3 Critical Issues You Need To Know About These Popular Plastics

Many industrial plastics can “overlap” in applications where sometimes the optimal choice is only marginally better than several others. Many plastics may work in an application, such as nylon and acetal for sheaves, but certain issues in the operational environment may mean you need to stay away from a certain plastic! Three of the most popular plastics we carry are UHMW polyethylene, cast nylon, and PTFE. But each of the following has a critical issue you need to know about that often discredits the material in certain applications.

UHMW – Impingement

UHMW is a great wear material at an affordable cost…Usually. The one place where it isn’t good at all is with impinging wear, that is wear from a mating partner (could be anything from grains, to rocks, to another sliding component). Impingement is when something hits that UHMW on an angle. With UHMW anything that is remotely abrasive needs to hit it on a 90 degree angle. If the angle is any sharper you risk very quick deterioration of the UHMW plastic. It simply does not hold up to impingement. Often polyurethane, which has excellent impingement resistance, is a substitute and one can be creative, for example only using polyurethane in the impact zone and use UHMW for the rest of the application.

Nylon – Cold Temperatures

Many people know that nylon is affected by moisture swell, what fewer people know is that it gets brittle in cold temperatures, about 10 Fahrenheit or -12 Celsius. This can come as a shock, as nylon is known as a high-load plastic able to handle 4,000 PSI in bearing applications. It is not intuitive to think that cold temperatures would greatly affect the nylon but it is true. Fortunately, replacements are available, specifically Redco Tuffkast is often best to replace nylon. Tuffkast solves not only cold weather issues with nylon but also absorbs much less moisture, so Tuffkast’s properties help in that case as well.

PTFE – Wear

It is often that customers request PTFE for a wear or lining application, even including heavy applications such as dump truck liners! We do try to warn them that PTFE has very poor wearing ability. It is a soft, almost waxy material, that while it is available in sheet form (and seems solid enough) it really cannot hold up to aggressive wear. Bronze filled PTFE is available which increases the wear capabilities; however, by that point there is often a less expensive, more available plastic, that can be suggested as a replacement. PTFE should be avoided in high wear applications wherever possible.

Hopefully you are surprised by at least one of those points, in the hopes that it will assist your material choice in your next application.

To discuss the optimal plastic for your application, get in touch with us today.

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Specifying Outrigger Pads

When customers consider a switch to plastic outrigger pads they sometimes don’t know where to start in how to get their quotation. Often we’ll be told that the customer has a certain piece of equipment and to spec a pad size and thickness for them but this over-complicates things a little. Regarding the size of the pad the simplest way is to just get the plastic pads with the same dimensions as the stock pads that came with your rig. If you don’t have your stock pads we can help you out but we do need to know the area of your outrigger feet (length x width and are the feet square or round?).

Thickness is a little trickier to specify. UHMW plastic, commonly used for outrigger pads, is virtually unbreakable but having a pad that is too small and thin may lead it to bend around the outrigger foot as it is more flexible than wood and this may destabilize the rig. A general rule of thumb for most vehicles in the 20-50 ton range is to go with 1.5″ thick pads. 2″ thick is usually good for 50-70 ton but using 2″ pads for lighter equipment will result in less flex with the pad and a more stable lift. Above 70 ton 3″ thick pads are strongly recommended. To reiterate: the plastic will most likely not break on a thinner pad; however, the amount of flex may be undesirable. This is partially dependent on where the pads are being used – we have certain customers who only ever lift on concrete surfaces and thus can use a thinner pad because it has more support. Customers who lift on soggy soils may need thicker pads. As always, we refer to OSHA in that lifts should only ever be done on stable, level, ground.

For questions about our Redco Outrigger pads or to get some pricing please contact us for a quote.

Product Spotlight: Redco VHMW

While we’ve been able to supply VHMW for a few months now, only recently have we updated our website with a separate Redco VHMW section that can be found by clicking here. VHMW holds a new “middle ground” in the polyethylene family between HDPE and UHMWPE. Redco VHMW, which stands for “very high molecular weight”, can be substituted in applications where UHMW is considered to be “overkill”. The price on VHMW will be less than equivalent UHMW; however, only if you require several sheets of material. We do not currently stock VHMW and therefore freight costs, minimum orders, and small order fees may apply.

Compared to UHMW, VHMW has similar wear properties at a less expensive cost. It also has a better surface finish and is smoother than the typically skived UHMW sheet. Like UHMW, Redco VHMW performs very well in cold applications and is quite durable. It is also FDA and USDA approved for applications with food contact. Typical manufacturing tolerances on UHMW permit a (+-) 10% variance on sheet thickness; however, VHMW is manufactured with a variance of only 5%. The standard sheet size is 4′ x 8′ in 1/8″-1″ thick but custom sheet sizes are available on request.

For more information on Redco VHMW please contact us.

Product Spotlight: Redco Acetal

In the world of thermoplastics acetal (polyoxymethylene or POM) sometimes gets overlooked in applications as customers consider more well-known plastics such as UHMW, nylon, or PTFE. However, acetal offers excellent versatility, overall properties – all while being the most machinable thermoplastic. Unlike many other plastics, acetal is quite hard with a dense weight that reminds one more of a metal than a plastic.

