An Informational Brief on Polymer Machining

 

Vespel Polyimide (PI) is a high-performance polymer frequently machined for end-use in aerospace, semiconductor and transportation technology. This material thrives in extreme environments with high strength, chemical resistance, high temperatures, and a low coefficient of friction. It also has impressive sealing and wear properties.

Our latest machining guide discusses what goes into machining Vespel and how its considerations differ from other manufacturing options such as metal machining, injection molding, and 3D printing.

How does AIP approach Vespel and its machining process? To start, we’ll explain the difference between machining PI, a thermoplastic, and machining thermosets.

 

Machining Thermoplastics vs Thermosets

 

We’ve already said that Vespel is a thermoplastic, but what does that mean exactly?

All polymers can more or less be divided into two categories: thermoplastics and thermosets. The main difference between them is how they react to heat. Thermoplastics like Vespel, for example, melt in heat, while thermosets remain “set” once they’re formed. Understanding the technical distinction between these types of materials is essential to CNC machining them properly.

What type of thermoplastic is Vespel in particular? PI is a semi-crystalline engineering thermoplastic, meaning its molecular structure is highly ordered.

 

Properties & Grades of Machined Vespel

 

Combining heat resistance, lubricity, dimensional stability, chemical resistance and creep resistance, Vespel works well in hostile and extreme environmental conditions. Vespel is able to overcome severe sealing and wear. As we mentioned before, these properties allow Vespel to be commonly machined for semiconductors and transportation applications.

Unlike most plastics, Vespel doesn’t produce significant outgassing, even at high temperatures. This makes it useful for lightweight heat shields and crucible support. Vespel also performs well in vacuum applications and extremely low cryogenic temperatures. However, it does absorb a small amount of water, which results in a longer pump time while placed in a vacuum.

Although there are polymers that surpass individual properties of this polyimide, the combination of these factors is Vespel’s primary advantage.

We regularly machine various grades of Vespel at AIP Precision Machining, including the Vespel SP and Vespel SCP family of products from DuPont. The former group is known for their durability and exceptional thermal resistance, while the latter is known for its mechanical properties and thermal stability.

 

Machining Vespel

 

Annealing Vespel

The process of annealing and stress-relieving Vespel reduces the likelihood of surface cracks and internal stresses occurring in the material. Post-machining annealing also helps to reduce stresses that could potentially contribute to premature failure.

 

Machining Vespel

 

Vespel offers ease of machining and tight tolerances due to its inherent mechanical strength, stiffness and dimensional stability. Machining Vespel isn’t too different from machining metals as a result of this; pretend you’re machining brass. Unlike metal, though, Vespel (like all thermoplastics) will deform if you hold it too tightly.

We generally recommend Tungsten Carbide Alloy Tooling, although we recommend diamond tooling for large volume runs or work requiring close tolerances. Be wary of overheating Vespel when you machine it. It shouldn’t become so hot that you can’t grasp it with your bare hands.

We also suggest non-aromatic, air-based coolants to achieve optimum surface finishes and close tolerances. Coolants have the additional benefit of extending tool life as well.

 

Preventing Contamination

 

Contamination is a serious concern when machining polymer components for technically demanding industries such as aerospace sciences. 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.

 

Vespel Machining Guide: Supportive Information

DuPont Machining Vespel Guide

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An Informational Brief on Polymer Machining

 

Celazole, known as Polybenzimidazole (PBI), is a synthetic fiber characterized by exceptional thermal and chemical stability. PBI is commonly used in electrical insulators and high strength situations, where it shines due to its compressive strength and insulation properties.

Our latest machining guide discusses what goes into machining Celazole and how its considerations differ from other manufacturing options such as metal machining, injection molding, and 3D printing.

How does AIP approach Celazole and its machining process? To start, we’ll explain the difference between machining PBI, a thermoplastic, and machining thermosets.

 

Machining Thermoplastics vs Thermosets

 

We’ve already said that Celazole is a thermoplastic, but what does that mean exactly?

All polymers can more or less be divided into two categories: thermoplastics and thermosets. The main difference between them is how they react to heat. Thermoplastics like Celazole, for example, melt in the heat, while thermosets remain “set” once they’re formed. Understanding the technical distinction between these types of materials is essential to CNC machining them properly.

What type of thermoplastic is Celazole in particular? PBI is an amorphous engineering thermoplastic.

