Intech Power-Core Thermoplastics Engineering Blog

Power-Core Plastic Components Take On Metals

Posted by Alexander Bartosch on Feb 27, 2014 8:17:00 AM

Even with all the advances in engineering polymers and processing methods, metal alloys still dominate the production of large parts used in power transmission and structural applications. And that dominance makes sense. Metals not only have the strength to withstand heavy loads over time but also have the advantage of familiarity. Most engineers know how to design with metals and how metals fail. Plastic properties can seem obscure in comparison.

It’s time, however, to shed some light on the capabilities of plastics in large part applications. Plastics can outperform metals in these some of these applications—but only under a very specific set of conditions:

  • Mechanical Properties Are Within Reach. To be sure, some large part applications have extremely high mechanical and thermal loads, which can rule out plastics of any kind. But don’t count out plastics prematurely. We have delivered larger polymer structural parts and power transmission components that withstand continuous forces of several metric tons. The key to these heavily loaded applications is picking the right material and manufacturing method. Our approach to large parts relies on a proprietary nylon material that we gravity cast. It has significantly different—and higher—strength properties than seemingly similar injection molded or cast polymers

  • The Application Requires Special Properties. No engineer in his right mind will replace a proven metal component with a plastic one—unless he has a good reason. Premature failure due to wear or corrosion represent two of the most common reasons to replace metal components with a high-performance plastic. The right plastic can eliminate wear altogether and resist corrosive environments in ways that metals cannot. Weight reduction is another good reason, since polymers like our Powercore (TM) weigh about 7x less than steel. The weight reduction comes in handy in many transportation applications where every ounce counts or in high-speed machines that have difficulties with inertia mismatches. Still other special properties revolve around the electrically and thermally insulatative properties of polymers.

  • Plastics Have To Cost Less. Plastics components often cost less than their metal counterparts, though their cost advantage is not always straightforward. Our Power-Core nylon material, for example, does not always offer an immediate cost reduction compared to metals. In fact, sometimes it costs more to produce the plastic component if it’s replacing a simple machined steel part. But the cost advantage will tip in favor of polymers over time whenever metal components fail prematurely due to wear or corrosion. Polymers also gain an advantage whenever they produce significant process advantage—such as higher speed or unit cost savings.The polymer component may also cost less because it eliminates the expensive lubrication needed to keep metal components running. When polymer components replace more complex metal parts, as opposed to a simple part, the cost reduction can be immediate. The reason boils down to a manufacturing edge. Polymer components can often be produced net-shape or near-net-shape, so they can cost less to produce then complex metal components that require multiple fabrication steps. A single casting can often replace multiple metal parts, producing more savings.

  • Polymer Properties Must Scale Up. A polymer’s physical properties won’t typically change with the size of the part. For example, a polymer that resists moisture will do regardless of part size. The inherent physical properties, however, paint only half the picture. Some polymer properties will change with size due to the influence of the processing method. Our gravity casting process, for example, can produce large parts without the internal stresses you would find in a high-pressure processing method such as injection molding. This low stress state is largely due to the resulting dense crystalline structure in the cast part as well as the gradual cooling in the mold. The low stress state allows the cast parts to remain dimensionally stable regardless of size. Indeed, we have produced parts that measure several meters across that have essentially the same dimensional stability parts measuring a few centimeters.

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Tags: PA12GC, cast nylon 6, nylon 66, delrin alternative, gluing delrin, plastic welding, Nylon 6 Alternative, Cast Nylon Alternative, PA12G alternative, PA12C Alterative

Large Cast Power-Core (TM) Propeller Dives Into Paper Pulp Mixing

Posted by Alexander Bartosch on Feb 20, 2014 8:00:00 AM

Most engineering polymers won’t stand up to the harsh conditions found inside the mixing tanks used in pulp and paper processes. High shear forces, elevated temperatures, aggressive chemicals and continuous wear can mean an early death for ordinary polymer pumps and impellers. And in fact, internal mixer components are typically made from expensive stainless steel grades or platings, not plastics.

Our Power-Core(tm) PA12GC Gravity Cast monomer, however, is different than other engineering plastics, and it has emerged as a emerged as a cost effective alternative to composites and metals in tank propeller applications. This ability to withstand the challenging conditions found in pulp and paper processing also makes Power-Core(tm) a natural fit for other types of mixers and processing machines.

