c ARISER Vol. 4 No. 2 (2008) 77-97 Engineering: Indu Arab Research Institute in Sciences & Engineering http://www.arabrise.org Online Publishing Group ISSN 1994-3253 Improvements in Product Quality and Productivity Through Pragmatic Analysis of Working Environment In Engineering Industries Dalgobind MAHTO and Anjani KUMAR Department of Production & Industrial Engineering, National Institute of Technology, Jamshedpur, INDIA [email protected]; anj [email protected]Received 15 April 2008; Accepted 10 May 2008 This paper presents a systematic structure and analytical approach required in today’s context, for the improvement in working environment with regard to safety. The focal point of study is to determine as to how the industries are responsive to customers and the proactive growth tactics of industries with im- plementation of Lean Manufacturing. The framework incorporates a detailed assessment of the level of manufacturing environment disorder and the impact of this turbulence on the enterprise. The results of this assessment may be used to identify and customize an implementation plan as well as in selecting the required lean tools to make an organization to transform into a world-class enterprise. Keywords: Working Environment, Productivity, Safety, Accidents, Safe Practices. Contents 1 Introduction ................. 77 1.1 Cost and system effectiveness .... 78 2 Objectives of the present study ....... 79 3 Literature Review .............. 79 4 Methodology .............. 81 4.1 Activities related to study and analysis 81 5 Machinery and Non Machinery Accidents and Available Past Records ......... 82 6 Observations and Analysis ......... 85 7 Application of Lean Manufacturing tools and techniques ................ 87 8 Design of Safety Features and Safety Measures 88 9 Simulation of the Maintenance department . 93 10 Productivity Improvement due to Improve- ment in Working Environment ..... 94 11 Conclusions ................. 96 1 Introduction Productivity and safety are two faces of a coin and to a large extent inter – dependent. Safety is the ability of an item not to cause injury to persons, nor significant material damage or other unacceptable consequences during its use. Safety is important in maintaining peak efficiency. Every accident causes damage to one or more of the elements of production namely Men, Machines, Materials, Capital, Power and Time. Interference with any one of the above means of production causes loss to both, the labour and the industry. Loss to labour is in terms of their wages. Loss to the industry is in terms of cost of compensation, the medical costs, costs of interruptions and other such losses, etc. The opportunity loss due to accident is multifold and its impact is experienced later. The reduction of such costs is an important incentive to industries and if properly followed up, it will certainly return the dividend in terms of improvement in its product quality and productivity {Galliker [11]}. Therefore, Safety evaluation must consider the following two aspects. – Safety, when the item functions and is operated correctly, and – Safety, when the item or part of it has failed. The first aspect deals with accident prevention for which many national and international regulations exist. The second aspect is the technical safety, which is investigated using many tools in order to safe guard from losses of any nature. The latest published data on major causes of accidents in registered factories in India shows that machinery including prime movers is the highest causative factor as compared to others {Govt. [24]}. Almost 3 out of 10 accidents reported in Indian factories are caused by machinery and almost 2.5 out of 10 accidents are caused by the enclosed tools, fixtures etc. The rates of incidence of machinery accidents are quite high when compared to
Arab Research Institute in Sciences & Engineeringhttp://www.arabrise.org
Online Publishing Group ISSN 1994-3253
Improvements in Product Quality and Productivity Through PragmaticAnalysis of Working Environment In Engineering Industries
Dalgobind MAHTO and Anjani KUMAR
Department of Production & Industrial Engineering, National Institute of Technology, Jamshedpur, [email protected]; anj [email protected]
Received 15 April 2008; Accepted 10 May 2008
This paper presents a systematic structure and analytical approach required in today’s context, for theimprovement in working environment with regard to safety. The focal point of study is to determine asto how the industries are responsive to customers and the proactive growth tactics of industries with im-plementation of Lean Manufacturing. The framework incorporates a detailed assessment of the level ofmanufacturing environment disorder and the impact of this turbulence on the enterprise. The results ofthis assessment may be used to identify and customize an implementation plan as well as in selecting therequired lean tools to make an organization to transform into a world-class enterprise.