PBI is characterized by high strength; it exhibits excellent thermal stability, is hydrolytically stable after exposure to high-pressure steam or water, is broadly resistant to hydrocarbons, alcohols, weak acids, weak bases, hydrogen sulfide, chlorinated solvents, oils, heat transfer fluids and many other organic chemicals.

 

Properties & Grades of Machined Celazole

 

Celazole PBI is one of the highest performing thermoplastics on the market today; it has the lowest coefficient of thermal expansion of all unfilled plastics. At above 400°F (204°C), Celazole possesses the highest mechanical properties of any thermoplastic. By itself, PBI offers a continuous use operating temperature of 1,004°F (540°C). Even after being submerged in hydraulic fluid at 200°F (93°C) for thirty days, Celazole retains 100% tensile strength.

When you combine those exceptional qualities with excellent wear and frictional properties, as well as extreme resistance to chemicals and hydrolysis, it’s no wonder that Celazole excels in industries that require high-performance in hostile environments. For example, semiconductor parts made with Celazole can last twice as long as those made with polyimides.

Other applications that Celazole is commonly machined for include gas plasma equipment, aircraft engine components and other applications for “hot” section areas or environments with harsh chemicals. Whenever dielectric properties are required or high-strength situations arise, Celazole PBI is an ideal material for your application.

We regularly machine various grades of Celazole at AIP Precision Machining, including Celazol U-60 and Duratron PBI.

 

Machining Celazole PBI

 

Annealing Celazole

The process of annealing and stress-relieving Celazole reduces the likelihood of surface cracks and internal stresses occurring in the material. Post-machining annealing also helps to reduce stresses that could potentially contribute to premature failure.

 

Machining Celazole

 

Celazole is known for its extreme hardness, which poses a challenge to HSS machining. Instead, carbide and polycrystalline diamond tools are recommended for machining Celazole PBI.

Keep in mind that Celazole PBI is notch sensitive as well and that high tolerance components machined from this thermoplastic should be stored and sealed to prevent any dimensional changes from moisture absorption.

We also suggest non-aromatic, air-based coolants to achieve optimum surface finishes and close tolerances. Coolants have the additional benefit of extending tool life as well.

 

Preventing Contamination

 

Contamination is a serious concern when machining polymer components for technically demanding industries such as medical and life sciences. 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.

 

Celazole PBI Machining Guide: Supportive Information

 

Extreme Performance Materials

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An Informational Brief on Polymer Machining

 

Polytetrafluoroethylene (PTFE) is a fluorocarbon-based polymer, known more commonly as Dupont’s brand name Teflon®. The enhanced electrical properties, high-temperature capabilities and chemical resistances of this thermoplastic make it a favorite for backup rings, coatings, distribution valves, electrical insulation applications and more.

 

Our latest machining guide discusses what goes into machining Teflon and how its considerations differ from other manufacturing options such as metal machining, injection molding, and 3D printing.

 

Read on to learn more about Teflon’s machining, applications and properties in AIP’s informational polymer brief below, starting with the difference between working with a thermoset and a thermoplastic.

 

Machining Thermoplastics vs Thermosets

 

We’ve already said that Teflon is a thermoplastic, but what does that mean exactly?

 

All polymers can more or less be divided into two categories: thermoplastics and thermosets. The main difference between them is how they react to heat. Thermoplastics like Teflon, for example, melt in heat, while thermosets remain “set” once they’re formed. Understanding the technical distinction between these types of materials is essential to CNC machining them properly.

 

What type of thermoplastic is Teflon in particular? PTFE is a fluoropolymer, making it a semi-crystalline thermoplastic. As a fluoropolymer, PTFE possesses an inherent high resistance to solvents, acids and bases.

 

Properties & Grades of Machined Teflon

 

Teflon has excellent electric stability in a wide range of conditions and environments, and its coatings are popular in the aerospace sector. Offering excellent chemical resistance and sliding properties, PTFE finds many applications in seals, housings, linings and bearings. Teflon also maintains very good UV resistance, hot water resistance and electrical insulation at higher temperatures.

 

Unfilled PTFE is chemically inert and has the highest physical and electrical insulation properties of any Teflon grade. Mechanical grade PTFE is often made up of reground PTFE and exists as a cost-effective alternative for industries that don’t require high purity materials while providing superior compressive strength and wear resistance to virgin Teflon.

