ABS Vs Polypropylene: Choose The Right Plastic For CNC Parts

The Problem: Selecting the Right Plastic Material

Are you confused about which plastic to pick for your next project? You are not alone! Many of our customers at Istar Machining face a big challenge when choosing between ABS and Polypropylene (PP) for their CNC machined parts. Using the wrong plastic can lead to:

Parts that break too easily
Pieces that melt when hot
Products that fail when exposed to chemicals
Money wasted on remakes

Why This Choice Matters Even More Than You Think

Think about it. Your final product is only as good as the materials you choose. When a plastic part fails in the field, it’s not just the part that’s at risk – it’s your whole product and reputation. Picture this: You’ve spent months designing a medical device that needs to be sterilized regularly.

If you pick ABS instead of PP, your device could warp or break down after just a few cleaning cycles. Your customers will be upset, and you might even face safety recalls! Or imagine making automotive parts that sit under the hood where temperatures get high.

The wrong plastic choice could mean part failure and expensive warranty claims. At Istar Machining, we see these issues all too often when customers come to us for help after choosing the wrong material.

The Solution: Expert Material Selection Based on Data

The good news? With the right information and a trusted CNC machining partner, you can make smart material choices that save money and make better products. Our team at Istar Machining has created this complete guide to help you understand the key differences between ABS and Polypropylene so you can make the best choice for your specific needs.

ABS vs. Polypropylene: The Basic Facts

Before diving deep, let’s understand what these materials really are:

ABS (Acrylonitrile Butadiene Styrene)

ABS is made from three different chemicals that give it special properties:

Acrylonitrile – provides strength
Butadiene – adds toughness
Styrene – gives rigidity

Polypropylene (PP)

PP is more simple – it comes from propylene and has a semi-crystalline structure that gives it different properties than ABS.

Key Differences: ABS vs. Polypropylene

Let’s look at the most important differences that will affect your decision:

Strength and Toughness Comparison

Property	ABS	PP	Best For
Tensile Strength	40-50 MPa	25-35 MPa	ABS
Impact Strength	200-400 J/m	20-100 J/m	ABS
Flexibility	More rigid	More flexible	Depends on need

ABS is the stronger option if you need parts that can take a beating or handle high impact. This is why LEGO bricks are made from ABS – they can be stepped on and still not break! [^1] PP bends more before breaking, which makes it better for living hinges or parts that need to flex many times without cracking.

Temperature Performance

Property	ABS	PP	Best For
Heat Resistance	Up to 96°C	Up to 110°C	PP
Cold Resistance	Gets brittle when cold	Stays flexible in cold	PP

If your parts will be in hot places or need to be sterilized with heat, PP is usually the better choice. PP keeps its shape at higher temperatures, while ABS might warp or deform. [^2]

Chemical Resistance

Chemical Type	ABS Performance	PP Performance
Acids	Poor resistance	Excellent resistance
Bases/Alkalis	Poor resistance	Excellent resistance
Solvents	Poor resistance	Good resistance
UV Light	Yellows and degrades	Better UV stability

PP is much better with chemicals, which is why it’s used for laboratory equipment and medical tools. ABS will break down when exposed to many chemicals. [^3]

Cost and Weight

Factor	ABS	PP	Difference
Cost per kg	$2.50-$3.50	$1.80-$2.20	PP is ~20% cheaper
Density	1.02-1.04 g/cm³	0.89-0.91 g/cm³	PP is ~15% lighter

PP is both cheaper and lighter than ABS. For large production runs or weight-sensitive applications, these differences can add up to big savings.

Best Applications for Each Material

Based on their properties, here’s where each material shines:

When to Use ABS:

Automotive interior parts – dashboards, trim pieces
Consumer electronics – housings, cases
Toys – building blocks, durable toys
Prototypes that need good surface finish At Istar Machining, we regularly CNC machine ABS for customers who need strong parts with good cosmetic appearance.

When to Use Polypropylene:

Medical devices that need sterilization
Food containers and packaging
Chemical storage containers
Outdoor applications exposed to weather Our custom plastic machining services can help you create perfect PP parts for these applications.

