Plastics Information, Plastics Materials, Uncategorized

Delrin AF Blend, not for food grade applications

Homopolymer Acetal (or Delrin) is one of the more versatile and popular plastics for job shops to machine. Acetal has great physical properties, is easy on tooling and both Homopolymer Delrin and Copolymer Acetal can be found in stock at any reputable plastics distributor.

Delrin AF is an enhanced version of Acetal that can help Delrin AF parts out perform and survive in very demanding applications that unfilled Acetal would not do well in. Despite having a relatively high cost when compared to unfilled Acetal, it is widely used and specified. What is Delrin AF and are all Delrin AF stock shapes the same?

First of all, let’s clarify that there are two types of Delrin AF: Delrin AF (full strength) and Delrin AF Blend. Delrin AF is a UL listed product made by DuPont comprised of a 20% PTFE fiber reinforced Homopolymer Acetal (for more information see What are the ingredients in plastics?). Delrin AF Blend is a 13% PTFE fiber reinforced Homopolymer Acetal. The blend is made by taking full strength Delrin AF and “blending” it down with Homopolymer Delrin (150) material. This is done for a variety of reasons but a primary motivator is to reduce the cost by reducing the amount of PTFE in the product. In the molding world it is common to see a Delrin AF or Delrin AF Blend. In the stock shapes world, Delrin AF Blend is the more readily available standard. A great deal of confusion occurs when a print was originally designed to be molded and then gets converted to a machined part instead. Delrin AF blend (13% Teflon) will have a slightly higher tensile strength, modulus, and impact since there is less filler in the material. Delrin 100AF (full strength) would have better wear since it has higher levels of Teflon. Delrin AF is also UL Listed where as Delrin AF Blend is made of UL Listed components but not necessary listed on its own as a stock shape product.

Now there is another product that lives in this same category but is a hybrid of sorts. Tecaform AD HPV13 is manufactured exclusively by Ensinger Inc and is a proprietary blend of Homopolymer Acetal with a 13% PTFE powder reinforcement. This product can offer similar properties and performance but still falls short of Delrin AF and Delrin AF blend. HPV-13 uses a resin that is not UL Listed but it does carry FDA approval so the primary benefit is that it can be used in food grade applications.

So for applications that require FDA approval in an enhanced Acetal material, HPV-13 is the only product for the job. Be sure to check out the physical property comparison sheets on our website to see how they compare and make sure the HPV-13 is tough enough for your food grade application. We are also ready to help with any questions or concerns you may have.

Plastics Information, Plastics Materials

Acetal: homopolymer (Delrin) versus copolymer, are they different?

Acetal Grades

In my twenty plus years in the plastics industry, there have been materials there have always been materials that were easily confused or misunderstood in terms of their physical properties and/or potential applications. By far the most commonly confused and misunderstood material is Acetal. There are a myriad of reasons why this happens, from a lack of training at the distribution level to the political alliances and capabilities at the manufacturer level.

Either way, we still spend a lot of time explaining and educating on this topic with our customers every day. Our goal is to make sure the Job Shop gets the best material for the job! The reason why this is so important? Acetal homopolymer (or Delrin) and Acetal copolymer (known by various trade names like Tecaform or Acetron GP to name a few) are not the same, they are not equivalents. What they really are is alternatives to each other. It’s not that one is necessarily better than the other, they each have a place in the market and offer some distinct advantages. Using the wrong one can be a source of failures and returns that will cost you time, materials and maybe even a customer.

Time and again we see prints that call out for “Delrin” in the title block are being substituted with Acetal copolymer because the pricing can be more favorable on the copolymer material when compared to Acetal homopolymer. The attraction of the lower price can allow some to rationalize that they are getting the same thing, only cheaper. Take a look at the comparison chart on our website. The tensile strength, creep and fatigue resistance and toughness of homopolymer Delrin are much different than that of copolymer Acetal. Homopolymer Delrin can have increased physical properties in excess of 20% of other Acetal’s.

Black Acetal-porosity line(Click on picture for a closer look)

Center line porosity is another differentiator. Acetal homopolymer has an inherent center line porosity that is not present in Acetal copolymer. Is this a bad thing? It depends on the application, but you have to know if it matters in the end use application. If there is a concern that Acetal homopolymer center line porosity will be a problem, the design can be modified or reinforced to allow the use of Acetal copolymer.

Fatigue endurance is another area of differentiation where homopolymer Delrin will significantly outperform copolymer Acetal. This makes it a more ideal material for various industrial applications especially when maintaining or improving long-term performance is important.

