Custom PP (Polypropylene) CNC Machining Services in China
Machining Lightweight, Chemically Resistant, and Tough Components for Industrial and Fluidic Systems.
- ISO 9001 Certified
- Excellent Chemical Resistance
- Natural & Black Grades
Your Expert Partner for Polypropylene Machining
Celerity Precision is a leading manufacturing service provider in China specializing in the CNC machining of PP (Polypropylene). Polypropylene is a versatile and cost-effective semi-crystalline thermoplastic, celebrated for its outstanding chemical resistance, high toughness, and very low density. It is the material of choice for applications involving the storage and transport of corrosive fluids, as well as for parts that require durability and light weight. From industrial tanks and chemical processing equipment to medical components and automotive parts, machining PP requires careful technique to manage its flexibility. Our facility is expertly equipped to machine Polypropylene, delivering dimensionally accurate and reliable components for your specific needs.
Why Choose Polypropylene for Your Machined Parts
Polypropylene offers a unique and valuable set of properties, chief among them being its near-universal chemical resistance. It is an excellent choice for any part that will be exposed to a wide range of acids, bases, and organic solvents. Furthermore, its ability to be bent repeatedly without breaking (high fatigue resistance) allows for the design of “living hinges.” While its softness and high thermal expansion can make it challenging to machine to very tight tolerances, Celerity Precision employs sharp tooling, high machine speeds, and proper support to create clean, precise, and functional Polypropylene parts.
Exceptional Chemical Resistance
Resistant to a very broad spectrum of acids, bases, and solvents, making it ideal for fluid handling.
Very Lightweight
One of the lowest density plastics, offering significant weight savings.
High Toughness & Fatigue Resistance
Durable and resistant to cracking from repeated stress or bending.
Zero Moisture Absorption
Does not absorb water, ensuring it is dimensionally stable in wet environments.
Good Electrical Insulator
A reliable insulating material for electrical components.
Cost-Effective
An affordable material, providing excellent performance for its price.
Homopolymer Polypropylene (PPH)
This is the standard, most widely used grade. It offers high stiffness, good strength, and excellent chemical resistance, making it a great choice for structural and chemical-contact applications. It is available in natural (a translucent white) and black.
| Tensile Strength, Yield (MPa) | 35 MPa |
| Elongation at Break (%) | 100% |
| Hardness (Brinnell) | 92 |
| Density (g/cm³) | 0.91 |
Surface Finishing Options for Polypropylene
Due to its high chemical resistance and low surface energy, PP is very difficult to finish, paint, or glue. It is almost always used in its natural, as-machined state.
Pros and Cons of Polypropylene CNC Machining
Pros
- Superior Chemical Resistance: The number one advantage, making it the best choice for chemical tanks, fittings, and lab equipment.
- Excellent Durability: High toughness and fatigue resistance mean it won't easily break or crack.
- Lightweight and Buoyant: Its low density makes it easy to handle and it will float in water.
- No Water Absorption: Perfect for submerged or high-humidity applications as its properties will not change.
Cons
- Difficult to Machine to Tight Tolerances: Its softness, flexibility, and high thermal expansion make it challenging to hold very tight tolerances compared to rigid plastics like POM or PEEK.
- Very Difficult to Bond or Paint: The waxy, chemically inert surface makes it nearly impossible to glue or paint effectively without extensive surface preparation.
- Poor UV Resistance: Natural (unpigmented) grades have poor resistance to sunlight and will degrade outdoors. Black grades offer much better UV stability.
- Low Temperature Strength: Its strength and stiffness decrease significantly at elevated temperatures.
Applications of CNC Machined Polypropylene Parts
Chemical & Fluid Handling
Tanks, manifolds, pump components, valve bodies, and nozzles.
Medical & Laboratory
Lab equipment, instrument trays, and components for diagnostic devices (medical grades).
Industrial
Components for clean rooms, insulators, and parts for wet processing equipment.
Automotive
Components for handling automotive fluids and battery casings.
Prototyping
Creating durable, functional prototypes for fluidic systems or parts requiring high toughness.
Living Hinges
Machining one-piece parts that have an integrated, flexible hinge.
Polypropylene Machining FAQ
What is the main difference between Polypropylene (PP) and Polyethylene (PE)?
They are very similar, but PP is generally stiffer, harder, and has a higher melting point, making it better for structural parts that need to withstand higher temperatures. PE (especially LDPE) is more flexible.
Why is it difficult to hold tight tolerances when machining PP?
PP has a high coefficient of thermal expansion, meaning it expands and contracts significantly with temperature changes during machining. It is also flexible, so it can deflect under tool pressure. We use specialized techniques to manage these challenges.
Can you glue Polypropylene parts together?
It is extremely difficult with standard adhesives. It requires specialized industrial primers and adhesives. For strong, permanent joints, plastic welding is the recommended method.
Is Polypropylene food safe?
Many natural (unpigmented) grades of homopolymer PP are FDA compliant and widely used for food containers and processing equipment.
What is a "living hinge"?
A living hinge is a very thin section of plastic that connects two larger sections, acting as a hinge. Polypropylene’s excellent fatigue resistance allows it to be bent back and forth millions of times without breaking, making it the perfect material for this design feature.
Does Polypropylene have good UV resistance?
Natural PP does not. It will become brittle with prolonged sun exposure. For outdoor applications, a black, UV-stabilized grade must be used.
How do you machine PP without it melting or getting "gummy"?
The key is heat management. We use extremely sharp cutting tools (often with a high rake angle for a shearing action), very high machine speeds, and effective cooling to remove material and heat before it has a chance to build up and melt.
What colors is Polypropylene available in?
The standard stock colors for machining are natural (a translucent, milky white) and black.