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
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.
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!
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-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.
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 …
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.
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.
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.
Fluoropolymers are used in multiple industries, including aerospace, transportation, chemical and petrochemical processing, pharmaceutical, medical, telecommunications, and electronics where they are used for seals, gaskets, bushings, bearings, hoses, tubing, wiring, and even fiber optic cladding. There are multiple ways to manufacture parts and components made from fluoropolymers, and injection molding is one of them.
What Are Fluoropolymers?
Fluoropolymers, as the name no doubt implies, are polymers that are based on bonding between fluorine and carbon. The first fluoropolymer was PTFE (polytetrafluoroethylene), which is perhaps better known by its trade name Teflon. Other common fluoropolymers include ETFE (ethylene tetrafluoroethylene), PFA (perfluoroalkoxy alkane), PVDF (polyvinylidene fluoride), PVF (perfluoralkoxy), FEP (fluorinated ethylene propylene), and ECTFE (ethylene chlorotrifluoroethylene).
They are popular materials because of their properties that include resistance to high temperatures, chemical attacks, and electrical current. They are also low friction, non-toxic, exhibit minimal aging and leaching of chemicals, and non-stick. In addition, many fluoropolymers are biocompatible, making them ideal for medical applications.
Injection Molding Process
Injection molding is a manufacturing method for thermoplastic materials where the plastics are heated almost to their melting point and then fed into aluminum or steel molds at extremely high pressures using a powerful screw mechanism. There are several benefits to injection molding:
Can handle high-volume production
Labor costs are relatively low
Products highly accurate parts that can meet tight tolerances
Supports fairly complex designs with fine details
Produces an excellent surface finish
In many instances, the scrap can be recycled
The major cost involved in injection molding is the tooling: to achieve good results, the molds must be high-quality and well designed. However, molds can be configured to make multiple parts at one time with minimal post-processing.
Note that injection molding can be used to manufacture otherwise challenging components, including thin-walled parts. The feasible envelope for parts can typically range from 0.01 in³ to 80 ft³ (depending on the fabricators’ capabilities) and can achieve tight tolerances and smooth surfaces.
Injection Molding Fluoropolymers
While fluoropolymers can be challenging to injection mold, the process is not impossible for most materials. Some of the best fluoropolymers for injection molding include PFA and FEP, which are both melt-processable. Additional consideration may have to be given to the tooling for molding fluoropolymers, including a hot runner system to keep the polymer flowing easily as it moves through the mold.
PTFE, however, is challenging to injection mold because even when heated above its melting point because it simply will not flow like other thermoplastic polymers. It does soften, but not enough to make injection molding possible. Fortunately, there are several other options when it comes to manufacturing with PTFE, including machining, compression molding, cold extrusion, and isostatic pressing.
Fluoropolymers are widely used in many different industries and applications. If you are looking for an effective way to reliably manufacture components using a fluoropolymer, injection molding may be an excellent option.
3D printing has seemingly taken over the world! Because of it’s increasing popularity with both manufacturers and hobbyists, more and more 3D printers are being produced each year. There also many different types of 3D printing technologies, which vary in cost, effectiveness, materials used, speed and cost. These include:
Selective Laser Sintering (SLS)
Fused Deposition Modeling (FDM)
Digital Light Process (DLP)
Multi Jet Fusion (MJF)
Direct Metal Laser Sintering (DMLS)
Electron Beam Melting (EBM)
Because there are quite a few, we will be breaking this post into two parts, with the next part coming next week, so stay tuned!
In the meantime, let’s discuss some 3D printing methods!
Fused Deposition Modeling (FDM) is one of the most widely available 3D Printing technology today. It uses a process called material extrusion, where a solid material, usually some form of thermoplastic (PLA, ABS, PET, etc.) is pushed through a heated nozzle attached to the printer head, melting the material. As the printer head moves along specific coordinates, it deposits the material, where it cools and solidifies, forming a solid object.
