For the most part, injection moulding is seen as a well traversed process. It is a widely used manufacturing process that allows for the mass production of complex plastic parts with excellent dimensional accuracy and mechanical properties. Unlike machined components, injection moulded parts can be easily produced, with a single part taking only about a minute to make, where the same part may have required anywhere from a few minutes to a few hours to machine, depending on complexity. The downside for injection moulding is that the up-front costs are far higher. An injection moulding die might cost anywhere from a few thousand dollars to many tens of thousands, again depending on how complex the part is or how many cavities are needed. The trade-off is therefore made along the lines of cycle-time and consumption per part (both which tend to be lower with moulding), set against the mould cost, which needs to be amortized over a high volume of parts to offset the increase in the per part rate as against machining.

However, even if moulding is a viable option, there exist limitations depending on the type of polymer we are looking at. Regular injection moulding polymers would include polypropylene, poly-ethylenes (HDPE and LDPE), nylons, and polyacetal. Each of these has been extensively worked with such that any experienced moulder would know the methods of working with them. However, once we move into the realm of high-performance polymers, the matter becomes more complex.

Before we go further, let us look at the polymers in question. 

PEEK (Polyether Ether Ketone)

PEEK is a high-performance, semi-crystalline thermoplastic known for its excellent combination of mechanical properties, chemical resistance, and thermal stability. PEEK components offer exceptional strength, stiffness, and dimensional stability even at elevated temperatures. Its resistance to chemicals, including harsh acids and bases, makes it suitable for applications in the chemical processing, oil and gas, and medical industries. PEEK's inherent biocompatibility also makes it a valuable material in medical implants and devices.

PPS (Polyphenylene Sulfide aka Ryton)

PPS is a semi-crystalline, high-temperature thermoplastic renowned for its excellent chemical resistance, dimensional stability, and flame retardancy. PPS parts exhibit superior resistance to a wide range of chemicals, including solvents, fuels, and acids. Its low moisture absorption, excellent electrical properties, and high thermal resistance make it an ideal choice for electrical and electronic components, automotive parts, and industrial applications.

PVDF (Polyvinylidene Fluoride and Kynar)

PVDF is a highly versatile thermoplastic known for its excellent chemical resistance, UV stability, and fire retardancy. PVDF components exhibit exceptional resistance to harsh chemicals, such as acids, solvents, and chlorinated compounds, making it suitable for applications in the chemical processing, semiconductor, and electrical industries. Its inherent UV stability and flame-retardant properties also make it a popular choice for outdoor applications and fire-safe products.

PEI (Polyetherimide aka Ultem)

PEI is an amorphous, high-temperature thermoplastic that offers outstanding dimensional stability, excellent electrical properties, and inherent flame retardancy. PEI parts exhibit remarkable mechanical strength, stiffness, and resistance to creep, even at elevated temperatures. PEI's excellent electrical insulation properties make it suitable for electrical connectors, switches, and semiconductor components. It is also commonly used in aerospace, automotive, and healthcare applications due to its flame-retardant nature and biocompatibility.

Polyimide (PI aka Kapton)

Polyimide is a high-performance, semi-crystalline thermoplastic renowned for its exceptional thermal stability, excellent electrical insulation properties, and resistance to wear and chemicals. Polyimide components offer exceptional dimensional stability, high strength, and excellent resistance to creep, making them ideal for demanding applications in the aerospace, automotive, and electronics industries. Polyimide's ability to withstand extreme temperatures and harsh environments has made it a material of choice in applications such as insulation, aerospace composites, and high-temperature electronics.

PAI (Polyamide-Imide aka Trolon)

PAI is a high-performance thermoplastic known for its exceptional mechanical properties, high temperature resistance, and excellent chemical resistance. PAI parts exhibit exceptional dimensional stability, high strength, and excellent resistance to wear and creep, even at elevated temperatures. Its inherent flame retardancy, low outgassing properties, and resistance to a wide range of chemicals make it suitable for aerospace, automotive, and industrial applications.

The superior properties of these polymers make them vital in several industries. However, there are drawbacks to moulding these polymers. For one, high-performance polymers tend to be far more expensive than regular polymers, often in the range of 20-50X the price. This makes moulding a challenge, as a new mould usually requires some trial and error before it is production ready. The second issue is that these polymers only melt at elevated temperatures, usually in excess of 300°C. Adding to the complexity is that when in a molten state, these polymers will give of effluents that can be highly corrosive to regular injection moulding equipment. As a result, the entire injection moulding machine and the mould itself need to be made of higher-grade metals and have high-temperature heating elements to ensure that the equipment can handle the process.

