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Materials

Our core expertise, and much of the work we do, involves processing of corrosion resistant and high purity fluoropolymers such as PTFE, PFA, FEP, PCTFE and PVDF.

PTFE

The fluoropolymers industry had its beginnings with PTFE (formerly referred to as TFE) which stands for Polytetrafluoroethylene, the polymer discovered by Chemours™ (formerly DuPont™) in 1938. Since then, other manufacturers entered the market and produce the material under their own trade names. A broad overview of the material can be found in the on-line encyclopedia Wikipedia here.

More specific sources of information come from the manufacturers themselves, including:
 

  • 3M, who manufactures PTFE under the trade name Dyneon™

  • Chemours™ (formerly DuPont™), who manufactures PTFE under the trade name Teflon®

  • Daikin America, who manufactures PTFE under the trade name DAIKIN-POLYFLON™

  • AGC Chemicals America, who manufacturers PTFE under the trade name Fluon®


Each manufacturer offers PTFE in a variety of formulations generally referred to as "compounds", differing mostly in the size of the raw powdered resin particles and various added fillers. Fillers can be materials such as carbon to increase electrical conductivity (making parts static dissipative) and glass fibers or beads to enhance certain mechanical properties. Of course, there can be trade-offs to consider in that fillers may adversely affect some material properties. Micromold's years of experience can help you intelligently select the best compound for your particular application.

Since PTFE will not flow above its melting point, it cannot be injection molded and requires special processing techniques. PTFE is processed by first compression molding the powder into preforms, and then sintering the preforms in a process analogous to sintered metal processing. This process creates geometric shapes that can then be machined, fused, and/or welded.

Click here for Properties of PTFE - Representative Values
Click here for the standards we manufacture to regarding superficial visual flaws in molded and extruded PTFE

The same chemical inertness of PTFE that makes it a good choice in corrosive chemical environments makes it difficult to join it to itself and other materials. While difficult, joining PTFE is not impossible. Welding and fusing PTFE are two of Micromold's specialties. For example, the three large outer PTFE body parts of our Y-strainer and the two end connection bosses are fillet welded using PFA welding rod. The sealing o-rings are FEP encapsulated and the PTFE inner and outer cartridge cages are snap-fit into the threaded PTFE removable knob. The standard strainer mesh is another fluoropolymer, Tefzel® ETFE. Combining all these materials results in a corrosion resistant assembly where all wetted surfaces are fluoropolymers of one form or another. It can withstand continuous service with hot 98% sulfuric acid, for instance—an environment that would rapidly destroy most metals.

Micromold processes all the material used in-house except the o-rings and mesh.

PTFE Y-Strainer cross-sectional view

Fusing is another technique for joining PTFE that Micromold specializes in. Our dip pipe and nozzle liner products both benefit from this process. Micromold processes the raw PTFE powder from molding through machining to create the flanges and then fuses the flanges to extruded PTFE tubes. Fusion is done using dedicated equipment developed at Micromold to combine carefully calibrated heat and pressure. This proprietary fusion process causes the parts to merge, essentially creating a single seamless product.

PTFE Lined & Jacketed Dip Pipes and PTFE Nozzle Liners

PFA

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PFA is similar to PTFE in chemical resistance and temperature capabilities with continuous operating temperature ratings approaching 500 °F (260 °C).

 

FEP

 

FEP has equal chemical resistance, but continuous operating temperature ratings are lower, on the order of 400°F (204°C). Both PFA and FEP, unlike PTFE, can be injection molded.

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PVDF

PVDF stands for Polyvinylidene Fluoride and is best known under its trade name, Kynar™ manufactured by Arkema Inc. who offers an on-line source of information here. An overview of the material can also be found in Wikipedia here. Another major source of PVDF is Solvay Solexis who manufacturers it under the trade names Solef® and Hylar® and supplies information here. PVDF is similar to PTFE in that it is resistant to attack from a wide range of chemicals and is able to operate at higher temperatures than most plastics. The range of chemicals it can handle is not as broad as that of PTFE and its continuous operating temperature lower, but it can be injection molded and it is much stronger than PTFE within its operating temperature range. PVDF products can be susceptible to cracking if not properly stress-relieved. Micromold is experienced at stress-relieving in our own ovens with annealing cycles tuned over the years to optimize the strength of our products and our customers' products.

The PVDF Basket strainer shown is another good example of Micromold's ability to mix and match fluoropolymers to optimize products for the end-user. This material is a good choice where the environment is harsh enough to need a fluoropolymer, but doesn't warrant PTFE. In this case, a Kynar® PVDF weldment gives the unit more strength at lower cost than Micromold's similar PTFE basket strainer, but the cartridge, which doesn't require the strength of PVDF, is PTFE for the ultimate in chemical compatibility. As with the Y-Strainer discussed above, the FEP encapsulated o-rings and Tefzel® mesh complete the assembly of 100% fluoropolymer wetted components.

PVDF Basket Strainer cross-sectional view

Other Materials

 

We routinely work with many other materials and have extensive experience in machining and fabricating them alone or in combination both for our proprietary products as well as for the OEMs we serve.  These include but are not limited to:

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  • PCTFE

    • PCTFE is chemically similar to PTFE, and thus resistant to many corrosive chemicals, but is melt processable and can be injection molded, compression molded or extruded. It has an upper useful temperature rating of 400 °F (204 °C), but it also has value in cryogenic applications down to -400 °F (-200 °C). It can be a difficult material to work with, sometimes requiring annealing, and Micromold has all the needed expertise based on years of experience working with it. Micromold CNC machines PCTFE valve seats and other OEM parts for semiconductor manufacturing, as well as other process industries. As discussed in depth on our OEM page here, Micromold also routinely works with the following materials, and has extensive experience in machining and fabricating them alone or in combination:

  • Acetal (Delrin®, Celcon®)

  • Acrylic

  • CPVC

  • Nylon

  • PBI (Celazole®)

  • PEEK

  • Polyamide-imide (Torlon®)

  • Polyimide (Vespel™)

  • Polyethylene

  • Polypropylene

  • PPS (Ryton®)

  • PVC

  • SP-Polyimide (Vespel®)

  • UHMW Polyethylene

• Acetal (Delrin®, Celcon®)

• Acrylic

• CPVC

• Nylon

• PBI (Celazole®)

• PEEK

• Polyamide-imide (Torlon®)

• Polyimide (Vespel™)

• Polyethylene

• Polypropylene

• PPS (Ryton®)

• PVC

• SP-Polyimide (Vespel®)

• UHMW Polyethylene

Trademark Attribution Chemours™ (formerly DuPont™), Delrin®, Vespel®, Tefzel® and Teflon® are trademarks or registered trademarks of E. I. du Pont de Nemours and Company or its affiliates. Dyneon™ is a trademark of the 3M Company. DAIKIN-POLYFLON™ is a trademark of Daikin America Inc. Fluon® is a registered trademark of AGC Chemicals America. Kynar® is a registered trademark of Arkema Inc. Hylar®, Solef® and Torlon® are registered trademarks of Solvay Solexis. Celcon® is a registered trademark of Ticona Engineering Polymers. Ryton® is a registered trademark of Chevron Phillips Chemical Celazole® is a registered trademark of Quadrant Engineering Plastic Products

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