Intech Power-Core Thermoplastics Engineering Blog

5 Advantages of Plastic Rack and Pinions in Motion Applications

Posted by Alexander Bartosch on May 21, 2014 4:00:00 PM

 Polymer Eliminates Contamination in Linear Motion Systems 

In an ideal world, linear motion systems would run only in squeaky clean operating environments. In the real world, linear motion systems usually have to run in plants with varying degrees of contamination, chemical exposures or moisture. These less-than-ideal conditions can shorten the lifespan of linear motion systems that rely solely on metal drive components—particularly rack-and-pinions.

KLEENLine conveyor with Intech Gear self lubricating rack and pinion

(Pictured Above: Intech Power-Core™ Gear and Stainless Steel Rack in a High Speed Retractable Bakery conveyor - Read More Here )

To meet the challenges posed by real-world operating conditions, we have designed and delivered many rack-and-pinion systems based on our Power-Core™ polymer.  Typically these consist of an Intech Power-Core™ gear with a stainless steel core and a stainless steel rack, though some applications have been best served by a Power-Core rack and a stainless steel pinion. 

Either way, we’ve found that use of polymers has five key advantages in rack-and-pinion applications:

  1. Eliminates lubrication. As a self-lubricating polymer, Power-Core™ does away with the need to apply lubricants over the life of the rack and pinion. The elimination of lubricant eliminates a key source of contamination in sensitive applications such as packaging, pharmaceutical, semiconductor or food processing. 
  2. Extends wear life. Power-Core and stainless-steel together offer an extended wear life and typically last for several years longer than all-metal designs. The user of Power-Core has also allowed us to create some design features that further extend wear life—such as pitch line control feature prevents pinions from bottoming out.
  3. Prevents corrosion. Traditional rack and pinion designs with metal gearing are subject to rust and corrosion, particularly in washdown applications. As a polymer, Power-Core does not corrode at all.
  4. Remains dimensionally stable.  Thanks to the physical properties of its base polymer, Power-Core does not suffer from dimensional and tensile property changes that affect conventional polymers when exposed to moisture, chemicals or elevated temperatures. Power-Core's base polymer has one of the lowest moisture absorption rates of any engineering plastic. Power-Core stands up to a wide range of industrial chemicals.  And Power-Core exhibits about 50% better high-temperature performance than comparable engineering polymers. 
  5. Improves motion control. Power-Core can produce rack-and-pinions that operate both smoothly and quietly as the rack moves back and forth, reducing noise by about 6 dBa compared to all meal components. The reason is that polymer has intrinsic vibration and shock load damping properties.  Power-Core components also weigh about 85% less than a comparable metal component. In motion applications, this weight reduction translates directly to reductions in moving mass and inertia.

Rack-and-pinions based on plastics components do have to overcome the perception that they won’t be as durable or carry the same loads as the all-metal designs familiar to motion control engineers. However, we’ve proven that perception false time and time again. 

Our experience with gear design and predictive analysis has allowed us to design polymer rack-and-pinion systems that can and do outlast all-metal designs in highly-loaded applications. To learn more, give us a call.

Contact an Engineer

Tags: rack and pinion system, self-lubricating gears, gear design, r gear life calculation, custom gear design

Intech Gears Could Eliminate Noise From Your Segway Gearbox

Posted by Alexander Bartosch on Jan 30, 2014 8:56:00 AM

Does your segway make too much noise? Have you ever wondered where it is coming from? Segway drive gears in the segway gear box are all metal (figure 1)

Segway Helical gear Gearbox

The metal on metal movement, in this beautifully constructed helical drive gearbox, creates noise. This noise can become worse with time as the gears wear.  See the video below for an example of the noise we are talking about.

Intech has conceptualized a segway replacement gear box to dampen vibration and reduce the noise of the segway metal on metal wear. Our simple bolt on attachment benefits from our  PA12GC Power-Core Cast Nylon (polyamide) which doesn't absorb moisture and won't crack in subzero conditions. The self-lubricating material allows our gears to run quietly and oil free. Removing another annoyance from the maintenance of your segway and its gearbox.

