engineering

Hand arm vibrations

Hand arm vibrations is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hand arm vibrations rather than just read about it. In short: In occupational safety and health, hand arm vibrations (HAVs) are a specific type of occupational hazard which can lead to hand–arm vibration syndrome (HAVS). HAVS, also known as vibration white finger (VWF) or dead finger, is an industrial injury triggered by continuous use of vibrating hand-held machinery and constituting a secondary form of Raynaud's syndrome.

Key takeaways

Hand arm vibrations belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Hand arm vibrations to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Hand arm vibrations from memory before moving on to harder problems.

Reference excerpt

In occupational safety and health, hand arm vibrations (HAVs) are a specific type of occupational hazard which can lead to hand–arm vibration syndrome (HAVS). HAVS, also known as vibration white finger (VWF) or dead finger, is an industrial injury triggered by continuous use of vibrating hand-held machinery and constituting a secondary form of Raynaud's syndrome. Use of the term vibration white finger has generally been superseded in professional usage by the broader descriptor HAVS, although it is still used by the general public. The symptoms of vibration white finger are the vascular component of HAVS. Hand-arm vibration syndrome is a widespread recognized industrial disease affecting tens of thousands of workers. It is a disorder that affects the blood vessels, nerves, muscles, and joints of the hand, wrist, and arm. Its best known effect is vibration-induced white finger (VWF), a term introduced by the Industrial Injury Advisory Council in 1970. Injury can occur at frequencies between 5 and 2000 Hz but the greatest risk for fingers is between 50 and 300 Hz. The total risk exposure for hand and arm is calculated by the use of ISO 5349-1, which stipulates maximum damage between 8 and 16 Hz and a rapidly declining risk at higher frequencies. The ISO 5349-1 frequency risk assessment has been criticized as corresponding poorly to observational data; more recent research suggests that medium and high frequency vibrations also increase HAVS risk.

Hand-arm vibration syndrome Excessive exposure to hand arm vibrations can result in various patterns of diseases casually known as HAVS or VWF. This can affect nerves, joints, muscles, blood vessels or connective tissues of the hand and forearm:

Tingling 'whiteness' or numbness in the fingers (blood vessels and nerves affected): This may not be noticeable at the end of a working day, and in mild cases may affect only the tips of the fingers. As the condition becomes more severe, the whole finger down to the knuckles may become white. Feeling may also be lost. Fingers change colour (blood vessels affected): With continued exposure the person may experience periodic attacks in which the fingers change colour when exposed to the cold. Initially the fingers rapidly become pale and feeling is lost. This phase is followed by an intense red flush (sometimes preceded by a dusky bluish phase) signalling the return of blood circulation to the fingers and is usually accompanied by uncomfortable throbbing. Loss of manual dexterity (nerves and muscles affected): In more severe forms, attacks may occur frequently in cold weather, not only at work, but during leisure activities, such as gardening, car washing or even watching outdoor sports and may last up to an hour causing considerable pain and loss of manual dexterity and reduced grip strength. In extreme cases, the affected person may lose fingers. The effects are cumulative. When symptoms first appear, they may disappear after a short time. If exposure to vibration continues over months or years, the symptoms can worsen and become permanent. Exposure to hand arm vibrations is a respectively newer occupational hazard in the work place. While hand arm vibrations have been occurring ever since the first usage of the power tool, concern over damage due to HAVS has lagged behind its fellow hazards such as Noise and chemical hazards. While safety engineers worldwide are collaboratively working on instilling both an Exposure Action Value and an Exposure Limit Value similar to the occupational noise standards, the Occupational Safety and Health Administration, the only regulatory public safety administration in the United States, has yet to offer either official values in the U.S.

Occupations at risk Occupations at risk of Hand and Arm Vibration Syndrome (HAVs) includes Mining, Foundry, and highest exposure being within construction. One unexpected occupation that is associated with HAVs is dentistry. Dentistry is mainly associated with Musculoskeletal Disorder (MSD). Consequently, HAVs is also linked to this field's ergonomic health issues due to the frequent use of dentistry hand-piece tools. As reported by the Vibration Directive of European Legislation, real-time or one-time use of the dental tools does not surpass the exposure limit. However, a long history of frequent handling of these tools has later been associated with Dental workers experiencing HAVs with inclusion of outside factors, such as high Body Mass Index (BMI). While these workplace industries more prominently affect men in the working population, there are still a significant number of women who also experience HAVs. According to a study conducted in Sweden, about 2% of all women and 14% of all men utilize vibrating tools for work. Women are more likely to experience the symptoms for HAVs at a higher prevalence than men.

Suggested guidelines While OSHA has yet to supply these values, other countries agencies have. The Health and Safety Executive of the British Government suggests to use an Exposure Action Value of 2.5 m/s2 and an Exposure Limit Value of 5.0 m/s2. which is based on the EU directive from 2002. However, it has been shown that those exposure levels still are not safe as 10% of a population would get sensorineural injuries after 5 years at action level exposure. The Canadian Centre for Occupational Health and Safety promotes the ACGIH Threshold Limit Values shown by the adjacent table. When the time-weighted acceleration data exceeds these numbers for the duration, damage from HAVS begins. There have been additional recommendations based from National Institute for Occupational Safety and Health (NIOSH) to minimize exposure of vibrating tools. Workplaces and Physicians' offices should not only view HAVs as a serious condition but should also look into implementing change. These implementations include engineering control, medical surveillance, and Personal Protective Equipment (PPE) to mitigate vibration exposure. Another implication refers to administrative controls, an example being limiting the amount of hours/days a worker is using the vibrating tools. Furthermore, companies could provide adequate training to workers on the hazards and protocols of handling vibrating tools, along with supplying tools that generate the least amount of vibration while still completing the assignment.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Hand arm vibrations

Start with the simplest possible case. Write down what Hand arm vibrations claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hand arm vibrations before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hand arm vibrations ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hand arm vibrations

In research: Hand arm vibrations appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Hand arm vibrations in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Hand arm vibrations is common in secondary-school and first-year university syllabi. It links to neighbouring topics Overuse injuries, Safety engineering, so understanding it makes those chapters shorter.
In everyday life: Look for Hand arm vibrations outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Hand arm vibrations in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Hand arm vibrations means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Hand arm vibrations out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hand arm vibrations in simple terms?

Why does Hand arm vibrations matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hand arm vibrations?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hand arm vibrations.