Material Focus: PET

Polyethylene terephthalate (PET) is the most common thermoplastic polymer resin of the polyester family, and is used in fibers for clothing, containers for liquids and foods, thermoforming, and manufacturing.

Today we are going to take a look at the type of PET we use here at Aeromat Plastics, which comes in solid machinable shapes. 

What is PET?

PET is a strong, hard, and dimensionally stable material that absorbs very little water. It has good gas barrier properties and good chemical resistance except to alkalis (which hydrolyse it). PET's crystallinity varies from amorphous to fairly high crystallinity; it can be highly transparent and colorless, but thicker sheets are usually an opaque white.

What is PET used for?

In the world of machining, PET is a cost effective, dimensionally stable material that can be used in a wide variety of applications. From components inside scientific equipment, to pulleys on industrial machines, PET is a versatile material that can be used in almost any industry.

Is it FDA approved?

Yes, in fact, it is the most widely used material for plastic bottles and food storage containers.

Typical Properties

You can download a copy of PET's mechanical properties by clicking here.

Material Focus: High Density Polyethylene (HDPE)

Chances are that you come in contact with High Density Polyethylene on a daily basis. It is used in many common consumer products including plastic bottles, food containers, plastic lumber, and much more.

What is HDPE?

High density polyethylene (HDPE) or polyethylene high density (PEHD) is a polyethylene thermoplastic made from petroleum.

In 2007, the global HDPE market reached a volume of more than 30 million tons.

Examples of HDPE Products

  • Fluid Holding Tanks
  • Cutting Boards
  • Playground Features
  • Marine Parts
  • Bottle Caps
  • Plastic Lumber
  • Plastic Bags
  • Food Storage Containers
  • Fuel Tanks
  • Cable Insulation
  • 3D Printer Filament
  • Hard Hats
  • Proofing Trays
  • Machined Parts
  • Fluid Handling Systems

Is HDPE FDA approved? 

Yes, in general HDPE is FDA Approved. As with all materials, you should ask your plastics distributor to verify this information as there are many manufactures of HDPE.

Is HDPE weldable?

Yes! HDPE is a highly weldable product, and is actually one of the "easier" materials to hot-air weld.

What colors is HDPE available in? 

HDPE is available in nearly any color!

Is HDPE chemically resistant?

In short, yes. HDPE is commonly used in applications where chemical resistance is a necessity. It's important to note, though,  that HDPE is not a one-size-fits-all for chemical resistance. To find out if HDPE fits your application, you can download a chemical resistance chart by clicking here.

Typical Properties

You can view UL's list of HDPE's typical mechanical properties by clicking here.

Material Focus: Nylon MD

You've probably heard of nylon before. Since its inception in 1935 it has become a household name, and it is used all over for many different applications. From apparel, to flooring, to machined or molded mechanical parts, you can find nylon just about everywhere.

The thing is, that "nylon" is just a generic name for a family of nylon products, each with their own specific uses and properties. In this Material Focus article we are going to take a look at Nylon MD.  

What is Nylon MD?

Nylon MD is a blend of Nylon and a Molybdenum Disulfide (MD) specifically designed to enhance the materials thermal, mechanical, and bearing properties. In a nut shell, the MD adder lowers surface friction, improves material strength and rigidity, and even helps to give it better dimensional stability.

Where is Nylon MD used?

Nylon MD is designed for wear & lubrication. As such, you will find it used frequently in high-wear applications that external lubrication is either not possible, or undesirable.  Sheaves, rollers, gears, bearings, valve seats, sleeves, pulleys, wear pads, and thrust washers are just a few of the many applications for this material.

Is Nylon MD chemical resistant? 

Yes! In fact that is one of the great things about Nylon. This material handles most organic acids, solvents, alkalis, greases and oils. If you are going to be using Nylon MD in an application that depends upon its chemical resistance, however, you should ask your plastics dealer for a chemical resistance chart  to verify its chemical resistance.

Engineers, take note.

Nylons can absorb up to 7% (by weight) water in high humidity or when submerged in water. This can result in dimensional changes up to 2% and a reduction of physical properties. 

Typical Properties

You can download a copy of Nylon MD's mechanical properties by clicking here.

Material Focus: UHMW-PE

Ultra High Molecular Weight Polyethylene aka UHMW is one of the most commonly used thermoplastics materials in the world. There are many reasons for this, but most engineers love UHMW for its excellent abrasion resistance, low coefficient of friction and it's tremendous impact resistance.

What does ultra high molecular weight mean?

Standard High Density Polyethylene has a molecular weight of between 10,000 and 100,000. UHMW has a molecular weight of between 3,000,000 - 6,000,000. The extra molecular weight of UHMW give it special properties that allow the UHMW materials to perform well where lower molecular weights fail. Abrasion, chemical, and impact resistance are all areas that the higher molecular weight flexes it muscles.

Where is UHMW used?

UHMW has an extremely wide array of uses, and is found in nearly every industry. To list just a few, UHMW is found in body joint replacements, gears, packaging machines, dump truck liners, bearings, and synthetic ice.

Is UHMW FDA approved?

UHMW is widely used in the food industry, and in general comes with FDA approval. It is important to note, though, that not all UHMW is FDA approved. Be sure and check with your plastic dealer or material manufacture before putting it to use in food applications.

Is UHMW weldable?

Yes and no. In general UHMW is not weldable, but there are a number a UHMW materials on the market that can be welded. Make sure to ask for weldable UHMW specifically when looking to order it from your plastics dealer.

What colors does UHMW come in?

UHMW can be found in nearly any color! Most commonly you will find UHMW stocked in virgin natural (white) and black, but material manufactures have many other colors available purchase.

Typical Properties

The typical properties of UHMW can be found here. It is important to note that these are generic properties and you should request to see that material manufacturer's data sheet to verify any given property.

Material Focus: Acetal

Before we dig into talking about Acetal, an important thing to note is that although Delrin and Acetal are similar materials, they are not the same! Delrin is a DuPont trade name for acetal homopolymer, while the name "acetal" is most commonly referring to acetal copolymer. The difference between them is slim, but worthy of mention. 

Where are acetals used?

The acetal resins are among the strongest and stiffest of all thermoplastics, and are known to have great fatigue life, low moisture absorption, high solvent and chemical resistance, and excellent electrical properties. Because of these properties, acetals often compete with nylons for many of the same applications. Bushings, gears, bearings, rollers, and wear strips are just a few common examples of how acetals are used. 

Are acetals FDA approved?

This is a tricky question to answer, mainly because there are a number of manufactures of acetal.  Some manufactures have their acetals FDA approved, and others do not. For this reason alone, its important to ask your plastic dealer or material manufacture for a data sheet on the material. 

What colors does acetal come in?

Typically acetals are found in natural and black colors, but are also available in blue.

Typical Properties

The typical properties of acetal can be found here. It is important to note that these are generic properties and you should request to see that material manufacture's data sheet to verify any given property.