Industrial Plastic: Strengths And Limitations

One of the key questions we ask customers is “what is the application?” This question isn’t asked in order to steal your idea but to ensure that the plastic you’re looking for is optimal, or even workable in that application! Industrial plastics are excellent mechanical materials overall; however, like anything they do have both strengths and limitations. This article will review the core line of industrial plastics we carry, give the strengths, the limitations, and common applications/places where the plastic is wrongfully specified.

UHMW Polyethylene

Strengths: Well balanced properties, economical, and readily available.

Weaknesses: Poor dimensional stability

Specification errors: high load bushings, unrealistic tolerances, not compensating for thermal expansion.

 

Nylon

Strengths: High load bearing strength, diverse formulations, suits a wide variety of applications.

Weaknesses: Absorbs water, poor impact and cold-temperature properties.

Specification errors: Impact parts, marine applications (without accounting for swell), using nylon bushings in high RPM applications.

 

Acetal

Strengths: High load bearing strength, replaces nylon in “wet” applications, machines to excellent tolerances.

Weaknesses: Impact, temperature (especially steam) resistance.

Specification errors: Using black (copolymer) acetal in food processing applications. It is not food-safe, unlike the blue and white.

 

Tuffkast

Strengths: Excellent impact, cold weather, bearing, and moisture-resistance properties.

Weaknesses: High cost, elevated temperatures.

Specification errors: Typically in applications that generate high internal heat, such as a hammer cushion for pile drivers. Tuffkast is also softer than nylon, which can lead to increased wear in certain applications.

 

Polycarbonate

Strengths: Extremely high impact strength.

Weaknesses: Very prone to scratching.

Specification errors: As glass/sight part without upgrading to a anti-scratch version of the plastic.

 

Acrylic

Strengths: Scratch resistant, economical, stronger than glass, fairly resistant to weathering.

Weaknesses: Difficult to fabricate, prone to cracking.

Specification errors: Using in “Do-it-yourself” projects without proper knowledge of fabrication procedures.

 

Polyurethane

Strengths: Impact resistance, rebound, good bearing strength (bearing grades only).

Weaknesses: Water saturation degrades the plastic (especially softer grades), vibration degrades the plastic’s composition.

Specification errors: Vibration or moisture applications.

 

Rubber

Strengths: Lots of choice between properties, cost, wide application variety.

Weaknesses: Polyurethane is superior in many applications, grades must be selected carefully.

Specification errors: Choosing an ineffective grade of rubber for an application to save on cost, assuming the lower grade will still function.

For more information about which plastic is best for your application, please contact us.

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New Product: Foamlite P Polypropylene

We have a new product available in our mix: Foamlite P Polypropylene. This is a lightweight plastic that offers 30% weight savings over other materials commonly used in similar applications which include everything from tank cladding, washdown areas, cargo crates among many others. Additional benefits to the product include excellent chemical resistance, UV and moisture resistance. The product is weldable and adhesives can be used (this is not the case for all plastics). One of the better rules of thumb for Foamlite is to use it as a replacement for wood, where wood’s deficiencies (rot, moisture absorption, cracking) are unacceptable.

Important to know as well is this is a European manufactured product meaning it is manufactured under metric system measurements not the imperial system like most North American made plastics. The sheet is available in thicknesses from 6mm (approximately 1/4″) to 21mm (approximately 7/8″) and in one size only that is 2000mm x 3048mm. We are not stocking this product at our locations but bringing it in from our supplier as necessary, therefore a 1-2 week delivery is typical. Lastly, Foamlite is available in three colors: black, grey, and white only.

If you’re interested in Foamlite P Polypropylene please contact us today.

 

Product Spotlight: King ColorCore

King ColorCore is a HDPE plastic sheet with laminated layers of different colors of plastic and is incredibly attractive and versatile in its uses. Need a sign that will not have the logo or lettering wash out? Then this product may be ideal for you.

