Cut Performance Levels and Testing

Know what the levels represent because the responsibility for testing products for specific end-user applications still rests with the end user.

• By Bill Bennett, Jeff Moreland
• Nov 01, 2011

Many safety and purchasing professionals question the level of cut protection they need and how the International Safety Equipment Association (ISEA) performance levels apply to their specific applications. During recent market research, customers identified better cut protection as their single most-frequent requirement.

Requests for cut protection include not only cut-resistant hand protection products, but also the accompanying education that will help keep workers safe and increase their ease and efficiency as they perform their jobs. Companies want their workers to have the right gloves and to know when and how to use them.

Cut Protection vs. Cut Resistance
Cut protection is the combination of influences that help to prevent a worker from suffering cut injuries. Material properties, such as cut resistance, tear strength, abrasion resistance, grip, and dexterity, fall beneath the umbrella of cut protection. Other factors unrelated to protective gloves and apparel also affect cut protection, including machine guarding, workplace set-up, working conditions, and worker training.

Cut resistance is defined as a material's ability to resist damage when challenged with a moving sharp-edged object. Because it can be measured using the Cut Protection Performance Test, or CPPT, cut resistance is often used to compare the safety of various products.

Cut Resistance Evaluation in Europe
In the European market, gloves are evaluated according to EN 388, the mandatory performance standard for all gloves as regulated by the CEN. During the evaluation process, the European test machine passes a blade back and forth across a material specimen, counting the number of cycles until the blade cuts all of the way through and makes electrical contact with the substrate. A cut index is calculated using data from the control fabric to compensate for the progressive dulling of the blade.

The European test method was developed by researchers at a French lab who were primarily concerned with cotton and wool fabrics, which makes the method generally unsuitable for highly cut-resistant products – the ones used in many of today's most hazardous industries. The blade used for testing these products is often worn dull after only one pass. In addition, the measured cut indices are hard to reproduce, and the resulting data are not very meaningful.

Cut Resistance Evaluation in the United States
In the United States, ASTM adopted an entirely different method, the CPPT, which has been approved for ASTM 1790-97 and 1790-05. ANSI-approved ISEA performance levels based on the results of this test method provide guidance in selecting cut-resistant safety apparel.

The CPPT provides data to differentiate the cut resistance of common materials by calculating the load required for a standard blade to slice through a protective material in a given distance. To conduct the test, a specimen of glove material is mounted on a cylindrical support and a standard blade moves across the material at a standardized speed until it cuts through, as measured by electrical contact with the substrate. Each blade is used only once and then discarded, so blade dulling cannot affect the test results.

A minimum of 15 cuts are made on each glove material specimen, with varying amounts of load used to press the blade onto the specimen. Data are plotted as load on the blade versus blade movement across the material until failure. Cut resistance is usually reported as the load on the blade in grams force that produces a cut-through in 20 or 25 mm of blade travel.

The charts below show the differences between the EN (Couptest) and the ASTM CPPT test method. The ASTM method is now required in Europe to evaluate highly cut-resistant materials.

EN (Couptest)
Blade Type: Circular Double Beveled
Blade Motion: Counter-Rotating
Blade Reuse: Blade used until dull
Blade Speed: Variable, 0-110 mm/s
Force on Blade: Constant, 500 gf (1 lbf, 5 N)
Cuts per Sample: 5
Cut Detection Method: Electrical Contact
Measured Property: Cycles to failure
Test Result: Calculated Cut Index (Unitless Ratio)

ASTM (CPPT)
Blade Type: Straight Double Beveled
Blade Motion: Slicing
Blade Reuse: New blade for each cut
Blade Speed: Variable, 0-14 mm/s
Force on Blade: Variable, 0-5000 gf (0-11 lbf, 0-50 N)
Cuts per Sample: 15
Cut Detection Method: Electrical Contact
Measured Property: Distance of blade travel
Test Result: Calculated Rating Force (grams-force or Newtons)

Please keep in mind that test results can be affected by a number of factors, including material construction, number of components, how the components are combined, fabric weight, thickness, quality, the “tester,” and other environmental issues.

ANSI-approved Performance Levels

As mentioned earlier, ISEA developed performance levels that are derived directly from the CPPT results as illustrated in the following chart. These levels help to provide guidance when selecting cut-resistant hand protection.

Level/Rating Force (gf)
0/ less than 200
1/ ≥ 200
2/ ≥ 500
3/ ≥ 1000
4/ ≥ 1500
5/ ≥ 3500

ISEA and ASTM both worked to develop this standard. ASTM defined the method. ISEA has specified the levels of performance based on results from ASTM 1790-97.

Below are examples of the types of materials that may fall within the various levels. Due to inherent variation as discussed above, the ANSI ratings provide only a general indication of the cut resistance of any protective material. These values also reflect laboratory measurements and may vary depending on the specific work environment, materials, sharpness of the blade or edge, and the force applied.

Level 0: Disposable Rubber
Level 1: Cotton, Leather, Light-Weight Synthetics
Level 2: Light-Weight Aramid or HPPE
Level 3: Heavy-Weight Aramid or HPPE
Level 4: Reinforced Products
Level 5: Heavy-Weight Reinforced Products

No matter what the level of cut resistance, most glove manufacturers do not recommend using cut-resistant gloves for protection against powered devices, especially those that exert rotational force, such as saws and drills. Gloves are usually tested for use with non-powered blades and tools only.

Other Considerations
Although any glove material will provide some level of cut resistance, finding the right glove often requires consideration of factors such as grip, abrasion and puncture resistance, size, and overall fit. Safety managers and purchasing personnel who consider only cut resistance when selecting hand protection products are missing part of the equation.

Abrasion resistance and durability are both important factors when choosing products that protect against cut. Most gloves are used for extended periods of time and should provide the same level of protection at the end of the shift as they do at the beginning.

Dexterity and comfort are essential in workplaces where workers handle small sharp objects or wear gloves for extended periods of time. A Frost & Sullivan survey showed 85 percent of respondents indicated comfort as the leading feature influencing their hand protection selection decision.

Individuals may require gloves that enhance their grip if they work with sharp-edged objects that pose a much greater threat when they are in motion. A secure grip combined with the proper level of cut resistance can significantly reduce the chance of cut injury by preventing slipping and slicing and providing the worker better control.

Summary
While the ISEA performance levels and general recommendations detailed above can help to provide guidance when selecting hand protection products, the responsibility for testing products for specific end-user applications still rests with the end user.

We can indicate, for example, that a medium-weight, uncoated Kevlar glove will typically have an ISEA cut rating of 3, but we cannot say the glove will provide the level of protection needed for the range of jobs on an automobile assembly line. Another Level 3 glove might be better suited to an application that requires the worker to have an oil grip.

As glove manufacturers, we know gloves. We do not know the details about every workplace. We therefore, must look to our customers to provide us the properties they need for hand protection products that will sufficiently protect their workers on the job.

This article originally appeared in the November 2011 issue of Occupational Health & Safety.