Acetal ASTM

When you request a quote and you want to make sure you will be quoted and sold Acetal homopolymer Delrin, ask the seller to certify it as such. Read the certification carefully. The primary ASTM heading for both items are the same (ASTM D6100-11). The devil is in details of the second level of the specification where S-POM0111=Acetal homopolymer Delrin and S-POM0211=Acetal copolymer.

Either way, Plastics International stocks a vast inventory of both Acetal homopolymer Delrin and copolymer Acetal in natural and black in sheet and rod form. We do not have a minimum order on in stock items so you can get as little or as much of which ever Acetal is right for you. We would be happy to help you make sure you have the right material to meet your customer’s specification. Visit our website at for more information.

Plastics Information, Plastics Materials

What is a near net shape?

Nylon parts can come in all shapes and sizes. I once worked with a company that made nylon sheaves that were larger than my dining room table. The various shapes and sizes of parts widgets are made out of in nylon can many times lend itself to a near net cast nylon shape. A near net shape is simply a molten nylon resin poured into a tool that will give it a near finish or “near net” geometry. This type of process can require a small or modest tooling investment but can greatly reduce the part weight and especially increase parts per our productivity and reduce other costs associated with the part. Typically near net shapes can be a static cast, an open pour mold which means a little finishing might be required on the top-side of the part. The savings in time are probably the greatest benefit, especially when dealing with larger or massive parts.

Near net parts may also offer a chance to add a custom color or other additives to enhance the nylon material in your applicaiton. If you have a part that might be a good candidate for a near net shape, just send the print to the email on our website or call us for more help ( One of our technical sales representatives would be glad to take a look at it and let you know what your options might be. You can send a DXF or PDF file. Since PI does not do any machining, you never have to worry about us competeing against you.

Plastics Information, Plastics Materials

Import vs. Domestic Plastics Materials

When it comes to cars or perhaps beer, we generally associate imports with higher performance or quality craftsmanship (depending on your taste of course). For the most part, we can all find something good about our favorite import beer or perhaps a european sports or luxury car that sets them apart in our mind. In plastics, there are many companies that import resin systems or stock shapes materials from very reputable and quality companies in Europe and Asia. There are times however that sourcing these items may have some risks, depending on what material is being sourced and from what manufacturer.

If you have been reading this blog, you may already know that Plastics International sources and sells engineering plastic stock shapes all over the world. We have seen extremely good products that work well in demanding applications and we have seen some not so very good products fail and cause problems for job shops and their end users. Unfortunately, many times the motivation to use an import material is primarily motivated by a low price. But a low price can have some high priced consequences.

Take for example Acetals. There is already a great deal of confusion in our industry about homopolymers acetal (Delrin) vs copolymer Acetal (i.e. Tecaform, Acetron GP, Pomalux). These two products are not the same and they each have their pros and cons. When copolymer Acetal is the right material for the job, there are many quality products that can provide a good, stable stock shape to machine from. Lately, we’ve been seeing a flood of generic imports of copolymer Acetal in the market. The primary reason these products have made their way into the market is not because of any issues with the established brands. The import products are being introduced because they are offering extremely low prices in order to gain market share. So these products will tell you about how they offer “competitive” pricing but they often leave out what they don’t offer. These suppliers do not offer things like in-house tech support or testing labs, consistent resin supply and quick turn around should there be material problems. In some cases the resins they use may not always come from the same supplier nor might they carry all of the same specifications or certifications.

For many, this isn’t a problem or anything to worry about until something fails. The industry standard for stock shape manufacturers is to only credit for material, not labor. That means if a machined part fails, only replacement or credit for material is offered. Keep this in mind when a low priced import seems to good to be true. Plastics International offers a quality driven supply chain and accurate part numbers to ensure you know what material you are getting and that it will be the same high quality product on every order. Always ask for material certifications and don’t settle for “no-name” products from “no-name” manufacturers. You can always find data sheets to our products on-line to compare and make sure you are meeting the specifications for the print.

And yes, we do offer many different options of imported and domestically made products. Depending on your application and capabilities there may be some advantages to consider. Either way, we just want to make sure you have access to the best materials, cut to your size and shipped out same day/next day to help you exceed even your most demanding customers expectations. We can be your trusted partner, just let us know how we can help.

Plastics Information, Plastics Materials

Why can’t I get that color in plastic?