Keywords: Working Environment, Productivity, Safety, Accidents, Safe Practices.
1.1 Cost and system effectiveness . . . . 782 Objectives of the present study . . . . . . . 793 Literature Review . . . . . . . . . . . . . . 794 Methodology . . . . . . . . . . . . . . 81
4.1 Activities related to study and analysis 815 Machinery and Non Machinery Accidents
and Available Past Records . . . . . . . . . 82
6 Observations and Analysis . . . . . . . . . 857 Application of Lean Manufacturing tools
and techniques . . . . . . . . . . . . . . . . 878 Design of Safety Features and Safety Measures 889 Simulation of the Maintenance department . 9310 Productivity Improvement due to Improve-
ment in Working Environment . . . . . 9411 Conclusions . . . . . . . . . . . . . . . . . 96
1 Introduction
Productivity and safety are two faces of a coin and to a large extent inter – dependent. Safety is the ability of anitem not to cause injury to persons, nor significant material damage or other unacceptable consequences duringits use. Safety is important in maintaining peak efficiency. Every accident causes damage to one or more of theelements of production namely Men, Machines, Materials, Capital, Power and Time. Interference with any one ofthe above means of production causes loss to both, the labour and the industry. Loss to labour is in terms of theirwages. Loss to the industry is in terms of cost of compensation, the medical costs, costs of interruptions and othersuch losses, etc. The opportunity loss due to accident is multifold and its impact is experienced later. The reductionof such costs is an important incentive to industries and if properly followed up, it will certainly return the dividendin terms of improvement in its product quality and productivity {Galliker [11]}.
Therefore, Safety evaluation must consider the following two aspects.
– Safety, when the item functions and is operated correctly, and– Safety, when the item or part of it has failed.
The first aspect deals with accident prevention for which many national and international regulations exist. Thesecond aspect is the technical safety, which is investigated using many tools in order to safe guard from lossesof any nature. The latest published data on major causes of accidents in registered factories in India shows thatmachinery including prime movers is the highest causative factor as compared to others {Govt. [24]}. Almost 3 outof 10 accidents reported in Indian factories are caused by machinery and almost 2.5 out of 10 accidents are causedby the enclosed tools, fixtures etc. The rates of incidence of machinery accidents are quite high when compared to
78 D. Mahto & A. Kumar
the % of accidents caused by machinery to industrially advanced countries. Further, accidents caused by machineryconstitutes as much as 11.19 % of the total machinery accidents in registered factories in India {Govt. [24]}. Thepublished data {Govt. [24]} on major causes and accidents caused by machinery have been presented in Fig.1 andTab. 1.
1.1 Cost and system effectiveness
Cost effectiveness is a measure of the ability of an item to meet a service demand of stated quantitative characteris-tics with the best usefulness of life cycle cost ratio. It has been proved that safety and productivity are interrelatedto the maximum extent. According to {Dorman [1]} the system effectiveness has two broad categories namely,Life cycle Cost and Operational Effectiveness. The operational effectiveness is further classified into capability,operational availability and Safety. The safety aspect deals with injury to persons, damage to property and damageto environment. Similarly, the operational effectiveness also deals with human factors and maintainability.Cost effective quality and productivity can be achieved, if every employee involved in the industries are maderesponsible for maintaining working environment congenial. 1
Major Causes of Accidents
Stepping On / Striking Against
Objects9.57%
Hand Tools7.30%
Material Handling10.92%
Falling Bodies11.22%
Machining34.28%
All Others26.71%
Machining Falling BodiesMaterial Handling Stepping On / Striking Against ObjectsHand Tools All Others
Table 1 Distribution of accidents to types of machinery in India
Sl No Types of Machinery % of Total Machinery Accidents
01
Machinery moved by power
a) Metal working 11.19
b) Wood working 06.48
c) Transmission Machinery 06.08
d) Prime movers 02.03
e) Lifting Machinery 01.83
f) All other Machinery 69.81
02 Machinery not moved by power 02.58 Total 100.00
Table 2 Manpower present per day (on an average) in each units under study during April 2002 to May 2007
FIG. 1: Distributions of accidents in Indian factories by major causes.