 

There are several different modified PTFE materials available with unique properties. Many of these modified grades offer greatly reduced deformation percentages under load, as well as a lower coefficient of friction. These include glass-filled, nanotube, synthetic mica and carbon-filled grades. Teflon (PTFE) is more commonly used as an additive to numerous other base polymers in order to provide reduced friction and wear properties.

 

Some of the PTFE grades we regularly machine at AIP include FLUOROSINT 207, FLUOROSINT 500, DYNEON, SEMITRON, ESD 500 HR, and SEMITRON PTFE.

 

Machining Teflon

 

Annealing & Stress Relieving Teflon

 

The process of annealing and stress-relieving PTFE reduces the likelihood of surface cracks and internal stresses occurring in the material. Post-machining annealing also helps to reduce stresses that could potentially contribute to premature failure. AIP’s special annealing process for Teflon is designed to take the specific properties of PTFE into account, and we advise anyone working with PTFE to hire a manufacturer that understands its unique demands.

 

Machining Teflon

 

PTFE’s density and softness make it deceptively easy to machine, and in virgin grade, has a temperature range from -450°F to +500°F (-267.7°C to +260°C). Teflon has low strength when compared to materials like Nylon, which has almost two to three times the tensile strength of Teflon. You’ll want to use extremely sharp and narrow tools to work with this material.

 

Teflon’s high coefficient of expansion and stress creep properties can make it difficult to achieve tight machining tolerances. It’s essential to design your application with PTFE’s inherent properties in mind, instead of trying to force the polymer to act against its nature.

 

We also suggest non-aromatic, water-soluble coolants, such as pressurized air and spray mists, to achieve optimum surface finishes and close tolerances. Coolants have the additional benefit of extending tool life as well.

 

Preventing Contamination

 

Contamination is a serious concern when machining polymer components for technically demanding industries such as medical and life sciences. 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.

 

Teflon Machining Guide: Supportive Information

 

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An Informational Brief on Polymer Machining

 

Delrin®, also commonly known as an acetal (polyoxymethylene) homopolymer, is an impact and wear resistant semi-crystalline thermoplastic popular for a broad range of machining applications. To list just a few of its impressive qualities, Delrin offers great stiffness, flexural modulus, and high tensile and impact strength.

Our latest machining guide discusses what goes into machining Delrin and how its considerations differ from other manufacturing options such as metal machining, injection molding, and 3D printing.

How does AIP approach Delrin and its machining process? To start, we’ll explain the difference between machining Delrin, a thermoplastic, and machining thermosets.

 

Machining Thermoplastics vs Thermosets

 

We’ve already said that Delrin is a thermoplastic, but what does that mean exactly?

All polymers can more or less be divided into two categories: thermoplastics and thermosets. The main difference between them is how they react to heat. Thermoplastics like Delrin, for example, melt in the heat, while thermosets remain “set” once they’re formed. Understanding the technical distinction between these types of materials is essential to CNC machining them properly.

What type of thermoplastic is Delrin in particular? Acetal homopolymer is a semicrystalline, engineering thermoplastic.

 

Properties & Grades of Machined Delrin

 

This strong, stiff and hard acetal homopolymer is easy to machine and exhibits dimensional stability and good creep resistance, among several other desirable qualities. Delrin is also known for its superior friction resistance, high tensile strength, and its fatigue, abrasion, solvent and moisture resistance.

The latter quality allows Delrin to significantly outperform other thermoplastics like Nylon in high moisture or submerged environments without losing high-performance in the process. In other words, Delrin can retain its low coefficient of friction and good wear properties in wet environments.

One of the main reasons for Delrin’s popularity is its sheer versatility. The above blend of unique qualities makes Delrin broadly applicable to various industries in the medical, aerospace and energy sectors. For example, you can machine Delrin for medical implants and instruments, or for industrial bearings, rollers, gears, and scraper blades. It is ideal for smaller applications at temperatures below 250 °F (121°C) and can have centerline porosity.

Some of the Delrin grades we regularly machine at AIP include:

 

PTFE-Filled Acetals

 

PTFE (polytetrafluoroethylene) filled grades of Delrin is ideal where impact strength and wear capability are of the highest importance.

 

Glass-Reinforced Acetals

 

Acetals that are reinforced with glass have a much higher strength and greater heat resistance than other grades of Delrin.

 

FDA-Compliant Acetals

 

There are FDA-compliant grades of Delrin available for use in medical and food-related applications.