Ease of Use
Wide Variety of Materials
Stereolithography (SLA) uses a printing method called vat polymerization, where a material called photopolymer resin is exposed to an ultraviolet laser, which is used to draw pre-preprogrammed designs or shapes onto the material. This process is repeated for each layer until a 3D object is completed, and then washed in a solvent to remove excess resin. Because of this, SLA printing is often messy. You are also restricted to printing with resin materials, which can be expensive. The benefits, however, include:
Higher quality prints than FDM
Faster Print Speed
Stronger Finished Products
Selective laser sintering (SLS) uses a laser to sinter powdered material together until a 3D model is formed. Unlike FDM and SLA, which have become incredibly popular in the hobbyist market, SLS has remained mostly in the realm of industrial manufacturing, because of the high cost (and potential dangers) of the lasers and materials. There are many advantages to SLS printing, including:
The ability to print objects without support structures.
High Strength and Stiffness
Good Chemical Resistance
Incredibly fast print speed
Stay tuned for next week for part two, where we discuss even more 3D printing methods!
There are several distinct benefits to be had from using canted coil springs in place of more traditional springs. Because of this, it should come as no surprise that these springs are used extensively in medical applications.
Canted Coil Springs Are Effective Electrical Connectors and Contacts
Canted coil springs are being used more and more for electrical contacts and connectors. Canted coil connectors make it easier to replace leads and lead segments without harming the patient, and lead interface solutions based on canted coil springs can significantly reduce risk to the patient. In some applications, the procedure time and the patient’s recovery time can be reduced through the wise application of canted coil springs. Canted coil springs also provide high contact power density with a minimal amount of temperature rise. In many instances, they can also reduce the size of the medical device and provide multi-channel connections.
Canted Coil Springs Can Provide EMI and RF Shielding
Another benefit of canted coil springs is their ability to provide shielding from harmful EMI and RFI interference in applications such as ultrasound equipment and vital signs monitors. Many times the medical data being transmitted cannot afford a compromise in its integrity of the disruption of the data flow. Canted coil springs can actually be tuned to meet specific impedance specifications so that medical equipment and devices can be protected from dangerous crosstalk interference.
Canted Coil Springs Can Be Used in Spring-Energized Seals
Canted coil springs can be used in spring-energized seals in medical equipment and external devices as well as implantable devices. Spring-energized seals are often used to maintain a seal when there are problems with hardware gaps, runout, eccentric contact surfaces, and vacuum pressures. In short, spring-energized seals can provide an effective seal where other seals would fail, and when canted coil springs are used then a far more consistent spring force can be applied.
Canted Coil Springs Serve as Reliable Mechanical Connectors
Canted coil springs can provide a reliable connector in three specific ways:
Holding and retaining two parts in alignment with customized forces, often used for surgical instrumentation
Securely fastening two parts together while allowing them to still be unlatched (where the latching force can be customized), which is also being used with surgical instrumentation
Permanently locking two parts together, including use during orthopedic implant surgery
Unlike most mechanical connector solutions, canted coil springs can achieve these connections with strength, reliability, and incredibly high precision. In addition, when canted coil springs are used as mechanical connectors, there is an option to customize the forces for insertion and breakaway.
Medical Applications of Canted Coil Springs
There are a host of specific medical applications where canted coil springs have proven invaluable. The following is just a sampling:
Implantable medication pumps
Insulin delivery systems
High-speed surgical power tools
Pain management devices
Vital signs monitors
Cardiac rhythm management devices
Canted coil springs are used in connection with everything from neurostimulators to orthopedic implant surgery. Their ability to serve as electrical connectors/contacts, shield from EMI and RF interferences, serve as the energizer in spring-energized seals, and provide tailored mechanical connections make them ideal solutions for many different medical devices and implantables.
There are three leading materials used for most back-up ring (BUR) applications: PTFE, Nylon, and PEEK. Each of these materials has specific benefits that it can bring to your application, starting with their stiffness and compressive strength.
Why Back-up Rings Are Important
Seal extrusion is one of the most common causes of polymer seal failure. Whether the cause of extrusion is a large gap between the mating surfaces, high temperatures, or extreme pressures, back-up rings can help. The right choice of a BUR can prevent seal extrusion, lengthen the useful life of the seal, and reduce the chances of a catastrophic failure.
