Teflon or polytetrafluoroethylene (PTFE) is a chemically inert, low-friction plastic with many industrial applications. In addition to other engineering plastics such as ABS and PVC, most manufacturers that work with Teflon use machining techniques.
This article explains in detail the machining methods suitable for working with Teflon. Furthermore, the material properties, advantages and applications of custom Teflon parts are discussed.
What is Teflon/PFTE material?
Teflon is a popular brand of polytetrafluoroethylene (PTFE), a thermoplastic fluoropolymer. The one with Dr. Plunkett accidentally discovered that engineering plastic is resistant to chemicals like acids and bases. Furthermore, it has a low coefficient of friction, which makes it a useful material in industries such as automotive and medical.
Teflon Properties
Many of Teflon's properties result from the thermoplastic's nature as a fluoropolymer (consisting only of fluorine and carbon). For example, it appears white and solid at room temperature. Other properties of the plastic material are:
- Chemical resistance
- High insulating properties
- UV resistance
- Low coefficient of friction
- Low dielectric constant/low loss tangent
- Non-stick effect
- Fatigue resistance
Different grades of PTFE
Various types of Teflon can be used in various industries that process plastics. Some are branded and all have unique characteristics. Types of Teflon commonly used in plastics processing include:
- Pure PTFE has high chemical resistance as well as good flexural strength and electrical properties.
- Pigmented PTFE with better visibility;
- Chemically modified PTFE with reduced creep, smooth surface and better permeation resistance;
- Glass-filled PTFE is suitable for the production of parts that require high compressive strength as well as excellent wear and chemical resistance.
- Peek filled PTFE is known for its compressive strength.
Teflon material applications
Teflon is an important material in several industries. Below are common examples of custom Teflon parts:
- Important material in the construction of pipelines;
- It is suitable for the production of anti-friction devices.
- An important material for coating medical parts and devices;
- Used to coat laboratory equipment.
Different processing methods for Teflon/PTFE
Several machining processes are available to produce custom Teflon parts. Below is an overview of the process and how you can optimize it further.
Mechanical/manual processing
This machining process does not involve computerized control and is therefore less accurate and precise. They are suitable for machining PTFE parts that do not require complex designs, tight tolerances or manufacturing processes. Mechanical processing processes can be used in the DIY sector.
CNC processing
CNC machining is the most common process for producing custom Teflon machining parts. It is a subtractive process that uses computer-controlled tools to remove portions of the Teflon material to form the desired part. PTFE machining includes the following techniques:
1. CNC milling involves using a milling machine to remove Teflon material to shape machined parts. CNC milling machines allow rotation and movement along multiple axes. This makes them accurate and precise. This machining technique can be used to produce Teflon parts with rough edges.
2. CNC turning involves holding and rotating a workpiece and feeding it to the CNC lathe to produce PTFE parts with hollow molds.
3. CNC drilling involves drilling a hole in the Teflon part with a drill. There are several aspects to consider when using CNC drills. For example, the wave must allow adequate evacuation. Additionally, the drill bit should be perpendicular to the workpiece to minimize runout.
4. CNC turning-milling combines turning and milling processes, suitable for the production of complex Teflon parts. Although it is not comparable to multi-axis machining, it can produce some complex parts, such as: B. a hollow part with rough floor characteristics.
5. Multi-axis/5-axis machining is the advanced Teflon machining method to produce complex special parts. It uses a multi-axis and tooling configuration to machine PTFE parts to improve the accuracy and precision of the final product.
Considerations and tips for working with Teflon
Teflon is a material exclusive to machines. Therefore, it is important for machinists to understand the properties of materials. Below are some tips to keep in mind when working with the material:
Tight tolerance
When machining Teflon, there is an increase in stress creep and a high coefficient of expansion, making it difficult to obtain tight tolerances. A suitable solution for this is to use coolants to obtain the best tolerances and surface finishes.
Softness
Teflon is also a soft thermoplastic that makes machining easier. However, due to the extreme lack of rigidity, tool vibration can easily occur during machining. However, you can introduce materials that can strengthen it or use better quality Teflon.
Deformation under extreme pressure
Remember that Teflon deforms when processed under extreme pressure. Additionally, you can customize it for each piece, for example. B. removing tight tolerances and complex features to ensure the material is suitable.
The shape of custom Teflon parts
Teflon is unsuitable for the production of asymmetrical parts, such as curved or disc-shaped parts, due to its softness and the heat generated by the various machining processes.
Other tips for processing PTFE
- Use a carbide tool with a polished surface to improve the surface finish and protect the tools;
- Supports PTFE material to ensure precision during the machining process;
- Use the correct machining tool to improve chip evacuation and prevent clogging.
