 

Next, it can come back to its original shape after bending or torsion. Injection molding of propylene resin is ideal for the following applications:

Table: Prefferd Applications of Propylene Injection Molding 

Application Why PP? Examples
Food Packaging Resistant to chemicals; good barrier properties Containers, bottles, processing components 
Automotive Parts High impact resistance; durability Bumpers, dashboards, battery cases
Medical Equipment Sterile for medical use; safe for contact with skin Surgical instruments, syringes, vials
Industrial Components Resistant to fatigue; withstands daily wear and tear Gears, pumps, valves

However, it is flammable, and UV-light and clod environment degrades the material. So, injection molded polypropylene parts are unsuited for external environments(Sunlight exposure) and if there is a risk of fire.

 

Polyethylene(PE)

Although PE is not highly strong or hard, it is nontoxic and offers excellent chemical resistance, moisture, resistance, and lightweight properties. Typically, there are two PE grades: High-density and Low-density Polyethylene. They have primarily differences in their hardness, melting temperature, and transparentness. HDPE is rigid and has a high melting point. In contrast, LDPE is relatively soft, flexible, and easily moldable. 

 

PE injection molding part

Due to all these properties, polyethylene excels as an injection molding material for consumer product packaging. Some examples are packing bottles, containers, and plastic bags. Additionally, its food-safe and chemical-neutral nature makes it indispensable for packaging foods, chemicals, and medicines.

Consequently, its ability to withstand UV radiation and corrosion ensures long-lasting and maintenance-free applications. Thus, PE injection molding parts are also suitable for outdoor applications like custom furniture.

 

Polyoxymethylene (POM)

It is also popular with the name Delrin( Brand name) among Injection Molding Materials. POM Shows inertness to gasoline, oils, alcohols, and other solvents. On the other hand, it can not resist hard acids like nitic and hydrochloric (HCl) acids. Next, high rigidness, toughness, thermal stability, and mechanical strength are the other worth mentioning polyoxymethylene properties. 

POM parts from Injection Molding 

Based on the above properties, POM is a suitable material for injection molding of the following parts and products.

Table: POM Injection Molding Applications 

Application

Why POM? 

Injection Molding Examples

Precision Engineering

High stiffness, dimensional stability, excellent machinability

Precision gears, watch parts, medical devices

Gears and Bearings

Low friction, high wear resistance, mechanical strength

Conveyor belts, small gear wheels, bearings

Electrical 

Good electrical insulation, resilience to heat, low moisture absorbance

Insulators, connectors, switch components

Automotive 

Fuel resistance, durability, impact resistance

Fuel system components, fasteners, door handles

 

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Teflon of PTFE

Teflon is the brand name of polytetrafluoroethylene (PTFE). It is renowned for high heat resistance, chemical inertness, low friction coefficient, and excellent electrical insulation. 

Table: Properties of Teflon. Source 

Property

Value

Tensile strength

15 MPA(Minimum)

Hardness

55/65(Type D)

Compressive strength (0.2 Offset)

8.2 MPA

Thermal coefficient (25°C to 100°C)

138.4 µm/(m·°C)

Young’s modulus

653.2 MPa

However, you might wonder, can Teflon be injection molded due to its high melting point (327°C)? On the contrary, Teflon injection molding parts are suitable for several manufacturing needs.

  • Chemical Industry: Seals, gaskets, and linings in chemical processing equipment.
  • Electrical Components: Insulators, connectors, and components.
  • Aerospace and Automotive: Bearings, gears, and seals. 
  • Medical Devices: Catheters, grafts, and other medical device components.

Related: Can Teflon be Injection Molded? Process and Challenges 

 

Silicone Rubber 

Silicone is used in injection molding processes due to its versatility and resilience. It can maintain its original properties in a wide temperature range, -55°C to 300°C. Furthermore, silicone rubber is highly chemical resistant, is an excellent electrical insulator, and offers excellent elasticity. 

Silicone injection molding part 

In contrast to other plastic molding, silicone uses a heat-activated curing process, often with a platinum or peroxide catalyst. Molds used for Silicone Injection Molding are typically heated before opening the two halves. 

Hence, silicone is the best injection molding material for the following application scenarios:

Table: Silicon as an Injection Molding Material 

Industry

Applications

Reasons 

Automotive

Gaskets, seals, hoses

Temperature and chemical resistance

Medical Devices

Implants, tubing, medical applications

Biocompatibility

Electronics

Insulation, keypads, protective covers

Electrical insulating properties and durability

Aerospace

O-rings, seals, gaskets

Ability to withstand extreme temperature variations

 

Aluminum 

The injection molding technique is not limited to plastics. It can also process metal and ceramics. In Metal Injection Molding (MIM), aluminum is the most common raw material. The injection molding process utilizes a high strength-to-weight ratio and other physical and mechanical properties of aluminum by converting it into functional components and products.