 

Machining Delrin

 

Machining Delrin

 

It’s true that Delrin is an easy material to work with in terms of machining. It is a very stable material, which makes precise, tight tolerances easier to achieve for this thermoplastic.

While machining, keep in mind that Delrin is sensitive to heat at or above 250 °F (121°C).

Balance the material removal as best as you can to keep your dimensions stable.

We also suggest non-aromatic, air-based coolants to achieve optimum surface finishes and close tolerances. Coolants have the additional benefit of extending tool life as well.

 

Preventing Contamination

 

Contamination is a serious concern when machining polymer components for technically demanding industries such as medical and life sciences. 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.

 

Delrin Machining Guide: Supportive Information

 

General Engineering Materials

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An Informational Brief on Polymer Machining

 

Did you know that PPS (or Polyphenylene sulfide) products offer the broadest resistance to chemicals of any high-performance thermoplastic? It’s no surprise that this makes them a popular choice for industrial applications such as wheel bushings, chemical pumps, and compound clamp rings for semiconductor wafers.

 

What goes into machining this thermoplastic, however, and how does it differ from metal machining, injection molding, or 3D printing?

 

With Machining PPS: A Plastics Guides, AIP provides you with a guide to this material and its machining process. First, let’s start with the basics: thermoplastics vs thermosets.

 

 

Machining Thermoplastics vs Thermosets

 

We’ve already said that PPS is a thermoplastic, but what does that mean exactly?

 

All polymers can more or less be divided into two categories: thermoplastics and thermosets. The main difference between them is how they react to heat. Thermoplastics like PPS, for example, melt in heat, while thermosets remain “set” once they’re formed. Understanding the technical distinction between these types of materials is essential to CNC machining them properly.

 

What type of thermoplastic is PPS in particular? It’s a semi-crystalline, high-performance thermoplastic that has an extremely stable molecular structure. The chemical resistance of PPS is often compared to PEEK  and fluoropolymers.

 

 

Properties & Grades of Machined PPS

 

There’s a lot to like about PPS’s material properties. As we mentioned before, PPS has exceptional chemical resistance that makes its bearing grades especially favorable for the chemical industry or caustic environments. In particular, its resistance to acids, alkalis, ketones, and hydrocarbons lend PPS stellar structural performance in harsh chemicals.

 

Additionally, PPS materials are inert to steam as well as strong bases, fuels and acids. Combine that with a low coefficient of thermal expansion and zero moisture absorption, and you get a material that is ideal for continuous use in corrosive or hostile environments. PPS has replaced stainless steel for a lot of industrial applications for this reason.

 

Most impressively, PPS will not dissolve at temperatures below approximately 200 °C, no matter what solvent is used. In fact, all grades of PPS share UL94 V-0 flammability ratings, without requiring flame retardant additives, resulting in an excellent material for aircraft where flame resistance is paramount.

 

Some grades of PPS that we regularly machine at AIP Precision Machining include Ryton®, Fortron®, TECHTRON®, TECTRON® HPV, TECATRON PVX and TECATRON CMP.

 

 

Machining PPS

 

Annealing PPS

The process of annealing and stress-relieving PPS reduces the likelihood of surface cracks and internal stresses occurring in the material. Post-machining annealing also helps to reduce stresses that could potentially contribute to premature failure. AIP’s special annealing process for PPS is designed to take the specific properties of PPS into account, and we advise anyone working with PPS to hire a manufacturer that understands its unique demands.

 

Machining PPS

PPS is a fantastic material for machining. Its low shrinkage and stable dimensional properties make it easy to machine to incredibly tight, precise tolerances. A unique characteristic of PPS is that when dropped, it sounds just like a piece of metal hitting the floor.

 

PPS, like many other thermoplastics, is notch sensitive, so take care to avoid sharp corners in design. We recommend carbide tipped cutting tools for working with PPS as they provide an ideal speed and surface finish.

 

We also suggest non-aromatic, water-soluble coolants, such as pressurized air and spray mists, to achieve optimum surface finishes and close tolerances. Coolants have the additional benefit of extending tool life as well. No known coolants attack nor degrade PPS.

 

Preventing Contamination

Contamination is a serious concern when machining polymer components for technically demanding industries such as aerospace. 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.

 

To learn more, read our article “Three Ways to Ensure Sterilization in Your Plastic Machined Medical Applications.”

