by Jackie Johnson Jackie Johnson No Comments

CNC Machining: A Brief Look

Computer Numerical Control, or CNC, Machines have been the gold standard in manufacturing for many decades now. But how did they get started? And how do they work? In today’s blog post we will discuss just that!

A Brief History

Rudimentary versions of Computer Numerical Control machines (CAMS) have been around since the 19th century. But CNC machines as we know them today have been in use since the 1940s. It was during that time that John T. Parsons and Frank L. Stulen of Parsons Corp. in Traverse City, Michigan, developed a machine that could read punched-card calculators to automatically produce a machined part.

Close up of CNC machine at work

Close up of CNC machine at work

How do They Work?

The general idea behind CNC machining is to take a stock material such as metal, wood, or plastic and transform it into a finished product. The machine, which can be anything from a milling machine, to lathe, router, welder, or grinder, relies on instructions from a Computer-Aided Design file, or CAD file. It is important to note that the CAD file does not actually run the machine, but rather creates the code, also known as g-code, for it to follow to create the object.

What is G-Code?    

G-code, also known as ISO code, is a relatively simple computer language specifically designed for the CNC machine to execute. The g-code tells the machine exactly what moves to execute and in which order. It provides a roadmap for the machine to step-by-step create a finished product. G-code was developed by MIT in the late 1950s and by the 60s became standard use for CNC machines.

In Conclusion

CNC machining is a huge advancement in manufacturing, enabling companies to reproduce their products or parts in a way that is much quicker and more efficient. And with the aid of a computer, the make is much more accurate as well.

Need machining solutions? Contact us today to learn more!

by Jackie Johnson Jackie Johnson No Comments

Spring Energized Seals vs. O-Rings

As long as your application involves static pressures, no extremes in either temperature or pressure, and no corrosive chemicals, an elastomeric o-ring will probably suffice. But things become more challenging outside of those conditions and you will need a better sealing solution: a spring energized seal.

O-Ring Seals

O-rings are a common type of seal that’s used in a wide variety of applications. Elastomeric o-rings are made from materials such as silicone, Neoprene, Nitrile, Buna N, and EPDM Rubber and consist of a toroid with a circular cross-section. In fact, the official definition of an elastomer component is that it does not break when stretched 100% (i.e., stretches to twice its original length). 

O-rings can effectively provide a barrier to prevent fluids from leaking and work well for static applications and some dynamic applications as long as there are no extremes in pressure or temperature. However, there are times when a spring-energized seal provides a better sealing solution than an o-ring. 

O-rings often fail due to issues with clearance as high pressures, large temperature changes, or cyclical changes in either pressure or temperature, all of which can cause dimensional changes that force the o-ring into the seal extrusion gap and cause excessive wear that leads to premature failure. In addition, environmental conditions and temperature changes can lead to the elastomeric material becoming brittle, thus losing its ability to stretch and compromising its ability to provide an effective seal.

Spring-Energized Seals

The spring energizer seal is the engineer’s choice when O-Rings cannot provide adequate seal performance.The energized seal applies a consistent force that enables the lip to adapt to the contact surface as it rotates. Because of this, spring-energized seals are often used to effectively maintain a seal even when there are challenges such as vacuum pressures, eccentric contact surfaces, runout, and hardware gaps. In short, where other static and dynamic sealing options fail, spring-energized seals rise to the task.

Operating Conditions Where Spring-Energized Seals Excel

Despite the additional cost, spring-energized seals are preferred over elastomeric o-rings when there are …

  • Extreme pressures (including vacuum pressures)
  • Extreme temperatures (including cryogenic environments)
  • Dynamic (as opposed to static) pressures
  • Corrosive media (when materials such as PEEK and PTFE are used)
  • Cyclic pressures or temperatures

In such conditions, even the best elastomeric O-rings will start losing their ability to seal. They can become brittle in extreme temperatures, and exposure to corrosive media will accelerate their natural wear. Using O-rings in such operating environments can seriously compromise the reliability of equipment and the safety of personnel, not to mention potential environmental impacts.