One of the cool things about plastics over traditional materials is the variety of colors it can be made in. Everyone can relate to something that was made out of a plastic in some sort of cool color that made their product standout. In the graphics or decorative world of plastics, colors are somewhat easy to come by and are readily available. In the engineering plastics world, colors are very much a luxury. Black and Natural (technically white in color for many materials) are the extent of the variety unless you get into very exotic medical grade materials. If you really need a color though, this can get expensive in a hurry and it is still hard to find.

The reason colors can be difficult has to do with how many materials are made. In order to get a color, you need to mix enough material in color to fill the “hoppers” of very large capacity manufacturing equipment. In addition, when you transition from one color to the next, there is a large amount of waste generated as equipment purges the previous color and eventually gets to the proper color with no contamination. This just adds costs and time that can make colors in some materials unaffordable or practical to make.

For this reason, copolymer acetal is now being made in a blue color to break away from the everyday, black and white world. The material is standard copolymer acetal, with no special medical grade compliance to add to the cost. It has limited sizes available in rod and plate, if this might be a nice alternative in your application, check us out online or give us a call today.

Plastics Information, Plastics Suppliers

That’s not something we stock…

It’s been a busy week, you’ve been working hard all week to get a new target account to give you a chance to quote their next opportunity. Today you finally get the call, they send you prints and its time to really impress them with your knowledge, quick turn around and lead time. You gather all your information and then call your plastic supplier to get a quote on the plastic stock shape, then you hear: “That’s not something we stock, I’ll have to call the mill and get a price and lead time” (screeching tires). Now you have to wait, and wait…and wait. Finally (maybe days later), you get the call back only to hear there is a minimum purchase and a lead time for the item. Now what?

Wikipedia defines distribution as: The process of making a product or service available for use or consumption by a consumer or business user, using direct means, or using indirect means with intermediaries. I’m sure you will agree with me, my expectation of “making a product available” is having it in stock, ready to go when needed. That’s the role of a distributor, it’s the service we provide. All too often today, we see distributors acting more like brokers. They don’t stock anything, they drop ship everything and they really don’t bring any value. In our example above, the minimum buy will hurt the job shops chances of getting the business.

Today’s distributors are under enormous pressures for financial performance, needing to achieve ever greater margins and inventory turns. Instead of meeting those demands with superior service, they cut back on the service offered. Job shops don’t know when (if ever) a job will repeat. If the job shop has to invest money and space into stocking materials, it will distract them from the things they do best, machining parts!

The next time your plastics supplier tells you “that’s not something we stock…I’ll have to call you back”, think about giving Plastics International a call. We have a huge inventory available to meet your needs, keeping partial sizes inventoried in our system to give you quick access to them. Plastics International can price you right over the phone, even on cut to size items. And once you place your order, it will ship same day/next day. All of this is offered with no minimum order for stocked items.

So give us a call or check us out online at

Plastics Information, Plastics Materials

What are the ingredients in plastics?

Plastic materials offer a wide variety of properties and design flexibility that have made them the material of choice for making many different products. From injection molded toys to machined bearings or bushings, plastics are allowing for creative ideas to become realities in a more affordable way to solve difficult problems. There are times when a plastic material by itself, may not be able to meet all of the demands of particular application. When an alternative material becomes cost prohibitive or will not work either, there are some options that can make the palstic material suitable for use.

Different things can be introduced to help enhance a specific property or set of properties to help the plastics sheet, rod, tube or film bridge the gap in performance. In this article, we will endeavor to explain and/or clarify some commonly used and confused terms.


Additives are a general term referring to anything added to a plastic.  This term covers both fillers and reinforcements. The term additives refers to a wide range of chemicals that are added to plastics. The major categories of additives are antioxidants, antistatic agents, colorants, coupling agents, curing agents, flame retardants, foaming/blowing agents, heat stabilizers, impact modifiers, lubricants, nucleating agents, plasticizers, preservatives, processing aids and UV stabilizers. Most additives are compounded into base material prior to manufacturing.


Reinforcements are used to improve tensile strength, flex strength and stiffness of a material. There are many reasons for adding reinforcements. One important reason is to produce dramatic improvements in the physical properties of the base material. Reinforcements are often confused with fillers. Fillers are small particles and contribute only slightly to strength (see next section). On the other hand, reinforcements are ingredients that increase strength, impact resistance and stiffness. One major reason for the confusion is that some materials may act as a filler, reinforcement or both.