Tab. 1: Distribution of accidents to types of machinery in India.
1
Table 1 Distribution of accidents to types of machinery in India
Sl No Types of Machinery % of Total Machinery Accidents
01
Machinery moved by power
a) Metal working 11.19
b) Wood working 06.48
c) Transmission Machinery 06.08
d) Prime movers 02.03
e) Lifting Machinery 01.83
f) All other Machinery 69.81
02 Machinery not moved by power 02.58 Total 100.00
Improvements in Product Quality and Productivity Through Pragmatic. . . 79
2 Objectives of the present study
The main objectives of the present study are:
1. To determine the causes of common accidents, which occur to metal working machineries and in the processof fabrication work.
2. To make an appraisal of the safety features in the machines, jigs, fixtures and tooling as provided by manufac-turers and users.
3. To find out and suggest the preventive measures required for control of accidents in the use of these machines,jigs, fixtures and tooling.
4. To conserve and ensure availability of machineries and resources for making the best use of manpower skillsto achieve highest productivity at a minimum cost.
5. To test the relationship of working environment with product quality and productivity, statistically.6. To convince the industries and industrial masses about the importance of safety in terms of productivity gains.
3 Literature Review
An investigation of past work has been done on the Linkage of Working Environment with Product Quality andProductivity. The survey of literatures gives an insight into the available publications on the subject. The selectionof literatures mainly focuses on recent publications and references that highlight the key issues. According to{Dorman [1]}, the available literatures on the subject can be separated into three groups.
– Firstly, a limited number of references are dealing with related management issues.– Secondly, a selection of references that give evidence on the link between a good working environment, product
quality and productivity.– Thirdly, a more elaborate overview is given of references that present models on how the costs and benefits of
Overall Safety and Health (OSH) can be measured
According to {European Centre [2]} for Total Quality Management, and the management of health andsafety, many forward-looking companies are adopting strategies to achieve ‘business excellence’ and ‘world-classperformance’, through the use of total quality management (TQM) with an integrated approach to business man-agement inclusive of health and safety management. Their studies concluded that health and safety managementis lagging behind other facets of the business on the road to quality, greater integration will be encouraged bya more informed and improved application of process management and performance measurement skills to themanagement of health and safety.
– {Goetzel [3]} has introduced a method called ‘Health productivity management’. It aims to establish linksbetween today’s business climate, people, operational challenges, and ultimately the productivity of an orga-nization.
The survey by {Smallman & John [4]} of employers revealed, for instance, the following statements:
– The majority of large and medium-sized firms report that they are trying to reduce the cost of employer liability.Only minorities of small firms state this view.
– There is a clear association between company size and the perceived link between their health and safetyperformance and the cost of employer liability.
The authors {Vassie & Lucas [5]} and {Mansikka [6]} concluded that it seems likely that the ‘high ground’ inOSH lies in thinking about moving beyond monetary values or indeed corporate reputation. The target, it seems,is to bind OSH in with business excellence within which OSH is a performance determinant rather than an end initself. {The American Society of Safety Engineers (ASSE) [7]} has produced a White Paper addressing the returnon investment for safety, health, and environmental management programmes.{Petersen [8]} revealed that personnel’s high work ability, work satisfaction and organizational commitment
had a positive relationship to workplace success. Variables describing personnel well-being had a similar effecton success in metal industry and retail trade, and also in workplaces of different sizes. Some statistical significantinteractions were found between variables of personnel’s well being. Staff well-being seems to be one factoraffecting company performance. According to {Bunn et al. [9]}, the health and productivity management model
80 D. Mahto & A. Kumar
at the International Truck and Engine Corporation includes the measurement, analysis, and management of theindividual component programmes affecting employee safety, health, and productivity. The economic impact hasbeen documented following intervention.{Cooper et al. [10]} assessed the costs and benefits to organizations of stress prevention in the workplace.