Additional Benefits

Also keep in mind that spring-energized seals are available with FDA approved jacket materials such as PTFE and PEEK that make them safe for use in applications such as food processing, pharmaceutical, biochemical, and medical. Their extreme durability makes them ideal for harsh environment industries such as petrochemical, oil and gas, and aerospace. 

Conclusion

When all other sealing solutions fail, a spring-energized seal is likely the answer. They consistently provide reliable sealing in operating environments that destroy o-rings, and in turn enhance the dependability, safety, and performance of the equipment that depends on them for proper operation. 

Want to learn more? Contact us today!

by Jackie Johnson Jackie Johnson No Comments

The Different Types of 3D Printing, Part 2

Last week, we talked about a few of the 3D printing technologies that are on the market. Today’s blog post is a continuation of last week’s post, with even more 3D printing methods to discuss!

DLP

Digital Light Processing (or DLP) uses a projector to cure photopolymer resin. DLP printing is very similar to SLA, the differencing being the use of a safelight instead of a UV laser. Also, like SLA, DLP creates highly detailed objects with very little visible layers. And while DLP can print much faster than SLA, the objects printed have similar properties.  Benefits of DLP printing include:

  • Highly Reliable System
  • High Quality Prints
  • Easier to Maintain than SLA Printers
  • Cheaper than Most SLA Printers

MJF

Multi Jet Fusion (or MJF), developed by HP, is unique in that it uses inkjet to create a 3D-object. An inkjet array selectively applies fusing and detailing agents across a bed of nylon powder, which are then fused by heating elements into a solid layer. This process repeats itself until the object is formed. After that, the entire powder bed is moved to a processing station where loose powder is removed and then bead blasted and dyed. Benefits of MJF printing include:

  • Lowest Cost to Print
  • More Design Flexibility
  • No Supports Needed
  • Benefits of Being Backed by HP

DMLS

Direct Metal Laser Sintering (or DMLS) is one of the best ways to make functional metal prototypes and parts. The process begins by sintering each layer with a laser aimed onto a bed of metallic powder. The powder is then micro-welded and the process is repeated layer by layer until an object is formed. Benefits of DMLS include:

  • Ability to Print Complex Parts
  • High Quality Prints
  • Rapid Print Speed
  • Print is Strong and Durable

EBM

Electron Beam Melting (or EBM) is very similar to SLS printing. There are, however, several key differences- the most significant differences being that the energy source comes from an electron beam instead of a CO2 laser, and that EBM printers work with conductive metal instead of thermoplastic polymers. The benefits of EBM printing are:

  • High Density Prints
  • Fast Printing Process
  • Non-Sintered Powder can be Recycled
  • Fewer Supports Needed

3D printing has evolved and expanded since it’s beginnings in the 1970s. Since then, there have been several different 3D printing technologies created, each with their own pros and cons. Regardless of material used, time and budget, there is a printer for you.

by Jackie Johnson Jackie Johnson No Comments

The Illustrious History of PTFE

Spring Energized PTFE Seals

Today PTFE is one of the most widely used materials in the world. So, it may come as a surprise to learn that it was discovered entirely by accident!

How was PTFE discovered? In April of 1938, Dr. Roy Plunkett and his assistant Jack Rebok were working as chemists at DuPont’s Chemors Jackson Laboratory in New Jersey. On the night of the 6th, they stored the gas they were experimenting on (tetrafluoroethylene) in small cylinders where they were then frozen and compressed.

When the men returned the next day, they discovered that the gas they stored was gone. When they released the nozzle of the cylinders, no gas was released. Thinking this odd, they split the cylinders open to find the gas had turned into a solid, white, and waxy material.

This material would later become known as PTFE (polytetrafluoroethylene) or better known by its brand name Teflon.