Fillers are things added to plastics to control other properties such as impact modifiers, lubricants, glass beads, MoS2 and the like. The term filler is often confusing. Filler was originally selected to describe any additive used to fill space in the polymer to lower cost. Because some fillers can be more expensive that the base material, the word extender can be misleading. The terms dilutant and enhancer are sometimes used to describe the addition of fillers. Ambiguity of terms and and overlapping of function add to the problem. For our purposes, a filler will mean any minute particle from various sources, functions, composition and morphology.

According to ASTM, a filler is a relatively inert material added to a plastic to modify its strength, permanence, working properties or other qualities or to lower costs. Fillers can be both organic and inorganic ingredients of plastic resins. They can increase bulk or viscosity, replace more costly ingredients, reduce mold shrinkage and improve physical properties of the composite item.

There are many ways that additives such as reinforcements and fillers can benefit a plastic material for a given application. There is a wide variety of materials that are stocked with fillers and reinforcements, feel free to look them up online at or send in a request form to review the application with us.

Plastics Information, Plastics Materials

Beware… Plastics Aren’t Always What They Seem To Be

Here’s a real life experience we would like to share with everyone:

Plastics International has had a long history of stocking 30% GF Ultem for one of our OEM customers. Their Machine Shop vendors were directed to order the material from Plastics International to ensure the material would be consistent for quality, responsibility and traceability for the life of the project.

A couple years into this project, one of the machine shops had quality problems with their 30% GF Ultem parts.   When these parts failed to pass QC at the OEM, the machine shop sent the rejected parts back to us for credit and replacement material. The OEM Company requested that Plastics International supply a corrective action response for the cause of the machine shop’s material failure. We had the rejected parts evaluated by the test lab and discovered that an unknown filler had been added to the 30% Glass Filled Ultem’s base resin. Since our 30% GF Ultem did not contain the unspecified filler, we knew it wasn’t purchased from Plastics International.

Plastics International called the machine shop and discussed the findings of our evaluation process and asked them to check their purchasing records. After checking their records, the machine shop apologized because their buyer had mistakenly ordered the defective material from Coyote Plastics.

(Coyote Plastics is a fictional name we use to represent those Plastics Distributors who not only sell plastics to machines shops…they also have in house machining…or they own their own machine shop.  Coyote Plastics uses their internal machining capabilities to compete for fabrication business against their machine shop customers.)

The filler was present as the result of Coyote Plastics using a lower cost manufacturer who provided a modified 30% GF Ultem resin. In doing so, Coyote Plastics was able to accomplish 2 positives and 1 negative. Unfortunately, it was a Big Negative.

1st Positive: The filler made the GF Ultem easier to extrude…possibly at faster speeds and with less abrasion on extrusion dies.

2nd Positive: The added filler also lowered the overall resin cost of the GF Ultem, allowing Coyote Plastics to sell it at a cheaper price.

Big Negative: The filler material also lowered the published and specified physical property values of the GF Ultem, resulting in part failures from the intricate machining and application requirements. As a result of trying to lower their material costs, the machine shop ordered from the wrong vendor, received the wrong material and wrongly certified to the OEM’s specifications. It was a costly mistake. As a consequence the machine shop’s reputation was damaged and it negatively impacted their business.

We can quote lower cost resins too. However, before doing so, please consider the risks in using lower cost resins (which can lower the material’s physical properties and increase the chances of non-conforming parts or failures in the field). Instead, Plastics International can help you with our large inventory of quality materials, cut to size yielding and no minimum order to meet your most demanding specification requirements with minimal risk.

There are reasons why plastics can vary significantly in cost and performance. Resins and extruded materials are available in different price ranges and from numerous sources. To protect yourself before problems arise, request material certifications and make sure they match your customer’s specifications. Rejected or replacement parts are expensive and Plastics International pays close attention to material certification requirements so your raw material meets your end user specifications.

You can find technical specifications to help with your plastics application at

Plastics Machining

Finding the Sweet Spot in Plastic Cutting Tools


There are a number of factors to consider when setting up to machine plastics.  Most importantly, plastic has a higher thermal expansion rate than most other materials, such as metal or wood products.  Thermal expansion is the tendency of the material to change volume in response to the heat introduced during the formation of chips created during the cutting process.   Reducing thermal expansion is key to producing clean and effective cutting in any plastic cutting operation.

Following are some key tips to reducing thermal expansion and improving your cutting success.  The first thing to consider is tool geometry and quality.  This is true for any type of cutting tool:  Router bits, saw blades and wing-type cutters.  For this article we will be discussing router bits, but the techniques discussed are applicable across the board.