Machining Considerations: What You Need to Know

The material you choose affects how we will machine your parts:

Machining ABS:

Good dimensional stability
Easy to machine with sharp tools
Excellent surface finish
May need cooling during high-speed operations
Can be glued and bonded easily

Machining Polypropylene:

More flexible – may need special fixturing
Can be difficult to hold tight tolerances
Not as easy to get a smooth finish
Harder to bond or glue
May gum up tools if machined too fast At Istar Machining, we have extensive experience with both materials and know exactly how to adjust our CNC settings for perfect results every time.

Real-World Case Studies

Case Study 1: Automotive Dashboard Components

A customer came to us needing parts for a car dashboard. They initially considered PP for cost savings, but after consulting with our team, they chose ABS instead. Why?

The parts needed high impact resistance
Good surface finish was critical
Parts needed to snap together without breaking
Temperature requirements were moderate The result: Parts made from ABS have performed perfectly for over 5 years in the field with zero failures.

Case Study 2: Medical Device Housing

A medical equipment manufacturer needed housings for a device that would be cleaned with strong chemicals daily.

Initially considered ABS for better appearance
Our team recommended switching to PP after learning about the chemicals used
Design was modified to improve the appearance of the PP parts The result: The customer avoided a costly mistake, and their product has successfully passed all regulatory requirements for chemical resistance.

Environmental Considerations

Factor	ABS	PP	Better Option
Recyclability	Recyclable but less common	Widely recycled (#5 code)	PP
Energy to Produce	Higher	Lower	PP
Biodegradability	Not biodegradable	Not biodegradable	Equal

PP is generally considered the more environmentally friendly option because it’s widely recycled and takes less energy to produce. [^4]

How to Make Your Final Decision

Still not sure which material to choose? Follow these steps:

List your requirements
- What temperatures will the part face?
- Will it be exposed to chemicals?
- How strong does it need to be?
- What’s your budget?
Ask for samples
- At Istar Machining, we can provide material samples so you can test them yourself
Consider a prototype
- We offer rapid CNC prototyping to test your design in both materials
Consult with experts
- Our engineering team can help analyze your specific needs

Frequently Asked Questions

Can PP replace ABS in automotive parts?

It depends on the specific part. PP works well for fluid reservoirs and some interior components, but ABS is usually better for structural or visible parts where appearance and impact resistance matter.

Which is better for medical devices?

PP is generally preferred for medical applications because it can withstand sterilization and has better chemical resistance. However, ABS may be used for parts that don’t require frequent cleaning.

Does ABS warp more than PP?

Yes, ABS has a lower heat deflection temperature and is more prone to warping when exposed to heat. PP maintains its shape better at higher temperatures. [^5]

Which is easier to paint?

ABS accepts paint much better than PP. PP often requires special primers or surface treatments before painting.

Why Choose Istar Machining for Your ABS or PP Parts?

At Istar Machining, we specialize in precision CNC machining of both ABS and PP materials. Our advantages include:

Material expertise – We’ll help you choose the right plastic
Precision machining – Tight tolerances on even the most complex parts
Quick turnaround – Fast production when you need it
Quality control – Every part inspected before shipping
Custom finishing – Surface finishes to match your exact needs

Take the Next Step

Don’t let material selection challenges hold back your project. Contact Istar Machining today for expert advice on choosing between ABS and PP for your specific application. Request a quote online or call us to discuss your project requirements. Our team is ready to help you make the perfect material choice and deliver flawless CNC machined parts on time and on budget.

Conclusion

Choosing between ABS and Polypropylene doesn’t have to be difficult. By understanding the key differences in strength, temperature resistance, chemical compatibility, and cost, you can make an informed decision that will lead to successful products. Remember these key points:

ABS excels in strength, appearance, and impact resistance
PP wins for chemical resistance, temperature stability, and cost At Istar Machining, we’re committed to helping you navigate these choices and producing the highest quality CNC machined parts for your projects. Contact us today to start your next project with confidence!

[^1]: Data from Protolabs materials comparison guide, 2023 [^2]: Based on heat deflection temperature testing at 0.46 MPa [^3]: Results from chemical resistance testing conducted by UVTeco Labs [^4]: Environmental data from EPA recycling guidelines, 2024 [^5]: Thermal performance testing by Ryd Tooling materials research