The History of PTFE

Dr. Plunkett continued research on this strange new material and found that it was not only one of the slipperiest materials known, but that it also had several other incredible properties such as:

  • Non-Corrosive
  • Chemically Stable
  • Extremely High Melting Point

In 1941, Kinetic Chemicals Inc, a company founded by DuPont and General Motors, patented the new fluorinated plastic. In 1945 the name Teflon was trademarked. By 1948, Kinetic Chemicals was making over two million pounds of the Teflon brand PTFE.

PTFE-Coated Cookware

It wasn’t until 1954, when French-woman Collette Grégoire, wife of engineer Marc Grégoire, asked him to try the material he had been using on fishing tackle on her cooking pans. He subsequently created the first non-stick pans under the brand name Tefal (which is an amalgamation of “Tef” from “Teflon” and “al” from aluminum). The first PTFE-coated pan was introduced in the US in 1961 as “the Happy Pan”. Since then, non-stick cookware has been a staple in kitchens around the world.

Aside from cookware, PTFE has been used in a wide variety of applications, from food processing to the space industry. In fact, PTFE was used in the initial moon landing in 1969, as it was the only plastic that could withstand the extreme atmosphere of space.

Since then, PTFE has become a staple in our everyday lives and will continue to be so for many more years to come.

Need PTFE sealing solutions? Contact us today for more information!

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Spring Energized Seals for Use in Food Processing, Pharmaceutical, and Medical Applications

Spring-energized seals are a popular choice for applications that involve food, dairy, and medicinal applications, as well as medical devices. However, not just any polymer can be used for these seals because of the risk of contamination. In this blog post, we are going to review why FDA approved materials are so important, and then talk about the three most common engineering polymers that are used with spring-energized seals.

FDA Approved Materials

The FDA CFR 177 is contained in Title 21 of the Code of Federal Regulations and deals with indirect food additives in the form of polymers. The term indirect additive refers to something that inadvertently makes its way into food, pharmaceuticals, or inhaled substances (i.e., via an inhaler or oxygen machine).

Real-world applications where FDA approved materials are of concern include filling and mixing equipment for food and beverages as well as pharmaceutical products that can include pills, powders, caplets, tablets, liquids, oral suspensions, and inhalers. In the context of medical equipment, FDA approved materials are key to the design of devices that must be free of contamination.  For analytical equipment it is vital that samples are not contaminated; machines and devices for treatment, such as blood dialysis machines or ventilators, must not have any contaminants that can harm the patient.

Spring Energized Seals with FDA Approved Materials

When spring-energized seals are combined with FDA approved materials, the result is a durable, reliable seal that is safe for use in food processing, pharmaceutical, and medical applications. Three of the most common materials used are UHMW PE, Virgin PTFE, and mineral-filled PTE

UMHW PE

UHMW PE (Ultra High Molecular Weight Polyethylene) is an FDA and USDA engineering polymer with an extremely low coefficient of friction, low moisture absorption, and good chemical compatibility. In addition, it can withstand rigorous sterilization requirements that may involve hot water, steam, or aggressive chemicals. One of its key characteristics is its self-lubrication, which eliminates the need for lubricants that could cause contamination issues.

Virgin PTFE

PTFE (Polytetrafluoroethylene) often goes by the trade name Teflon. Virgin PTFE, which has no fillers added, has the lowest coefficient of friction of any material in existence. It is also one of the most chemically inert engineering polymers and handles extreme temperatures (both cold and hot) and is both thermally and dimensionally stable. Like UHMW PE, it is also FDA and USDA approved as well as self-lubricating.

Mineral-Filled PTFE

Mineral-filled PTFE takes the outstanding properties of PTFE and enhances them for improved wear performance and strength. It, too, is FDA and USDA approved, self-lubricating, a wide range of operating temperature, chemical inertness, and compatibility with even the most aggressive cleaning and sterilization regimens.