They presented three case studies; first in Sweden, second in the Netherlands and the third in United Kingdom andfound that stress prevention presents a means whereby an organization cannot only reduce or contain the costs ofemployee health but can also positively maintain and improve organizational health and productivity.{Galliker [11]} states that improving the well-being of its workers, offers a company the opportunity to enhance
its performance. {Hendrick [12]}, states that it is important to identify the costs and economic benefits that canbe expected from ergonomic programmes and to outline how they will be measured. He determines four majorclasses of costs: personnel, equipment and materials, reduced productivity or sales and overheads. If followedthese characteristics greatly enhance the likelihood of a high cost-benefit result. The documented cases resulted inbenefits such as less sick leave, fewer injuries, greater employee satisfaction, higher productivity, and so forth.{Kuusela et al. [13]}, Studies on the inter-relationship between the working environment and product quality
and productivity have revealed a positive correlation between the two. {Kupi et al. [14]} studies are based oneconomic evaluations. It is recommended by him that product quality and productivity are affected if the workingenvironment is not safe.
According to {Levy & Sarnat [15]}, occupational safety and health contributes to corporate goals. Pelletierreviewed mostly on studies of clinical-effectiveness and cost-effectiveness of comprehensive health promotion anddisease prevention programmes at the worksites.{Seeley & Marklin [16]}, have formulated an analysis tool that took into account medical injury and illness
statistics, workers’ compensation, worker replacement and retraining costs.{Serxner et al. [17]}, examined the impact of a worksite health promotion programme on short-term disability
days in a large telecommunications company. The evaluation used a quasi- experimental, multiple time-seriesdesign with inter-group comparison of workdays lost due to short-time disability to determine impact. This studyfound that participation in a health promotion programme had a significant impact on average net days lost foremployee short- term disability absence.
The case studies by {Ministry of Social Welfare, Finland [18]}, describe positive effects such as decreasedphysical and mental stress, increased motivation and improved productivity. The literature provides a wide rangeof methods that can be used to demonstrate the link between a good working environment, quality and productivity.These methods can be divided into three categories:
– Methods calculating the costs of accidents;– Methods analyzing the costs and benefits or effects of OSH interventions;– Methods focusing on the performance of the safety and health system.
{The Aarhus School of Business (Denmark) [19]} developed a systematic accident costs analysis (SACA)method. {Kuchler & Golan [20]} have developed several methods based on the principles of the cost-benefitanalysis or the cost-effectiveness analysis.
According to {Mossink & Greef [21]} in 1991–92 there were 136 accidents per 1000 employees. This haddecreased to 53 accidents per 1000 employees by 1995–96. Using the industry-wide representative cost for anaccident, South West Water calculated that it had saved GBP 2546000 through its accident prevention measuresover the period April 1992 to March 1998.
Work is essentially an economic activity. Companies are established in order to manufacture products or pro-vide services for the market. Every company tries to do this in the most efficient way and to improve its per-formance. The approach takes financial factors, but also customer, internal business and innovation and learningperspectives into a full and ‘balanced’ account {Kaplan & Norton [22]}.
Quality reflects the desire, not just to defend minimum standards, but also to promote rising standards andensure a more equitable sharing of progress. It delivers results embracing the economy, the workplace, the homeand society at large. It links the dual goals of competitiveness and cohesion in a sustainable way, with clear eco-nomic benefits flowing from investing in people and strong, supportive, social systems. These findings have beenpresented in several publications of {European Agency [23]}.
Some of the other most important findings are from the reviews like Statistical Pocket Book of India; {Govt.of India [24]}, {Hand book of Systems and product safety [25]}, {Grouping of accidents as Human and Envi-ronmental [26]}, {Identification of Factors for occurrence of industrial Accidents [25,26]}, {Occupational health
Improvements in Product Quality and Productivity Through Pragmatic. . . 81
[25,27]}, {Psychological causes of accidents [25]}, {Physiological factors [25,26,27]}, {The concept of socio –technical approach to job design [28]}, and {Human Engineering [26]}. Their concluding remarks are in supportof improvement in working environment to get higher productivity and quality product.