King ColorCore is primarily routered or engraved by the customer, which will allow words, designs, or logos to appear. The color is either a two or three color “sandwich” such as red/white/red. All the colors are the same price (a commonly asked question about this product). The lamination consists of a few thin “cap” about 0.05″ thick which is typically CNC engraved 3/8″ thick. A machining “quick guide” is available for customer’s use. The sheets are available in a standard 48″ x 96″ size in thickness of 1/4″, 1/2″ and 3/4″ with the latter being considered the “standard”. These products are not stocked by Redwood Plastics and Rubber; however, most sizes are stocked by the supplier and most orders will ship in 1-1.5 weeks. Due to varying freight costs to “land” an order at each of our RSOs (Regional Sales Offices) it is not possible to provide a price list: each request must be quoted as it comes in.

King ColorCore meets ASTM D4976. The raw material used to make King ColorCore does not contain BPA’s or Phthalates. Tolerances on the sheet are (+-) 5% at room temperatures. The product can be supplied on special order with either antibiological/fungal additives (for protection against stains or odor) or flame-retardant additives to meet ASTM E-84 Class A or B. Please realize that this is a premium plastic product that will be imported to the customer’s local branch for distribution and prices will vary.
For questions about King ColorCore’s suitability for your application, please contact us today.
King_Colors

Product Spotlight: Redco Tuffkast

Nylon applications are very common and alongside UHMW-PE, cast nylon is probably the most well-known industrial plastic. The issue is with nylon, as most plastics, is that it’s ideal in some applications but performs poorly in others. No plastic is a complete panacea: they all have advantages and disadvantages. However, in most applications where nylon has problems, Tuffkast can solve them.

Where is nylon not ideal?

That’s the question you have to ask and there are three areas. Firstly, nylon does poorly in submerged or “wet” applications. Unlike most plastics, nylon readily absorbs water and will swell about 4% of its size in 24 hour saturation. This makes it a poor choice for marine applications unless tolerances are taken into account. Secondly, nylon is brittle especially in the cold. While nylon can take lots of pressure (4000 PSI) it is poor in taking impact. Nylon should not be used in impact applications. The final area of concern with nylon is what was just hinted at – cold. Nylon’s properties get worse in cold exposure, about -12 degrees Celsius is the lowest you can comfortably go.

How does Tuffkast solve these problems?

Tuffkast is a “copolymer” meaning it’s a mix of different plastics. While it is “nylon-like” is performs much better in areas nylon is deficient. It has significant benefits to impact resistance and in fact is an excellent impact and shock absorbing plastic. In addition, Tuffkast absorbs much less water (about half) as much as nylon does. In addition, it does not weaken in the cold like nylon does. Customers rightly wonder what the “catch” is with this material as it would seem to be easiest to just use Tuffkast in every nylon application but that isn’t so. The main difference is cost, depending on the grade Tuffkast can be 50-80% more expensive than nylon. The other potential drawback of Tuffkast is that it is softer than nylon, this can lead to increased wear or susceptibility to wear. An example would be use of Tuffkast as a wheel on a railed track. Tuffkast will deform more quickly due to imperfections in the rail and will wear more quickly in general.

If you have more questions about how Redco Tuffkast or nylon might be ideal in your application please contact us today.

 

Tolerances And Surface Finish

When we here at Redwood Plastics and Rubber get our estimators to work on a project we are required to fill out an internal form that, among other properties, specifies surface finish of the part and tolerances. Assumptions in these matters can occasionally result in customer disappointment but equally important the customer may be paying for tight tolerances or a surface finish that isn’t required for proper performance of the part. To reiterate: requiring tighter tolerances and a smoother surface finish than is required for a part means you are wasting money!

One of the biggest barriers to figuring out what tolerances and surface finish are required is that technical drawings rarely provide accurate information. Most commonly, drawings are supplied with metal tolerances – these are tolerances that are difficult or impossible to hold with plastics. Certain plastics such as acetal can be held to fairly tight tolerances but other commonly specified plastics such as UHMW-PE cannot. Questioning about how critical tolerances are at the very least can delay a quotation until we figure out what is required and doable.

A similar issue is that drawings often come with parts that have 90 degree square corners. This is also very difficult to supply and definitely adds cost. Our standard edge radius would be .125″ and knowing how critical the edge is or not will potentially save you, the customer, money and time.

