Delrin® is the commercial name of polyoxymethylene (POM) or acetal offered by DuPont. It is considered a viable alternative to metal thanks to its excellent physical and mechanical properties.
If you are hoping to use it for machining purposes, whether for prototyping or high-volume manufacturing, it’s going to be quite challenging. This is because Delrin® plastic comes in several grades that vary in performance, melt viscosity, and durability.
Our guide will help you understand the characteristics and various uses of Delrin® and how to select the right type for your needs.
Why is Delrin® Suitable for Rapid Prototyping Requirements?
Delrin® possesses the characteristics required to undergo rapid prototyping processes effectively and deliver a flawless output. Here are some of them.
Delrin® plastic displays good dielectric properties over a wide range of temperatures and in humid and wet conditions. It is an ESD-safe material with low thermal conductivity.
With low dissipation factors, it is highly suitable for insulation purposes and is frequently chosen for manufacturing electrical components.
Durability and toughness also make Delrin® stand out from its counterparts. It’s a very rigid and heat-resistant material. But this doesn’t mean it’s not moldable. Delrin® plastic won’t melt gradually with heat. Instead, it will melt sharply once it reaches its melting point.
With a high tensile strength of 10,000 psi at room temperature and a high level of stiffness, Delrin® is one of the best thermoplastics for products that need to bear high loads and perform in harsh conditions.
Abrasion resistance, impact resistance, fatigue resistance, and low friction are some other factors that contribute to its superior strength.
Cyclical stress can cause some materials to fail at levels below their optimal tensile strength, but Delrin® has showcased that it can resist fatigue failure. Its mechanical strength, hardness, and structural integrity make it outstanding at resisting fatigue without compromising its performance.
With superior creep resistance, it tolerates stress well and won’t dent or deform easily. It can resist moisture absorption and chemicals. As it can also withstand repeated sterilization cycles, Delrin® is often chosen for manufacturing medical-grade instruments.
Delrin® has an impact strength of 0.75-2 ft-lb/in. You can expect the product to retain its shape and form even when subject to sudden or continuous impact.
Even at low temperatures of around -40°C, it loses its impact resistance only by 20%. It also doesn’t become brittle at low temperatures. So, Delrin® is suitable for producing heavy-duty parts.
Delrin® is a very stable plastic because of the properties we discussed above. It is moderately resistant to chemicals and doesn’t succumb to the pressure of environmental factors.
The dimensional stability also makes it easily machinable to tight tolerances compared to many other thermoplastics. It supports a working temperature range of -40°C to 120°C. It’s vital to melt Delrin® at its optimal temperature to retain its structural stability.
Delrin® has very low coefficient friction of 0.1-0.3, and it remains largely unchanged despite changes in temperature, load, and movement.
It’s a self-lubricating plastic and cannot be subject to frictional wear easily. For this reason, Delrin® is great for manufacturing mechanical parts with long service life.
Drawbacks of Delrin® Plastic as an Injection Molding Material
As with every other engineered plastic, Delrin® comes with a set of disadvantages that are important to consider before you decide whether it’s the right choice for your design idea.
Delrin® is flammable, and the flame is nearly invisible, making it hard to detect. It’s not self-extinguishing and can only be put out with a class-A extinguisher.
As Delrin® is also reactive to chlorine, it’s difficult to make it flame-retardant with additives. It can catch fire during machining if the heat is too high.
It can also expose you to toxic fumes. Delrin® is not suitable for producing flame-resistant or electric components prone to sparking.
While Delrin® is good at resisting heat up to 121°C, it is sensitive to temperatures beyond it. Extreme heat can subject it to deformation.
Therefore, the heat generated during the machining process must be kept as low as possible. Overheating can also produce toxic formaldehyde fumes. The workstation must be well-ventilated.
As with many other high-performance polymers, Delrin® is a material with low surface energy and high resistance to chemicals. Therefore, it’s difficult to bond the plastic using typical solvents or adhesives like epoxies and polyurethane.
You can improve the bondability by roughening the surface, chemical etching, and flame treatment. However, they may not create a strong bond.
While Delrin® wins in stiffness compared to most other thermoplastics, it falls behind compared to metals. So, it may not be a suitable replacement for metals in applications where maximum stiffness is desired.
Also, when using Delrin® to produce large-sized products, you have to machine the walls extra thick.
Different Types of Delrin®
Delrin 150® is durable, hard, and impact-resistant. It also boasts metal-like mechanical properties and a high level of moisture resistance. It is an injection-molding grade polymer that’s high in viscosity.
Delrin 150® is one of the most versatile materials and is available in the form of sheets and rods. However, it’s not very chemical resistant and is only suitable for general-use products.
It comes in its natural color (white) or black and is compliant with FDA, NSF, and USDA standards. Applications include home appliances, gears, electric insulators, food packaging, gas caps, and sturdy plastic products.
Delrin AF 100 (13% PTFE Filled)
Delrin AF 100® is an optimal combination of PTFE with acetal resin. This grade excels in lubricity, friction, and durability compared to unfilled Delrin®. Its self-lubricating property also means you don’t need external lubricants like grease to improve the performance.
In addition, the material brings you the tough and wear-resistant properties of acetal homopolymer. Delrin AF 100® is available in sheets and rods and is dark brown. Its applications include bearings, automotive parts, laboratory products, moving parts, and machinery.
