Weathering and Exposure Concerns

There is unfortunately some misinformation in the plastics world regarding weathering, exposure, and UV-resistance. In some cases where applications go wrong, customers simply did not consider how a certain plastic might handle being exposed to certain environmental factors. One of the largest pieces of misinformation is that reprocessed-black UHMW often called “UHMW black” is UV-stable. It is not; however, and has only some limited UV-resistance due to the addition of carbon black in the resin. The following are examples of weathering and exposure concerns for some popular plastics and options to mitigate these issues.

Nylon:

-Brittle in cold temperatures (below -15 degrees C)

-Absorbs water

Solution:

-Switch to acetal or Tuffkast

UHMW/Polyethylene:

-Poor UV-resistance makes it prone to cracking with UV-exposure

Solution:

-Procure a fully UV-stable grade

Polyurethane:

-Certain varieties weaken and break down in wet environments (hydrolysis)

Solution:

-Work with a plastics expert to select a polyurethane variety not weakened by hydrolysis

Polycarbonate:

-Poor weathering resistance, will yellow and crack with exposure

-Poor scratch resistance and tends to become cloudy with small marks when used in outdoor applications

Solution:

-Request sheets with UV stable and/or scratch-resistant masking. These will be typically unstocked.

 

 

 

 

 

 

 

 

 

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Industry Spotlight: Construction

The construction industry is a cornerstone customer for Redwood Plastics and Rubber. We supply a vast array of stock shapes and fabricated parts to construction firms across the world. However, there are a few applications that are worth special attention.

  • Dynamex() elastomeric bearing pads: We offer a wide line of rubber elastomeric bearing pads to meet a variety of specifications. We can also meet testing requirements.
  • Redco MD sheaves: Our sheaves using wear-resistant moly-filled (MD) nylon are popular for use by cranes.
  • FRP grating, handrails, and ladders: Fiberglass reinforced plastic offers substantial weight savings and other benefits over similar metal alternatives.
  • Outrigger pads: UHMW or nylon outrigger pads offer a long-lasting, weight-saving proven alternative to metal or wood pads.
  • Pile driving cushions: Redco IRG nylon pile driving cushions can be provided in any required size and come with heat-dissipative additives. No minimum order on cushions.
  • Rise-It Paver Pedestal System: Our premium support system for hardscape pavers.
  • Switchblade Belt Scrapers: Polyurethane belt scrapers with replaceable blades.

We can assist with many other construction related applications, for details on these or for help with your application please contact us today.

Dura CRIB vs. Dura STAT

The two most popular products of our cribbing and blocking line are Redco “Dura Stat” and “Dura Crib”. Customers often request quotations on both, or confuse each product, but the differences are distinct and important enough to create a write up. The “Stat” is Dura stands for “static” it is designed solely for cribbed storage of equipment that is not dynamic, IE. no movement. An example of a Dura Stat application would be lowering an engine onto the cribbing for storage. The Dura Stat set up should not be moved after the load is placed.

It is very important for Dura Stat that what is being cribbed is loaded vertically. The product is not resilient to sheer pressure and could break. Also, as a non-interlocking product, there could be slipping issues as well. Dura Crib on the other hand, is meant to be stacked and is commonly available in interlocking forms it is designed to handle applications where there may be a little dynamic movement. An example of this application would have Dura Crib providing cribbing for a railway maintenance vehicle’s outrigger feet. The stack of cribbing will endure vibration and oscillation as the load shifts on the feet while the vehicle works.

For more information on our cribbing products please check out our First Responders literature available here.

Super-Crib

Simplicity = Savings

Customers with a budget in mind often ask us how they can reduce the price of their part. They think that the price is always tied up in expensive material costs but in reality it’s usually the labor costs or a complex mold that results in a high price. What you should understand is that the more complicated a part is, the more expensive it will be. In the case of a molded or extruded part, the tooling needs to be more complex and this takes more time and effort, therefore the mold will cost substantially more. In the case of machined parts this is even more acute as every hole, angle, and cut adds cost.

Labor for machining is quoted based off “passes” that is how many times a tool needs to touch the plastic material in order to make the cuts needed to manufacture the parts. These passes are the labor cost – the more passes, the more cost. A good example to discuss are “webbed” sheaves. These are sheaves or pulleys that have the sides machined out around the outside of the hub on either side. This has the sometimes beneficial property of reducing sheave weight because it’s now made of substantially less material. However, these weight savings mean lots of extra machining has to be done and this increases the cost of the sheave. Where lowest price is desired and weight savings are not critical, webbing is not advantageous to your application.

