Puncture and Cut Gloves: Engineered Composite Materials

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In this post Knit and woven materials are reviewed and compared for protection and dexterity

In the Post“Safety Gloves: Cut and Puncture Resistant Fibers Explained”we covered the most common fibers used in cut and puncture gloves. While this review of fiber types is useful you cant select gloves based on fiber type alone. Most advanced protective materials are composite textiles and are made from multiple fiber types and combine other non-fiber materials.

Puncture and Cut Gloves Textile Options 

 Knits: The fastest growing textile for puncture and cut gloves is the knit. This is driven by automated glove knitting machines which allow us to manufacture the basic glove knit shell with low labor content.  Knits have some great advantages for gloves, jersey knit textile has 2 way stretch and stretch is a significant advantage for glove sizing, comfort and dexterity.  Like most things in life, knits and stretch come with a down side. The more open the knit and the more stretch the lower the protection will be for both cut and puncture.  Thin comfortable knits with stretch don’t have high fiber content per unit area. This fiber content per unit area is a simple idea for optimizing cut gloves.  the more of a given fiber type your have under the cutting edge the better the cut glove  performance will be.  With regard to puncture this is pretty clear, an open stretchy knit is not a very effective barrier to puncture.  Even large EN388 penetrators just push the knit fiber out of the way and slide right through the knit materials.  Smaller ASTM nail type penetrators and hypodermic needles penetrate knits with no resistance.

Wovens: Many puncture and cut gloves are sew from woven textiles,  however wovens don’t have much stretch so a glove made from all wovens has to be very carefully designed and sewn to fit well.  Wovens may not be as easy to use as knits but  they are standouts for cut and puncture performance. The weaving process can product a very dense textile like our TurtleSkin woven.   TurtleSkin  wovens have very high fiber density and deliver cut 5 performance in a very thin package.  Even better TurtleSkin weaves that have no sliding yarns so these weaves have high puncture resistance even to the smallest 28 gauge hypo needles. Puncture and Cut gloves made of TurtleSkin wovens preserve you tactile sense. You can really feel the shape of small object with these gloves because the wovens are so thin.

Coating-Knit-Woven Composites 

In the TurtleSkin line of Puncture and cut gloves we have found that the best marriage that is both comfortable and protective is to use a composite of both knits and wovens. We put the high protection wovens in the area where the risks are on the hand. Then in the areas that are not at risk  we use the stretch and openness of the knit to keep the glove comfortable.  This is an important concept in puncture and cut glove selection. Don’t over spec your protection area. If you ask for 100% protection when you don’t really need this much you will end up with a glove that is both more expensive and less comfortable. If you are not getting injuries on the back of the hand then don’t spec in high protection in this area.

The puncture and cut glove design process does not stop with the combination of multiple types of textiles, coatings play a large role. The mechanical strength for cut and puncture resistance is provided by the textile. Grip and abrasion resistance can be greatly improved with a well engineered coating. Soft polyurethane rubber coatings offer some of the best grip and wear performance around.  In addition to grip coatings provide an opportunity to improve cut and puncture resistance.  The coatings can include hard materials and can be engineered to increase the internal friction in the textile so the performance of puncture and cut gloves are improved. Just as in the case of the use of wovens, coatings reduce the stretch and dexterity in the glove so don’t over spec your coating area. Palm and finger tip coating is a great compromise. Full dipped puncture and cut gloves are not as comfortable as palm dipped gloves

Summary

  1. Knits are very important to comfortable puncture and cut gloves because of their stretch.
  2. Look for wovens for improved Cut and Puncture glove protection
  3. Look at the glove coating materials: Do they have enough grip and durability

 

© 2014 Warwick Mills Inc. All rights reserved.

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Filament LCP yarn ready for  blending in safety gloves

Safety Gloves: Cut & Puncture Resistant Fibers Explained

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A very common mistake in selecting safety gloves is picking the wrong fiber type.  As you see in each fiber type’s description below, the fibers used in safety gloves are not all created equal. When you are looking for protection and make purchasing decisions for safety gloves, consider the fiber and the coating.  The fiber is one just element of a safety glove’s construction.  After reading this post on fiber, I also suggest taking a look at a separate post on safety glove construction.  It details the glove’s textile construction and how the whole design of a safety glove works.  It is titled: “The  Puncture and Cut Resistant Textiles and Composites”

Polyester Safety Gloves

Polyester material is perhaps the most widely used synthetic fiber.  It is low in cost and available in many sizes and types.  It has moderate tensile strength and low cut performance, which limits the protection when is used alone.  Polyester yarn is available as a textured yarn.  In this form, it has quite good abrasion for its price point.  Polyester has broad chemical resistance.  However polyester is a moderate temperature fiber, with a burn and drip risk. This material is useful as a blending fiber for controlling the cost of a composite yarn.  Polyester, called PET for short, is used in most of the light weight, palm dipped safety gloves.