Aluminum part from MIM 

Furthermore, aluminum is an optimal material for automotive & aerospace parts due to its lightweight, corrosion resistance, and robust nature. Moreover, its thermal properties make it suitable for heat sinks and engine components. The high conductivity makes it applicable in electronic casings and connectors, ensuring effective heat dissipation. Consequently, its corrosion resistance and strength are advantageous for aerospace components, where durability and reliability are paramount.

Related: Aluminum CNC Machining: Everything You Need to Know 

 

Alumina(Al2O3)

It is probably the most common among Ceramic Injection Molding Materials. The hardness, high melting point, durability, and electrical insulations are the critical alumina properties.

The process begins with mixing the ceramic powder with a thermoplastic binder to form a feedstock. Then, feed is injected into a mold. The molded part is for de-binding and sintering. Finally, creating a dense, rigid structure.

Alumina injection molding is ideal for:

  • Insulators, substrates, and other electronic components
  • Heat sink and semiconductor parts
  • Cutting tools and abrasive linings

 

How to Choose the Best Material for Injection Molding?

Choosing the injection molding material that best suits any component or product requirement is a detailed and complex process. It demands consideration of several factors, such as mechanical properties, cost, moldability, and application environment. Basically, these factors are the criteria to match the material with the desired properties and specifications. 

Here is the step-wise elaboration to guide you through the best material for your injection molding project.

Step 1: Asses Mechanical and Physical Requirements 

First, identify the mechanical and physical requirements of the final product or part. It might include assessing the required strength, toughness, elasticity, thermal performance, resistance to UV, chemicals, and more.  

For example,  if the product needs to bear significant loads or impacts, materials with high tensile strength and toughness, like polycarbonate or ABS, could be suitable. 

Step 2: Consider Aesthetic and Functionality 

Consider the intended color, transparency, and surface. Then, match which material can fulfill that. For example, materials like acrylic offer excellent clarity and are ideal for transparent components. 

Step 3: Evaluate Cost and Production Efficiency

Cost is another crucial factor in material selection for injection molding. It includes the raw material cost and production cost. Some materials may require longer cycle times or special handling, impacting production efficiency and cost. Additionally, consider the availability and any potential supply chain issues.

Step 4: Regulatory and Compliance Needs

Regulatory compliance is critical, especially for medical, automotive, or food industries products. Injection Molding Materials must meet specific standards and certifications. For instance, medical-grade plastics should comply with the ISO 10993 standard. 

Step 5: Leverage Expertise and Material Data

Finally, leverage expertise and data when selecting materials. Consulting with material experts and engineers or using databases that provide detailed information about various materials can be invaluable. 

This step ensures a well-informed decision that aligns with the technical requirements and the practical aspects of production. Inject molding experts in the industry, like Prolean can help you to identify the best match using their knowledge and experience. 

 

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Plastic Injection Molding Services at ProleanTech

At ProleanTech, our expertise in plastic injection molding is unmatched, covering over 100 materials. We have a robust network of material suppliers. This network enables us to handle a wide range of material options.

Injection Molding Service

Our advanced injection molding facilities and experienced engineers work closely to bring precision and perfection to injection-moded parts. Prolean injection molding services handle everything, from mold manufacturing and rapid prototyping to large-volume production.

We provide tailored solutions to meet diverse client needs, ensuring high-quality results irrespective of the material complexity or project scale. Upload your design and request a quote to start your project today! 

 

Summing Up

You can get hundreds of material options for injection molding, including plastics, metals, and ceramics. Although, it is mostly used for thermoplastic parts manufacturing, especially on a large scale. The best material for injection mold

These diverse material options allow injection molding to cater to different manufacturing applications. However, the best material for injection molding depends on the requirements and specifications of the desired part. So, every material is best for some unique application. 

 

FAQs

What is the strongest material for injection molding?

Polycarbonate is the strongest material commonly used in injection molding. It is renowned for strength and durability. 

What is the most common material used in injection molding?

Polyethylene is the most commonly used material due to its versatility and affordability.

What is the cheapest material for injection molding?

Polypropylene is often the cheapest material for injection molding. It offers a good balance between cost, ease of molding, and physical properties.

What is the best material for injection molding?

The “best” material depends on the specific application and desired properties. 

 

Resources 

  1. Omnexus: The Material Selection Guide. (2021). Comprehensive Guide on Acrylonitrile Butadiene Styrene (ABS). Retrieved from https://omnexus.specialchem.com/selection-guide/acrylonitrile-butadiene-styrene-abs-plastic.
  2. Bi, Z. M., & Mueller, D. W. (2018). Friction prediction on the pin-to-plate interface of PTFE material and steel. Friction, 7(3). Retrieved from http://dx.doi.org/10.1007/s40544-018-0224-8
  3. Freeland, B., Mccarthy, E., & Balakrishnan, R. (2022). A review of polylactic acid as a replacement material for single-use laboratory components. Materials, 15(9), 2989. https://doi.org/10.3390/ma15092989

1 Comment

  1. Pressure washing siding

    Excellent items on injection molding materials. Really a wonderful article

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