Industrial Engineering

Term Project:Noise And Vibration

What Is Noise 

Any disagreeable or undesired sound.

 Sound-level

meters are used to measure the pressure variations producing audible sound.

 Practical

Unit :- DECIBEL (dB)

Frequency Levels  For  Ear

a Human Ear = 20 to 20,000 Hz.

is sensitive to very low or very high levels of sounds.

Equipment used for noise measurement



Sound level meter



Octave band analyser

Equipment used for noise measurement

•Magnetic tape recorder

•Noise average meter

Noise Law          

The noise control standard for factories is set at 75 dB for 32 hours 80 dB for 16 hours 85 dB for 8 hours 90 dB for 4 hours 95 dB for 2 hours 100 dB for 1 hour 105 dB for 0.5 hour 110 dB for 0.25 hour 115 dB for 0.125 hour of exposure It is recommended that workers be provided with protective equipment when they are exposed to more than 80 dB

Complexity of Decibel 1

machine  2 machines  3 machines  4 machines  5 machines  6 machines  10 machines

80 dB(a) 83 dB(a) 85 dB(a) 86 dB(a) 87 dB(a) 88 dB(a) 90 dB(a)

INDUSTRY SEWING ROOM NOISE CALCULATIONS TYPE OF MACHINES

Single Needle Lockstitch M/c Overlock Machine Buttonhole Machine Buttonhole Attachment Bar tack Machine Eyelet Machine Loop Making

No.

138 3 2 3 1 1 1

Noise Produced By

Noise Levels

Single Needle Lockstitch Machine

81

Overlock Machine:-

65

Buttonhole Machine:-

63

Buttonhole Attachment

63

Bar tack Machine

65

Eyelet Machine

60

Loop Making

60

TOTAL = 81 < Noise Level in a Sewing Room <84

INDUSTRY CUTTING ROOM NOISE CALCULATIONS  Band Knife Machines = 1 Noise Produced = 75  Straight Knife Cutting M/c = 4 Noise Produced = 81  Embroidery Machine = 1 Noise Produced by it = 75 Total = 81 < Noise Produced < 84

INDUSTRY ROOM NOISE CALCULATIONS Number of Ironing Tables with Suction = 8 Noise Produced By Each = 75 Total Noise Produced In the Finishing Room = 84

What Triggers Noise Problem  High

levels of Mechanization

 Increased  Density  Lack

machine speed

of machinery at the workplace

of Knowledge

Problems Caused by Noise  Impedes

Sound Communication by :-

- Masking effect which every sound has on the other of the same frequency or immediately higher frequency - Temporarily raising the threshold in the event of exposure to a noise exceeding 78-80 dB(A).

Harmful Effects of Noise DISEASES: Sensory-motor  metabolic disorders. INDUSTRIAL: Fatigue  Irritation  Reduced Productivity  Occupational Accidents

General Effects of Noise a. Disturbs

concentration, causes annoyance.

b. Interferes c.

with speech communication.

Causes noise induced hearing losses.

ADMINISTRATIVE CONTROL These are essentially short term controls which are aimed at protecting the workers overexposed to noise levels of about 90 decibels before the management can plan and implement long term solutions. “ Worker Rotation” is an effective administrative control which aims at management of work schedule in such a way so as to ensure that no worker is exposed to high noise levels beyond permissible limits.

Noise Control In Industrial Establishment ENGINEERING CONTROL

Protection of personnel

Isolation of personnel by total or partial enclosures

To control Noise levels 

Control at source, can be implemented by replacing noisy machines or equipment/ process by less noisiness, using dynamically balanced rotating parts, using resilient mounting pads, rubber parts in place of metallic ones.



Control of transmission by increasing distance of source from the background noise, segregation of noise source by brick walls etc.



Protection at receiver ensured through use of ear plugs made from glass fiber/ foam plastics etc.

VIBRATIONS

VIBRATION Vibration is a form of motion oscillation. It occurs in all forms of machinery and equipment.