- Use sandblasting to create a smoother surface for the Teflon part and to remove irregularities.
Why is CNC machining the best method for producing Teflon parts?
We rarely hear of 3D printing or injection molding being used to manufacture Teflon parts. However, CNC machining is the common method for the reasons listed below:
Decomposition before melting at high temperature
PTFE has a high melting viscosity and, in its amorphous state, is very sensitive to heat at high temperatures and can decompose before melting. Most importantly, at temperatures above 250°C, PTFE releases some toxic gases that can have a negative impact on both the operator and the user of the product. Therefore, both 3D printing and injection molding involve high temperatures and are not the correct method for processing Teflon.
Fewer defects and greater precision
CNC machines are autonomous, meaning they do not require human intervention and there are fewer errors caused by human operators. Additionally, unlike the other manufacturing methods listed above, there is less chance of errors during the manufacturing process and greater repeatability. Repeatability remains unless the CNC machine programming language is intentionally changed.
Heat generation
In CNC machining and most manufacturing processes, heat is generated during the machining process due to the movement of tools. Therefore, when working with Teflon material, a cooling system must be installed to take this heat development into account. The material is very sensitive to heat and the lack of a cooling system can cause defects such as deformation during the machining process.
Suitable for complex shaped parts
CNC machining, especially multi-axis machines, is suitable for the precise production of complex parts. This is an important feature that classifies CNC machining into Teflon precision machining.
PTFE Machining Parts Application
To ensure the accuracy of the process, machined Teflon parts must be used. Some application areas are listed below.
Auto Industry
The automotive industry uses Teflon machined parts due to its accuracy and precision in the machining process. Common PTFE applications include gears and valves.
Medical parts industry
Teflon machine parts are widely used in the manufacturing of medical parts due to its flexibility and chemical inertness. They are biocompatible because they maintain their structural and chemical stability when implanted in the body. Examples of PTFE machine parts used in manufacturing medical parts include valves and needle cases.
food industry
Teflon is also suitable for food processing due to its chemical inertness. Therefore, there is no negative reaction to the food. It can be used, for example, in the production of components for kitchen machines.
aerospace industry
Teflon machine parts are also applicable in the aerospace industry due to their mechanical properties such as strength and low friction, as well as the precision and flexibility of the CNC machining process. Common Teflon parts manufactured using this process include anti-seize system components and coatings.
Alternative materials to Teflon
In addition to Teflon, there are other materials you can substitute when working on other projects. Below are the most common materials and how they compare to Teflon:
Ethylene chlorotrifluoroethylene (ECTFE)
ECTFE is a semicrystalline fluoropolymer and a copolymer of ethylene and chlorotrifluoroethylene. Like Teflon, it is a fluoropolymer. However, unlike Teflon, it has better chemical resistance and corrosion resistance. Therefore, it is an important alternative for manufacturing parts that require such properties.
Perfluoroalkoxy (PFA)
Like PTFE, PFA is a fluoropolymer. The material is similar to PTFE in terms of chemical resistance, but is softer and less resistant to abrasion. This reduces its use in structural parts. However, in contrast to Teflon, PFA is used less frequently for processing.
Polychlorotrifluoroethylene (PCTFE)
PCTFE is another alternative to Teflon material. Unlike PTFE, it is a chlorofluorocarbon. Material properties include high water resistance and the lowest water vapor permeability of all plastics.
WayKen Provides Teflon/PTFE Machining Services
-Feedback from DfM: With feedback from DfM, we can ensure the part you ship is manufacturable. In addition, we also analyze the part for a simpler and more economical manufacturing process.
-CNC Machining: We offer various machining methods such as milling, turning and multi-axis machining for better custom machining of Teflon/PTFE with tight tolerances.
-Parts machining: We also offer parts machining processes to remove imperfections or burrs on Teflon machined parts and other machining options such as polishing, shot peening, anodizing and painting.
Common questions
Is PTFE a thermoplastic or thermoset?
Teflon is a thermoplastic. This means it melts when heated, solidifies when cooled, and the process continues. In contrast, thermosets, such as phenolic resins, epoxy resins and polyurethane, remain “solidified” in their form.
What is the difference between PTFE and Teflon?
Both materials are the same. However, Teflon is the brand name of PTFE material.
What are the limitations of Teflon machining?
The limitation in processing Teflon is based on the properties of the material. For example, PTFE has low density and softness. Therefore, you need the right editing tool. Furthermore, it is difficult to obtain tight tolerances due to the high creep and expansion coefficient under high stresses.
