HDPE vs UHMW: When to Use High-Density Polyethylene
HDPE and UHMW are popular and well known types of plastics across many different industries for their reliability, so much so that many people have started to use them interchangeably. However, their uses don’t coin cide nearly as often as many think–HDPE has different qualities that lend well to different applications. While both materials are very light, with a density of .94 – which means they both float in water.
When best to use HDPE
High-Density Polyethylene or HDPE is known for its versatility and low moisture absorption, which result from its high-density chemical makeup. Its chemical composition also makes it highly chemical resistant, so it’s excellent for applications that involve moisture or mild chemicals.
HDPE is also very easy to machine and shape. As a result, it has been used successfully to make plastic lumber, milk jugs, containers, cutting boards, and many other products.
In addition to being easy to machine, HDPE sheet and rod are also relatively lightweight, and can be NSF and FDA compliant. This very durable material can not be glued or bonded, and thus must be heat welded together or attached with mechanical fasteners. HDPE is excellent for applications where reduced weight and low costs are paramount. This, combined with its easy machinability, allows HDPE to be cut, drilled, routed and shaped for many different end uses. Food cutting boards, piping, storage vessels, marine components, and many more benefit from HDPE. It’s also been successful in outdoor furniture, signage, playground equipment, structural tanks, food processing equipment, vacuum-formed parts, transfer boards, tank liners–and this is just a small number of its applications.
When not to use HDPE
While HDPE and UHMW have similar properties, they are often better suited to different tasks. Both plastics do have high impact resistance, but UHMW (Ultra-High Molecular Weight Polyethylene) performs better in applications where friction and constant impact are present. The UHMW molecular chain is much longer, thus giving UHMW the extreme wear resistance. This results in UHMW being used more often in functional components, like conveyor systems, concrete chute liners, mated parts, bumpers, and bearing applications. HDPE does not perform as well as UHMW under constant friction, making HDPE better for food processing surfaces, chemical resistant parts, decorative products, or components that will not experience constant friction. If a reduced friction application is needed, the use of UHMW with a coefficient of friction of just 0.08 (compared to HDPE with a coefficient of friction of 0.20) is much more suitable.
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Is HDPE Sheet and Acetal Homopolymer Sheet the same?
Here is another popular question asked by our clients. Is HDPE the same as Acetal Copolymer / Delrin Acetal Homopolymer? No, they are two totally different materials. Although the natural color of both is a milky white to opaque white, and they do look a bit similar, they are not. (HDPE is milky white to almost translucent depending on thickness, and the Acetal materials are a more opaque white to slightly milky – once again depending on thickness . See picture below of .500″ thick samples of HDPE and Acetal sheets)
HDPE and Acetal – Some Differences
The HDPE sheet and rod is a softer material, and is commonly known for its FDA certification and used in numerous food applications, such as: one gallon milk jugs, cutting boards, colored water glasses/cups, and many, many more. While it can be machined, because it is a bit softer and lighter, the tolerances it can be machined to are not very tight. It is not bondable, so it makes a great non-stick surface for sticky foods and adhesives.
The Acetal Copolymer and the premium Delrin® Acetal Homopolymer also have FDA certification, and are used heavily in the food processing industry. This material is a more mechanical material and is used in bearing and wear applications, cams, feeder screws, etc. This material is can be machined to tight tolerances, and will wear for long periods without lubrication. Due to its exceptional wear properties, it is not bondable, thus requiring mechanical fastening or threads to assemble. It has a very low water absorption, and you will find it in your toilet tank as the white moving parts in the filler mechanism. It is an extremely popular material for machinists, as it works much like soft brass.
While HDPE Sheet and Acetal Sheet look similar, they perform quite a bit differently.
While both materials are FDA approved, are machinable and can be used to make rigid wear resistant parts, they are two different resins and have drastically different physical properties. Another major difference is in the weight of these items, HDPE sheet and rod material weighs about 35% less than the Acetal sheet and rod material. Please check the data sheets for more information to assist in proper material selection.Acetal Data Sheet and HDPE Sheet Data
Acetal is commonly known as: Delrin Homopolymer Acetal, Tecaform AH,Ensital, Unital, Pomalux, Ultraform and many more.
HDPE is also known as: Ultraethylux,Densetec, Polystone G, Fortiflex, Versadur, Hostalen, and many more.
