Choosing the Right Plastic for Injection Molding | Expert Insights

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Plastic for injection molding machine
Plastic for injection molding machine


There are a lot of reasons responsible for the success or failure of any injection molding project a critical one being the selection of the right plastic for injection molding. While there are several technical factors to consider during an injection molding process, using the wrong plastic material can be very costly. It can result in defects in the end product, or it may even affect the integrity and quality intended by the designer for the product. It’s no fluke that plastic molding engineers take great care in choosing a befitting plastic material to suit the intention of the designer for the product. So if you are interested in understanding the impact of choosing the right or wrong plastic material for your project then this article is for you. We delve deep into these impacts, including the different types of plastic materials that injection molding experts often turn to when they require certain properties in the final plastic part. So strap up as we delve in together. 

Plastic pellets for injection molding
Plastic pellets for injection molding

2. The Significance of Material Selection

The potential for full functionality and optimum visual appeal of a plastic product is often determined by the properties of the plastic material used in its manufacture. Consequently, using a very soft plastic material while expecting to get a rigid and strong plastic product may be considered daydreaming. However, having an understanding of the full extent to which material can affect the property of the final plastic part can help designers and engineers choose the most favorable material for their project. 

Imagine the cost of inefficient plastic production and rework as a result of using the wrong plastic material. This cost can be huge considering that most plastic production is done in high volume. also, the mechanical properties, environmental impact, and product durability are all impacted by the choice of material employed in the plastic injection molding process. Hence, manufacturers have the obligation to ensure that the right plastic material is always used to avoid huge losses at any given point.

Additionally, different plastic material have their strong points especially when it comes to the properties required by design for the final product. Depending on the product, properties such as chemical resistance, tensile strength, and thermal resistance are some common desired product qualities.  For instance, electronic and consumer goods often require a combination of aesthetic appeal and strength which can be found in materials like acrylonitrile butadiene styrene (ABS). in contrast, products that receive high-impact stresses like automotive and aerospace components often prefer materials like polyoxymethylene (POM) and high-impact polystyrene (HIPS). 

3. Common Injection Molding Materials

When it comes to high-quality mold manufacturing and plastic parts manufacturing the margin of error is slim regardless of the industry. This is considering that this production is often done en mass and any wrong decision can be very costly. With this realization, manufacturers often have to be very accurate when choosing a plastic material that will represent the design parameter. To make this precise decision, knowing the various plastic materials available for producing plastic products is often the most important thing for manufacturers and engineers. Let’s highlight some of the most common of these plastic materials. 

1. Acrylonitrile Butadiene Styrene (ABS): With its outstanding combination of durability, visual appeal, and strength, ABS is usually a preferred molding material among injection molding industry experts. It has applications across several industries including automotive, electronics, and consumer goods. 

2. Polypropylene (PP): While it is often chosen for its lightweight, PP’s phenomenal ability to resist chemical impact is also very admirable, especially for packaging and medical applications. 

3. Polycarbonate (PC): For industries like automotive and electronics that require the perfect blend of both transparency and strength, polycarbonate material is often preferred. Components like car headlights, and camera lenses are some popular applications of this material. 

4. Polystyrene (PS): When a combination of lightweight and easy handling are the critical production requirements, polystyrene materials always come in handy. They are the raw materials for producing components like disposable cups and plates, cosmetics containers, and packing containers. 

5. High-Impact Polystyrene (HIPS): As the name implies, HIPS is particularly potent for resisting high-impact stresses without a noticeable dent or damage to its core. Its strength and affordability make it especially useful for producing consumer electronics and food packaging. 

6. Polyoxymethylene (POM): Not forgetting the star of low friction, polyoxymethylene is a friction-resistant material coupled with its ability for consistent dimension makes it suitable for mechanical elements including bearings and gears. 

7. Thermoplastic Polyurethane (TPU): This flexible material also combines the advantages of strength and durability. Its application includes tubings, phone cases, and door lips where elasticity and strength are critical. 

Plastics And Polymers
Plastics And Polymers

4. Material Properties and Considerations

Using material properties as a yardstick for choosing a suitable production material is a standard production process. This process is even critical for injection molding considering that it directly affects the quality and outlook of the product. Here we delve into some of the essential material properties that determine the functionality and visual of the product. 

  • Impact Strength: The ability of the product to resist impact is often one of the most critical considerations during design. This is because a beautiful product that cannot handle normal stresses when in use will only bring dissatisfaction to the user. Consequently, designers often prefer materials such as PC and ABS when the product is required to resist cracks and absorb shocks.
  • Tensile Strength: When plastic components are subjected to loads or forces, the tendency is for them to expand until the load is lifted. This ability which is also known as tensile strength is more in some plastic materials than others and designers often choose materials like TPU with an outstanding tensile strength when they need parts to resist tension. 
  • Heat Resistance: When you have plastic elements that are likely to be subjected to extreme temperatures for extended periods, the need for heat-resistant materials becomes necessary. POM and PC are some of the most suitable materials in this regard seeing that they retain their structural consistency in the face of extreme temperatures. 
  • Chemical Resistance: For plastic bottles and containers that are used for storing chemicals, being able to stay unreactive to the chemical is an important feature. For this use case, POM and PP are some of the materials that designers often prescribe as they do a good job without interfering with the chemicals they hold. 

This understanding will empower you to choose the right plastic, ensuring your molded parts not only meet but exceed the expectations of your project.

5. Surface Finishes and Material Selection

Aside from technical requirements like tensile strength and impact resistance that guarantee the structural integrity of plastic products, aesthetic considerations are also very important. Especially for products that rely heavily on visual appeal rather than functionality for sales, taking a careful look at the design to make it more pleasing to the eye will be pragmatic.  