PTFE Back-Up Rings
PTFE is well-known for its extremely low friction, dry running capabilities, and outstanding chemical resistance. Filled PTFE (either glass, carbon, graphite, or bronze filled) can handle operating pressures up to 5,800 psi, making it an excellent choice for both medium and high-pressure applications. Virgin PTFE has a much lower maximum operating temperature (around 3,600 psi) and is limited to low-pressure situations. PTFE also has a maximum operating temperature of 575°F, and that combined with chemical compatibility and the high-pressure capabilities of filled PTFE mean that it is an excellent option for harsh condition environments.
Nylon Back-Up Rings
Nylon 6,6 (sometimes written Nylon 6/6 or Nylon 66) is a polyamide material commonly used for back-up rings. It can handle high pressure very well but is limited to temperatures below 186°F. It possesses excellent rigidity, good compressive strength, and thermal stability, all of which are key to effective backup rings.
When used for back-up rings, Nylon is typically filled with Molybdenum Disulfide (MoS2) to achieve an even lower coefficient of friction. It is not recommended for use in wet or humid environments because it does absorb water unless fillers such as glass are added to offset the absorption effects.
PEEK Back-Up Rings
Another commonly used back-up ring material is PEEK, which can handle temperatures of up to 500°F and pressures up to 20,000 psi. Like PTFE, it is low friction, dry running, and resistant to a wide variety of aggressive chemicals. It is also available with fillers to enhance properties such as compressive strength and stiffness. However, PEEK is much harder than PTFE: PTFE has a Shore hardness of D50 while PEEK has a significantly greater hardness of D85. For these reasons, PEEK back-up rings are often used in aggressive environments, such as those found in the oil and gas industry.
If you are having issues with extrusion-related seal failure, polymer back-up rings are a cost-effective solution that can extend the life of your seals. When it comes to polymer back-up ring materials, the top three choices are PTFE, Nylon, and PEEK. While each has its own pros and cons, they are excellent options for solving the problem of seal extrusion. PEEK works best for high pressure, high temperature environments that can involve exposure to corrosive materials. PTFE can also handle high temperatures and corrosive environments, but its maximum operating pressure is lower than that of PEEK. Nylon is also an excellent choice with excellent hardness and thermal stability, with its main limitations being high temperatures and exposure to humidity and moisture.
You’ve seen them on the internet, in libraries and schools and maybe you even know someone who owns one. 3D Printers have changed the way the world and continue to provide many benefits for a number of industries. But how do they work?
Does additive manufacturing, or 3D printing, benefit the industrial market? Additive manufacturing, or 3D printing, benefits the industrial market by reducing tooling costs, allowing for faster manufacturing, and eliminating the need for inventory.
How Additive Manufacturing Works
With additive manufacturing, objects are designed using computer-aided design software (or CAD software) and are then saved as .stl files which are then digitally sliced into ultra-thin layers. It is these layers that are extruded through a hot nozzle or print head and deposited onto the previous layer. The process is repeated layer by layer until a 3D object is formed.
There are several different materials used in additive manufacturing. Thermoplastics are the most common materials used. These include PET, PEEK, Nylon, ABS, Polycarbonate, etc. Other materials that are often used include metal, ceramic, rubber, and even bio-materials.
What Are the Benefits of Additive Manufacturing?
The benefits of additive manufacturing, particularly for the industrial space, are many!
Reduced Tooling Costs
Tooling cost is a major driver in the manufacturing industry. And the upfront cost can impede many low-volume manufacturing companies, where a significant amount of capital expenditure is required before the first unit is even produced. But with the lower tooling costs of additive manufacturing, low-volume manufacturers can finally enter the marketplace.
When the success of a business is won or lost based on speed to market, the ability to quickly manufacture goods is imperative. One sure-fire way to be one of the firsts to market is to leverage additive manufacturing to reduce lead time. With 3D-printing, the production time is reduced by weeks or even months.
No Need for On-Hand Inventory
While traditional manufacturing requires warehouses full of premade parts and products, additive manufacturing allows a business to have a virtual inventory. Part information is stored in the cloud via .stl files and can be printed on demand. This removes the need for warehouse space, saving businesses space, rent money, and piles of parts.
