Vibration-Reducing Gloves, What Can They Do?

Hand Arm Vibration (HAV) is a hidden danger that slowly degrades the health of the workforce.  Fortunately, there are many countermeasures that can be implemented to secure the health and productivity of the workforce.

Hand Arm Vibration Syndrome (HAVS) is caused by an over-exposure to vibrations, such as when using handheld power tools. Symptoms include nerve damage that reduces sensitivity and finger dexterity, bouts of vibration white finger (where fingers lose all feeling and turn white in cold temperatures), and muscle fatigue, potentially resulting in disability. Unlike many injuries like cuts, there is no well-defined time of injury, but rather gradual, accumulating, and irreversible damage.

Symptoms can take time to become apparent, but once evident there is no treatment to reverse the harm and quality of life impact for sufferers can be significant. The indirect and sneaky nature of how injuries are sustained is a major concern and contributes to the low awareness in the industry.

Gloves are very important to keep hands warm, protect from bruises, but also must be flexible enough not to increase strain. Vibration-reducing gloves introduce a whole new layer of complexity.

Vibration basics

The strength of vibrations is measured by acceleration. The “rate” or frequency is measured by Hertz (Hz), where 100 Hz corresponds to a motor frequency of 6,000 rpm.

Vibration exposure and risk assessments

Slow tools with an rpm of 1,800 RPM (30hz) will cause a resonance and hence land most of the energy in the wrist, lower palm, and forearm while faster tools of 12,000 RPM (200hz) cause more resonance and injures to the fingers. Despite that, different tools cause resonances in different parts of the hand-arm system and they must be compared to each other. This simplification of putting one relevant value of vibration strength is the ISO 5349 frequency weighted average acceleration. The ISO-weighted vibration acceleration value, despite its shortcomings, is a convenient tool for estimating risk to the workforce. An 8-hour day with exposure to 10m/s^2 is expected to cause blood circulation injures to 10% of the workforce after three years of working. To compensate for the simplifications of the ISO 5349 weighted acceleration, it is wise to expect a significantly faster injury rate for fast (15,000 RPM) or high-impact tools.

Who is at risk?

Employees are at risk if they regularly use hand-held or hand-guided power tools and machines such as chainsaws, brush cutters, and hedge trimmers.

Employees are at risk if they regularly use hand-held or hand-guided power tools and machines such as:

• Concrete breakers, concrete pokers
• Sanders, grinders, disc cutters
• Hammer drills
• Chipping hammers
• Chainsaws, brush cutters, hedge trimmers
• Powered mowers
• Scabblers or needle guns
• Powered lawn mowers and brush cutters

Workers are also at risk if they hold workpieces, which vibrate while being processed by powered machinery such as pedestal grinders.

Also, workers who regularly operate:

• Hammer-action tools for more than about 15 minutes per day; or
• Some rotary and other action tools for more than roughly one hour per day, as they are likely to be well above safe exposure.

What are the early signs and symptoms to look out for?

• Tingling and numbness in the fingers (which can cause sleep disturbance)
• Not being able to feel things with the fingers
• Loss of strength in hands (may be less able to pick up or hold heavy objects)
• In the cold and wet, the tips of fingers going white, then red and being painful on recovery (vibration white finger)

What can be done?

There is not one quick fix answer, but rather a full range of countermeasures that combined can significantly reduce the risk.

Assess the risk

It is important to identify the most exposed work tasks and the tools used (try to put an acceleration number to each task).

Reduce exposure time

Use work rotation to avoid prolonged exposure time to the most exposed job tasks.

Training of operators

The damage sustained can be reduced by a number of means, such as using a modest grip force, keeping fingertips firm on the handle, and applying a comfortable work posture.

Good tools & gloves

Well-serviced tools and preferably tools that are “low vibration” due to built-in balancing rings or counterweights help, too. Keep in mind that cutting tools should be kept sharp. Fast, high-frequency tools might have a lower stated ISO-weighted acceleration number but can be just as bad as slower tools with a higher ISO 5349 acceleration value. In the search for better machines, be sure to move to balanced tools, not just to shift to faster, higher frequency tools.

Gloves and vibration-reducing gloves

Hand Arm Vibration Syndrome (HAVS) is caused by an over-exposure to vibrations, such as when using handheld power tools.

Gloves are very important to keep hands warm and protect from bruises, but also must be flexible enough not to increase strain. Vibration-reducing gloves introduce a whole new layer of complexity. The gloves themselves introduce new resonance frequencies to the hand-glove-tool system. Simply said, vibration-reducing gloves can be dangerous in certain situations.

Yet, vibration-reducing gloves are very effective to remove transient and high frequency vibrations from impacting tools. However, for rotating tools, it gets difficult as you have to know what you are exposed to and what the gloves can protect from.

Luckily, there is a system of vibration-reducing gloves that is tailored to specific tools to avoid the dangers of misuse. The matching of task, tool, and glove can be done with different accuracy; the simplest way is to separate the impact vibration family of gloves for impacting and very fast tools above 15-20,000 RPM. Tools slower than this will require a different solution to avoid dangerous resonance to the fingers. It’s very important for the glove manufacturer to secure a uniform and consistent quality of the foam padding in order to deliver the promised protection at each frequency.

It is possible to improve dexterity and fingertip feeling while still being protected if you are working with impacting tools, such as rock drills or impact wrenches. During prolonged work with polishing or finishing with grinders where requirement for protection is high but dexterity is low, there are still solutions.

Multi-norm

It’s very important to keep hands warm, hence the necessity of winter vibration gloves for both fast and slow tools. Multi-norm vibration-reducing gloves are required when multiple risks are involved, such as cut hazards, high temperature, or fire.

Are vibration-reducing gloves worth a try?

Vibration-reducing gloves are expensive, and some types may also reduce finger dexterity and increase the required grip force, so you may ask yourself, “why bother?”

The simple answer is that in the medium term, improved health means higher productivity and less staff turnover. The use of vibration-reducing gloves is likely to increase the number of years that employees can work without getting vibration injuries. Plus, the cost of gloves is still very small to the cost of losing skilled operators, not to mention the human side of it too. CS

Markus Berger is the CEO of Eureka Safety, a division of Y.Berger & Co., a family-owned textile company based in Sweden. Eureka’s focus is on high-performance gloves for demanding work situations, primarily in the industrial sector (eurekasafety.se).