 

Power-Core(tm) has four key characteristics that allow its use in these propeller applications:

  • Resists Aggressive Chemicals. Power-Core resists the strong acids and bases found in pulp and paper processing. As a result, the material avoids the environmental stress cracking and brittle failure that would put an end to propellers made from less capable plastics.

  • Fights Wear. Because of their continuous contact with viscous liquids, mixer propellers tend to suffer from hydroabrasion. Power-Core has an innate resistance to this wear mechanism.

  • Scales Up. The propellers measure 1,500 mm across. So none of Power-Core’s chemical and wear resistance would make much of a difference in this application if the material didn’t lend itself to large structural parts. Regarding size, Power-Core’s proprietary gravity casting process can produce stress-free parts that measure more than 3 meters across. What’s more, the Power-Core gravity casting process allows the polymer to be cast over structural steel parts. The propellers, for example, have a structural steel hub to optimize the power transmission from the shaft to the blades.

Costs Less. No one would replace steel propellers unless there was a clear advantage to polymers. Power-Core has just such an advantage in the form of a longer life than steel, which tends to give into hydroabrasion prematurely. Power-Core also has a manufacturing advantage in that it can be cast net shape, eliminating expensive machining and finishing operations required by stainless propellers.

 

Contact an Engineer

Tags: PA12GC, paper pulp mixer, plastic for paper pulp, Voith plastic parts, cast nylon 6, PA12G alternative, PA12C Alterative

Power-Core Withstands Pulsed High Voltages

Posted by Alexander Bartosch on Feb 6, 2014 8:57:00 AM

The development of high-voltage pulsed power systems for both research and commercial applications has created a tricky design problem related to electrical insulation. Ceramics would be the traditional choice for bushings that insulate the metal electrodes in these systems, but ceramics are bulky and expensive to manufacture.

Intech Power-Core™ has emerged as compact, cost-effective alternative to ceramics. This gravity-cast nylon 12 polymer offers a combination of electrical and physical properties that make it uniquely suited to high-voltage pulsed power applications. These include:

When used in a recent experimental design for a pulsed electron accelerator, the Power-Core insulation was cast over the system’s stainless steel electrode to form an insulating bushing. Often these bushings will have to separate different insulating media—for example, vacuum on one side and transformer oil on another. So both low-outgassing and chemical resistance can come into play simultaneously.

One advantage of casting in this application has to do with the interface between the polymer insulation and steel electrode. Casting the polymer over a knurled surface on the electrode creates a seamless mechanical interface that helps produce a stable vacuum around the electrode and prevents any leak paths between the different insulating media.

To date, we’ve helped design and test insulation for pulsed electron sources up to 400 kV with pulse durations from 20 to 30 nanoseconds in vacuum, oil and gas environments. However, our experimental data suggests that Power-Core insulation bushings could withstand pulsed voltages to 1 MV. With more development work, Power-Core bushings could go even further—to voltages in the 5 to 10 MV range.

For more detailed information about our work insulating our pulsed power supplies:Contact an Engineer

Tags: cast nylon 12, electrically insulated, PA12GC, PA12C, PA12G, Cast Nylon, Nylon 6 vs Nylon12, Nylon Vs Delrin

Actuator Redesign For High-Speed Belvac 795 Can Making Machine

Posted by Alexander Bartosch on Feb 25, 2013 12:01:00 PM

Though the necker on a can making line performs a very specialized task, the mechanical subsystems found on this machine offers a number of design lessons that can be applied more broadly by any engineer working to improve the performance and reliability of high-speed equipment.

Consider, for example, the necker’s cam-driven ram actuators. Mounted on a rotating turret and moving at speeds up to 250 strokes per minute, these rams push the round can shell onto a series of shaping dies that gradually reduce the diameter of the can to form its neck.

Traditionally, these Belvac rams have consisted of a round moving pin that translates axially within a barrel-like steel housing, with a machined keyway to keep the pin from rotating. The ram was driven directly via a pair of metal cam followers that mount on the rear end of the pin and engage a stationary cam.