Additive marketing, or 3D printing, is the manufacturing process of the future. Because of its ease of use, quick turn-around, and relatively low cost, additive manufacturing (AKA 3D printing) is quickly becoming one of the go-to manufacturing processes for a wide variety of industries.
Polymer bearings can be found in almost any industry and environment, and this includes the clean rooms of electronics to the harsh conditions of the oil and gas industry. And this is no surprise considering the host of benefits that polymer bearings provide, including their resistance to corrosive chemicals, low maintenance, lightweight, and low friction.
So, what exactly are the top five materials used in polymer bearings? The top five polymer bearing materials include Torlon PAI, Bearing Grade PEEK, Bearing Grade PPS, Lubricated PET, and Lubricated Nylon.
1. Torlon PAI
PAI stands for Polyamide-imide and it is the highest performing polymer that is melt-processable. It offers excellent wear resistance, has an extremely low coefficient of friction, and can handle operating temperatures up to 500°F. The primary drawback of Torlon PAI lies in its relatively high level of moisture absorption. On the other hand, it has a low coefficient of thermal expansion and a high level of creep resistance, both of which are key characteristics for an effective bearing. Torlon PAI is often used in bushings, bearings, and wear rings.
2. Bearing Grade PEEK
Bearing grade PEEK is known for its excellent wear characteristics, good abrasion resistance, extremely low coefficient of friction, and outstanding chemical resistance. It can handle environmental operating temperatures up to 500°F and performs well even when continuously exposed to hot water and steam. Bearing grade PEEK is also easy to machine, has low moisture absorption, and possesses a high PV rating.
3. Bearing Grade PPS
PPS (polyphenylene sulfide), like the other bearing grade polymers discussed so far, has excellent wear resistance and a low coefficient of friction. However, it also offers very good wear resistance and dimensional stability even at elevated temperatures. Bearing grade PPS has a rated operating temperature of 425°F and offers outstanding chemical resistance. In addition, bearings can be made to extremely high tolerances when PPS is used.
4. Lubricated PET
Lubricated PET combines the stiffness, wear resistance, and dimensional stability of PET with the low friction demands of bearing applications. It offers extremely low water absorption, good abrasion resistance, and can be machined to very tight tolerances. It is internally lubricated using a dispersed solid and is dry running (needing no additional lubrication). The internal lubrication is released during operation, further reducing the naturally low coefficient of friction that PET possesses.
The primary drawback of PET lies in its limitations with regard to temperature: its continuous service temperature is 210°F, which makes it unsuitable for extreme temperature service conditions.
5. Lubricated Nylon
Nylon does an excellent job of balancing toughness and strength while combining good abrasion resistance with the ability to be extruded, cast, or machined. Lubricated Nylon, much like lubricated PET, includes a solid dispersal of lubricants that greatly reduces the standard coefficient of friction of virgin Nylon and allows it to be used in dry running applications. One of the more common lubricants used is MDS or Molybdenum Disulfide.
The primary issue with Nylon is its ability to absorb up to 7% of its weight water, which can affect its dimensions. However, it does have an extremely high limiting PV rating and excellent wear characteristics.
The top five polymer bearing materials–Torlon PAI, bearing grade PEEK, bearing grade PPS, lubricated PET, and lubricated Nylon–are commonly used to replace metal bearings in a variety of applications. They offer the wear resistance, high PV ratings, low friction, and chemical resistance that are required. If you are in the market for new or replacement bearings, be sure to consider polymer bearings and bushings, also.
When it comes to polymer bushing, are machine or injection mold a better choice? Both machine and injection mold polymer bushing provide benefits in different applications. You must consider your unique application to select the polymer bushing that is best suited for your needs.
What’s the Difference Between Machine & Injection Mold Polymer Bushings
Before we dive into this topic, it is important to quickly review why we use polymer bushings. Bushings, which are also referred to as plain bearings, are used to reduce the level of friction between two surfaces that are in rotating or sliding contact with one another. They can also serve secondary functions, such as providing additional support and alignment.