4 Methodology
The study has been carried out in a group of six units of a manufacturing industry, located in Adityapur, (Jamshed-pur), India. The study and analysis were made considering 114 machine tools of various types /makes.The types of machine tools studied consist of all types of machine tools namely, General Purpose Machine tools,Single Purpose Machine tools, Special Purpose Machine tools and CNC Machine tools.
The General Purpose Machine tools (here in after GPM) are those are designed to perform a great variety ofwork pieces by using number of attachments. Examples of this type of machine tools are Engine Lathe, UniversalRadial drilling machine, Universal Milling Machine etc.
On the contrary, Single purpose machine tools (here in after SPM) are those machine tools, which are designedto perform a single definite machining operation in machining number of identical work pieces. Examples of thistype of machine tools are for turning the cam counters on camshafts, finishing operation of riffle barrel etc.
Special Purpose Machine tools and CNC Machine tools (here in after CNC) are manufactured individuallyand intended for performing a certain specified operations in machining a large number of identical work pieces.Applications of these machines are in large lots and mass production.
All the 114 machines were closely examined and thoroughly studied with respect to their design, operation andmaintenance status.
The said six units under study covered around 400 employees, with a recorded absenteeism of an average rateof 9.65%. Tab.2 shows the Manpower preset per day (on an average) in each unit under study during April 2002 toMay 2007.
Tab. 2: Manpower present per day (on an average) in each units under study during April 2002 to May 2007
2
Table 2 Manpower present per day (on an average) in each units under study during April 2002 to May 2007
Total 35 30 29 22 34 24 15 20 11 13 124 109 Summary All Total 233 MA % 53.22 NMA % 46.78
4.1 Activities related to study and analysis
The detail outlines of the activities related to our study and analysis are given bellow.
– The brief overview and salient information are being gathered at the General Manager levels of each unit andsampling plan was discussed in consultation with the unit in-charge and other associates of the concerned area.
– After Sampling of the plant facilities, the basic principles of the process were studied and the value streammapping was done.
– Then, records related to accidents containing reported first hand information were examined. This exercise wasnecessary in order to understand and compare the past and current levels of plant status, so that proper leantools could be suggested in the present situation to avoid accidents. The main aim was to understand drivingforces behind the decision to go for lean.
82 D. Mahto & A. Kumar
– It has been observed during the study and analysis that maintenance department is the worst resourced areaand there is no adequate manpower available to manage the machines. Quite often the machines have to waitfor repairs for long time, resulting to the loss of production. Only two persons were deployed for the repairand maintenance. A simulation model has been developed to assess the actual requirement of the manpowerfor the purpose of repair and maintenance.
The maintenance department needs further special and immediate attention as witnessed by the analysis of pastrecords. A team was formed to examine the machine conditions and to do area demarcations within 5-S principlesand basic TPM like lubrication, tightening and cleaning.
– The Lean Manufacturing tools and techniques were also introduced in the Machine shop.– The detail study and analysis were brought into the open session for discussion with the employees, so that
any new idea may come up and secondly, all the employees may know as to how to implement the lean tools.This had also helped in giving a message to them that the area, which was not selected during sampling, alsorequires improvement like others.
5 Machinery and Non Machinery Accidents and Available Past Records
The data of accidents were collected for a long span of period of five years, from April 2002 to March 2007. Therewere 124 cases of accidents reported during this period. The records of 124 sample accidents were examinedcarefully. For the analysis, the accidents were classified broadly into two types namely Machine Related Accidents(MA) and Non Machine Related Accidents (NMA). Tab. 3 presents year wise total number of Machine RelatedAccidents (MA) and None Machine Related Accidents (NMA) during April 2002 to May 2007 in the units coveredin our study.
Tab. 3: Year wise total number of Machine Related Accidents (MA) and None Machine Related Accidents (NMA) duringApril 2002 to March 2007 in the units covered in the study
2
Table 2 Manpower present per day (on an average) in each units under study during April 2002 to May 2007
Total 35 30 29 22 34 24 15 20 11 13 124 109 Summary All Total 233 MA % 53.22 NMA % 46.78
Number of accidents to different categories of machine tools for the period April 2002 to March 2007 has beenpresented in Tab. 4. More past record data are presented in Tab.5 through Tab. 11.
