Key Moments in Aircraft & Aerospace Innovation

 

Aviation technology has come a long way to get to where it is today. Over the course of the last century countless test flights, thousands of blueprints, and endless research from passionate minds have propelled the evolution of aircraft and aerospace technologies. Read on to discover how aviation materials have shifted to create a better, safer, and more efficient flight experience.

 

The Pioneers of Aviation

 

For much of human history, we have been fascinated with taking flight. The ancient Greeks contemplated sprouting wings in myths like Icarus and Daedalus – the boy who flew too close to the sun with wax and feather wings. Leonardo Da Vinci sketched flying machines that were way ahead of Renaissance times. It all came to fruition in 1857 when Félix du Temple de la Croix, a French Naval officer, received a patent for a flying machine. By 1874, he had developed a lightweight steam-powered monoplane which flew short distances under its own power after takeoff from a ski-jump.  Finally, in 1903, the Wright Brothers made the first controlled, powered, and sustained flight near Kitty Hawk, North Carolina. The Wright Flyer featured a lightweight aluminum engine, wood and steel construction, and a fabric wing warping. According to the U.S. Smithsonian Institution, the Wright brothers accomplished the “world’s first successful flights of a powered heavier-than-air flying machine.”

 

 

Just 12 years later, the first all-metal airplane (Junkers J1), built by Hugo Junkers (1859-1935), took flight in 1915. Previously, aircraft experts believed that airplanes can only fly with light materials such as wood, struts, tension wires, and canvas. Junkers thought differently and believed that heavier materials like metal were necessary to transport passengers and goods.

 

The Golden Age

 

The Roaring 20’s ushered in airplane racing competitions, which led aircraft designers to focus on performance. Innovators, such as Howard Hughes, found that monoplanes (aircraft with one pair of wings) were more aerodynamic in comparison to biplanes, and that frames made with aluminum alloys were capable of withstanding extraordinary pressures and stresses. Due to its lightweight properties, aluminum also made its way into the internal fittings of the aircraft decreasing the weight and allowing for a more fuel-efficient design.

 

In 1925, Henry Ford acquired the Stout Metal Airplane Company, utilizing the all-metal design principles proposed by Hugo Junkers, Ford developed the Ford Trimotor, nicknamed the “Tin Goose.” The “Tin Goose” propelled the race to design safe and reliable engines for airline travel. A few years later, Henry Ford’s Trimotor NC8407 became the first airplane flown by Eastern Air Transport, a leading domestic airline in the 1930s flying routes from New York to Florida. This positioned metal as the primary material for domestic aircraft, and eventually military applications with the onset of WWII.

 

 

Plastic’s Mettle: Wartime Materials Take Flight

 

By the 1930’s, the use of wood became obsolete and all-metal aircrafts were produced for their durability. Imperial Airways, known today as British Airways, made headway in the air travel industry with advertisements of luxury and adventure to cross borders. However, those borders were sealed off with the breakout of WWII. In 1939, Imperial Airways, a private commercial airline, was ordered to operate from a military standpoint at Bristol Airport.  Across the Atlantic, engineers focused their efforts on building aircraft meant specifically for military strategy – strength, durability, agility, and weaponry.  The Boeing P-26 “Peashooter” entered service with the United States Army Air Corps as the first all-metal and low-wing monoplane fighter aircraft. Known for its speed and maneuverability, the small but feisty P-26 formed the core of pursuit squadrons throughout the United States.

 

 

In times of war, there are often significant advancements in material usage, weaponry, and machinery. World War II was no different. Plastics entered the scene during World War II, starting with the replacement of metal parts for rubber parts in U.S. aircraft after Japan limited metal trade with the United States. Following that, plastics of higher grades began to replace electrical insulators and mechanical components such as gears, pulleys, and fasteners. Aircraft manufacturers began to replace aluminum parts with plastics as they were lighter and thus more fuel efficient than aluminum.

 

The Race for Space

 

Lighter and more fuel efficient were the key words following World War II as nations turned their attention to the skies and beyond. The space program in the 1960’s brought together illustrious minds to solve the seemingly impossible feat of being the first country to put mankind on the moon, thus, the great race for space began. Aircraft were now going beyond the sky and NASA scientists knew they were dealing with new territory in aero innovation. They needed a material that could break the Earth’s atmosphere and carry a hefty amount of fuel, while protecting the spacecraft’s crew from extreme temperatures. NASA scientists turned to plastics, specifically Kevlar and nylon. Layers of nylon and other insulators were wrapped under the body of the spacecraft to protect the crew from the extreme temperatures of space. Both of these plastics are still staples in the aerospace industry – keeping the Hubble telescope and many other satellites scanning humanity’s charted and uncharted expanse.