But what does all this have to do with choosing a plastic material?

Well, everything.

You see, there are plastic materials that enhance the surface finish of a product with a sleek and polished feel. Whereas there are others that guarantee firm grips with a textured surface finish. So, choosing a rough textured material where a polished surface is required will only defeat the aesthetic purposes of the product. 

For instance, adopting a material like ABS will guarantee a sleek glossy surface finish that you’ll often see on phone cases and other electronics. However, a high-impact polystyrene material will only yield a matt textured surface often required for firm grips in components like point-of-sales displays. It’s all different strokes for different flexes. 

The texture and surface finish of your product can impact its visual appeal, grip, and functionality. Consider the tactile experience of a smartphone case or the visual allure of a cosmetic container. The choice of material can enhance or detract from these qualities.

When selecting plastics in the high-quality mold manufacturing industry, and for your injection molding project, it’s essential to align your material choice with your desired surface finish.  and for your injection molding project, it’s essential to align your material choice with your desired surface finish. 

6. Expert Insights in Material Selection

While many individuals are injection molding enthusiasts embarking on DIY projects due to the availability of compact and efficient machines, the insights of experts are still always needed. This often clears any doubt and removes the time-wasting that accompanies experimenting for many newbie injection molding fans. They’ve gone through those treacherous injection molding terrains and know how best to navigate them safely. 

Most importantly when selecting a suitable plastic material for your injection molding project, an expert such as a plastic molding engineer or designer can be of tremendous help. It’s like having a trusted guide that can help you examine the peculiar needs of the project and come up with a suitable plastic material. The place of the expert is to consider all necessary factors such as budget, mechanical and aesthetic requirements, as well as environmental impacts. These factors help in identifying the plastic material that is the best fit for the project. 

The extensive experience of experts also helps beyond the theoretical knowledge of injection molding. Their wide experience makes them an authority in the operation of injection molding machines along with other ones like high-quality CNC machining while looking out for likely potholes in the process. 

What’s more, they understand the strengths and weaknesses of every plastic material as they worked with them for so long which gives them vital firsthand practical wisdom in selecting the right plastics. 

Plastics for phone manufacturing
Plastics for phone manufacturing

7. Injection Molding Materials vs. Application

If you can compare injection molding to tailoring then selecting a suitable fabric for a custom-made suit aptly describes the selection of a plastic material for a bespoke injection molding project. The strengths and seeming weaknesses of different plastic materials make them suitable for a certain type of application and not for another. Check out these common plastic materials and their different applications across various industries.  

  • ABS for Consumer Goods: When it comes to consumer goods Acrylonitrile butadiene styrene (ABS) is the GOAT (Greatest Of All Time) in the plastic material realm. Its rare marriage of durability, visual appeal, and strength make it the darling of injection molding designers and specifiers. Its application includes kitchen appliances, phone cases, and toys. You can count on ABS to deliver when you need it just like a dependable friend. 
  • Polycarbonate for Optical Clarity: in dark situations when you are in need of a transparent material to allow for light passage, polycarbonate materials always come through. Its unique combination of sturdiness and transparency makes it the best fit for medical devices, lenses, and car headlight covers. 
  • Polyoxymethylene for Gears: POM is another unique plastic material often preferred for its reduced friction and dimensional consistency which does not require additional methods like 3D printing technology. It is a sought-after material for creating gears and bearings, especially in the automotive industry. 
  • Thermoplastic Polyurethane for Flexibility: TPU is yet another incredibly phenomenal plastic material especially useful for its flexibility and elasticity. It is often required in designs where resistance to tensile stress is critical for instance in shoe soles. 

Just like in a symphony where every note is precious and should be accurate, likewise in injection molding where matching a plastic material with the correct application must be done with precision. 

8. Material Sustainability and Environmental Impact

Many manufacturers drop the ball once the technicalities of manufacturing plastic products are over. For them, these only include the mechanical properties and aesthetics that make the product functional and attractive. Some never consider the negative impact of plastic waste on the environment even in this modern world where greenhouse gases are causing huge climate changes. Selecting suitable materials for your project should not be the end of your concerns, rather using these materials responsibly should be the focus. 

Thankfully, modern material science is providing some innovative ways of recycling and reusing plastic waste materials. Plastics including high-impact polystyrene (HIPS) and polypropylene (PP) often find preference for their reusability and reduced environmental footprint. Preferring these materials over other plastic materials with no recyclable option makes you a contributor to the sustainability of the environment. 

However, a holistic approach to environmental sustainability in injection molding projects should be the goal of every plastic manufacturer. A critical look at the injection molding process usually leaves an opportunity for optimizing the process for low energy consumption that reduces carbon footprints. Also, you can choose materials that have minimal wastage and low emissions during the production process. In all the entire lifecycle of the plastic material from manufacturer to disposal is crucial and should be examined for optimization opportunities. 


The quest to always find the right plastic for injection molding projects is one that is continuous. This is even truer with advancements in technology constantly finding innovative materials to make things faster and better. Nevertheless, the facts highlighted in this piece remain instructional but can be of tremendous help whenever you embark on a new plastic molding project. Always remember that the properties of the plastic raw materials significantly determine how the final product will come out. And depending on the desired outcome which is often guided by the design your most critical requirement should be your priority. This can either be the mechanical properties including strength, and impact resistance or it may simply be the surface finish. Whatever the case ensure to always use plastic material responsibly for a sustainable environment. 


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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