Tab. 4: Number of accidents to different categories of machine tools for the period April 2002 to March 2007
3
Table 4 Number of accidents to different categories of machine tools for the period April 2002 to March 2007
Sl No Categories of
Machineries No of Machines
Covered No of
Accidents No of Accidents
Per Machine 1 General Purpose 46 68 1.48 2 Single Purpose 34 32 0.94 3 Special Purpose 34 24 0.71
Total 114 124 1.09
Table 5 Distribution of non-machinery accidents and its cause and nature of occurrence
It can be seen in Table 6 that for the present analysis 29.03 % of the accidents occurred at the time of feeding, holding or maneuvering job during machining operation, whereas 19.35% of the accidents occurred while unloading the blank.
Improvements in Product Quality and Productivity Through Pragmatic. . . 83
.Tab. 5: Distribution of non-machinery accidents and its cause and nature of occurrence
3
Table 4 Number of accidents to different categories of machine tools for the period April 2002 to March 2007
Sl No Categories of
Machineries No of Machines
Covered No of
Accidents No of Accidents
Per Machine 1 General Purpose 46 68 1.48 2 Single Purpose 34 32 0.94 3 Special Purpose 34 24 0.71
Total 114 124 1.09
Table 5 Distribution of non-machinery accidents and its cause and nature of occurrence
It can be seen in Table 6 that for the present analysis 29.03 % of the accidents occurred at the time of feeding, holding or maneuvering job during machining operation, whereas 19.35% of the accidents occurred while unloading the blank.
It can be seen in Tab. 6 that for the present analysis 29.03 % of the accidents occurred at the time of feed-ing, holding or maneuvering job during machining operation, whereas 19.35% of the accidents occurred whileunloading the blank.
Tab. 6: Detail of accidents and their occurrence
4
Table 6 Detail of accidents and their occurrence
No of accidents Sl. No Phase of Operation or Activity during which the Accident had occurred GPM SPM CNC
Total %
1 Setting adjusting tools, dies etc 15 9 5 29 23.39 2 Feeding / holding / maneuvering job at point
of Operation / feeding device 23 6 7 36 29.03
3 Removing job / scrap from point of Operation 13 5 6 24 19.35 4 Incidental to feeding or removing job / scrap 9 5 4 18 14.52 5 Maintenance 8 7 2 17 13.71
Total 68 32 24 124 100.00% 54.84 25.81 19.35 100
Table 7 Types of accidents occurred
No of accidents Total % Sl No Types of Accidents Occurred
GPM SPM CNC
1 Trapped between tools and job or tool and dies etc 15 6 5 26 20.97
2 Struck by / striking against job or die (including their fall) 19 10 8 37 29.84
3 Struck by/ Trapped at feeding devices or aids 9 5 2 16 12.90
4 Struck by Hand tools excluding feeding aids 7 3 2 12 9.68
5 Hit by flying particle from the machine 2 1 1 4 3.23 6 Hit by broken / detached machine parts 6 2 1 9 7.26
7 Striking against machine frame, guards, job stack, etc including their fall 7 5 4 16 12.90
8 Contact with / Trapped at power transmission mechanism of the machine 3 1 4 3.23
Total 68 32 24 124 100.00 It would be seen from Table 9 that out of 24 cases GPM, SPM and CNC have 14, 9 and 1 serious accidents.