 

 

Plastics of the Future

 

Plastics continue to lead the future of materials in aerospace and aviation industries for their durability, precision, and ingenuity. For example, in 2009, the 787-8 Dreamliner made its first maiden flight, becoming the first aircraft to have wings and fuselage made from carbon-fiber plastics. Besides being lightweight, plastics offered increased safety with their resistance to high impact, and their proven ability to withstand chemically harsh environments. This proved plastics an invaluable material when compared to alternative material choices like glass or metal.

 

 

Starting in the 1970s, plastics began to play a more crucial part in the defense and military industry, especially in stealth aircraft. The U.S. Air Force saw the potential of plastics when they learned that plastics could absorb radar waves. The added benefit of reduced radar signature makes plastics ideal for creating stealthy aircraft. Plastics continue to contribute to innovation in the defense industry, especially with stealth fabrics and other composite materials which can virtually create invisibility to radars in the near future.

 

Aside from plastics becoming increasingly popular for use in the defense and military sector, high grade plastics like PEEK are highly favorable for space travel due to its ability to function in hostile environments, critical in space exploration. Plastics are even being researched for lightweight radiation shielding for the International Space Station and flights to Mars.

 

At AIP, we’re proud to be a continued part of aviation and aerospace advancements and we look forward to engineering solutions for the next frontier. In fact, at the time this article was written, we are AS9100D:2016 certified, which means we meet the high-quality standards of applications in the aerospace industry. In addition, we are also ISO 13485:2016, ISO 9000:2015, FDA audited, and ITAR certified. Above call, we strive to create genuine relationships with our customers to deliver mission critical components with promise. To learn how we can help you, contact us today.

 

Interested to learn more? Read “Plastics in Aerospace: The Secret to Fuel-Efficient Aircraft

 

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An Informational Brief on Polymer Machining

 

Kynar®, Polyvinylidene Difluoride (PVDF) is a specialty fluoropolymer thermoplastic known for its ease of processing and its versatility in a variety of applications.  PVDF’s manufacturing not only ensures durability in its utility, but also delivers an innate resistance to acids, bases, high temperatures, and solvents.  Harsh industrial environments are no match for PVDF parts, which is why it is commonly used in environments requiring extreme resistance to a broad range of chemicals.

 

Additional demand for fluoropolymers like Kynar® PVDF is driven by the increasing trend of specialized, small-batch production for customized parts and components. Companies developing prototypes find it extremely convenient to have access to a fluoropolymer part manufacturer such as AIP.  Furthermore, AIP’s experience with custom-engineering plastics ensures our customers’ evolving needs are always met with the same level of innovation and excitement for creating new ways to deliver value in fluoropolymer applications.

 

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

 

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

 

Machining Thermoplastics vs Thermosets

 

We’ve already said that PVDF 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 PVDF, 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 PVDF in particular? PVDF is a semi-crystalline, high purity engineering thermoplastic, meaning its molecular structure is highly ordered.

 

Properties & Grades of Machined Kynar® (PVDF)

 

As a thermoplastic, Kynar® PVDF offers industrial-grade resistance to pH changes due to varying thermal conditions, as well as solvent-resisting capabilities. This can be an advantage in petrochemical industries where fluoropolymer parts are in contact with or exposed to bursts of gases, oil or detergents.

 

It should also be noted that Kynar® PVDF is known for its high degree of crystallinity, which results in a stronger and strain-resisting component. Add to that a natural resistance to fungus, ozone and weather, which makes Kynar® PVDF a great fluoropolymer for coatings and manufactured parts exposed to the elements.

 

Finally, adding to its versatile performance in industrial environments, Kynar® PVDF provides excellent resistance to nuclear radiation, allowing it to be used in both Power Generation and military applications.

 

AIP offers a range of Kynar® and PVDF grades that provide different strength, thermal stability, and corrosion resistance and can help you select the best grade of PVDF for your application..

 

Machining Kynar® (PVDF)

 

Annealing PVDF

 

The process of annealing and stress-relieving PVDF 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 Kynar

 

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

 

We generally recommend Tungsten Carbide Alloy Tooling. Also, keep the part very cool and support it well.

 

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.

 

Case in point, Kynar® PVDF can be manufactured into industrial equipment components that may include piping and tubing, valves, tanks, nozzles, and fittings—among many other formats. It can also be combined with other materials, helping customers innovate and create new product classes with utility that exceeds its original applications.

 

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.  This allows us to de-risk the process from metallic cross contamination.

 

Kynar® (PVDF) Machining Guide: Supportive Information

 

Chemical Resistant Materials

 

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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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Energy Sector Materials

Extreme Performance Materials

 

 

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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

Aerospace Market Materials

Energy Sector 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

 

Chemical Resistant Materials

 

 

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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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