Given this property, acetal can be used to replace precision machined acetal parts that were formally metal. Examples are gears, valves, and parts like the bolt in paintball markers. Acetal is often used as a nylon replacement in marine applications. This is because it can take similar load yet will not absorb water like the nylon will. But there is often no reason why you could not have specified acetal as a nylon replacement in the first place.

Where acetal really excels; however, is dimensional stability. It is one of, if not, the most dimensionally stable plastic. What this means is it can be machined to tighter tolerances than other plastics and will hold those tolerances better. In addition, it has excellent resistance to creep at normal operating temperature. If dimensional stability in an application is of top priority than acetal should be near the top of your list!

As with any plastic, acetal does have some concerns. They are attacked by strong acids and oxidizing agents so keep that in mind. Acetal comes in two common grades the homopolymer and copolymer, with the copolymer being better in hot air or water environments. Acetal is available in FDA approved grades, including metal and x-ray detectable grades. Acetal should not; however, be used with chlorine washdowns or cleaners. In that case PET should be selected as a substitute.

For answers to your questions about Redco Acetal please contact us.

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Plastic Plow Blades & Cutting Edges – Saving The Paving!

One of our employees recently took a couple photos after parking at an area we won’t disclose in Metro Vancouver a day after a recent snowfall. Upon pulling into his parking spot he noticed that every single stall had a large pothole where the snow had been pushed. Having been a weekly visitor to this lot he knew the holes were not there a few days before and therefore must have been caused by the snow removal contractor. The damage is extensive and will be a huge headache to fix! How much money will it cost to repair? What will happen to the reputation of this snow removal vendor?

And it was a completely avoidable disaster that never needed to happen.

Industrial plastic plow blades (or “cutting edges”) have been used for years to prevent this sort of issue. The cutting edges, made of polyurethane, rubber, or UHMW, are simple rectangular strips that are bolted to the bottom of a metal plow or bucket. Therefore it is this softer, non-damaging, plastic surface that actually touches the ground as the equipment scrapes and pushes the snow instead of the metal blade. There are multiple ways the metal-on-pavement contact can cause damage as besides creating potholes the blade can also destroy things like lights or reflectors embedded in the asphalt. Such as is common at airports for example.

The blades are an investment: even the least expensive blade will be at least a few hundred dollars. But how much is that few hundred dollar investment compared to losing contracts, a hit to your reputation as a contractor, and even potential lawsuits? The simple fact is you are “playing with fire” if you don’t have a high-quality plastic cutting blade – it’s an investment that must be made! Several plastics with different prices, properties, and suitability to applications are available so please contact us with the details of your application.

And save the paving!

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Tuffkast: The Problem Solver

Plastics solve problems and they can overcome issues that plague traditional materials such as metals and wood. But for the most part a plastic still has some weak spots that under certain situations can create a trade-off in properties: the optimal material but not perfect. Redco Tuffkast; however, is our material with the fewest weak points and therefore can solve problems that other plastics simply cannot.

Tuffkast is most commonly a replacement for nylon in areas where nylon suffers deficiencies: water absorption, impact, and low-temperature performance. In each case Tuffkast’s properties are superior to nylon: it absorbs much less water, is an excellent impact and low-temperature material. This means in applications where nylon is commonly used Tuffkast can be substituted, applications such as bearings and sheaves. To reduce the coefficient of friction, Tuffkast is available in both oil-filled and dry lubricant grades. Tuffkast has excellent wear abilities and impact resistance that is over double that of nylon.

Any drawbacks to Tuffkast are minimal. It does have a higher cost than many plastics of the engineering-grade tier but this is offset by its excellent performance. The higher coefficient of friction than materials it replaces (such as UHMW) needs to be considered but again, this can usually be offset by getting one of the lubricant filled grades. In general, Tuffkast is an extraordinarily versatile engineering plastic that is able to solve many problems other plastics simply cannot. For more information on Redco Tuffkast please contact us.

 

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UHMW Extrusions vs. Machined Lengths

Requesting a quote on a UHMW extrusion is a common request but the option of getting the part machined should not be discounted. Each type of manufacturing process has its pros and cons and a custom extrusion is not always the best method for parts where it is requested. An extrusion is best when you 1.) Have time to permit tooling and initial run manufacturing (8+ weeks) and 2.) Have a very high, ongoing volume of extrusion needed (24,000+ feet per year). If you do not require such a high amount of extrusion than machining can be an option in certain cases, particularly with larger, simple extrusions like rail caps or channel. In regards to channel, we’ve had success adapting our sawmill chain channel extrusions (commonly stocked by our branches) for different applications. A list of our channels can be found by clicking here.

Machined UHMW profiles will likely be more expensive per-piece than extruded profiles. However, the lead time will be less and you will save on tooling costs. The tooling costs of a custom extrusion – often in excess of $5,000 – can make small runs impractical. In those cases, even at a higher per-piece cost, a machined profile will save the customer money. For more information or to discuss a UHMW extrusion or machined profile contact us today.

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