Though it has the properties of a thermoplastic, PTFE cannot be worked with in the same ways as other polymers because of its high viscosity. To create a solid PTFE mold, the polymer particles must first be cold-molded before undergoing a heat treatment.
If you want to machine PTFE successfully, you must ensure that your application takes advantage of the material’s natural characteristics rather than fighting them.
However, PTFE’s high coefficient of expansion and stress creep qualities can make it challenging to attain fine machining tolerances. Despite the material’s density and softness, which make it surprisingly easy to manufacture.
Because of its adaptability and other desirable qualities, PTFE machined manufacturers frequently choose parts for use in various products.
Machining Teflon – The Process
1. Teflon Annealing And Stress Reduction Process
It is possible to lessen the likelihood of surface cracks and internal tensions in PTFE by subjecting it to an annealing and stress-relieving process.
Post-machining annealing also aids in lowering tensions that could lead to failure. Anyone working with PTFE would be wise to hire a manufacturer that is familiar with the material, as the specialized annealing process for Teflon is tailored to accommodate the unique qualities of PTFE.
2. Teflon Machining
A virgin grade of PTFE can withstand temperatures from -450 degrees Fahrenheit to +500 degrees Fahrenheit (-267.7 degrees Celsius to +260 degrees Celsius), and its low density and high pliability make it seem surprisingly simple to manufacture.
When compared to other materials, such as Nylon, which has twice or three times the tensile strength of Teflon, the former is clearly inferior. Tools for working with this material should be very sharp and thin.
Because of its high coefficient of expansion and stress creep qualities, Teflon can make it difficult to machine precise tolerances. If you want to get the most out of PTFE machining in your application, you need to work with the polymer’s natural tendencies rather than against them.
To get the best surface finish and tolerance results, we recommend using non-aromatic, water-soluble coolants such as pressured air and spray mists. A further advantage of using coolants is that they help keep tools in working order for longer.
3. Avoiding Pollution
The risk of contamination during machining is high when working with polymer components for use in highly technical fields like medicine and biology.
PTFE Precision Machining only develops, heats processes, and manufactures plastics, processing any metal sub-manufactured parts elsewhere to assure the highest level of sub-molecular sanitation. Some of the common examples are special oil valves and other plumbing products.
Teflon Machining Tips
- Machining PTFE (Teflon) yields CNC parts with a wide range of potential applications. As a material, PTFE requires special care when being machined. The CNC machining of Teflon calls for an understanding of the material’s qualities and limitations, as well as machine operation expertise.
- The availability of high-caliber finishing services is constrained. Since Teflon has a high coefficient of expansion and stress creep qualities, it is already challenging to attain tight tolerances while finishing the material.
- The softer nature makes it more challenging to machine plastics with tight tolerances. While +/-.001 per inch is a decent rule of thumb for tolerances of plastic parts, tighter tolerances are feasible with particularly solid, reinforced materials.
- Consider the stress on the moving parts when machining Teflon, as PTFE can distort under high pressure.
- PTFE is not suited for processing into bowl or disk shapes since they are inherently unbalanced.
- Carbide tooling with polished top surfaces is recommended to preserve the tool and enhance the surface finish.
- Materials that provide enough backing to prevent straying too far from the method.
- The chip clearance must be large enough to prevent clogging.
Machining Teflon And Its Uses
Because of its high heat stability and low friction coefficient, Teflon is not the most flexible material for CNC machining, but it does have some crucial niche uses.
About half of the world’s PTFE is used for wire insulation, yet CNC machines aren’t used to make either wires or insulation. Teflon’s other most well-known application is as a nonstick coating for aluminum cookware.
In this case, Teflon is sprayed or rolled onto the etched metal surface. Teflon-coated cookware is often hand-made rather than manufactured.
However, CNC machining can be helpful for working with Teflon in its solid state. Industrial components such as gears, bushings, fittings, and valves are examples of machinable Teflon parts.
Several industries, including healthcare, food processing, science, and aerospace, rely on CNC-machined PTFE components. Some of the common parts are:
The Benefits Of Teflon Machining
Teflon machining has a number of benefits, both those that come from the material itself (PTFE) and those that are produced by the cutting and shaping processes themselves.
Among the many benefits of using Teflon as a machining material are:
- Resistant to chemicals
- Anti-UV and weatherproof
- Insensitive to or fearful of water; hydrophobic
- Powerful impact resistance
- Insulates electricity well.
- Adaptable even when chilled
- Temperature resistance from -260 degrees to 260 degrees
- A very low coefficient of friction
- Low risk of fire
- Easily wipes clean
Teflon’s Machining Restrictions
- A high expansion coefficient
- Creeping tension
- Complicated to maintain precise dimensions
- Weak mechanical characteristics
- Weak dimensional stability
- Because of the suppleness of the cloth, burrs may form.
In addition to being inexpensive and very adaptable, PTFE also has a tensile strength that is about average. It’s highly resistant to heat and is chemically inert, especially to strong acids.
As an electrical insulator, PTFE performs exceptionally well over a wide temperature and frequency range. For this purpose, it’s often used in underwater filtration systems such as those with ceramic filter media or power generated filter kits
Its qualities are sometimes enhanced by adding fillers like carbon, graphite, or glass, as with many other high-performance polymers.