 

 

PPS Machining Guide: Supportive Information

Chemical Resistant Materials Guide

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Aerospace Sector Materials Guide

 

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Ask the Plastics Professionals at AIP Precision Machining!

 

Do you know why AIP Precision Machining includes stress-relieving and annealing plastics as part of our machining process? We’ve talked about this a bit in our plastic machining guides (like our polymer machining brief on RADEL, but this post serves as a more thorough explanation of annealing does to improve your machined parts.

 

What’s the purpose of stress relieving and annealing plastics, then? Read on to learn the answer from the plastics professionals at AIP Precision Machining.

 

What is annealing, and how does AIP anneal its plastic parts?

 

Let’s start with the basic definition of annealing: it’s a heat treatment that changes the properties of a material to make it easier to machine. Annealing does this by increasing ductility and reducing hardness for the material.

 

AIP Precision Machining has programmed annealing ovens for plastics that heat the material above its recrystallization temperature. By maintaining the heat at that specific point, the structure of the material changes to become finer and more uniform. This process relieves internal stresses in the material.

 

The final part of annealing is allowing the material to cool back down once after it’s been heated for a suitable amount of time. Proper annealing requires precise temperatures and timing control to accomplish the right result, which is why AIP uses computer controlled annealing ovens for plastics.

 

Why is annealing & stress-relieving crucial for plastics?

 

While not every machined component has to rely on annealing, we at AIP believe it is an important part of the plastic machining process for several reasons. For one thing, it reduces stress in the material.

 

Plastics that experience internal stress can turn out warped or cracked, have inferior physical properties, or finish with unexpected changes in their part dimensions. Obviously, we want to avoid this as much as possible.

 

Reducing stress enhances the mechanical and thermal properties of a material by limiting the opportunity for cracking and other issues like the ones above. Since stress build-up can lead to part failure or reduced performance, stress-relieving improves the overall quality of your product.

 

By doing this, annealing extends the life of your machined plastic parts and components.

 

Is the process of annealing plastics the same for different materials?

 

Not at all. Some engineering plastics like ULTEM and TORLON benefit enormously from post-machining annealing. At AIP, proper annealing of TORLON can require more than seven days in special ovens!

 

Other materials that will undergo a lot of machining time, like some applications of PEEK, can require more intermediate annealing steps to make sure they maintain critically tight tolerances and flatness.

 

That means it’s essential for your machinist to know what plastic material you’re working with and what particular needs it has. Be sure you’re working with an experienced plastics manufacturer like AIP or else you risk having a lower quality product.

 

With over 35+ years of experience working with hundreds of polymers and composites, we’re more than just familiar with the machining process. We’re ready to handle any geometry and any challenge.

 

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How Aluminum Got Dethroned by Thermoplastics in Aerospace

 

Cup holders. Magazines. Suit cases. Aircraft engines. Here’s a riddle, what do these items all have in common? If you’re an aircraft operator, the answer is obvious: they all add weight, making them a drain on your fuel costs.

 

If weight is one of the main operating costs of an aircraft, then it’s no surprise that airlines want to lose a few pounds. Over the last 35 years, AIP has witnessed firsthand the incredible weight savings that can be gained from using lightweight polymers and composites for aerospace applications.

 

How Airlines “Slim Down” Operating Costs


How much can an ounce cost you? Plenty. In the case of United Airlines, removing a single ounce from its in-flight magazine has translated to saving $290,000 a year. Yes, a single ounce can hit an airline with up to six digits in costs.

 

If thinner paper can have such an impact on your bottom line, then you can imagine the significant cost savings that can come from manufacturing lighter aerospace components. What’s the most lightweight solution for aircraft operators today? We have one word for you: plastics.

 

What Makes Plastics the Secret to Aircraft Fuel-Efficiency


Aluminum was popular during the “Golden Age of Aviation” because of its strength and durability as well as its lightness when compared to other metals like steel. As a result, many aircraft components have traditionally been metal, from aircraft interiors, to landing gear, aircraft engines and structural components.

 

Now consider the fact that polymer and composite materials can be up to ten times lighter than metal. It’s no wonder that as more thermoplastic materials come on the market and new manufacturing opportunities arise, metal replacement has been seen as one of the best opportunities to reduce airline weight.

