Plastics are essential materials in various CNC machining projects. The lightweight, excellent strength, corrosion resistance, and high machinability of plastics make it a suitable option for many applications, from simple toys to advanced automotive parts.
When it comes to plastic CNC machining, there are numerous material alternatives. The most often used plastics in CNC machining projects include PVC, PTFE, ABS, Nylon, Delrin, and Polycarbonate. Each of these plastics has distinct qualities and uses of its own. The focus of this article will be on the CNC machining of Delrin, including its properties, advantages, and applications.
What is Delrin?
Delrin CNC machining
The engineering thermoplastic named Delrin is a particular type of acetal polymer. Delrin is also known as polyoxymethylene (POM) in the manufacturing sector. The high structural integrity, tensile strength, stiffness, chemical inertness, and other various properties of Delrin are extensively useful.
Formation of Delrin involves hydrocarbon fuel distillation followed by polymerization or poly-condensation process with a catalyst. Delrin can be utilized in various manufacturing approaches, such as Injection molding, 3D printing, and CNC machining to shape into desirable parts.
For the CNC machining, Delrin comes in sheets and bar forms. These shapes can be manipulated by milling, cutting, routing, drilling, and other machining processes. Now, let’s see what the popular Delrin machining grades are.
| PTFE | It stands for polytetrafluoroethylene and offers excellent wear resistance and impact strength. |
| Glass-Reinforced (30% Glass Filled) | Delrin is reinforced with glass to customize the thermal capability and mechanical strength. |
| FDA | It is highly chemically resistive and suitable for food processing and medical equipment. |
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Why is CNC Machining Better than Injection Molding for Thermoplastic Prototyping?
What are the Properties of Delrin?
Delrin sheet
Delrin is a semi-crystalline rigid plastic that offers a range of physical, mechanical, and chemical properties.
- Mechanical Strength
Because of its high mechanical strength & hardness, Delrin is often considered the best alternative to metal in many CNC machining projects.
The strength of Delrin ranges from 60 – 89.6 MPa, and yield strength between 48.6 – 72.4 MPa. It is one of the high strength-to-weight plastic, which can withstand heavy force & pressure.
- High Impact resistance
It can withstand sudden forces and does not get failure. Delrin can preserve all the properties under continuous and rapid shocks. The high toughness of Delrin makes it capable of handling impact forces.
- Moisture resistance
Delrin is a water-resistant material that nearly never absorbs water and retains its structural integrity for a long time. As a result, it can be used in CNC machining to create underwater and water-sealing parts.
- Electrical insulation
It offers excellent electrical insulation and can sustain high electrical stress. It can insulate high electrical voltage, and superior moisture resistance supports this character.
- Rigidity
Delrin is compact and hard material as compared to other plastics. Although, the rigidity does not influence the CNC machining capabilities. It also prevents wear & tear, making it highly durable.
- Lubricity & low friction
Delrin offers excellent lubricity because of its slippery nature. It produces low friction while they rub (contact each other), which is very useful for low-friction applications.
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CNC Machining of Delrin
Because of their high machinability character, Delrin workpieces can be manipulated into the desired shape using CNC machining operations, such as milling, turning, routing, and drilling.
Delrin can be machined with hard-steel tools, similar to aluminum and copper. It produces the best machining quality with a low feed rate and high cutting speed. In addition, coolants are necessary while machining at a high cutting speed of 250 ft/min (SPEEDS AND FEEDS, 2020).
Delrin CNC Milling
CNC-milled Delrin part
Milling is the most common CNC machining operation done with Delrin to create different shapes. It is recommended to use sharp cutting edges to facilitate continuous chip formations. Delrin milling requires single-fluted mills to prevent heat formation and low chip clearance.
Delrin CNC Drilling
The drilling of Delrin can withstand the standard twist drill. Ground-flat leading edges of drills are the ideal choice when drilling Delrin, which can be altered by changing lip angles. The perfect scenario is a cutting speed of 1500 rpm, 118° twist drill, medium feed, and no coolant (General Design Principles ).
Delrin CNC Turning
Turning of Delrin material is quite similar to brass turning operation. It demands high speed and medium feed rate grounded tool bits for smooth operation. A chip breaker can be beneficial in preventing large chip formation, which will also restrict drag and interference.
Blanking & Punching
For the small size parts, blanking & shaping of Delrin sheets is the perfect option. It can be punched using hand-or automated punching press with high speed. The sheet cracking is a significant problem in punching or blanking the Delrin sheet, which can be solved by pre-heating the sheet.
