Intech Power-Core Thermoplastics Engineering Blog

Cast Nylons Replace Structural Aluminum and Gluing Delrin Parts

Posted by Alexander Bartosch on Jan 16, 2014 10:23:00 AM

P 500 System resized 600

Robotic arms for e-coat systems have traditionally been made from aluminum, whose strength-to-weight ratio made it seem like a good choice for this application. Aluminum, however, has a downside.

Its electrical conductivity allows the arm to attract paint particles whenever the painting system experiences voltage fluctuations. The resulting paint losses quickly build up—typically to more than $300,000 per paint line annually.

To eliminate those losses, a leading paint robot manufacturer and Intech teamed up to engineer an electrically-insulating plastic arm. That engineering proved to be easier said than done for three reasons.

For one, any plastic used in the arm had to offer high-end structural properties and be capable of insulating against 100 kV charges. For another, the part is big—too big to be cost-effectively injection molded in this application. Finally, the part has a challenging geometry.

When looking for a plastic with the right balance of properties, we quickly ruled out common reinforced plastics. Both fiberglass and carbon-fiber reinforced materials would easily have met the structural requirements, but both were too conductive.

Delrin, another possibility, was a suitable insulator, but it was only available in small chunks. The robot manufacturer had also ruled out the possibility of gluing delrin to form the arm.

Ultimately, Intech's knowhow and innovation allowed for a suitable arm to be cast from  Power-Core™ cast nylon 12 and for the last 3 generations of robots has proved to be the best choice for the job. Because Power-core™ met the structural and electrical requirements and could also be cost-effectively cast into large, complex shapes, the manufacturer has been able to successfully file and receive patent protection on 5 aspects of the arm that would not have been possible were it not for Intech engineers.

Plastic Requires Design Changes

Switching from aluminum to plastics did require a rethinking of the arm design to account for differences in tensile strength. With a 40,000 psi tensile strength, aluminum could carry the robot payloads with a 100 x 100 mm cross section. The cast nylon has a tensile strength of 8,800 psi, so the cross section had to be increased and a minimum wall thickness of 15 mm had to be maintained throughout the part.

The finished arm ended up at 120 x 30 x 18 cm at its widest point. It weighs 45 kg and is capable of carrying a 150 kg.

Result: because of the uniqueness of our engineering approach and our ability to push the boundaries of our material supply beyond where other material suppliers could Intech was proud to be rated a sole supplier to the automotive paint robot supplier.

For more details on the design and manufacturing challenges using polymers, please contact us using the form to your left.

 

Contact an Engineer

Tags: washdown application, cast nylon 12, electrically insulated, Intech Corporation, forming nylon, non-hygroscopic, PA12C, PA12G, Cast Nylon, Power-Core material, Nylon 6 vs Nylon12, Nylon engineering, fanuc p700, Fanuc P500, Fanuc p1000, Fanuc P-20ia

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

Still Lubricating your Rack and Pinion System?

Posted by Simon Barrell on May 13, 2011 1:52:00 PM

Lubricating a rack and pinion gear drive is often done manually. In industries, such as in food processing or packaging, where frequent washdowns are required, or where the gears are difficult to access, lubrication may be done only infrequently. Automated lubrication systems represent additional cost and require regular monitoring as they can clog up.

Intech Power-CoreTM gears do not require lubrication, reduce noise, and transmit motion with higher efficiency. The gears are precision machined from Intech’s Power-Core material with integral metal core for a secure shaft attachment. For wash down applications the core is available in stainless steel.

An important factor in designing today’s high speed machines is low inertia especially in systems where reversing motion is required. Intech Power-Core gears are up to 7x lighter compared to steel, absorb shock and vibration when movement in one direction is reversed,  allowing higher machine speeds without sacrificing performance or wear life.

Intech engineers review each application and using a proprietary gear calculation, will advise the customer about the expected life of the gear. In many instances engineers are able to suggest design modification significantly improving the gear’s wear life. Intech rack and pinion gears can be found in bakery conveyors, position devices on packaging machines, cutting mechanisms on plastic bottle blow machines or on long gantry motion systems, to name a few.

Power-Core gear for bakery conveyor system  Power-CoreTM gear for bakery conveyor system

Tags: Power-Core gears, lubricating gear, rack and pinion system, washdown application, shock and vibration, gear wear life, automated lubrication system