One service we offer to customers is that we provide “blanks” these are partially machined plastic parts that are not completed, just the general profile is done. Once the parts arrive on site the end-user themself then finishes the machining. An example of this is our Redco chain channel for sawmill applications. We can offer the channel pre-drilled with weld washers but this adds about $0.85/hole. Many customers elect to simply buy the channel and drill their own holes on site. Perhaps the best method to figure out if a part can be simplified is to just talk to one of our plastic experts. We’ll take a close look at the application and ask you if the part can be redesigned to a simpler format to save money.

For assistance with your plastic application please contact Redwood Plastics and Rubber.

Redco 90A Polyurethane Forklift Socks

Redco Forklift socks are an upgrade over traditional low-grade cold bonded rubber socks. A “forklift sock” is an elastomer solution that provides a covering to forklift forks, this makes them less likely to damage sensitive equipment being lifted. The problem is that the rubber sock covers easily delaminate from the forks and can also crack. This creates a situation where the loose sock causes an unsafe lift.

Unlike the cold bonded rubber, our solution uses a proprietary 90A polyurethane in a “hot bond” to the metal socks. This is a superior way of applying a sock solution and will vastly outwear rubber socks. In addition, our material is colored “safety yellow” for high visibility. The product reduces the risk of driver error and material damage while greatly improving grip when lifting. Redwood Plastics and Rubber can provide this service in two ways. Firstly, you can ship your existing steel forklift socks to our Langley, BC, Canada facility and we can re-coat the socks in-house. Alternatively, we can machine the complete new steel socks, coat them, and send them to your facility.

For a quotation on your forklift sock needs please contact us today.

To Grease Or Not To Grease?

Whether or not to grease a plastic bushing is a frequently asked question, or even just an assumption customers make (that they need to). While there are times where greasing is important, and times where it is absolutely critical, in most cases with many materials you will not need to.  Avoiding the need to grease a bushing is a strong advantage plastics have over metal in application. Many plastics are self-lubricating and can come impregnated with solid or liquid lubricants. Certain bushings, such as the Rulons, will never require grease. In general, if you want to switch from a greases metal bushing and are flexible on material, an oil-filled option would be quoted. The cost difference between oil-filled and unfilled materials is about 30% so you need to judge how important it is not to grease.

In the case where an unfilled bearing grade material is required, grease grooves can be machined into the part. These would come with a “grease nipple” or small hole in the bushing to permit application of the grease. This is common for applications such as kiln wheel bushings or sprockets. That said, there is one case where you *must* grease and that is if the demands of your application exceed the P/V/PV ratio of the plastic. P/V/PV needs to be under all three maximum limits for the bearing material; however, that’s a discussion that requires it’s own article.

If you are looking for grease-less bearings or have questions on our Redco bearing materials please contact us.

24″ Diameter Tivar 88 Pipe Lining

The pictures below are of an application completed at our Langley, BC facility. This involved lining a steel pipe with an internal diameter of 24″ inches and is a job we’ve done several times before. It’s innovative work and we wanted to share some details and pictures in case the application might be of interest to other companies. The customer ships their pipe segments to our facility where the lining is done on site. We have fabricated 3/4″ thick Tivar 88 sheet that comes pre-scored to permit bending. This is important since Tivar 88 is not available in pipe format, so the solution must be made from sheet stock.

As you can see in the second picture there are not too many fixation points. There is a middle strip of plastic serves as a wedge, and the pressure alone holds the lining solution in place (though the strips on either side of the wedge also have fixation hardware, to help secure the wedge). Tivar 88 is a premium grade of UHMW polyethylene and its blue color is readily identifiable. It provides additional strength and slickness that virgin or reprocessed grades of UHMW do not. Tivar 88’s primary benefit is increased material flow and less material hangups. Secondarily, Tivar 88 provides a wear surface that protects the steel from wearing out.

Tivar 88’s lifespan will vary in applications but it is sacrificial, meaning that it will need to be replaced at some point. The performance benefits and increased life of the pipe do make up for the cost of the lining. While not important in this application, Tivar 88 does include UV stabilizer in its chemistry and is suitable for long-term outdoor use. The product also has a long history of success in hopper lining applications

For assistance with your application please contact us.

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