 

How big is the impact of switching from aluminum to plastic parts like PEEK and ULTEM in aerospace applications? Operators can earn weight savings of up to 60%. This translates to lower lifetime fuel costs, reduced emissions and extended flight range for operators.

 

“Weighing” the Option of Plastics in Aerospace


Weight alone is a massive reason to consider thermoplastics for aerospace, but weight isn’t the only factor at play in material selection.

 

After all, wood is lighter than metal, but there’s a reason we don’t build spruce airframes like the first plane from the Wright brothers: it wouldn’t be safe today to fly a wooden plane! Aerospace components need to be able to survive in corrosive, harsh environments as well as provide resistance to high temperatures.

 

In other words, it’s crucial that your mission-critical components aren’t just lightweight, but also high-performing.

 

At AIP, we carefully apply our decades of material expertise to select the right material for your application’s needs. Remember that your aerospace plastics manufacturer should understand the unique demands of your industry and your application, and have experience machining the material you require.

 

Want to learn more about how AIP reduces costs for aircraft operators?

Read how machined polymer components can take a load off aircraft interiors in our aerospace case study.

 

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An Informational Brief on Polymer Machining

 

Machining RadelRADEL 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.

 

 

Machining 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.

 

 

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 an 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.

 

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.

 

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.

 

 

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.

 

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.

 

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.

 

 

RADEL Machining Guide: Supportive Information

 

Medical Sector Biomaterials Guide

Energy Sector Materials Guide

Aerospace Sector Materials Guide

Amorphous Materials

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3D Additive Manufacturing vs CNC MachiningThere’s no doubt that plastics have become more and more popular in modern medicine. Short lead times are essential in this industry, and both 3D additive manufacturing and CNC machining provide fast production times. When is your medical application better suited for 3D printing, though, and when does precision plastic machining have the upper hand in plastic manufacturing?

 

There are a few key differences and similarities between these types of plastic manufacturing that you should keep in mind for your medical applications. It helps to have a basic understanding of each manufacturing process, first.

 

Subtractive vs Additive Manufacturing

Subtractive Manufacturing

CNC machining is a type of “subtractive manufacturing.” This means that the process generally begins with a solid block of plastic material which is cut or shaped into the desired product through “removing” excess material.

 

While CNC machining requires more initial setup than 3D printing, it offers repeatability, accuracy for both large and small parts, and a wide range of polymers and composites to choose from, as well as a variety of surface finishes. It scales easily between one-time jobs and high-volume production.

 

Additive Manufacturing

3D printing is “additive manufacturing,” which means the initial material is built layer by layer, rather than removed as in subtractive manufacturing. 3D printing creates three-dimensional objects from reading a digital file’s blueprint. When working with plastics, you’re primarily talking about FDM 3D printing. While FDM is widely considered the most quick and cost-effective way of producing custom thermoplastic parts and prototypes, it also has the lowest dimensional accuracy and resolution of any other 3D printing technology.

 

Another option for additive manufacturing is SLS 3D printing, which fuses together the particles of thermoplastic polymer powders. This version of 3D printing has higher accuracy than FDM; however, it comes at the cost of longer lead times, which can be expensive in the medical industry.

 

Choosing the Right Technology for Your Medical Application

As always, choosing the correct technology is dependent on your particular medical application. What you value in your completed product can help determine which style of plastics manufacturing works best for your needs. Some of your considerations should be:

 

Material Consultancy

Both CNC machining and additive manufacturing work with a wide variety of thermoplastics, but those plastics react to manufacturing in different ways. Some materials machine more easily than others, while certain thermoplastic materials are more prone to warping in 3D printing.

 

Your manufacturer should be familiar with your chosen material and be able to discuss the process of machining or 3D printing it with you. At AIP Precision Machining, we have 35+ years of material and machining expertise and we include consultancy as an integral part of our manufacturing process.

 

Mechanical Properties

CNC machining ultimately provides greater dimensional accuracy and better performing properties than additive manufacturing. Machined thermoplastics possess both great mechanical and thermal properties with fully isotropic behavior. If your product requires unique, strong design with critical tolerances, then FDM 3D printing may not be not ideal; this type of printing is inherently anisotropic, meaning it isn’t the best option for mechanically critical components.

 

Medical applications, in particular, have unique considerations that ought to be taken into account, both for choosing your initial material and determining how it ought to be manufactured.

