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.

 

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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

Medical Latex Dipping Device for Easy Cleaning with Proprietary Gear Design

Posted by Simon Barrell on Oct 28, 2009 11:30:00 AM

Power-Core™ gears have been used to upgrade the design of a latex dipping gear cassette assembly in a unique arrangement that replaces standard gears in order to meet critical performance and cleaning challenges.

The original gear box design resembled a tightly fitting cassette made with standard off-the-shelf gears. Unfortunately, as the latex material was being processed, the gears reacted with the latex material and expanded in size until the ceased turning. Cleaning required a complete disassembly of the cassette, followed by awkward and time-consuming hand scrubbing of individual components to yield less-than-satisfactory results.

In addition to requiring an easier cleaning process, the medical device manufacturer wanted longer wear-life and improved performance from the gears. Frequent cleaning and premature gear failure caused by gear swelling resulted in wear stress that resulted in system downtime and replacement on average every few months.

As part of a failure analysis, Intech provided an engineering design review that included a custom gear life calculation. Our engineering team recommended a system design modification to address performance uptime, improve wear life, and to create a user-friendly non-hazardous cleaning process.

open sandwich design allows easy cleaningThe gear box modification design features custom Intech Power-Core™ gears with a larger pitch diameter, wider face width, and an integral stainless steel shaft that extends on each side of the gear and rotates directly within the load bearing cover plates. The open sandwich design, which can be seen in this image, allows for easy cleaning.

Compared to the previously used injection molded gears which vary in size due to internal stresses and moisture absorption, the precision machined Intech Power-Core™ gears provide consistent, smooth-running operation at reduced torque. Uniform Power-Core material will not distort or change size, so individual gears can be interchanged easily without matching pre-existing gears for a uniform fit, whereas injection molded gears had to be matched to other gears in order to function.

Intech Power-Core™ gears are machined from an inert, stress-free non-hygroscopic material with integral stainless steel shaft that offers outstanding performance where corrosion, abrasion, noise, lubrication, vibration, shock, and moisture create hostile operating environments.

Tags: Power-Core gears, wear life, gear box, vibration, gear life calculation, gear design, non-hygroscopic