Surface finish is a little bit of a tougher issue to tackle. Many customers do not know that a variety of surface finishes are available. Our standard is a “125 end mill” but do you know what that actually looks like? The tough part here is the customer may be expecting a “smooth” (very smooth!) part but if that isn’t specified we’d default to the end mill, which has small, but noticeable, grooving. Likewise, a rougher surface finish like a “500 shape turn” will potentially save the customer money.

At the end of the day we rely on you, the customer, to give us as precise information as is possible. It helps us not only supply a quicker quote but also a more competitive quote and that helps you as much as it helps us!

4 Tips For Your Fabricated Plastic Application

Have an idea for an application requiring machined, molded, or fabricated plastic and now you’re ready for some pricing? Having your requirements organized and prepared will not only lead to a quicker quotation but could also lead to a more successful application and quite possibly – save some money. If you’re ready for that quote these tips will help make it the smoothest possible process:

1.) Have some sort of drawing or sketch to send

We don’t expect everyone to have a technical drawing but we at least need a sketch to get started. Sometimes applications that seem simple (a bearing or a pulley) are more involved than you would think. Take a bearing for example, if you just give us the outer diameter/inner diameter/length that doesn’t answer all we need to know. We’d want to know what the tolerances are, specifically in relation to a press fit or running clearance. Does it have a grease groove? Any flanges? A simple sketch can answer many of those questions.

2.) Have quantity and budget in mind

Truth is there isn’t always just one plastic that works in an application. Often there are multiple options that are “good, better, best” and your budget determines where the ideal material lies. Quantity is important too, as quantity can (but not always) lead to price breaks. However, narrow it down to 2-3 quantities at most for quotation. There are not price breaks at all quantities and putting too many tiers will delay your quote.

3.) Know the operational environment and inform us proactively

Often our reps will ask you questions about your application. Basic, yet important parts of the operational environment often get overlooked when choosing a plastic, so think of this in advance and, better yet, inform us at the outset. For example: is the application outside and therefore needs UV-protection? Is it exposed to any chemicals, acids, or bases? Does it take impact or is immersed in water? All of those are critical to the success of an application.

4.) Ask questions

We can’t answer absolutely everything, but we do know our plastics. So if you’re unsure if a plastic is best for your application then ask. Even if we’re not familiar with the application itself, we can at least discuss how other plastics compare to the one you’re considering and that may lead to more success and satisfaction with the end result.

For help with your plastic applications please contact us.

Budgetary Expectations And Lifecycle Cost

One of the most important topics that comes up in a plastic application are issues of cost, budget, and expectations. Most commonly the request we get is to provide a better better performing plastic at less cost. In the vast majority of situations, frankly, this is unreasonable. Plastics, like any quality product, generally follow the old cliche “you get what you pay for” and a better performing, longer-lasting, plastic will almost always cost more money. There are rare exceptions, for example everything being equal, reprocessed (“repro”) UHMW will actually outperform the slightly more expensive natural grade in wear applications specifically. However, these are very rare exceptions to the rule.

It is important to know your budget up front. If there is no ability to fund a higher priced solution you may simply need to make due. However, if you have room in your budget then we have some room to work. Most commonly, a premium grade of the same material would be suggested. For example, switching from reprocessed UHMW to Redco Titanium or Tivar 88. This is generally the first step to take as the premium product provides all of the properties of the lower grade, just much improved. For example, slicker, better wear properties, and UV resistance or weathering.

At times, the application may require a jump to a new plastic. For example, if a nylon part is failing due to being brittle in cold temperatures or moisture swell, then a switch to Redco Tuffkast may be in order. Similarly, most plastics cannot hold tight tolerances; however, acetal is perhaps the best at doing so and bears a similar load to nylon. Were a nylon part to fall out or be unable to retain tolerances, acetal would be an excellent substitute in most applications.

However, the most important point of all is this: selection of the optimal material for an application will almost always result in a lower lifecycle cost and therefore cost-savings. Reduced maintenance costs, replacement, and downtime, will all save the customer money in the long run. It is this critical factor which is often overlooked in the decision to switch to a premium grade of plastic or a more expensive, but ideal, plastic for an application!

For assistance in choosing the best grade or plastic for your application please contact us.