Because of these challenges, there exist very few moulders that will take on parts in these polymers. However, as the demand for these polymers increases, so too will the demand for processors that have focused their efforts on developing these plastics.

In 2023, Poly Fluoro embarked on a venture to develop an injection moulding machine tailored to moulding high-performance plastics. The addition of this equipment will make Poly Fluoro one of the very few polymer companies world-wide that can take on high-volume injection moulded parts in these high-performance polymers. We look forward to yet again being pioneers in our field and moving to areas that others would otherwise hesitate to go.

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1. PTFE Machined Conduits

2. Expanded PTFE (ePTFE) Vents

3. PTFE in Brake Cables

The versatility of PTFE as a material is only matched by its difficulty to process and fabricate. The properties of PTFE mean that it is invaluable in certain applications. However, as PTFE cannot be injection moulded or melt-processed in any way, there lie certain challenges in creating the shapes needed by the end applications. As always, the work around these challenges is what makes PTFE such an interesting polymer to manufacture.

Specifically, when making PTFE conduits, the requirement for a monolithic part with multiple entry and exit ports results in a complex machining problem. While not insurmountable, this problem is usually solved by a combination of moulding, shaping, and machining using a variety of tools and techniques.

PTFE is a high-performance fluoropolymer known for its excellent chemical resistance, low friction coefficient, and wide temperature range. It is non-reactive to most chemicals, including corrosive substances, and its low friction coefficient ensures smooth fluid flow. Moreover, it can withstand extreme temperatures, ranging from cryogenic conditions to high heat environments. These properties make it an ideal material for conduits in various industries.

PTFE machined conduits offer numerous advantages over traditional conduit materials. Firstly, their chemical inertness ensures compatibility with a broad range of aggressive chemicals and solvents, making them suitable for applications in the chemical, pharmaceutical, and food processing industries.

Secondly, PTFE's low friction coefficient significantly reduces pressure losses and minimizes energy consumption. This characteristic makes PTFE conduits highly desirable in fluid transfer systems, improving efficiency and reducing operational costs.

Thirdly, PTFE conduits exhibit excellent electrical insulation properties, making them suitable for applications requiring electrical or thermal insulation. They are widely used in the electrical and telecommunications industries to protect wires and cables from environmental factors and potential damage.

The usefulness of PTFE machined conduits enables their utilization in various industries:

Automotive: In the automotive sector, they are used for fuel and brake systems, thanks to their resistance to corrosive fuels and high-temperature performance

Aerospace: PTFE conduits also find applications in the aerospace industry, where they are employed in hydraulic and fuel transfer systems due to their lightweight nature and ability to withstand extreme temperature fluctuations.

Medical: PTFE conduits are extensively used in the medical field for applications such as catheters, endoscopes, and fluid transfer systems. Their biocompatibility and resistance to chemicals and high temperatures make them ideal for medical devices.

Semi-conductors: PTFE machined conduits are also employed in the semiconductor industry, where they are utilized for chemical delivery systems and in corrosive gas handling. Their resistance to aggressive chemicals and high-purity characteristics ensures the integrity of the manufacturing process.

Machining PTFE conduits

Because of the challenges to melt-process PTFE, the conduits must be machined out of a single block. This can often be costly, as the extensive removal of material results in a lot of wastage. Furthermore, the more the part is machined, the higher the cycle time. Add to this that the part itself might require multiple operations and the compounded effects of material wastage, cycle time, and setting and programming can result in an expensive final component. Typically, the machining time for a single part can range from as low as 15 minutes, to as high as 2 hours. Manufacturers – such as Poly Fluoro – spend a significant amount of time optimising this process, creating special moulds such that the ‘stock shape’ is as close to the final shape as possible. Furthermore, 4-axis and 5-axis capabilities increasingly allow parts to be machined in fewer settings, thereby reducing the set-up time, and increasing the accuracy of the final component’s dimensions.

Regardless of the methods used, the process of making a PTFE conduit is difficult and can defeat most that are unfamiliar with PTFE machining and its peculiarities. Nonetheless, there are applications where nothing but PTFE will do and in such cases, it falls to the experts to step in and show how it can be done.

