Posts Tagged ‘home projects’

UHMWPE (Ultra-High Molecular Weight Polyethylene) often abbreviated as “UHMW” is one of the most popular and well known industrial plastics. UHMW is seen as a “Jack of All Trades” in many applications while being more available and less expensive than other plastic options. While this is true to a degree, UHMW has limitations that means it will not solve all problems in all situations. In fact, it has some properties which make it deficient and the “DIY” community should keep this in mind.

When to use UHMW:

UHMW excels at taking impact and it is virtually unbreakable, it’s also very slick and the colder the operating temperature is, the better it performs. This is why UHMW is so popular in applications such as toboggans or as rails on sleds: impact + cold + slickness are all important to the application, and it does really well in this application. UHMW is also easy to work with as it drills, saws, and lathes well. It functions as wear pads, sliding blocks, fenders, and in other impact absorbing applications.

When NOT to use UHMW:

The main application we here at Redwood Plastics see UHMW incorrectly used in is bearing applications. UHMW is a poor choice as a bearing for two reasons:

1.) it is difficult to machine to tight tolerances (+-) 0.02″ are the best you can usually hope for and

2.) UHMW has low load bearing capabilities (500-800PSI). In a DIY bearing application nylon or Tuffkast will be superior.

The issue with tolerances is important to hit home: UHMW is not a dimensionally stable material. Not just compared to metals but even compared to many other plastics. We regularly receive drawings and requests for UHMW parts where we cannot quote based off the requested tolerances (or have to get a written waiver for acceptable tolerances). This lack of dimensional stability extends to thermal expansion and contraction which is why it is so hard to guarantee tolerances: if the part is manufactured in 30 degree weather but used in 90 degree heat the dimensions of the UHMW will drastically change!

We hope this points you in the right direction if UHMW is or isn’t right for your project. But if you have questions, or might be wondering what an alternative material could be, please contact us and we’d be glad to help!

Believe it or not one of the most popular “DIY” plastic projects is making bushings. It makes sense as bushings are a part of so many applications and plastics are an excellent bushing material, outperforming metals such as bronze and babbit in many situations. Plastics are easy to machine and usually last much longer than metal in a bushing application. Cast nylon is probably the most popular material for bushings, as it can take loads up to 4,000PSI and is readily available in filled grades to increase wear resistance and low RPM performance (moly-filled nylons) and reduced coefficient of friction or reduced lubrication requirements (oil-filled nylons). Nylon does have three weaknesses: shock/impact, cold, and water. If impact may occur to the bushing, if it’s in an environment -10 degrees Celsius or below, or in a wet (or marine) operational environment then Redco Tuffkast by Redwood Plastics may be an ideal solution for all three problems. It is a bit softer and can handle a little less load but in many DIY applications this will not matter.

Redwood Plastics offers a handy bearing machining guide that not only supplies typical running clearances but gives an honest comparison between nylon and other bearing materials. You can find the PDF Bearing Machining Guide here.

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Sometimes here we get a little focused on the different plastics and helping you with your applications that you’re already working on. But how about a few ideas on what plastic projects you could work on using industrial plastic? Just maybe this will get your creative juices flowing…

-Hockey fan? How about a synthetic ice surface using UHMW or HDPE?

-Build your own twin-wall polycarbonate greenhouse

-Drill holes in PVC piping and affix to a garden hose in order to make a great summer water attraction for the kids

-Make home saw guides made out of Micarta

-Line your mud room with FRP wall panel to protect from grime and damage

-Replace your wooden dock with a mini-mesh FRP grating surface

-Cut and affix UHMW strips to your snowmobile steering rails or dog sled

-Make a sunroof or solarium out of twin-wall polycarbonate

-Secure your sailboat rigging with Micarta grade CE washers or blocks

-Machine at home pulleys for a home robot or model using natural nylon

-Affix UHMW to the bottom of your shallow running boat to protect from impact

-Make a bolus game “goal frame” out of PVC pipe

-Line your dog house or other animal pen with HDPE puckboard to protect the walls and the pets

For help with your “DIY’er” project’s materials contact Redwood Plastics

 

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