What is the Easiest Plastic to Injection Mold?

Table of Contents

When it comes to injection molding, the material you choose can make all the difference. The right plastic not only ensures ease of molding but also impacts the quality and efficiency of your final product. So, which plastics are the easiest to work with? Let’s find out.

Key Takeaways

    • Easiest Plastics to Mold: Polyethylene, Polypropylene, ABS, Polystyrene (and more)
    • Material Properties: Viscosity, melting temperature, chemical resistance
    • Expert Tips: Consultation with material experts, supplier engagement
    • Why Material Matters: Affects product quality and production efficiency
    • Challenging Plastics: Polycarbonate, Polyoxymethylene, Nylon

Table 1: Easiest Plastics for Injection Molding

Material Type

Ease of Molding

Melting Point (°C)

Key Properties

Common Uses

Challenges in Molding

Polyethylene (PE)



Low viscosity, chemical resistance

Plastic bags, bottles, pipes


Polypropylene (PP)



Chemical resistance, high tensile strength

Automotive parts, syringes





Mechanical toughness

Lego blocks, electronics


Polystyrene (PS)



Dimensional stability, moisture resistance

Food packaging, medical items


Polycarbonate (PC)



High durability, impact resistance

Durable items

Warping, cracking

Polyoxymethylene (POM)



High stiffness, low friction

Mechanical gears, bearings

High melt viscosity

Nylon (PA)



Strength, durability, chemical resistance

Industrial applications

Moisture absorption

Polyethylene (PE)


Polyethylene is a low-cost plastic material that’s incredibly versatile. It has a low melting point, which ranges from 110 to 115°C, and a low viscosity. 

This makes it easier to flow into molds – even those with intricate designs. 

Additionally, Polyethylene is resistant to most acids and bases, giving it a longer lifespan.


Polyethylene is the most commonly used plastic globally. You’ll find it in a wide array of products, from plastic bags and bottles to heavy-duty industrial pipes. 

Its low cost and ease of molding make it a popular choice for manufacturers across various industries.

Polypropylene (PP)


Polypropylene is another low-cost option but with a higher melting point, usually around 160°C. 

It’s known for its excellent chemical resistance, which means it doesn’t react with most solvents, acids, or bases. 

It also has high tensile strength, making it tough and fatigue-resistant.


Polypropylene is a staple in both consumer and industrial applications. 

It’s commonly used in automotive parts, including bumpers and dashboards. In the medical field, it’s used for syringes and other disposable items. Its chemical resistance also makes it ideal for containers that hold liquid substances. (1)

Acrylonitrile Butadiene Styrene (ABS)


ABS is a terpolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The result is a plastic that is both tough and easy to work with. 

It has a melting point of around 105°C and offers a balanced mix of mechanical toughness, making it easier to mold.


ABS is incredibly versatile. 

You’ll find it in everything from Lego blocks to automotive components. 

It’s also commonly used in consumer electronics – particularly for the outer casings of products like keyboards, mice, and other peripherals.

Polystyrene (PS)


Polystyrene is a rigid plastic that offers excellent dimensional stability.

It has a low melting point of about 100°C, making it easier to mold. 

It’s also highly resistant to moisture, which helps in maintaining its shape and size.


Polystyrene is often used in food packaging, particularly for items like disposable cutlery and plastic cups. It’s also used in the medical field for items like test tubes and petri dishes. 

Its rigidity makes it suitable for these applications – where dimensional stability is crucial. 

Polyvinyl Chloride (PVC)


Polyvinyl Chloride, commonly known as PVC, is a plastic that offers excellent chemical resistance. 

It has a melting point that ranges from 100 to 260°C, depending on whether it’s rigid or flexible PVC. 

One of its standout features is its flame retardancy, which makes it a safer option in certain applications.


PVC is a ubiquitous material. 

In the construction industry, it’s the go-to for pipes and fittings. In healthcare, it’s used in medical devices like tubing and blood bags. The material’s flame-retardant properties also make it ideal for cable insulation.

Polymethyl Methacrylate (PMMA)


Polymethyl Methacrylate, or PMMA, is also known as acrylic. 

This material is prized for its excellent transparency, comparable to that of glass. 

It’s UV-tolerant, which means it doesn’t yellow over time when exposed to sunlight. 

Its melting point is around 160°C, and it offers good weather resistance.


PMMA is often used in applications where clarity and transparency are essential. Think aquariums, motorcycle helmet visors, and even retail displays. 

Its UV tolerance and excellent light transmittance make it a popular choice for outdoor applications as well.

Polyoxymethylene (POM)


Polyoxymethylene, commonly known as POM or Acetal, is a semi-crystalline plastic known for its high stiffness and low friction. 

It has a melting point of around 175°C and offers excellent dimensional stability, which means it doesn’t deform easily under stress.


POM is often used in precision parts that require high stiffness and low friction. 

You’ll commonly find it in mechanical gears, bearings, and fasteners. 

Its dimensional stability makes it ideal for components that need to maintain their shape under varying conditions.

The Most Challenging Plastics to Use In Injection Molding

1. Polycarbonate (PC)

This material is known for its high melting point, which makes it difficult to mold. 

It also has a tendency to warp and crack during the cooling process, which can lead to defects in the final product. 

However, PC is highly durable and has excellent impact resistance, making it ideal for applications that require strength and toughness.

2. Polyoxymethylene (POM)

POM is a high-performance thermoplastic that is often used in industrial applications. 

It has excellent stiffness and dimensional stability, but it can be difficult to mold due to its high melt viscosity.

POM also has a tendency to shrink during the cooling process. This can lead to warping and other defects.

3. Nylon (PA)

Nylon is a popular material for injection molding due to its strength, durability, and chemical resistance. 

However, it can be challenging to mold due to its high melt viscosity and tendency to absorb moisture from the air. Nylon also has a tendency to warp and shrink during the cooling process, which can lead to defects in the final product.


Selecting the right material for injection molding is a critical factor that influences not just the ease of molding, but also the quality and efficiency of the end product. Whether you opt for the versatile Polyethylene or the robust Polyoxymethylene, your choice will significantly impact your project’s success. 

Ready to take your injection molding project to the next level? Consult with the seasoned experts at JDI Plastics and make an informed decision today!


Frequently Asked Questions (FAQs)

  1. What factors should I consider when selecting a plastic for injection molding?
    • Consider the material’s melting point, chemical resistance, and tensile strength.
  2. Is Polyethylene the cheapest option for injection molding?
    • Generally, yes. Polyethylene is often the most cost-effective choice.
  3. Can I use ABS for medical applications?
    • ABS is generally not recommended for medical applications due to its lack of bio-compatibility.
  4. Is PVC safe for food packaging?
    • PVC is generally not used for food packaging due to potential health risks.
  5. What is the most durable plastic for injection molding?
    • Polyoxymethylene (POM) is known for its high stiffness and durability, making it ideal for heavy-duty applications.


  1. Plastics Materials, Professor Marianne Gilbert, https://www.sciencedirect.com/topics/materials-science/plastic-material