Dupont Delrin rod and Acetal Rods

Many of our clients assume that Delrin rod and Acetal rod is the same thing. This is not quite true. Yes, all Delrin rod is Acetal rod, but not all Acetal rod is Delrin rod. Delrin is a trade name for Homo-Polymer Acetal made by Dupont. This is the most recognized of all Acetal materials, but far from the only available Acetal material.Black and Natural Acetal - Delrin Rod
The Co-Polymer Acetal is produced by a wide variety of large plastic manufacturers, BASF is probably one of the largest and most well known. Some main resin names are: BASF Ultraform H4320, Kepital F10-02, or Hostaform M25. While Delrin is a wonderful material, in larger cross sections or larger diameters, the Delrin brand Homo-Polymer can exhibit center line porosity. This can sometimes be seen with the naked eye, and is a darker white in a normally milky white natural colored material. This center line porosity can cause problems in some applications. This porosity can cause leakage of fluid if under pressure, or ‘soft centers’ of Delrin Rod and Delrin Sheet.

This should not stop you from considering Delrin though. Many other properties of the Delrin resin are superior to the Co-Polymer resins. These properties are:

General Property ASTM
Test
Typical Value
Unfilled Delrin®

Homo-Polymer
Typical Value
Unfilled Co-Polymer
Specific Gravity D792 1.42 1.40
Tensile Strength Yield D638 9,600 – 11,000 9,000 – 10,200
Tensile Modulus D638 450,000 400,000
Izod Impact – Notched D256 1.2 1.0
Hardness – Rockwell D785 M94 M90
Deflection Temp @ 264psi D648 257 220
Deflection Temp @ 66 psi D648 347 335
Water Absorption @ 24 hrs
% 0.24 0.25
Co. Thermal Expansion D696 6.83X10-5 5.4X10-5

The key properties that Delrin are: higher tensile strength, increased Izod impact, higher deflection temperatures and it is slightly harder. The co-efficient of thermal expansion is a bit higher, and needs to be considered when designing a new part. Delrin brand material also comes in several resin variations, including: Delrin 150 and Delrin 507, contact us for details.

Many of our clients prefer the Delrin brand rod and sheet for small machined parts. This is due to the increase in a few key properties, and of course brand recognition. Both resins meet the standard ASTM-D-6778, and the cancelled specs, L-P-395 and ASTM-D-4181.Colored Acetal - Delrin Rod - Pomalux

The Acetal family of plastic resins are excellent for wear resistance, great mechanical strength, and superior machining properties. It is available in a huge range of sizes and shapes. Click here for more details on Acetal – Delrin Rod, and sometimes referred to as plastic dowel. We also have the capacity to supply colored Acetal – Delrin rod; click here from more details on the colored Acetal material.

Similar materials to Acetal – Delrin are Nylon Rod, PET Rod and Noryl Rod. Most materials are available as round rod, square rod, bar, strip, sheet and plate.

Please contact us for more details on these and other plastic materials. For a comparison chart of plastic materials click here: Plastic Materials Selection Guide

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Unitrex Lf20 – PTFE Filled PEEK

A newly released form of Filled PEEK is now available. This PEEK is filled with PTFE and is called Unitrex Lf20, and it is filled with 20% PTFE. This new grade of PTFE Filled PEEK plastic is produced by Nytef Plastics. It is an extruded thermoplastic that comes in both rod and sheet form. This grade has significantly improved properties over the standard unfilled grades of PEEK. The PTFE filler provides excellent wear properties and has a very low co-efficient of friction, which makes this a great material for sliding and wear applications, and is made to last for long periods of abuse. Unitrex Lf20 has great machinability and dimensionally stability. It has a wide range of uses in such fields as medical, semi-conductor, and aerospace seals, where standard PEEK is too rigid. These properties enable this material to replace Polyimide (Vespel®) and PCTFE (formerly Kel-F) in many applications of high chemical resistance and the ductility for use in seals. This Filled PEEK works extremely well in Medical, Semi-Conductor and Aerospace Seal applications. Nytef Plastics Unitrex Lf20 Manufacturer

PTFE Filled PEEK vs. PTFE Filled Acetal – Delrin

 

Comparable to Lf13 which is 13% PTFE filled Delrin (Delrin AF), which is also good for most of the same types of applications but cannot withstand the high temperatures than that of Unitrex Lf20. The PTFE Filled PEEK has a melting point of 650 degrees F while the PTFE Filled Delrin – Unital Lf13 has a melt point of 347 degrees F, making both materials high temperature plastics.

Because the Nytef Unitrex Lf20 is filled with PTFE (which has the lowest co-efficient of friction of any plastic), it is ideal for sliding and wear applications. It also has a kinetic and static friction resistance of 0.1 which makes it the perfect choice for jobs were heat from friction should not be generated and part longevity is critical. Unitrex Lf20 offers superior properties to many other plastics, such as high heat and chemical resistance but also great friction resistance along with improved properties to make it a great plastic for a wide spectrum of uses.

Why Change from Vespel SP-1 or PCTFE to Unitrex Lf20?

While this new PTFE Filled PEEK will not replace the Vespel SP-1 and PCTFE in all applications, it certainly will in many applications (see table for comparison). The main reason to make a change is, drum roll please, COST. The Unitrex Lf20 is up to 30% less expensive that the other materials. With similar and comparable properties, consider making the change.

Unitrex Lf20 also exhibits a far superior chemical resistance to that of its Delrin counterpart due to PEEK having a far better range of chemical resistance to aqueous and organic environments as well as acids and alkalines. Delrin tends to degrade when exposed to such chemicals like sulfuric acid and chlorine while PEEK only tends to be attacked by halogens and hydrocarbons such as in crude oils. For additional properties and to compare the Unitrex LF-20 to Dupont Vespel SP-1 and PCTFE see the table below. Here is a copy of the full data sheet on Nytef Unitrex Lf20.

 

Standard Properties Table

Properties TestMethod Unit UnitrexLF20 Nominal Value PCTFE(Kel-f) Nominal Value VespelSP-1 Nominal Value
Specific Gravity ASTM-D-792 1.42 2.1 – 2.14 1.43
Tensile Strength ASTM-D-638 psi 11,500 4,800 – 5,300 12,500
Tensile Modulus ASTM-D-638 psi 460,000 207,000
Flexural Modulus ASTM-D-790 psi 500,000 180,000 450,000
Rockwell Hardness ASTM-D-785 84-D 90-D 45 – 60 E
Melting Point DSC degress F 650 410 – 415 680+
Flammability UL 94 @ 3.0mm V-0 V-0 V-0
Kinetic Coef. of Friction ASTM-D-1894 0.1
Static Coef. of Friction ASTM-D-1894 0.1

For additional details on these and other materials, please contact us here or call us at 866-832-9315

Unitrex and Unital are registered trademarks of Nytef Plastics, Ltd.
Nytef is a US manufacturer of plastic sheet and rod, is based in Bensalem, PA
Delrin and Vespel are registered trademarks of E.I. Dupont

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