Delrin (30% Glass Filled)
Glass-filled Delrin® is manufactured by mixing powdered glass with acetal to enhance the stiffness by up to 80% compared to natural Delrin®. It also means that the tensile strength, durability, and wear resistance of the material are also considerably higher.
Glass-filled Delrin® is also renowned for lowering thermal expansion by half compared to unfilled Delrin®. So, it will stay put despite changes in temperatures. This grade is also available in rods and sheets and is usually white.
Glass-filled Delrin® is preferred for products that need to excel in fatigue and impact resistance. Some applications are bearings, fuel system components, construction supplies, and automotive parts.
Delrin AF DE588®
Delrin AD DE588® is filled with 20% PTFE for optimal strength. Excellent dimensional stability, low coefficient of friction, strength, low water absorption, and wear resistance are some defining characteristics of this resin.
If you are looking for a plastic ideal for products with high load-bearing ability and parts that need to move at high speed, this is it. Delrin AD DE588® was a material specially developed for US Naval use and is used for manufacturing submarine parts.
Some other applications are valve seats, electrical components, bearings, pulleys, wheels, wear plates, and forming dies. Delrin AF DE588® is available as sheets, rods, and tubes and is dark brown or gray.
What Are Some Applications of Delrin®?
The automotive field demands high-performance plastics that can withstand regular wear and tear and have a good load-bearing ability. Delrin® fits into the criteria very well while bringing a host of other beneficial properties.
As it’s self-lubricating, it doesn’t make noise, and it is a crucial factor for the seamless performance of vehicles. At present, it is primarily used for interior components of vehicles such as,
- Gear systems
- Windshield wipers
- Automotive control switches
- Fuel pumps
- Wiring clips
- Electric windows
Tools, machinery, and other supplies in industrial settings need to be manufactured with strong materials to resist depreciation. Delrin® can withstand repeated impact without deformation and is especially great for components with smooth movement.
It’s also very stiff and resistant to moisture and most chemicals. All of these are essential characteristics of industrial gear. Some common parts manufactured using Delrin® are,
- Conveyor belts
- Automated door systems
- Electrical insulation
- Handles and hooks
- Safety restraints
Consumer and Commercial Products
Delrin® is a highly preferred material for products designed for home and office environments. It’s a high-quality alternative to unreliable plastics that limit the lifespan of the product.
It has a very resilient and sturdy surface that’s convenient to clean and maintain. The low friction of Delrin® makes it easy to design parts that can slide in and out easily.
Moreover, the resin’s water resistance and anti-corrosiveness make it ideal for appliances for kitchen and bathroom spaces. Some popular consumer products and components made from Delrin® are,
- Wheels for kitchen cabinetry
- Safety helmets
- Knife handles
- Rollers in sliding doors
- Hinges and locks
- Water pump systems for gardening
The impressive dielectric properties of Delrin® make it a sought-after resin for manufacturing different components in electronic items. It provides good insulation to protect the user from potential injuries due to malfunctions.
Good mechanical strength is another reason why this plastic is chosen for electrical parts like,
- Casings or covers for electronic products
- Electronic cigarettes
What to Consider When Selecting Delrin® for Prototyping Needs
The moisture absorbed by Delrin® plastic is minimal. However, if the particular component will be frequently exposed to moisture or will be submerged in water, then you should go with a grade that offers the optimum moisture resistance.
It’s also important to note that the presence of chlorine can affect the plastic’s performance. For example, Delrin AF DE588® is a naval-grade resin that can resist the effects of fresh and saltwater.
While natural Delrin® is excellent at impact and creep resistance, the addition of Teflon fibers or powdered glass to the plastic can improve its wear characteristics.
So, if your product is geared towards heavy industrial use and has to perform in harsh environmental conditions, go with a Delrin® grade like Delrin AF 100®, Delrin (30% Glass Filled)®, or Delrin AF DE588®. You can also consider Delrin 577®, which has carbon black for better weather resistance.
Delrin® is one of the best choices for rapid prototyping, but the quality of the final output depends on the manufacturing solution. You can fabricate the plastic using injection molding, extrusion, blow molding, machining, and stamping processes.
It is particularly popular for injection molding processes and is great for manufacturing high-precision parts with complex geometries that are difficult to produce using metal or some plastics.
However, shrinkage is common in Delrin®, as with every other material. Glass-filled Delrin® or tougher grades like Delrin 570® or Delrin 577® can minimize the shrinkage effect.
Finally, consider the intended purpose of the product or part to select the best type of Delrin® for your needs. It will also help you determine if there are better polymers than Delrin® for your requirements.
For example, Nylon is less flammable than Delrin® and is a better choice for products prone to extreme heat or sparks. Consider the environment it will function in and the elements it will be exposed to during usage.
While Delrin® is chemical-resistant, we don’t recommend it to be used with acids, bases, or oxidizing agents.
Common Questions about Delrin®
Delrin® is a great material but it’s far from perfect. While its mechanical strength and sturdiness are huge benefits, it’s not suitable for all kinds of applications.
We hope our guide helped you understand better and clarified your doubts. Always speak to an expert or your manufacturer to get an expert opinion on the material you have chosen for the product. They can also help you with determining shrinkage rates and tolerances of Derin® materials.