Conclusion

Spring-energized seals provide the often mission-critical reliability that is demanded in industries involving food, medicine, and medical treatment. However, they must be matched with an FDA approved polymers such as UHMW PE, virgin PTFE, or mineral-filled PTFE.

by Jackie Johnson Jackie Johnson No Comments

A Growing Medical Market

There are many factors that contribute to the rapidly growing medical plastics market. There is an increased demand for advanced medical devices, a rise in disposable income and changing lifestyles, and a demand for affordable and efficient healthcare systems.

These and more are currently driving the medical market, with a current estimated net worth of 22.8 billion USD.

And it is only growing.

Experts suggest that by 2024, the market will grow to a whopping 31.7 billion, with a CAGR of 6.8%.

Medical Plastics Market

Source: Markets and Markets, Medical Plastics Market

Applications of Medical Grade Plastics

Plastic packaging is widespread across many industries, but no more so than in the medical field. Within the next few years, packaging is expected to grow at a CAGR of 7.8%, due to the increased use in pharmaceutical packaging, device packaging, and more.

Surprisingly though, it is devices such as medical implants and machinery that are generating the largest revenue and driving the industry forward. A perfect storm of an ever-growing population and an increase in chronic diseases, along with the lower manufacturing cost of these devices has led to the largest growth in the medical plastics industry.

Global medical polymers market

Source: Grand View Research, Medical Polymers Market Size

An Industry Standard

Since the 1980s plastics have dominated the medical device industry on account of their low manufacturing cost, flexibility, ease of replacement, and low risk of infection.

Plastics also provide radiolucency, enable light-weighting, and reduce stress-shielding. Because they are radiolucent, polymer-based surgical devices allow surgeons to have an unobstructed view.

All these combine to make medical-grade plastics the gold standard in the industry. Which in turn creates a very lucrative market.

In Conclusion

The medical-grade plastic industry has taken off in an incredibly short amount of time. With increasingly easy to manufacture products coupled with an ever-expanding market, the industry will only get bigger over time. Want to learn more? Contact us today! 

 

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Polymers for Implantable Devices

Polymers for Implantable Devices

Due to the growing demand for implantable devices, there is also a growing demand for approved materials for use in manufacturing these devices. Polymers are an increasingly important material for use in medical implantable devices, with UHMW PE and PEEK being the most popular.

The Implantable Device Market

According to the FDA, implants are defined as devices intended to stay within the body for more than 30 days. Implantable devices are an ever growing market that was already worth $96.6 billion back in 2018 and expected to reach $143.3 Billion by 2024. These implantable devices include joint replacements, deep brain neurostimulators, pacemakers, insulin pumps, gastric stimulators, and more. 

Requirements for Implantable Device Materials

When it comes to materials, the implantable device market is divided into metals, ceramics, polymers, and biologics. For implant materials to be considered safe, they must remain stable in the presence of body fluids, not elicit an adverse response from the host, and, if applicable, meet requirements related to strength, stiffness, and performance. Long-term long-term biostability and biocompatibility are also key, as well as compatibility with medical imaging methods. For load bearing implants such as those used in hip replacements, how a polymer responds to wear can also be critical.

Implantable Polymers

The two most widely used implantable polymers are FDA approved grades of UHMW PE (Ultra-High Molecular Weight Polyethylene) and PEEK (Polyether ether ketone), although there are other polymers in use.

UHMW PE for Implantables

UHMW PE has been in use for orthopedic applications for over 30 years. UHMW PE can be found in joint replacements and spinal disc implants, where properties such as a low coefficient of friction, excellent fatigue resistance, and good impact strength are vital. Its primary drawback is a lack of strength, which is why it is not used in applications that involve significant load bearing. Note that UHMW PE can be machined or molded, but cannot be injection molded.

PEEK for Implantables

Implantable PEEK offers some properties similar to UHMW PE, including good impact strength and a low coefficient of friction. It is also self-lubricating, possesses a high compression strength, and offers good wear resistance. As a matrix material combined with carbon and graphite fibers, it can be customized to offer improved properties related to strength, stiffness, and dimensional stability. Unlike UHMW PE, PEEK is more versatile when it comes to manufacturing: it can be machined, molded, extruded, and even powder coated. One of PEEK’s more recent applications is implantable spinal cages, which requires significant load bearing capacity.