That design, however, suffered from three problems in the field. For one, it required an aggressive lubrication regimen to combat ram and cam wear. For another, it allowed the pin to lift and twist in the barrel, causing premature wear that extends all the way back to the can. And lastly, the traditional design limited the operating speed of the necker.

We eliminated all three problems with a radical redesign of the ram that:

  • Eliminated the need for lubrication. The redesign replaced lubrication-hungry metals with lube-free polymers wherever possible. The redesign completely does away with the metal-on-metal wear between the cam and cam followers, which had been the primary failure mode with the traditional ram design.

  • Optimized the geometry of the ram. The redesign features a square ram, rather than round. The square ram does a far better job at managing the actuator’s on- and off-axis forces. It also guides the pin more effectively, reducing wear.

  • Removed moving mass. Thanks to the use of polymer components and structural aluminum, the redesigned ram weighs in at less than half the weight of the traditional round ram design. Total reduction of moving mass on a 10-stage line is nearly one metric ton.

Now in use by can makers around the world, the redesigned ram has offered a compelling payback. It has resulted in reduced maintenance costs, including the elimination of expensive automated lubrication systems. It has also contributed to reduced defect rates and faster line speeds.

Learn more about the redesign in our latest design case study, Redesign Improves High-Speed Can Making Machine. The case study offers a deeper look at our design process, including a glimpse at the finite element analysis (FEA) work that guided some of our decisions. The case study also highlights the side-benefits of designing for lubrication elimination.

 

Download the design case study

Tags: Belvac 595, cam follower, cam followers, reduce noise, reduce shock, reduce vibration, Self-lubricating, non-lubricated, cams, PA12GC, iCamFollowers, Cast Nylon, can making, low inertia, high load capacity, friction-reducing coating, production line shut-down, Belvac necker, Belvac 795, Belvac super k

Lube-Free Rotary Positioning for Cleanrooms and More

Posted by Georg Bartosch on Oct 3, 2012 3:58:00 PM

Intech’s Power-Core® rollers have found uses in applications ranging from industrial machines to transportation. Most of them have seen use in linear motion systems of one kind or another, but there’s no reason that these gravity cast nylon 12 rollers cannot be incorporated into rotary motion systems such as our new rotary index table.


iCam Turntable resized 600.gif resized 600Designed for integration into third-party servo systems, this new rotary index table makes extensive use of rollers and gearing made from Power-Core gravity cast nylon 12. The table’s drive mechanism consists of a pinion-driven ring gear whose helix tooth profile eliminates wear and backlash. The gravity cast nylon 12 gear is machined from a polymer blank that has been cast around an aluminum ring. This ring serves as a circular rail and as the mounting surface for the payload.The Power-Core nylon 12 rollers, which mount on the unit’s base plate, support the rotating gear and integrated mounting surface. They feature enclosed stainless steel bearings, making the unit suitable for washdown and other corrosive environments.

The use of gravity cast nylon 12 for the drive and bearing elements helps this rotary table outperform all-metal designs in several ways:

  •  Low wear without lubrication. This design avoids the metal-on-metal contact that can shorten the working life of motion systems. The only contact is between two Power- Core nylon components in the case of the drive mechanism and between Power-Core and aluminum in the case of the supporting rails. Power-Core nylon is formulated with an internal lubricant, so no external lubricant is needed. The metal bearings are lubed for life too.
  • Backlash free. Power-Core gravity cast nylon 12 gears offer a couple of intrinsic advantages when it comes to reducing backlash. For one, their dimensional stability eliminates the need for the backlash compensation required by moisture-sensitive plastics. For another, the uniform crystalline structure of Power-Core nylon 12 and our gravity casting production methods produce gear blanks with very low internal stresses and uniform machining resistance. These characteristics allow very precision machining of tooth profiles that have been optimized for backlash reduction–and would be difficult to achieve in metal. 
  • Fast and smooth. The low-inertia of the gearing and
    the rollers helps the table operate at higher speeds. By producing a tighter inertia ratio between the motor and driven load, the low inertia of the Power-Core drive components also makes it easier to tune the controls for a smooth, precise motion profile, particularly when moving light payloads. 
  • Washes down, resists chemicals. Power-Core nylon 12’s dimensional stability in the presence of moisture and its thermal stability make this rotary table a good fit for washdown, high-humidity and high-temperature applications that would prohibit the use of less capable polymers. Nylon 6, for example, can exhibit a dramatic loss in tensile properties and undergo dimensional changes when exposed to moisture and high heat levels. Power-Core nylon 12 also offers excellent chemical resistance compared to nylon 6 and other polymers used in power transmission applications. 
  • Cleanroom friendly. Because Power-Core nylon 12 resists wear and does not throw off the particulate associated with externally lubricated metal power transmission components, clean room use is a natural fit for this rotary table design. 
  • Scaleable. By manipulating the size of the gear and roller components, the table design can be scaled to handle payloads ranging from ounces to tons.