Advantages of Delrin CNC machining
Using Delrin in CNC machining projects is beneficial for prototype development to mass production. Let’s discuss some of the specific advantages in detail.
- Machinability
It is thermoplastic with a free-cutting character, which can be machined with standard cutting tools. Delrin can retain a high degree of dimensional precision with the proper cutting speed and feed rate and doesn’t hurt the machining tools. In addition, it does not get deformed in any CNC machining conditions.
- Accuracy & complex shapes
It is highly compatible with CNC machining operations and can maintain high accuracy. If the designs are not very complex, it is possible to machine them with tolerances as small as ±0.0005″. The excellent dimensional stability facilitates the creation of complex parts. It does not necessitate a particular set-up in addition to a CNC machine.
- Durable parts
CNC machining of Delrin creates durable parts. The excellent creep resistance and fatigue endurance make it functional for an extended period.
- High production speed
Creation of Delrin parts with CNC machining provides a fast turnaround. The high machinability allows for lower cycle time and boosts the production rate.
- Wide range of working temperature
Delrin parts are capable of working in a wide range of temperatures. It can be used in operating environments of -40 0C to 120 0C without losing properties (Amanda, 2021).
Limitations of Delrin CNC Machining
Delrin CNC machining has various restrictions and disadvantages as well. Understanding these restrictions lowers the likelihood of errors and failures.
- Difficult to bond: It has low compatibility with adhesives. Although, Delrin can quickly bond if you compare it with POM copolymers.
- Flammability: Delrin has a decent level of flammability, which can burn as long as the presence of oxygen.
- Thermal Sensitivity: Delrin works in the temperature range of -40 to 80 C and will deform if the operating temperature becomes slightly less or more than this range.
What are the surface finishing options for Delrin parts?
Delrin part with bead blasting finish
As-machined surface finishing could be sufficient in some applications, such as furniture parts. However, most applications require surface finish operation of CNC-machined Delrin parts to remove tool marks and obtain an appealing surface.
| Deburring | In most cases, the deburring brush can remove the attached chips, burrs, and tool marks from the Delrin surface. |
| Bead blasting | Delrin parts can be blasted with sand, glass buds, or other abrasive media to get a uniform finish throughout the surface. |
| Metallic coating | Based on the intended use, metallic coating of aluminum, copper, and other metal can be a fine choice for surface finishing. |
There are other surface finishing options for CNC-machined Delrin parts, such as painting, hot stamping, laser marking, etc.
Is Delrin the best replacement for metal CNC machining?
Due to various corresponding qualities, Delrin is regarded as the ideal substitute for metal and alloys in CNC machining projects. Like metals and alloys, it provides outstanding strength, toughness, machinability, impact resistance, corrosion resistance, fatigue resistance, and other advantages.
In addition to these similarities, it provides other properties such as electrical and moisture resistance. However, Delrin can lack some criteria for metal & alloy machining. The low-cost and lightweight nature defiantly makes it a suitable alternative to metals.
The specifications and intended use of the machined parts will determine whether Delrin is a perfect substitute for metals in your CNC machining project.
Applications of Delrin CNC Machining
Delrin part
Delrin CNC machining applies for prototype development to large-volume production. Let’s overview some of the key applications in depth.
- Automotive parts
Different parts in the automotive industry rely on Delrin CNC machining. The high strength and low weight make it the best material option for door lock systems, fuel sender units, windows gears, gas caps, hardware of seat belts, and loudspeaker grilles.
- Oil & gas
Since Delrin does not react with harsh chemicals and fuels, it is a good choice for oil & gas equipment, such as pipes, storage tanks, components for the transportation system, and other diverse petroleum-handling elements.
- Furniture
Delrin CNC machining can be used to make both basic furniture and the separate components of luxurious furniture. Some examples include handles, locks, physical structure, and many more.
- Electrical & Electronics
The electrical insulation behavior of Delrin is advantageous for creating electrical parts, such as insulators, housing, connectors, bobbins, switches, and many more.
- Food processing & Medical
Additional lubricants in food processing and medical equipment can cause contamination, whereas Delrin parts can be used without external lubricants because of their natural lubricity nature.
- Consumer Devices
If you look closely, Delrin is used in many handles, clips, and even housing for everyday appliances like cookware, washing machines, and ovens.