Using plastics to design high load, high shock, and highly critical applications is our specialty here at intech and being engineers the segway was always a toy we've wanted to tinker with. Making plastic gears for an application of this type was not without challenges. The first of which is the tooth root stress, you see metal gears can be much thinner and carry far more load than any plastic. The second is power transmission, very few - if any plastics can evenly and continuously transmit the power needed to drive a segway in the way its meant to operate. Imagine a right gear box transmitting less efficiently than the left and the circles or compensation a rider would need to make. Luckily, Intech's Power-core PA12GC material and its unique gravity casting process allows it to chemically bond to a metal core allowing it to transmit power evenly and continuously while perserving the benefit of a self lubricating gearing.

The retrofit is not inexpensive but if noise or vibration are causing you problems a new intech gearbox might be the solution to give you the quite and smooth riding personal movement device you've always wanted.

 Contact an Engineer

 

Photocredit: http://segwaynz.files.wordpress.com/2012/08/gearbox.jpg

Tags: Power-Core gears, cast nylon 12, gear box, gear backlash, gear design, plastic gears, Power Train Design, Plastic gear box, plastic helical gears

Large Underwater Gear Highlights Nylon's Moisture Resistance

Posted by Alexander Bartosch on Mar 22, 2013 2:00:00 PM

Wear and moisture resistance are two recurring themes in the engineering problems solved by Intech Power-Core™. Oftentimes, these problems involve small components, such as gears, cam followers or rollers. Yet Power-Core’s wear and moisture resistance properties can just as easily apply to large parts. Consider, for example, the large geared ring produced in our material for underwater use in a nuclear reactor pool. Measuring 2,200 mm across and 80 mm thick, this geared ring weighs in at 100 kg. It withstands a load of 150 kN at 6 rpm.

Intech Underwater GearLarge Part Size, No Problem. The sheer size of the part stands stands out, but our gravity casting process actually allows us to scale up the size of our components easily. Gravity casting results in low internal stresses, even when the parts have metal structural inserts. So going “big” is not really an issue for Power-Core.

Physical Property Advantage. What was even more important in this underwater application were the physical properties of the polymer. The geared obviously needed to be produced from a material that resists continuous exposure to liquids and corrosion. Various metals fell short due to their poor corrosion performance compared to polymers such as Power-Core.

Many other polymers, however, do not tolerate long-term exposure to moisture. Power-Core does. Its ultra-low moisture uptake allows it to remain dimensionally stable even when submerged in water for long periods of time. In this nuclear application, Power-Core’s radiation resistance also weighed in its favor over other polymers. And its wear properties allow it to avoid the fretting that can occur when component surfaces rub together in the presence of water.

In this application like in most applications engineers had a selection of materials to choose from. The common conception of most engineers when it comes to wet environments is that a polyester material such as ERTALYTE or an Acetal (POM) would be the best choices. In many cases these engineers would be on the right track - both materials are excellent in many applications - however for underwater gears specifically these materials wouldn’t be able to accomplish the task. For one the size of the gear leaves only very few material options, second when using Ertalyte or Acetals you have to be very careful what type of environment you expose them to – chlorine – like that found in drinking water could destroy the polyester compound over time and Acetals don’t react well to acids such as those used in wash downs, and booth are susceptible to weakening caused by extended UV exposure. 

Most Nylons, on the other hand, perform poorly when submerged in water, so naturally engineers tend to steer away from the entire nylon family when designing underwater motion systems. Powercore has a unique place in the family of Polyamides in that its moisture absorption, even when fully submerged, is negligible.  Our site contains numerous studies and documentation showing the effects of moisture absorption on nylon and nylon 6 and nylon 12’s dimensional change when submerged. When designing your next motion system of marine or underwater use please remember to consider the environment and look of a suitable polymer for your application.  

Learn more about Power-Core’s moisture resistance

Tags: gear design, Nylon 6 vs Nylon12, ultraviolet resistance, Nylon Vs Delrin, underwater gear, ertalyte

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