Nylon Safety Gloves

Nylon is the second most widely use synthetic fiber. Nylon has  moderate tensile strength and low cut.  Nylon has really standout abrasion resistance and this makes it very useful in safety gloves. The military has used nylon in combination with cotton for BDUs and other garments for many years.   Like polyester, nylon is an excellent choice for safety glove components. It is  slightly more expensive than polyester but higher in durability. Nylon has moderate temperature resistance and a burn and drip risk if used by itself. Nylon’s chemical resistance is lower than polyester. Like PET, nylon is used extensively in light weight palm dipped safety gloves.

Para-Aramid Safety Gloves

Ball-and-stick model of a single layer of the crystal structure

Para Aramid structure showing the carbon rings connected by nylon linkages

This is the old stand by Kevlar.  The same material, para-aramid also is available under  brand names  Twaron and Technora. Chemically all these fibers are aromatic nylon.  From the image above, notice the hexagonal carbon rings connected into long chains by nylon.  The aromatic carbon rings make these fiber strong. However para aramid yarn must have small filament size. Small filaments have poor abrasion and this  limits it performance for light knit safety gloves.  The high tensile strength with small filaments make this fiber a better puncture material than a cut product.  For cut level 4 and 5 gloves, we need high density knit fiber cover. These high cover knits are bulky and not very comfortable.  For the Para-Aramid TurtleSkin product, there is enough fiber density to provide both cut and puncture.  Cost is a consideration for Para-Aramid fiber as well these yarns are 5-8 times the cost of nylon or polyester. Many safety glove producers blend Para-Aramid with outer lower cost fibers to control cost.  The gloves become some what bulky above level 3 and these is more of an issue as the lower cut fibers are blended in for for cost control. One side benefit of the Para-aramids is they are high temp materials and have excellent flame performance. On the down side Para-Aramids have iffy chemical performance, acids and chlorine bleach are big trouble for these materials.  One last caution, because Para-Aramid fibers have low abrasion, safety gloves made from these fibers should have a coating or a cover glove. Ultra High Molecular Weight Polyethylene UHMWPE Safety Gloves

UHMWPE is a common fiber used in safety gloves

UHMPE is very strong and chemically resistant but does not tolerate high temperatures

UHMWPE (PE) is Spectra and Dyneema fiber significantly stronger than the Para-aramids. They are also small filament yarns with the exception of the new Dyneema Diamond fiber.  Good cut performance and excellent chemical resistance to most common compounds. On the down side these materials can only handle about 220F and start to fail at just slightly higher temperatures. Because PE is polyethylene it is very low friction. This makes PE a poor choice for puncture resistance.  In addition PE will burn and has a bad melt drip issue so all around not a good high temp material. Many users prefer PE knits to Para-Aramids knit gloves. The PE fiber is slippery and this appears to help a knit safety glove stretch and move to accommodate the users hand.  Many cut level 3-5 safety gloves are build of PE fiber. Like the Para-Aramids, UHMWPE bulk is an issue for designs of knit safety gloves, particularly above level 3. Liquid Crystal Polyester  Safety Gloves

 High end safety gloves are produced from LCP yarns

LCP yarn has high strength and large filaments resulting in excellent cut and abrasion.

The LCP or Vectran material has tensile strength between UHMWPE and Para-Aramid.  LCP is a large denier per filament fiber and has very good cut. Because LCP is Aromatic Polyester it is also a high temp fiber.  LCP fiber is resistant to most industrial chemistry and has some flame resistance. LCP is better all around in abrasion than either Para-Aramid or UHMWPE.  Bear in mid that abrasion and durability in safety gloves is a complex topic and this review is a summary.   The combination of large filament, tensile, chem resistance, high temp, and abrasion make Vectran a strong competitor. Great combination performance in cut and puncture applications. Given the higher cost of LCP, almost all safety gloves use this material blended with lower cost fiber.

Fiberglass in Safety Gloves 

Fiberglass is just glass, and as you would expect it is fragile.  Fiberglass does not do well in abrasion or in flex, the damaged surface of fiber glass yarn has sharp ends of broken filament exposed and this shape filament can cause skin irritation.  However fiberglass is very hard when compared to all the organic fibers we have talked about, fiber glass is harder than most cutting tools. The glass fiber breaks down the cutting edge of the threat and and gives good cut resistance.  Fiberglass yarn can help make a high performance safety glove. The fiberglass needs  a protective cover of one of the other fibers on the list to protect the more brittle glass fiber.   Not a surprise that fiberglass has great thermal resistance and will not burn safety gloves with ratings up to 2000f can be build with fiberglass yarn. Chemical resistance of fiberglass is uneven.

Stainless Steel in Safety Gloves 

Like fiberglass stainless steel fiber is a specialty item that is used in combination with one of the other fibers. This fiber has all the properties of steel, hardness, toughness and stiffness. Good thermal and chemical resistance, however as this material is used in a blend these properties are only as useful and the total performance of the blended yarn. To address the stiffness of steel these fibers a low denier per filament and this limits the performance to some degree. The exception is ring mail gloves that overcome the stiffness issue with a special welded fabrication process. Stainless is difficult to work with in textile constructions and this results in high costs for filament stainless yarn  or welded ring male materials.   © 2014 Warwick Mills Inc. All rights reserved.

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