Short Guide to Glove Cut Testing Methods

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Introduction:

Cut testing has 2 primary modes, knife edge only cutting and knife tip cutting. The standard evaluations for glove and safety gear use the knife edge only. The edge only cut data provides a good baseline for users on cut resistance. There is good agreement between the EN388, ANSI 105 an the NIJ cut criteria.  Users and glove specifiers should take note of the scalpel cut data for a better understanding of the actual resistance of the gloves and equipment in service. Real cut injuries generally include the knife tip.

ANSI/ISEA 105 Cut Level (ASTM F 1790-97 or -05)

The ANSI cut levels are based on the force required to cut through the protective material with a razor knife edge.

In this test the tip of the knife does not contact the material only the blade edge.

The most common cut testing method ASTM 1790-97 is based on a cutting distance for the knife of 25mm (1 inch). The force required to cut through the protective material in 25.4mm of knife travel is the test output.  

The levels are set as follows.

(25 mm of blade travel – ASTM F1790-97)
(20 mm of blade travel – ASTM F1790-05)
Level Grams force newtons lbf
1 ≥ 200 2.0 0.44
2 ≥ 500 4.9 1.10
3 ≥ 1000 9.8 2.20
4 ≥ 1500 14.7 3.30
5 ≥ 3500 34.3 7.71

Modified ASTM F 1342 Scalpel Cut Levels WMI

This Scalpel test is alternate to the straight knife cut tests.  This test measures the force required for the Scalpel blade to puncture and cut through the protective material.

Unlike the ANSI cut test the Scalpel test simulate cut events that involve the tip of sharp tools, sheet metal and glass shards.

The levels have been set to roughly correlate to the ASTM cut method, however because this is knife tip test there are differences in material performance.

The cutting force is measured on a compression testing machine with the sample held in a drum head clamp ring.

Level Grams force Newtons lbf
1 ≥ 75 0.7 0.17
2 ≥ 150 1.5 0.33
3 ≥ 300 2.9 0.66
4 ≥ 600 5.9 1.32
5 ≥ 1200 11.8 2.64

NIJ 99-114 cut rating (ASTM F 1790-97)

The NIJ  cut levels are based on the force required to cut through the protective material with a razor knife edge.

In this test the tip of the knife does not contact the material only the blade edge.

The most common cut testing method ASTM 1790-97 is used by NIJ for this rating. The test is based on a cutting distance for the knife of 25mm (1 inch). The force required to cut through the protective material in 25.4mm of knife travel is the output of this test.  

These levels are roughly the same as ANSI 105 levels 2, 3 and 4

The NIJ levels are set as follows.

Newtons Grams force lbf
Low < 5 509.9 1.12
Moderate ≥ 6 611.8 1.35
High ≥ 16 1631.5 3.59

EN388 Cut resistant levels Rotary Knife or ISO13997 Cut testing

The EN388 cut testing program has 2 tests. A test using a rotary knife machine that measure the rotations to cut through the sample. The calibration process for this machine make it unsuitable for some materials at the higher cut levels so a second test method ISO13997 is used. This is a straight razor knife force test. The ANSI 105 cut levels are similar at level 4 but are quite different for level 5. The ANSI 105 cut level 5 is a higher requirement.

Level Cut Index

(turns of knife)

EN388 rotary

ISO13997 testing

cut force Newtons

ISO13997

cut force grams

ISO13997

cut force lbf

1 >1.2
2 >2.5
3 >5
4 >10 13 1326 2.9
5 >20 22 2243 4.9
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Puncture and Cut Glove

Cut Glove Optimization: Knit Needs to Work with the Dip

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Knit Basics for Cut Gloves

Knit gloves are made on knitting machines with a limited range of needle density. Thick gloves made from large yarns are generally knit on machines of 8-10 gauge (8-10 needles per inch). These yarns are the same size you find in winter coats. The larger yarns require the larger needle spacing.  Many high cut level gloves  (level 4-5)  use these large yarns and 8-10 gauge knits. For finer and thinner knit gloves the most common knitting style is 13 needles per inch. The 13-gauge knits often use small yarns such as 210 denier nylon. This is about the size of the yarn you use in an oxford shirt. Larger yarns contain more fiber and offer more cut resistance for a cut glove.

Openness in Knit Fabric

The knitting machine gauge and the yarn size controls how open the glove textile will be. As an example,  for 13-gauge knits using our 210 denier yarn there is perhaps 30-40% open area in the textile. The % openness in the knit affects how the glove feels and how much stretch it will have. Most users would agree that more open knits result in cooler more comfortable and dexterous gloves.  The down side of more open knits is that it is much harder to create high level cut glove with small yarns with open space. (More on this in another post.)

The Knit Needs to Work with the Dip for Best Cut Glove Dexterity and Cut

Most users like the grip and durability that palm coated knit gloves offer.   Knit gloves with high levels of openness have an additional benefit for dipping and coating.  With high open area the dip coating can penetrate the textile and encapsulate the yarn on the palm of the glove.  The dip can by nitrile,  polyurethane or NR latex. When the dip can penetrate the knit the coating has the best possible attachment to the textile.  We all want our gloves to be durable and comfortable.  For comfortable gloves with good dexterity the coating and the knit must be thin, no more than 2-4mm in thickness total.  For this type of thin coating layer to be durable it must be well supported by the textile. The rubber in the coating does not have good tear strength. The yarn in the glove provides the reinforcement to prevent premature failure of the coating layer.  A special kind of glove coating uses dots or pads of coating that are thicker than a full dip layer. This dotted coating provides the option to increase the coating thickness and wear resistance without making a cut glove stiff.

For optimal cut glove design the knit density and the coating work together to give you good dexterity and good cut performance.

When the knit works with the dip you can build a thin comfortable durable cut glove.

© 2014 Warwick Mills Inc. All rights reserved.

 

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