Plastics fall into two main categories: Hard and Soft.  Harder plastics, or those with a higher durometer rating, generally have a lower rate of thermal expansion.  Softer plastics will obviously have the opposite properties.  Softer plastics tend to be more difficult to cut due to the fact that it will tend to “push” out of the way of the cutting edge of the tool, increasing friction and thus heat, introduced to the chip formation.  When the threshold of heat exceeds the melting point of the material the chips being formed, the chips will melt causing a problem.

Generally we select tooling with higher shear or helix angle when cutting softer plastics.  The higher shear angle can reduce cutting pressure, thus reduce heat created.  However, factors such as material thickness and hold down will limit the ability to introduce high shear tools into the cut.

One thing we have recently introduced to our line of plastics bits is a highly polished flute.  High polish dramatically reduces friction created during the cut.  This will create cleaner cuts in most applications.

Selecting the proper chip load is another important factor for proper cutting.  Hitting the “Sweet Spot” is one of the most critical factors for successfully cutting.  The window for the proper chip load is much smaller for plastics than in any other material.  Typically, one or two thousandths of an inch will make the difference for plastics where wood, for example, can machine well across tens of thousandths of an inch.  Chips load is calculated using the following formula:


Chip Load = Feed Rate (IPM)/(# Cutting Teeth X RPM)


Chip loads for plastics are generally between .004” to .008”.  The important point is that plastics will have a very small “window” of acceptable chip load and all conditions of the cut will factor into what chip load will be successful in a particular application.  Learn to calculate chip loads in your application and make small incremental adjustments to “Dial in” what works best for your particular application.

Tool deflection is another factor that needs to be addressed in order to reduce friction created at the cutting site.  Router tooling, cutting tool diameter, geometry and tool holding all play a role.  In general, larger tool diameter will deflect less, thus reducing tool deflection.  Work with your supplier to select the best tool geometry/diameter that will work for your application.  The tool itself is driven by the tool holding device.  There are numerous options for driving your cutting tool.  The important point is to realize that the more substantial your tool holding is, the better the results you will see in cutting.

The final area to consider to improve your cut quality is “Part Hold Down”.  Again, the more rigidly the part is held, the better your results will be.  When fixturing parts, it is imperative that the part be held securely as close to the cutting site as possible.  This is especially true for thinner materials.  If the part can fluctuate due to part instability, it can make the difference between a good cut quality and a poor one.  In a vacuum hold down situation you want your gasket seal as close to the cut edge as possible.  If you are clamping parts, the same is true.  Basically, the more you invest in fixturing, the better your results will be.

In closing, to increase your cut quality in plastics there are four things to concentrate on.  First: select the proper tool with the optimal tool geometry for your application.  Second: make sure that your tool is run at the optimal parameters for your application (feed rate).  Third: Review your tool holding devices and make sure to optimize as best you can.  And finally, make sure your parts are held in the best way possible.

(Reprinted with permission of Mike Serwa, VP-Vortex Tool Co.)

Plastics Information

What is laminating?

Lamination occurs when two or more layers of material are put together by either cohesion or adhesion. Plastic laminates are usually various layers of material held together by some sort polymer or plastic material. Laminates and reinforced plastics can be difficult to distinguish from reinforced plastics because the layers often provide strength and reinforcement as well to the base plastic material. The primary way to tell the two products apart is that laminates are usually made up of layers of material. Laminates are also primarily made in to flat sheet or tubes and rods versus reinforced plastics can be molded into complex shapes or geometries.

There are many types of laminates processes to consider. Processes like co-extrusion are technically a laminate. Many different materials can be laminated together as is the case in bullet resistant polycarbonate which is made up of polycarbonate, acrylic and some sort of urethane interlayer. Another process yields what are considered either low pressure laminates or high pressure laminates. For the purpose of this article we will focus on high pressure laminates, also called high pressure laminates.

A paper, fabric or cloth are usually saturated or impregnated in a plastic resin system of some kind of thermosetting resin system like melamine, phenolic, polyester or epoxy. Originally high pressure laminates found applications as counter top material. Today, these materials are being used in much more dynamic applications like printed circuit boards, gears and pulleys and the like.

A major disadvantage of high-pressure laminates is the slow production process compared to other plastics technology processes. However, the properties of the material in regards to strength and stiffness at elevated temperature can be a useful product in solving certain challenging applications.

If you would like a more information regarding high pressure laminates, click on this link to our online sortable material chart.