Polymer bushings are replacing more and more metal bushings because polymers are typically lighter-weight, are more corrosion resistant, lower friction, often dry-running, and can be enhanced with fillers to improve properties such as wear-resistance and strength.
Manufacturing Polymer Bushings
When it comes to manufacturing polymer bushings, there are two primary methods to choose from: machining and injection molding. Both of these methods can generate reliable bearings to extremely tight tolerances, but they have significant differences and situations where one is preferred over the other.
Machining Polymer Bushings
When someone refers to machining, most people think of working with metals such as steel and aluminum, but plastics can also be machined. Machining is a material removal process where the material that is not needed in the final part geometry is removed with a cutting tool and may involve numerous steps.
Depending on the part geometry, this may involve a lathe (for parts with rotational symmetry). Most modern machining facilities use CNC (Computer Numerical Control) and CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) to make parts that meet strict tolerances and are consistent in their dimensions. For polymer bushings, CNC lathes are typically used and multiple process steps are required to achieve the final part geometry and surface finish, including boring, reaming, and facing.
Benefits to machining include a short lead time and cost-effectiveness for low volume production runs of less than 1,000. Machining also avoids residual stresses (which we will discuss in a moment) that can warp the bushing and works extremely well when there are very tight tolerances or thin walls. Machining is also well adapted for situations where there is a need for non-standard shapes or bushing dimensions.
Injection Molding Polymer Bushings
Injection molding is a commonly used polymer manufacturing process that forces molten plastic into steel molds at extremely high pressures. Injection molding machines use a screw system to transport the plastic at high pressure into detailed molds that are typically designed to make multiple parts at a single time. The major expense in injection molding lies in the engineering and fabrication of the molds.
Injection molding of bushingsis fast once the tooling is engineered and machined, ideal for production runs over 5,000 parts, and works exceptionally well for bushings that are standard-sized. However, injection molding does have its drawbacks. The most problematic drawback in the context of polymer bushings is residual stresses that develop as the part cools, but it is possible to eliminate these stresses through plastic annealing.
There can also be issues with shrinkage and dimensional change, which can make it a poor option if the plastic bushings need to meet high tolerances. In addition, injection molding is not a reliable approach if the bushings have thin walls.
The demand for polymer bushings and plain bearings continues to rise. When it comes time to specify the bushings for an application, it is important to choose the best manufacturing method. For situations with small production runs, non-standard dimensions, tight tolerances, or thin walls, polymer bushings should be machined. When a large production run is involved and the bushings have standard dimensions and/or geometries, injection molding is the best option.
Expanded PTFE (or ePTFE), like regular PTFE, is an incredibly versatile and rugged material. And like PTFE, ePTFE began as an accident. Before we can get to that, however, we should start at the beginning.
What is the history of ePTFE? When his ideas for expanding the use of PTFE was turned down by his employers at DuPont, chemist Wilbert “Bill” Gore left the company to start his own. And in 1958 Gore and his wife Genevive “Vive” Gore founded W.L. Gore and Associates out of the basement of their Delaware home. During this time, Gore’s company began to serve the burgeoning computer industry by using PTFE to insulate multiple copper conductors and fashion them into ribbon cable resulting in a product known as MULTI-TET.
Learn More About the History of ePTFE
Bob Gore recreating his discovery of ePTFE
As the years went on it became clear to Gore that trends in computer technologies meant that computers were becoming smaller and smaller, resulting in the need for less cables for circuitry. In 1968, Gore tasked his son, Robert “Bob” Gore, to come up with a solution. One night in October 1969, Bob Gore was researching a new process for stretching extruded PTFE into pipe-thread tape when he discovered that the polymer could be “expanded.”
After several failed experiments in which Bob tried to slowly expand the material even further, he became frustrated and yanked the material. As it turned out, this was the exact conditions PTFE needed to become expanded. This sudden yank resulted in the transformation of solid PTFE into a microporous structure that was about 70% air. This material would later become known as ePTFE, or Gore-Tex.
Today, ePTFE is used in a wide variety of applications. These applications include:
And much more
Interested in learning more about ePTFE and how Advanced EMC Technologies can offer you premiere sealing solutions? Contact us today!