DuPont’s Delrin from the United States was the world’s first homopolymer acetal resin, boasting characteristics remarkably similar to metal.
It’s often referred to as “super steel” and can be used to create a variety of impressive components.
However, if you’re looking to embark on a new injection molding project, it’s crucial to consider the material properties, manufacturability, and gain a deep understanding of the process conditions and applicability of Delrin injection molding .
What Is Delrin ?
Delrin, a homopolymer of formaldehyde, is notably represented by DuPont’s version in the U.S., with many designers frequently using this name to identify this type of plastic.
Delrin material mirrors many of metal’s distinctive traits, such as high tensile strength, low friction, compact density, inherent lubrication, resistance to corrosion, and exceptional weather resistance.
It skillfully balances these attributes, narrowing the divide between traditional plastics and metals.
Since its debut in 1960, Delrin has found extensive applications globally, spanning industries like automotive, industrial machinery, electronics, and consumer goods.
What Are The Properties Of Delrin Material?
Polyoxymethylene (POM) is a linear polymer with no side chains, high density, and high crystallinity. Based on the chemical structure of its molecular chain, it can be divided into homopolymer acetal and copolymer acetal.
Delrin is a homopolymer acetal. Distinct from copolymer acetal, Delrin features a larger crystalline block structure. Consequently, it offers greater rigidity and superior mechanical properties, including enhanced fatigue resistance, repeated impact resistance, and wear resistance.
Furthermore, the melting point of Delrin material is about 10°C higher, and its heat distortion temperature is also elevated.
However, correspondingly, its flexibility, hot water resistance, alkali resistance, and weather resistance are not as remarkable as those of copolymer acetal.
Delrin 100ST POM Physical Properties Table Parameters | |||
Density | 1.34g/cm3 | Molding Shrinkage Rate | 2% |
Melting Temperature | 178℃ | Glass Transition Temperature | -35.0℃ |
Heat Distortion Temperature | 65℃ | Flame Retardancy Rating | 0 |
Tensile Strength | 70MPa | Flexural Modulus | 1100MPa |
Pros and Cons of Delrin Plastic
The advantages of delrin plastic include:
- Higher tensile strength, impact strength and stiffness
- Outstanding creep resistance and long-term fatigue resistance
- Dimensional stability, and excellent resistance to latent deformation.
- Good electrical insulation and self-lubricating properties
- Good flow characteristics, fast molding cycle and thermal stability
- Saves costs and provides perfect mechanical properties while cutting costs and time
The disadvantages of delrin plastic include:
- Poor thermal stability
- Narrow processing temperature range
- Sensitivity to radiation sterilization, which tends to make POM brittle
How To Design A Delrin Mould?
During the delrin molding process, the injection mold plays a crucial role. To ensure the process’s successful completion, it’s necessary to design the Delrin mold according to specific requirements.
Material Selection
Since corrosive gases are decomposed during pom injection molding , or wear caused by glass fibers, the choice of mold material needs to consider those that possess both wear and corrosion resistance.
Additionally, nitriding and hardening treatments are beneficial to enhance wear resistance.
Runner Design
It’s recommended to use round runners. If a round runner can’t be formed, then a trapezoidal runner is suggested, and semicircular runners should be avoided. The runner size should be as large as possible, and its distribution needs to be symmetrical.
Gate Dimensions
The thickness should be 60-70% of the injection molded product thickness. The width should be 1-1.5 times the gate thickness.
Draft Angle
The commonly used draft angle is 1°, with the minimum being 1/4-1/2°.
Venting
A rough surface of about 1/100 can be designed around the molded product’s perimeter, followed by a venting groove of approximately 1mm.
Conditions for Delrin Injection Molding
Injection molding Delrin, or Polyoxymethylene (POM), requires specific processing conditions to achieve optimal results. Here’s a general guide for Delrin injection molding conditions:
Drying: Delrin plastic itself has minimal moisture absorption; therefore, drying isn’t always necessary. However, if the moisture content exceeds 0.1% during molding, drying is required to prevent the appearance of mold scales. The recommended drying conditions are 85°C for 3-4 hours.
Mold Temperature: It’s recommended that the mold temperature be set between 80-105℃. Depending on the characteristics of the Delrin molded item, its surface condition, dimensional changes during use, and molding cycle requirements, adjust the mold temperature accordingly.
Injection Pressure: Set based on the resin’s flowability, shrinkage, and the physical properties of the molded item. Generally, it should be above 98MPa. The holding pressure ranges between 49-98MPa.
Injection Speed: Typically between 5-50mm/s. However, smaller components might benefit from a faster injection speed to prevent premature cooling.
Back Pressure: To stabilize metering and prevent nozzle dripping, it’s recommended to set the back pressure at 0.5-1.0MPa.
Applications Of Delrin Plastic Injection Molding
ince its introduction, Delrin has been replacing markets traditionally dominated by metals due to its superior overall performance and costs lower than many other plastics.
It is substituting materials like zinc, brass, aluminum, and steel in the manufacture of various components and is widely utilized in automotive parts, electronics, machinery, and engineering fields.
Automotive Industry
Delrin boasts excellent rigidity and strength, allowing it to bear significant weight and vibrations without deforming even at high vehicular speeds. Its wear-resistance aligns with the requirements for automotive components, protecting them from wear and extending the vehicle’s lifespan.
As a result, injection-molded Delrin parts, such as engine camshafts and connecting rods, are extensively used in the automotive sector.
Electronics Industry
Furthermore, owing to Delrin’s excellent insulative properties, it’s extensively employed in producing electronic product casings, electronic component packaging, and other electrical accessories.
Delrin’s electrical performance is stable, ensuring the consistency of electronic components while effectively preventing potential hazards like electrical fires.
Medical Devices
Delrin plastic, with its high strength and corrosion resistance, does not produce toxic substances within the body, making it highly suitable for manufacturing medical devices. Examples include prosthetics, artificial hearts, and artificial joints.
Choose FOWMOULD to Perform Delrin Injection Moulding
With over 40 years of injection molding expertise, FOWMOULD is dedicated to delivering the highest quality Delrin injection molds and plastic products.
For customized Delrin injection molding designs, FOWMOULD’s designers will provide you with complimentary modification suggestions and guide the subsequent design phases to ensure the product meets your exact requirements.
Furthermore, FOWMOULD offers services such as 3D printing, CNC machining, plastic injection molding, insert molding, overmolding, and metal injection solutions.
If you’re interested in Delrin injection molding, contact us, and we’re here to serve you at any time!