Contact us for more details on the HDPE and Acetal families of plastic materials, e-mail us or call 866-832-9315 Topic: HDPE sheet and Delrin Sheet (Acetal Sheet)
A wide variety of plastics are available in sheet form.
The term: ‘Plastic Sheet‘ or ‘Plastic Sheets’ is more of a general statement covering over a hundred types of plastic materials and plastic products. Some of the most popular plastic materials made as a sheet are:
In addition to the wide range of plastic materials available as plastic sheet, most of these materials are also available as: thin gauge or film, strip, plate, block, slab and plastic panels. The thin gauge or film materials are frequently available with or without a pressure sensitive adhesive also called ‘tape’. Sheet in some materials is available over 4.0″ thick and perhaps as thick as 8.0″ thick in a few materials. The standard sheet size on most of our plastic sheets is either 24″ X 48″ or the larger 48″ X 96″ sheet size; although some materials are available as: 48″ X 120″, 60″ X 96″ or 72″ X 96″. Contact us with with questions on your required piece sizes, we are happy to provide plastic sheets cut to size.
While there are lots and lots of different materials available as plastic sheet, there may only be one or two materials that are right for your application. We want to assist with your search. If you need help choosing the proper plastic material for your application, check out our free Plastic Material Selector Guide. Also, feel free to contact us for further assistance. As a leading plastic sheet distributor since 1975, we feel that we are your best choice as your new plastic sheet and sheets supplier. Give us a call at 866-832-9315.
Next time you are cutting vegetables on your cutting board, the material most likely to be used is Polyethylene. Because it is stain, moisture and odor resistant, Polyethylene is a perfect choice. Other cutting boards made out of wood are more susceptible to bacteria and odors because they lack the properties that Polyethylene sheets offer, such as its chemical resistance and FDA approval for food contact. Polyethylene is a very durable and lightweight material that comes in many forms and is a great for a wide variety of applications.
NSF Approved Cutting Boards
The HDPE is available in .500″ thick in several FDA / NSF approved colors, and is great for use in kitchens where cross contamination is a problem.
The Ultimate Cutting Board
Polyethylene has many names. The most common are HDPE, LDPE, and UHMW. The difference has to with the molecular weight and branching which is when a monomer or atom is replaced by a longer chain of polymers (a long repeating chain of atoms). High Density is commonly used for milk jugs and food containers. Low Density is commonly used for bottles and plastic bags. UHMW, which has higher molecular weight (2-6 million) allows for an even transfer over the length of material which makes it stronger and able to be used for bearing applications due to its great wear resistance. Commonly used in the food and dairy industry, UHMW is a great replacement for other materials and solution to many problems. All of these polymers are derived from the same family but all have certain properties that make them a little different. HDPE provides great chemical resistance, with high impact strength and great energy absorption. LDPE has most of the same properties as High Density but is not as dense at 9.15, opposed to HDPE which is 9.34. It also has a lower tensile strength and easier formability.
UHMW is a strong material that has great durability and low co-efficient making it an ideal for sliding applications. Polyethylene offers a wide range of material choices and properties and has great durability that can be suitable for a number of applications. From the food industry to automotive, the kitchen or the warehouse, whatever your Polyethylene needs are; High Density, Low Density or UHMW, Polyethylene is a great choice.
Typical Resin Properties:
General Property
ASTM Test
Typical Value HDPE
Typical Value LDPE
Typical Value UHMW
Specific Gravity
D792
.941 – .965
.91 – .925
.93 – .94
Tensile Strength Yield
D638
3,800 – 5,500
1,400 – 2,000
6,800
Izod Impact – Notched
D256
2.0 – 3.5
>16
No Break
Vicat Softening Temp
D1525
257ºF
219ºF
260
Hardness – Rockwell
D785
D60 -70
D42 – 50
R64
Continuous Use Temp
–
-100 – 180ºF
174ºF
180ºF
Deflection Temp @ 66 psi
D648
171
124
174
Co. Thermal Expansion
D696
7X10-5
4.6 -5.5X10-5
11.0X10-5
Please contact us for more information on FDA and NSF approved plastic materials. Email us here, or call us at: 866-832-9315
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cide nearly as often as many think–HDPE has different qualities that lend well to different applications. While both materials are very light, with a density of .94 – which means they both float in water.
