Posts Tagged ‘advice’

Quadrant Engineering Plastics is a major manufacturer of industrial plastics. While they do not sell directly to end-users, and instead sell through distribution, they still invest in many resources for end-users to help them reach their goal with their applications. One of the best is the “Machinists Toolkit” which is available by clicking here. This gives a variety of tips from what coolant to use, to tool tips and even troubleshooting specific issues that come up. It also gives feed rates and end milling/slotting guides for various plastics.

One handy section the toolkit has is a rating of the machinability of various plastics on a rating system. Acetal is usually the best where tight, critical tolerances are involved. But like with all plastics, there are situations where acetal is not ideal. In those cases when reviewing the various options you need to know what the “next best option” is. More useful still, is on the left side of the toolkit page is a link to the chemical resistance chart. This will allow you to look up alphabetically various plastics and their resistance to various chemicals. Please do not think that just because plastics in general are resistant to many chemicals, that a given plastic will be resistant to chemical exposure in your application! And do not assume that just because a chemical is “household” that it will not attack your plastic – it might, so do not assume!

Finally, Quadrant has also released a short video giving some machining tips. While the video says it is geared for a few high performance materials, much of the advice given is relevant to any home machinist working with plastics. That video can be seen here:

 

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Nylon is a fairly popular plastic used by the DIY community: and it should be! Versatile, strong, and available in small quantities it offers many properties valuable to the public’s plastic applications. In most cases, nylon will be an ideal material for mechanical parts such as sheaves or bushings. But it isn’t perfect and it like anything it has its drawbacks in certain applications. Here are some tips on using nylon that will serve you well.

1.) Don’t use it in the cold

Ok, well you can but you just need to be aware of impact. Nylon gets brittle in the cold, at about 5 degrees Fahrenheit and if it’s taking any sort of impact it could break. In fact inĀ  any application where you expect impact, use Redco Tuffkast instead (it has been developed to replace nylon in applications with impact.)

2.) Don’t use it in water

Unlike most plastics, nylon absorbs a significant amount of water – up to 4% of its volume in 24 hour saturation. For marine applications or those involving tight tolerances you probably want to go with an alternative material. Acetal is commonly specified in this case but Tuffkast may be an option as well, it depends on the application, so ask your distributor.

3.) Do use it under load

Nylon can handle 4000 PSI in application and this is one of the highest loads of readily available thermoplastics. This makes nylon excellent as a bearing, sheave, or other load bearing part.

4.) Pick the optimal grade

Nylon isn’t just “nylon”. It’s available with a variety of fillers: glass for dimensional stability, moly for high load low RPM applications, oil filled for reduced friction, UV stabilizers for outdoor use, and PVM (pressure velocity maximum) for the highest load applications. These fillers add only a minor cost, or in some cases cost the same as the natural grade, and are well worth it for certain applications. Unsure if you need a filler? Discuss your application with your distributor.

Even though three of these four tips are “don’ts” knowing when to avoid a material is just as important as knowing when to use it! Don’t get us wrong – nylon is a versatile, excellent, affordable plastic for a wide range of applications. Just keep in mind that it has advantages and drawbacks: just like every other material out there.

3 “Insider” Plastic Tips for the DIY Community

Posted: September 30, 2016 in Uncategorized
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When you’re a member of the public who just needs some plastic for a home project, dealing with a plastics distributor can be a little awkward. They’re not like a “store” in the traditional sense, with product neatly displayed with nice little price tags. Product is quoted based on specific needs – and often, you don’t even know what those needs are! Sure, you may have an application in mind, and you might have heard of a plastic that works well in that application. But how do you know for sure? In addition, industrial plastics are a premium material and the cost can be a surprise to some people. Here are three “insider” tips from those of us in the plastic industry which will help you have a more satisfying experience with your DIY application:

1.) Be open-minded – and don’t care about looks

Many people have an idea that, like with products made of consumer or “commodity” plastic, that a wide array of colors, textures, and sizes are available. This is not the case at the level of industrial plastic. Most plastics only come in one color per grade and the color is often just white or black. Colorful plastics like frosted acrylic are hard to come by in small quantities. You need to place the needs of your application beyond color matching or other aesthetics.

Also, be open-minded about material. It’s quite possible a knowledgeable salesperson will recommend a different material. If you’re worried about the increased costs, ask for some clarification on why the suggested plastic might be better and what other options you have available.

2.) Ask about offcuts

For many smaller projects you don’t need a lot of material but plastics will commonly be offered in 4′ x 10′ or 4′ x 8′ sheets. One potential option is to ask your distributor if they have some offcuts they would be willing to sell. Many plastic distributors will have companies under contract to buy their offcuts, but some are usually kept on the shelf and either way the distributor usually makes a bit more by selling offcuts for cash. You may have to take a slightly larger piece, but it could save you money, and it’s worth an ask.

3.) Arrange your own pickup/freight

“Quote and include the freight” is a common request a plastic distributor gets but do you know what you’re actually asking for? True, to get a contract done industrial supply companies will mostly quote the freight. But what they’re doing for the most part is contacting a freight broker and getting them to spit out a quote, which is then marked up to you by 10-15%. The time a salesperson takes away from their primary job needs to be compensated for. Your best option is to just ask for the product weight and dimensions and contact a logistics provider yourself. Or make a UPS, Purolator, or Loomis account for the smaller orders.

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Choosing Your Plastic

Posted: March 8, 2016 in Education
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The question comes up a lot in the DIY community: “I am planning to make _______ so what plastic do I need?” The good news is selecting a plastic for your application is very similar to how heavy industry would select a plastic for their projects. You need to select a plastic based on certain properties it gives you, not some sort of bias to what you “heard” worked – and especially not based on color!

So when thinking about your what you need for your application consider the properties of these plastics:

 

UHMW Polyethylene:

-Slick, low-coefficient of friction

-Good wear properties

-Good abrasion properties

-Thermoformable (at home)

 

Polyurethane:

-Elastomer: will regain its shape after depression (excellent as mallet heads)

-Excellent cut & tear resistance

 

Nylon:

-Bearings (takes up to 4000PSI)

-Wear plates

 

Tuffkast:

-Replaces nylon in cold operating environments or where impact is a concern

 

Acetal:

-Small parts, replacing metal

-Where machinability is key, can hold tight tolerances

-Replacing nylon in “wet” applications

 

PVC:

-Anywhere a “frame” is needed.

 

Industrial laminates/Phenolic/Micarta:

-Mechanical or electrical applications

-High load bearing