Why is Delrin considered a metal replacement in CNC machining projects?
Yes, Delrin plastic, also known as acetal or polyoxymethylene (POM), can be a viable metal alternative in various applications due to its unique properties. Delrin offers several advantages over metals, making it an attractive option for specific use cases:
- Lightweight: Delrin plastic is considerably lighter than metals, which can help reduce the overall weight of components and systems, ultimately leading to energy savings.
- Lower friction and wear: Delrin has a low coefficient of friction, which allows for smooth operation, reduced wear, and a longer lifespan for components.
- Corrosion resistance: Delrin is resistant to many chemicals, making it suitable for applications where metals may corrode or rust.
- Excellent dimensional stability: Delrin exhibits minimal swelling and shrinkage, maintaining its shape and size under various conditions, including temperature and humidity changes.
- Electrical insulator: Delrin is a good electrical insulator, making it suitable for applications where electrical conductivity is undesirable.
- Noise reduction: Delrin components produce less noise than metal parts, particularly in applications with moving parts.
However, it is essential to consider that Delrin may not be suitable for all applications where metals are used, particularly in high-temperature environments, heavy load-bearing situations, or applications requiring high electrical conductivity. The suitability of Delrin as a metal alternative largely depends on the specific requirements of the application.
Here’s a comparison table to provide a clear insight into Delrin plastic as a metal alternative:
Table: Comparision of Delrin properties with metals
| Property | Delrin Plastic | Metals |
|---|---|---|
| Weight | Lightweight | Heavier |
| Friction and Wear | Low friction, reduced wear | Higher friction, increased wear |
| Corrosion Resistance | Resistant to most chemicals | Varies, susceptible to corrosion |
| Dimensional Stability | Excellent, minimal swelling | Good, but it may deform under stress |
| Electrical Conductivity | Good insulator | Conductive (varies by metal) |
| Noise Reduction | Less noise in moving parts | Noisier in moving parts |
| Thermal Conductivity | Low | High (varies by metal) |
| Temperature Resistance | Limited high-temperature use | Suitable for high temperatures |
| Load-bearing Capacity | Moderate, varies by application | Generally higher |
| Machinability | Easy to machine | Varies, can be more difficult |
Conclusion
Delrin is a versatile engineering plastic with strong physical, mechanical, and chemical properties, which makes it a suitable replacement for metal & alloys in various CNC machining projects. The CNC machining process can manipulate Delrin into the desired shape and size. However, the accuracy and quality of parts rely on the technology and experience of engineers & operators.
Prolean is a specialist in CNC machining for plastic and metal parts. We have cutting-edge CNC technology and expert professionals to convert your design into the physical part. Please let us know if you are confused about this topic or need any CNC machining service for your current or upcoming project.
FAQs
Why should I choose Delrin for CNC machining?
CNC machining of Delrin is well known for its machinability, high production turnaround, the ability to convert into complex shapes, dimensional consistency, electrical insulation, and durability.
Can Delrin machined parts achieve tight tolerances?
Yes, Delrin is known for its excellent dimensional stability and ability to hold tight tolerances during machining. This property makes it a popular choice for applications requiring high precision and accuracy.
Can Delrin be machined using CNC techniques?
Yes, Delrin is an excellent material for CNC machining due to its machinability, dimensional stability, and ability to hold tight tolerances. Delrin can be machined using various CNC processes, including milling, turning, and drilling.
What are the major applications of Delrin CNC machining?
CNC-machined Delrin parts are applicable in automotive, furniture, food processing, oil & gas, medical, home appliances, electrical, electronics, and many more industries.
Bibliography
- (2021). About Delrin. Bantam Tools, from https://support.bantamtools.com/.
- (n.d.). General Design Principles. EncoPlastics, from www.emcoplastics.com.
- (2020). SPEEDS AND FEEDS. from https://mae.ufl.edu/.
You have mentioned that Delrin CNC Turing is similar to brass turning , is it only same for machining parameters or the quality of machining is also same?
Yes! the quality of final product could be similar such as Ra value
I found this article very professional with lots of technical insights on Delrin CNC machining
If you need any extra information on this topic or related services, let us know.
Can I use Delrin CNC machining for Valves and Pumps for fluid system components as a replacement of aluminum? Looking for your specific suggestion?
Yes you can use as a replacement
How could you combine all the CNC Delrin machining in one article. Amazing one
Thank you for your words Grace!