Vibration is characterized by amount of energy measured in terms of acceleration (m/sec²) of oscillating particles. Vibration is an UNBALANCED FORCE, or system of forces. These unbalanced force may be due to mass unbalance,, or it may be due to the variable inertia forces in machinery, which does not move uniformly.

The objectionable results of machine vibrations, if left uncontrolled, can be several : •High stresses and force levels may be set up as a result of vibrations and in extreme cases may lead to part failure. • Such failure can be sudden or gradual, as in fatigue. More frequently, there is increased wear of parts and unsatisfactory equipment performance.

Exposure Of Human Body To Vibration :

Vibration

Segmental / part body vibration e.g.. Hand arm vibration

Whole body vibration

Hand-Arm Vibration (HAV) HAV is vibration transmitted from work processes into workers hands and arms. It can be caused by operating hand-held power tools. Regular exposure to HAV can cause a range of permanent injuries to hands and arms, collectively known as hand-arm vibration syndrome (HAVS). The injuries can include damage to : • • • • •

Blood circulatory system (e.g. vibration white finger); Sensory nerves Muscles Bones Joints

• Vibration-induced white finger (VWF) is the most common condition among the operators of hand-held vibrating tools. • Vibration can cause changes in tendons, muscles, bones and joints, and can affect the nervous system. Collectively, these effects are known as Hand-Arm Vibration Syndrome (HAVS). . Workers affected by HAVS commonly report symptoms such as: Attacks of whitening (blanching) of one or more fingers when exposed to cold Tingling and loss of sensation in the fingers Loss of light touch Pain and cold sensations between periodic white finger attacks Loss of grip strength Bone cysts in fingers and wrists

Whole Body Vibration (WBV) 

When a worker sits or stands on a vibrating floor or seat, the exposure affects almost the entire body and is called whole-body vibration exposure.



Energy enters the body through a seat or the floor, it affects the entire body or a number of organs in the body.



WBV is caused by machinery vibration passing through the buttocks of seated people or the feet of standing people.



The most widely reported WBV injury is back pain. Prolonged exposure can lead to considerable pain and time off work and may result in permanent injury and having to give up work.

Control of vibration methods: 

Control at source by balancing all revolving and rotating parts, reducing speed of moving parts, reducing number of impacts, damping the joints of moving parts, providing a resilient bumper at point of impact and regular maintenance of machine and tools etc.



Control of transmission by isolating vibrating machine from floors and walls, use of damped foundation, vibration absorbing materials in floor joints, damping handles etc.



Protection at receiver end by minimizing exposure duration/ providing rest breaks between periods of exposure etc.

Safe Work Practices 

Employ a minimum hand grip consistent with safe operation of the tool or process.



Wear sufficient clothing, including gloves, to keep warm.



Avoid continuous exposure by taking rest periods.



Rest the tool on the work piece whenever practical.



Refrain from using faulty tools.



Maintain properly sharpened cutting tools.



Consult a doctor at the first sign of vibration disease and ask about the possibility of changing to a job with less exposure.

To reduce vibration levels in machines:

1. Use of vibration-absorbing mountings, provide heavy foundations. 2. Reduce the effect of vibrations Use vibration-damping handles. The use of appropriate vibration-absorbing materials (in gloves, for example), good work practices, and education programs. 3. Control the period of exposure

Disease Caused By Vibration 

Raynaud's phenomenon is a disorder that affects the blood vessels in the fingers, toes, ears, and nose.



This disorder cause the blood vessels in the fingers and toes to narrow.



Raynaud's phenomenon can occur on its own, or it can be secondary to another condition such as scleroderma or lupus.



This phenomenon is triggered by exposure to cold or emotional stress. In general, attacks affect the fingers or toes but may affect the nose, lips, or ear lobes.

Threshold Limit values for exposure of hand to vibration in X,Y,Z Direction Total Daily Exposure Duration (hours)

Maximum value of frequency weighted acceleration (m/s2) in any direction

4 to less than 8 hours

4

2 to less than 4 hours

6

1 to less than 2 hours

8

less than 1hour

12