Other Implantable Polymers

Other polymers for implantables include PSU (Polysulfone), which is known for its toughness, dimensional stability, and moldability. PSU can be found in implantable devices such as shunts and access ports. Another polymer is PPSU (Polyphenylsulfone), which combines toughness with transparency and is often used as a coating for wires and leads. Both of these polymers also provide excellent tensile strength and biocompatibility.

Conclusion

Materials for use in implantable devices must be stringent requirements, and for good reason. There are a host of issues, such as biocompatibility, biostability, wear properties, friction, stiffness, and strength, that all depend heavy on the application. However, there are polymers such as UHMW PE and PEEK whose performance and safety have been well established.

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Spring-Energized Seals for Cryogenic Environments

Spring-Energized Seals for Cryogenic Environments

Cryogenic environments deal with temperatures that range from below freezing all the way down to absolute zero, which is -460° F (or -273° C). Trying to seal fluids and gases at those types of extreme temperatures, but one of the most effective sealing solutions for cryogenic environments is the use of a spring-energized seal. 

Spring-Energized Seals

Energized seals are often used in situations where standard seal designs simply cannot provide the performance needed. And when cryogenic temperatures are involved, finding a reliable seal design is extremely challenging — and failure to do so can be fatal. 

How Spring-Energized Seals Work

A spring-energized seal includes a metallic spring (usually in the form of a coil) that applies a near constant load throughout the circumference of the seal. That load enables the lip to remain in contact with the mating surface, even during pressure and temperature variations as well as dimensional changes. In addition, the spring helps the seal compensate for eccentricity, misalignment, and wear. More importantly in cryogenic environments, energized seals can compensate for dimensional changes related to temperature variations.

The result of using a spring energizer is a highly reliable, almost leak-proof seal. This can be especially important when there are safety and environmental regulations are involved, as is often the case when cryogenic materials are in use. In addition, spring-energized seals can be used with both static and dynamic applications, with dynamic including rotary, linear, and oscillating motion (as well as any combination of these).

There are several different types of spring-energizers, from simple elastomeric o-rings and familiar coil springs to V springs, helical flat springs, and cantilevered finger springs. For cryogenic applications, V ribbon springs are typically used. They are found in the harshest of applications, including vacuum pressures and/or cryogenic temperatures.

 

For cryogenic applications, the spring lip is often made of PTFE and the energizing spring is made of metal. Typical spring metals include 17-7 precipitation hardening stainless steel or 301/304 stainless steel, Elgiloy, Hastelloy, Inconel, or 316 stainless steel.

Cryogenic Applications for Spring-Energized Seals 

Spring-energized seals are successfully being used for a wide in a variety of cryogenic applications:

  • Magnetic resonance imaging (MRI)
  • Biosystems
  • LNG fueling systems and compressors
  • Pharmaceutical and medical research
  • Rocket propulsion filling systems
  • Scientific instrumentation
  • Specialty gas manufacturing
  • Infrared telescopes
  • Radio astronomy
  • Satellite tracking systems

Typical fluids and gases involved include LOX (Liquid Oxygen), liquid Helium, liquid Hydrogen, liquid Xenon, refrigerants, coolants, liquid methane, LNG (Liquid Natural Gas), and LPG (Liquid Petroleum Gas). More specific examples include LAR (Liquid Argon) used in surgical environments, LN2 (Liquid N2) used in environmental test chambers, LCO2 (Liquid CO2) for cleaning and deburring. 

Conclusion

While finding a solution for a cryogenic sealing application can be challenging, it is certainly far from impossible. Spring-energized seals can provide durable, reliable sealing power in even the harshest conditions — including extremely low temperatures. By combining the right type of coil, seal geometry, and materials, you can engineer the right spring for applications ranging from rocket development to bioengineering.