 

Precision Tolerances

Precision CNC machining provides close tolerances for your applications with a fine, burr-free finish. In fact, 3D printed products for the medical field regularly go into CNC machining post-processing as a secondary step in order to accomplish better tolerances or a finishing cut, as FDM parts tend to have visible layer lines.

 

Extreme tolerances up to 0.002mm can be produced by AIP Precision Machining, which can be necessary in demanding industries such as the medical, aerospace and energy markets.

 

Quick Turnaround

Both CNC machining and 3D printing have quick turnarounds, especially when compared to injection molding. Machining designs are crafted on the same computer applications used by 3D printers, so there is no cost associated with design changes for either type of plastics manufacturing. However, when time is truly critical, 3D printed parts can be delivered in 24 hours. Quality and functional usefulness, in this case, may be sacrificed for expediency.

 

AIP Precision Machining can guarantee your complex polymers machined in as little as 10 business days, with quality assured from concept to completion.

 

Volume of Production

Smaller batches, such as 1-10 plastic components, can be more cost-effective if produced with additive manufacturing. This is because using a non-standard blank size increases the cost of machining. Plastic machining, however, easily scales between small and large outputs.

 

If you require a high-quality product that possesses extreme mechanical and thermal strength, it is worth precision machining for that reason alone.

 

The Final Consideration? Experience.

The medical field often has no room for error when it comes to implants, spinal devices and orthopedic equipment. This is why—no matter what type of plastic manufacturing you choose—you want to be sure you’re working with an expert who understands the importance of sterilization, biocompatibility, and other traits that may be necessary for your application.

 

AIP is FDA and ISO 13485:2016 registered and has been audited by some of the most stringent OEMs in the orthopedic and medical device industries. We process our plastics with strict hygienic procedures.

 

Whoever you work with, be sure they understand the needs of your industry and have the experience to prove it.

 

Click here to learn more about the utility of each technology with regard to precision efficiency, materials and more.

Or, request a quote with AIP Precision Machining here.

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An Informational Brief on Polymer Machining

 

 

One of the high-performance thermoplastics that AIP works with is ULTEM: a PEI, or polyetherimide. ULTEM was developed by General Electric Plastics Division (Now SABIC) back in the early 1980s. Polyetherimide (PEI) is an amorphous, amber-to-transparent thermoplastic.

 

Among other uses, ULTEM is popularly used in medical instrument components, aircraft interiors, missile and defense-related components, electrical insulation parts, and semiconductor equipment components.

 

AIP has over 35 years of experience machining complex components from ULTEM and various other thermoplastic materials. We are providing this Machining ULTEM as yet another insightful technical brief about our polymer component manufacturing process, and how it differs from that of metal machining or injection molding.

 

Plastic CNC Machining

Before discussing the process of machining ULTEM, it’s important to understand exactly what plastic machining is.

 

CNC (Computer Numerical Control) machining is a process in the manufacturing sector that involves the use of computers to control machine tools. In the case of plastic machining, this involves the precise removal of layers from a plastic sheet, rod, tube or near net molded blank.

 

The early history of CNC machining is almost as complex as a modern CNC system. The earliest version of computer numerical control (CNC) technology was developed shortly after World War II as a reliable, repeatable way to manufacture more accurate and complex parts for the aircraft industry. Numerical control—the precursor to CNC—was developed by John Parsons as a method of producing integrally stiffened aircraft skins.

 

Parsons, while working at his father’s Traverse City, Michigan-based Parsons Corp., had previously collaborated on the development of a system for producing helicopter rotor blade templates. Using an IBM 602A multiplier to calculate airfoil coordinates, and inputting this data to a Swiss jig borer, it was possible to produce templates from data on punched cards.

 

Parsons’ work lead to numerous Air Force research projects at the Massachusetts Institute of Technology (MIT) starting in 1949. Following extensive research and development, an experimental milling machine was constructed at MIT’s Servomechanisms Laboratory.

 

Due to the many different kinds of polymers and composites, it’s important to have strong technical expertise of polymer materials when machining plastic components; some plastics are brittle, for example, while others cut similarly to metal. The challenge of plastics is their wide range of mechanical and thermal properties which result in varying behavior when machined. Therefore, it’s important to understand the polymer structure and properties of ULTEM if you’re machining it.

 

Thermoplastics vs Thermosets

 

When it comes to polymers, you have two basic types: thermoplastics and thermosets. It’s crucial to know which one you’re working with due to distinct differences between how these two main polymer categories react to chemicals and temperature.

