Discover AIP’s process of machining RADEL PPSU plastics in this informational polymer machining guide.

1. Machining RADEL: A Plastics Guide
An Informational Brief on Polymer Machining

2. AIP’S EXPERIENCE
RADEL is a PPSU (or Polyphenylsulfone) widely
considered to be the highest-performing of Solvay’s
sulfone polymers. It’s no surprise then that we’ve
regularly machined RADEL at AIP Precision Machining
over the past three decades.
With superior impact strength and outstanding resistance
to stress cracking, RADEL offers exceptional hydrolytic
stability and toughness across a wide temperature
range, making it a favorite of the medical, electronics
manufacturing, and aerospace industries.
AIP has over 35 years of experience machining complex
components from RADEL and various other
thermoplastic materials. We are providing this Machining
RADEL as yet another insightful technical brief about our
polymer component manufacturing process, and how it
differs from that of metal machining, injection
molding, or 3D printing.
2

3. THERMOPLASTICS VS. THERMOSETS
Plastic CNC machining is affected by what type of material you’re
machining. Technical expertise is key to polymer machining, which is why you
have to know the polymer structure and properties of RADEL before
machining it.
There are two basic types of polymers: thermoplastics and thermosets.
Thermoplastics soften in heat and become more fluid, while thermosets
cross-link during curing, which eliminates the risk of a product re-melting in
heat. Since these categories react differently to chemicals and temperature,
it’s important to know that RADEL is a thermoplastic.
To be specific, RADEL PPSU is an amorphous, high-performance
thermoplastic that is lightweight, available in bone-white or black colors and
can be either transparent or opaque. Like other amorphous thermoplastics,
such as ULTEM, RADEL is thermoform capable, translucent and easily
bonded with adhesives or solvents.
3

4. PROPERTIES & GRADES OF MACHINED
RADEL
RADEL’s reputation as a high-performance thermoplastic is well deserved. RADEL
PPSU has an impressive heat deflection temperature of 405°F (207°C) and is
inherently flame retardant with low NBS smoke evolution, making it ideal material
choice for aircraft interiors. In addition, its retention of mechanical properties is
superior to all other amorphous transparent polymers.
With improved impact and chemical resistance over PSU and PEI, RADEL PPSU
has been tested for notched izod impact resistance as high as 13 ft.-lbs/in. It can
endure over 100 joules of force without shattering, even with repeated exposure to
moisture and extreme temperatures.
4

5. PROPERTIES & GRADES OF MACHINED
RADEL
These inherent qualities allow RADEL PPSU to withstand unlimited steam
autoclaving and provide RADEL with excellent resistance to EtO, gamma, plasma
and chemical sterilizations as well. Unsurprisingly, its extreme thermal properties
make RADEL ideal for reusable medical instruments and other applications where
sterilization is key.
Not all grades of RADEL PPSU share the same exact properties, of course.
Choosing the grade of your material that best meets your needs is an important
part of AIP Precision Machining’s expert material knowledge.
One grade of RADEL PPSU we machine regularly at AIP Precision Machining is
RADEL R5500.
5

6. GRADES OF MACHINED RADEL
RADEL R5500
RADEL R5500 is a unique polymer grade
that meets the stringent aircraft flammability
requirements of 14CFR Part 25, while also
being a biocompatible, medical-grade resin
that is FDA and NSF approved for food and
beverage contact. From that, it’s clear that
RADEL R5500 can be used for a wide range
of applications, whether it’s for aircraft
interiors, electronic burn-in sockets or
surgical instruments. RADEL R5500 can be
polished to a mirror finish and is available in
both opaque and transparent colors.
6

7. MACHINING RADEL PPSU
Annealing RADEL PPSU
RADEL PPSU, like many polymers, can be received in the form of rods, sheets, tube or
film. As we mentioned before, amorphous thermoplastics like RADEL are especially
sensitive to stress-cracking, so stress-relieving through an annealing process is highly
recommended before machining.
Annealing RADEL greatly reduces the likelihood that surface cracks and internal
stresses will occur from the heat generated. Post-machining annealing also helps to
reduce stresses that could potentially contribute to premature failure.
If the machine shop you are working with does not have a computer controlled annealing
oven for plastics, then “head for dee hills” as they are obviously not RADEL machining
experts.
7

8. MACHINING RADEL PPSU
Machining RADEL PPSU
Non-aromatic, water soluble coolants are most suitable for ideal surface finishes and
close tolerances. These include pressurized air and spray mists. Coolants have the
additional benefit of extending tool life as well.
Many metal shops use petroleum-based coolants, but these types of fluids attack
amorphous thermoplastics like RADEL PPSU. Many past experiences have shown parts
going to customer without cracks, only to develop cracks over time due to exposure to
metal machine shop fluids. Be sure to use a facility like AIP who machines polymers and
only polymers.
8

9. PREVENTING CONTAMINATION
Contamination is a serious concern when
machining polymer components for
technically demanding industries such as
aerospace and medical. To ensure the
highest level of sanitation down to the sub-
molecular level, AIP Precision Machining
designs, heat-treats and machines only
plastics, with any sub-manufactured
metalwork processed outside our facility.
This minimizes the potential for metallic
cross contamination.
9

10. RADEL Machining Guide: Supportive
Information
10
Supportive Guides
• Medical Sector Biomaterials Guide
• Energy Sector Materials Guide
• Aerospace Sector Materials Guide
• Amorphous Materials
AIP has well over three decades of expertise with thermoplastic materials,
and understands how plastics react when machined.
We are one of a very select few companies able to hold incredibly tight
tolerances in plastic parts. AIP has been successfully audited by some of
the most stringent OEMs and are ISO 13485:2016, ISO 9001:2015, IS9100
and FDA registered.

11. Let’s get started.
11
Any Product Puzzle.
Any Customer Challenge.
AIP is the niche that you need for all of your plastic parts.
724 Fentress Boulevard, Daytona Beach 32114
+1 386.274.5335
AIP.Sales@AIPprecision.com
AIPprecision.com