Custom PBT CNC Machining Services in China
Machining High-Performance Electrical Insulators, Connectors, and Dimensionally Stable Components.
- ISO 9001 Certified
- Excellent Electrical Properties
- High-Stiffness & Low Creep
Your Expert Partner for PBT Machining
Celerity Precision is a specialized manufacturer in China offering high-precision CNC machining of PBT (Polybutylene Terephthalate). PBT is a high-performance, semi-crystalline engineering thermoplastic from the polyester family, renowned for its exceptional combination of stiffness, dimensional stability, and excellent electrical insulating properties. It is a material of choice for demanding applications in the automotive and electronics industries, often used for connectors, sensors, and housings that require long-term reliability. Machining PBT, especially glass-filled grades, requires robust tooling and expertise. Our facility is well-equipped to machine PBT to tight tolerances, delivering parts with superior performance and a high-quality finish.
Why Choose PBT for Your Machined Parts?
PBT offers a compelling set of properties that make it a superior choice over many standard plastics for electronic and structural applications. It has very low moisture absorption, which ensures that its mechanical and electrical properties remain stable even in high-humidity environments. Its high strength and stiffness, combined with good chemical resistance, make it a durable and reliable material. At Celerity Precision, we have extensive experience in machining PBT, using specialized techniques to manage its characteristics and produce dimensionally accurate, high-integrity components.
Excellent Electrical Insulating Properties
High dielectric strength and insulating resistance, which are stable over a wide range of temperatures and humidity.
High Strength & Stiffness
A strong, rigid material that resists flexing and creep, even at elevated temperatures.
Outstanding Dimensional Stability
Very low moisture absorption ensures that parts hold tight tolerances and do not swell.
Excellent Wear & Fatigue Resistance
Resists wear, abrasion, and failure under cyclic loading, making it ideal for dynamic parts.
Good Chemical Resistance
Resistant to a wide range of solvents, automotive fluids, oils, and greases.
Good Heat Resistance
Has a high continuous service temperature, outperforming plastics like ABS and Nylon.
Unfilled PBT
This grade offers the best ductility and a good overall balance of properties. It is easy to machine and provides a high-quality surface finish. It is typically available in natural (white) and black.
| Tensile Strength, Yield (MPa) | 55 MPa |
| Elongation at Break (%) | 50-150% |
| Hardness (Brinnell) | 68 |
| Density (g/cm³) | 1.31 |
30% Glass-Filled PBT
The addition of glass fibers dramatically increases the strength, stiffness, heat resistance, and dimensional stability of PBT, making it a true metal-replacement material for many structural applications.
| Tensile Strength, Yield (MPa) | 120 MPa |
| Elongation at Break (%) | 2-3% |
| Hardness (Brinnell) | 90 |
| Density (g/cm³) | 1.52 |
Surface Finishing Options for PBT
PBT’s chemical resistance limits the types of finishes that can be applied. It is most often used in its as-machined state.
As machined
This is the most common and typically the final finish. PBT machines to a very smooth, clean, semi-gloss surface.
Polishing
A very light vapor polish can be used to enhance the surface gloss, but care must be taken.
Pros and Cons of PBT CNC Machining
Pros
- Superior Electrical Insulator: The top choice for high-performance connectors, switches, and bobbins.
- Dimensionally Stable: Low moisture absorption and low thermal expansion ensure it holds tolerances extremely well.
- Strong and Stiff (especially glass-filled): Can replace metals in many structural applications, offering weight savings.
- Good Chemical Resistance: Resists damage from fuels, oils, and cleaning agents.
Cons
- Brittle (especially glass-filled): Not as tough or impact-resistant as plastics like ABS or PC. Can be prone to chipping during machining if not handled correctly.
- Poor UV Resistance: Not suitable for long-term outdoor use unless it is a UV-stabilized or black grade.
- Abrasive (glass-filled): Glass-filled grades are very abrasive and cause rapid tool wear, which can increase machining costs.
- Prone to Warping: Can be susceptible to warping due to internal stresses if not machined with proper techniques and stress-relieving procedures.
Applications of CNC Machined PEEK Parts
Electronics
Electrical connectors, switch components, coil bobbins, sockets, and sensor housings.
Automotive
Housings for electronic control units (ECUs), ignition system components, and lamp sockets.
Industrial
Pump housings, gears, bearings, and components for fluid handling systems.
Medical
Housings and components for medical devices that require stiffness and chemical resistance.
Consumer Goods
Housings for small appliances like coffee makers and irons, and handles for cookware.
Prototyping
Creating functional prototypes for parts that will eventually be injection molded from PBT.
PBT Machining FAQ
What is the main difference between PBT and PET?
They are both polyesters and have similar properties. PBT is generally easier to process and has better impact strength and electrical properties. PET is typically stronger and stiffer. For machining, PBT is more common.
Why choose PBT over a material like POM (Delrin)?
Choose PBT when you need better electrical insulating properties and higher heat resistance. POM has better natural lubricity and wear resistance for mechanical sliding parts, but PBT is superior for electronic and high-temperature structural applications.
What does "glass-filled" mean and why is it used?
“Glass-filled” means that small glass fibers are mixed into the plastic resin. This dramatically increases the material’s strength, stiffness, and heat resistance, making it behave more like a metal.
Is PBT a good material for outdoor use?
No, standard PBT has poor resistance to UV radiation from the sun and can become brittle over time. A black or specially formulated UV-stabilized grade must be used for outdoor applications.
Can PBT be glued?
It is difficult to glue due to its chemical resistance. It requires surface preparation and specialized adhesives like epoxies or urethanes. It does not solvent-weld like ABS or HIPS.
Is PBT a good electrical insulator?
It is an excellent electrical insulator. Its high dielectric strength and the stability of its insulating properties in humid or high-temperature conditions are primary reasons for its use in electronics.
How do you machine glass-filled PBT without it chipping?
We use very sharp, hard cutting tools (like carbide), maintain high spindle speeds, and use specific toolpaths to minimize cutting pressure and prevent chipping at the edges of the cut.
Is PBT food safe?
Specific FDA-compliant grades of PBT are available for applications in the food processing industry.