 

Thermoplastics soften when heated and become more fluid as additional heat is applied. The curing process is completely reversible as no chemical bonding takes place. This characteristic allows thermoplastics to be remolded and recycled without negatively affecting the material’s physical properties.

 

They possess the following properties:

  • -Good Resistance to Creep
  • -Soluble in Certain Solvents
  • -Swell in Presence of Certain Solvents
  • -Allows for Plastic Deformation when Heated

 

Thermosets plastics contain polymers that cross-link together during the curing process to form an irreversible chemical bond. The cross-linking process eliminates the risk of the product re-melting when heat is applied, making thermosets ideal for high-heat applications such as electronics and appliances.

 

They possess the following properties:

  • -High Resistance to Creep
  • -Cannot Melt
  • -Insoluble
  • -Rarely Swell in Presence of Solvents

 

Phenolic, Bakelite, Vinyl Ester and Epoxy materials would be considered examples of a thermoset, while ULTEM, PEEK, DELRIN and Polycarbonate materials are examples of thermoplastics.

 

The thermoplastic category of polymers is further categorized into Amorphous and Crystalline polymers per the figure below:

 

Machining Ultem

 

ULTEM is considered an amorphous, high-performance thermoplastic. Most amorphous polymers are thermoform capable, translucent and easily bonded with adhesives or solvents.

 

Various Grades of Machined ULTEM

 

ULTEM PEI (polyetherimide) is a high-strength amorphous polymer. PEI has more than just excellent heat and flame resistance. It can perform continuously up to 340°F thanks to its high flammability rating. That’s not all, though: this polymer is also hydrolysis resistant and highly acid-resistant. ULTEM PEI also outperforms both Nylon and DELRIN with the highest dielectric properties of thermoplastic materials.

 

While ULTEM is relatively chemical resistant relative to lower end amorphous polymers, you will need to carefully assess the chemical compatibility for the application. This material is also more notch sensitive than RADEL PPSU.

 

There’s more than one particular type of ULTEM PEI you can machine, and each has slightly different properties for perfecting this material’s use in different applications.

 

Here are two grades of ULTEM PEI we machine regularly at AIP Precision Machining:

 

ULTEM 1000

ULTEM 1000 is an unfilled grade of ULTEM PEI. This is considered the “virgin” or “neat” grade of the resin… this basically means no-fillers. It’s well suited to interior aircraft components thanks to its impressive flame resistance and limited oxygen index. Its resistance to UV and gamma radiation and low NBS smoke evolution, low thermal conductivity, and ability to retain 85% of its tensile strength at 10,000 hours of immersion in boiling water make it useful for a variety of structural food processing components. ULTEM 1000 is also FDA, USDA, and NSF-compliant, as well as USP Class VI-compliant.

 

ULTEM 2300

 

ULTEM 2300 is a 30% glass-reinforced grade of ULTEM PEI. This gives the high-performance polymer greater tensile strength and rigidity than ULTEM 1000, plus greater dimensional stability, meaning less movement with temperature or load changes. It possesses low thermal conductivity and excellent electrical insulation properties. Additionally, it reacts well to autoclave sterilizations, making it useful for reusable medical applications where repeated cycles are required. ULTEM 2300 is commonly used for structural components where light weight is valuable such as found in many aerospace and defense-related components. ULTEM 2300 is a common direct replacement for aluminum as it has a similar coefficient of thermal expansion to 6061-T6.

 

Machining ULTEM

 

Annealing ULTEM

ULTEM can be received in the form of rods, sheets, tube or film. Stress-relieving before machining through an annealing process is crucial, as it reduces the likelihood that surface cracks and internal stresses will occur from the heat generated. This also helps prevent any warping or distortion of your plastic materials.
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 ULTEM machining experts.

 

Machining ULTEM

Glass-reinforced ULTEM will require coolants during drilling operations, as they are especially notch sensitive. 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 ULTEM. 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.

 

Another difference between glass-reinforced ULTEM and non-filled ULTEM is that non-reinforced thermoplastics can be machined with high-speed steel cutting tools. You’ll want hard metal tools for reinforced materials.

 

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.

 

ULTEM Machining Guide: Supportive Information

 

Medical Sector Biomaterials Guide

Energy Sector Materials Guide

Aerospace Sector Materials Guide

Amorphous Materials

 

Explore Materials Inventory

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