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Read More

1. Expanded PTFE (ePTFE) Vents

2. PTFE in Brake Cables

3. Graphene in Polymers - The Way of the Future

 

The development of Expanded PTFE (polytetrafluoroethylene) membranes has seen a range of potential applications where such materials can be used. From simple filtration to breathable fabrics, PTFE membranes have become the material of choice in a range of applications. Excellent chemical resistance, thermal stability, and permeability to gases and liquids makes PTFE highly sought after across various industries. 

One of the key applications of expanded PTFE membranes is in vents, where they are used to allow gases and liquids to pass through while preventing the ingress of contaminants such as dust, dirt, and water. Vents – which may include automotive vents, acoustic vents, or vents for chemicals – are unique in their properties. Developments in adhesive technologies have allowed ePTFE to be punched and a thin section of adhesive to be applied on the edge of the vent. The vent can then be removed, like a sticker, and placed as required.

The use of expanded PTFE membranes in vents has grown in popularity in recent years due to the increasing demand for high-performance ventilation solutions across a range of industries, including aerospace, automotive, medical, and industrial applications. The unique properties of expanded PTFE membranes make them an ideal choice for use in vents, as they offer a number of benefits over traditional venting solutions. 

One of the key advantages of expanded PTFE membranes is their ability to provide high levels of air and liquid permeability while maintaining excellent filtration properties. This is due to the unique structure of the material, which consists of a network of interconnected fibrils that create a three-dimensional matrix. This structure allows air and liquid to flow through the membrane while trapping contaminants and preventing them from passing through.

Expanded PTFE membranes are also highly resistant to a wide range of chemicals, including acids, bases, and organic solvents. This makes them an ideal choice for use in harsh environments where traditional materials such as paper or foam would quickly degrade. In addition, expanded PTFE membranes are resistant to UV radiation, which makes them suitable for use in outdoor applications where exposure to sunlight is a concern.

Another key advantage of expanded PTFE membranes is their ability to maintain their performance even in extreme temperatures. Unlike traditional venting materials, which can become brittle and lose their effectiveness at low temperatures, expanded PTFE membranes remain flexible and durable even at temperatures as low as -200°C. This makes them an ideal choice for use in aerospace and industrial applications where extreme temperature fluctuations are common.

In addition to their performance benefits, expanded PTFE membranes also offer a number of practical advantages over traditional venting solutions. For example, they are lightweight and easy to install, which makes them ideal for use in applications where space and weight are a concern. They are also highly customizable, which means that they can be tailored to meet the specific needs of a wide range of applications.

One area where expanded PTFE membranes are particularly useful is in the venting of batteries. With the increasing use of lithium-ion batteries in a wide range of applications, there is a growing need for effective battery venting solutions that can prevent the build-up of pressure and the release of potentially dangerous gases. Expanded PTFE membranes are an ideal choice for this application, as they can provide high levels of gas permeability while preventing the ingress of contaminants such as dust and water.

In the case of automotives, a vent can be placed over a hole in the dashboard casing. Any build-up of moisture within the electrical chamber of the dashboard can thus be exhausted, without risking any new liquids, dust or other contaminants entering the system. Similarly, for applications in fertilizer manufacturing, the vents act as a one-way valve, allowing gases that build up within a chamber to expelled, lest they build pressure and cause any accidents. The same property makes ePTFE vents invaluable in

Another area where expanded PTFE membranes are commonly used is in the venting of medical devices. With the increasing use of wearable medical devices, there is a growing need for venting solutions that can provide high levels of air and liquid permeability while preventing the ingress of contaminants such as bacteria and viruses. Expanded PTFE membranes are an ideal choice for this application, as they can provide a high level of filtration while maintaining excellent air and liquid permeability.

In conclusion, expanded PTFE membranes are a versatile material that offer a wide range of benefits for use in vents. Their unique properties make them an ideal choice for use in a wide range of applications, from aerospace and automotive to medical and industrial applications. With the increasing demand for high-performance ventilation solutions, expanded PTFE membranes are likely to continue to be an important material for the future.

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Read More

1. PTFE in Brake Cables

2. Graphene in Polymers - The Way of the Future

3. Injection Moulding of PEEK and PPS