Read More About Indexing Tables

Tags: washdown application, cam follower, cam followers, cast nylon 12, Clean rooms, PA12GC, anti-backlash backlash gears, Index table

Anti backlash gear design at the heart of clear tomography imaging

Posted by Alexander Bartosch on Sep 21, 2012 1:58:00 PM

 

Special gear design is at the heart of clear image in multi-axis tomography device.

For the rotational machines used to gather dental X-ray images, motion chatter can produce a fuzzy image, which is not suitable for diagnostic purposes.

Panoramic radiography is a branch of rotational tomography where the creation of images are through the movement of a source and receptor in such a way as to cause the foreground and background structures to blur, leaving a defined focal trough.

As a panoramic radiographic device, the Vantage Panoramic X-ray System, designed and manufactured by Progeny, Lincolnshire, IL, incorporates a DC X-ray source, CCD digital receptor, distributed processing circuitry, and an LCD touchscreen control panel for ease of use. What makes the Vantage system unique is that it is adjustable to the patient’s height via a motorized, 3-speed, telescoping column. The use of multiple lasers is to locate the patient and configure the device to the patient’s morphology. In addition, a workstation coordinates the individual processors.

The system incorporates an overhead, swing arm (lateral Y-axis) that supports a C-arm, which is the rotating member that moves around the patient’s head. The C-arm includes a tube-head, which produces the X-ray beam, and a removable CCD sensor, which is the digital image receptor. If this arm does not operate smoothly, a distorted image results.

The swing arm pivots on bearings located in the mounting casting fastened at the top of the column. Producing its motion is a ball screw drive, one end of which connects to the mounting casting and the other end to the swing arm. A step motor mounts at the column end. Both mechanical connections of the drive assembly are through ball bearing assemblies.

Suspension of the C-arm is on a pair of bearings mounted to the underside of the X-axis translation plate. The C-arm casting incorporates a 10" ID internal tooth ring gear that meshes with a pinion gear on a step motor mounted on the stationary X-axis translation plate. The motor is spring-mounted to maintain positive mesh and to minimize slop. The internal ring gear and pinion are sized and shaped to engage on the inside surface of the C-arm. With activation of the motor, the stationary pinion engages the teeth in the internal ring gear causing rotation of the C-arm.

The engineering team at Progeny worked with Intech to help design the C-arm casting and its interface with the gear drive for the C-arm’s rotation. Design of the company’s Power-Core products is specifically to reduce noise and vibration and run without lubrication, an important factor (a must) for medical equipment designers. Intech components are far lighter in weight than metal parts and offer longer life (less wear) and lower maintenance costs. Intech engineers used a proprietary gear load/life calculation to verify that the gears designed into the dimensionally restricted place would last at least 8,000 hours of operation or about 15 years in field use.

The challenge was to design a backlash free gear to produce a steady rotational movement of the image producing components. There was no room to employ the traditional split gear design. To eliminate backlash, installation of a spring, on slight angle relative to the axis connecting the gear centers attached to the pinion, pulls the pinion toward the 10" ID internal ring gear. The spring arrangement did eliminate the backlash, but caused the gear teeth to bottom out, resulting in chatter. The chatter registered on the X-ray image.

The precision gearing for the Vantage Panoramic X-ray System uses Intech’s Power-Core nylon materials for reduced chatter, resulting in clearer images from the system.

Drawing on its expertise in gear design, Intech engineers designed and precision-machined the pinion and the internal gear to incorporate a special contact surface, which allowed the components to control the center-to-center distance between the inner tooth gear and the motor pinion. Adding the center-to-center distance management element presented a method for precise gear positioning in the mesh, and drastically reduced system vibration generated by the spring force and the resulting bottoming out of the gear teeth in the earlier design.

This configuration provides precise control over gear mesh vibration and backlash, resulting in high image quality in both a clockwise and counterclockwise rotation of the C-arm. It also adds a robust design element, which helps to increase product life so that image quality does not degrade with component wear and tear. With no fuzzy imaging due to chatter, dentists can make better diagnosis and provide better service to their customers.

Shown is the Vantage Panoramic X-ray system with the C-Arm that holds the lasers as well as the removable CCD receptor..

 Learn More

This article was featured in Today's Medical Developments magazine and can be viewed at http://www.onlinetmd.com/TMD-0912-motion.aspx

Tags: Power-Core gears, vibration, PA12GC, calculating backlash, plastic gears, PA12C, PA12G, anti-backlash backlash gers, Medical

How to avoid design compromises when the equipment function calls for cam followers

Posted by Alexander Bartosch on Sep 10, 2012 10:40:00 AM

 

How to avoid design compromises when the equipment function calls for cam followers

Engineering design is an art of compromise. To achieve a design goal — for example, a certain machine function — engineers select components based on several criteria such as functionality, reliability, component’s availability, cost, and lead times. Pro and cons are analyzed and final selection made.

In the case of cam followers, in the past engineers did not have a choice other than selecting the manufacturer. With few options available, the engineers were forced to accept a host of costly requirements and operational limitations.

Intech iCams

Whether the application calls for high or low load capacity, the design has to provide for lubrication either manually or through a central lubrication system. Rail or cam surfaces have to be hardened. In operation, lack of lubrication of the bearing or the rail surface can lead to a catastrophic failure. Over-greasing can lead to the cam follower’s skidding, causing wear, and excess grease can contaminate the product being processed.

In addition, shock and vibration can cause metal to metal impact that has to be considered. Metal particles and grease contamination often prevent equipment manufacturers from entering the growing clean room market. The relatively low rotating speed of needle bearings, their high rolling resistance, and inertia may be limiting factors in high speed equipment design.

When selecting Intech iCamFollowers® the designer can eliminate most of the disadvantages of metal cam followers. This is especially the case in designs where the cam follower’s primary function is to transmit motion and not its high load carrying capacity.

Today the trend is toward high speed, light weight, and light duty machines in processing, packaging, medical, and semi-conductor machines, which account for about 40 percent of applications. In these applications, Intech iCamFollowers® can easily carry the load, help simplify design, and better achieve the design goal.

Considering the cost associated with design and operation of metal cam followers, it pays to better understand the actual load carried by the cam followers in the application. With load data, including radial and axial forces, load duty cycle, and desired linear speed, Intech engineers can use a unique plastic roller life calculation to quickly assess whether an iCamFollower can be used.

The load capacity of Intech standard iCamFollowers® is listed on Intech’s web site and represents the maximum load the cam followers can safely carry for 100 million cycles, under both static and dynamic loads, without developing a flat or excessive wear. A consultation with Intech engineers may lead to an alternative designs, opening the way to eliminating wear and lubrication as well as the number of modifications in the machine’s design.

If iCamFollowers® can be used, the advantages, compared to metal followers are many:

For New Equipment:
* Simplified design- cost savings
* No need for surface hardening- c
an run on aluminum rails
* No rail or cam wear
* No need for lubrication- manual or automatic
* Reliability
* Higher machine speed- Lower inertia, low rolling resistance
* Shock absorption
* Wash Down- stainless steel bearings and shafts, sealed design
* Sub-zero temperatures
* Elimination of lubrication and metal particles c
an open new markets

In plant Operations:
* Eliminating Lubrication
* Eliminating rail and cam wear
* Cost savings on maintenance

* Cost savings on production shortfall
* Longer maintenance cycles
* Noise reduction
* Low cost to try if iCams work

 

Learn More

 

 

Credits: As featured in Design World May 9 2011. http://www.designworldonline.com/how-to-avoid-design-compromises-when-the-equipment-function-calls-for-cam-followers/#_

Tags: cam followers, reduce noise, reduce shock, reduce vibration, Self-lubricating, cast nylon 12, Clean rooms, moisture absorption, PA12GC, iCamFollowers, PA12C, PA12G, sub-zero temperatures, Cast Nylon