Tab. 7: Types of accidents occurred
4
Table 6 Detail of accidents and their occurrence
No of accidents Sl. No Phase of Operation or Activity during which the Accident had occurred GPM SPM CNC
Total %
1 Setting adjusting tools, dies etc 15 9 5 29 23.39 2 Feeding / holding / maneuvering job at point
of Operation / feeding device 23 6 7 36 29.03
3 Removing job / scrap from point of Operation 13 5 6 24 19.35 4 Incidental to feeding or removing job / scrap 9 5 4 18 14.52 5 Maintenance 8 7 2 17 13.71
Total 68 32 24 124 100.00% 54.84 25.81 19.35 100
Table 7 Types of accidents occurred
No of accidents Total % Sl No Types of Accidents Occurred
GPM SPM CNC
1 Trapped between tools and job or tool and dies etc 15 6 5 26 20.97
2 Struck by / striking against job or die (including their fall) 19 10 8 37 29.84
3 Struck by/ Trapped at feeding devices or aids 9 5 2 16 12.90
4 Struck by Hand tools excluding feeding aids 7 3 2 12 9.68
5 Hit by flying particle from the machine 2 1 1 4 3.23 6 Hit by broken / detached machine parts 6 2 1 9 7.26
7 Striking against machine frame, guards, job stack, etc including their fall 7 5 4 16 12.90
8 Contact with / Trapped at power transmission mechanism of the machine 3 1 4 3.23
Total 68 32 24 124 100.00 It would be seen from Table 9 that out of 24 cases GPM, SPM and CNC have 14, 9 and 1 serious accidents.
It would be seen from Tab. 9 that out of 24 cases GPM, SPM and CNC have 14, 9 and 1 serious accidents.
84 D. Mahto & A. Kumar
Tab. 8: Severity of accidents causing injury, and loss
5
Table 8 Severity of accidents causing injury, and loss
Sl No
Categories of machineries
No of machines covered
No of accidents
Severity of accident causing injury and loss
Total Average Maximum in a single case
1 GPM 46 68 272.0 4.0 36
2 SPM 34 32 176.0 5.5 57
3 CNC 34 24 76.8 3.2 70
Total 114 124 524.8 4.2 70
Table 9 Detail of severe injury to operators due to accidents and their loss
Severity of injury / No of man days lost
Sl No
Types of
machine
No of serious accidents cases
Total Average Maximum in a single case
01 GPM
14 112 08 36
02 SPM
9 117 13 57
03 CNC
1 70 70 70
Total
24 299 12.45 70
Figure 2 presents in graphical form the predominant causes of accidents, whether it is caused by unsafe actions or unsafe conditions. It is clear from Fig.2 that 69.16 % of the accidents were caused due to unsafe conditions, and the remaining 30.84 % being caused by unsafe actions of persons. Analysis of Unsafe Actions 30.84 % would be seen at Table 10. It would be seen that improper maneuvering of hand tools, die, job etc accounted for a loss of 33.33% of total man-days lost.
Tab. 9: Detail of severe injury to operators due to accidents and their loss
5
Table 8 Severity of accidents causing injury, and loss
Sl No
Categories of machineries
No of machines covered
No of accidents
Severity of accident causing injury and loss
Total Average Maximum in a single case
1 GPM 46 68 272.0 4.0 36
2 SPM 34 32 176.0 5.5 57
3 CNC 34 24 76.8 3.2 70
Total 114 124 524.8 4.2 70
Table 9 Detail of severe injury to operators due to accidents and their loss
Severity of injury / No of man days lost
Sl No
Types of
machine
No of serious accidents cases
Total Average Maximum in a single case
01 GPM
14 112 08 36
02 SPM
9 117 13 57
03 CNC
1 70 70 70
Total
24 299 12.45 70
Figure 2 presents in graphical form the predominant causes of accidents, whether it is caused by unsafe actions or unsafe conditions. It is clear from Fig.2 that 69.16 % of the accidents were caused due to unsafe conditions, and the remaining 30.84 % being caused by unsafe actions of persons. Analysis of Unsafe Actions 30.84 % would be seen at Table 10. It would be seen that improper maneuvering of hand tools, die, job etc accounted for a loss of 33.33% of total man-days lost.
Fig. 2 presents in graphical form the predominant causes of accidents, whether it is caused by unsafe actionsor unsafe conditions. It is clear from Fig. 2 that 69.16 % of the accidents were caused due to unsafe conditions,and the remaining 30.84 % being caused by unsafe actions of persons. Analysis of Unsafe Actions 30.84 % wouldbe seen at Tab. 10. It would be seen that improper maneuvering of hand tools, die, job etc accounted for a loss of33.33% of total man-days lost.
4 Non coordinated stroke initiation of actuating of operating control
1 2 3 9.09
5 Non adherence to process sequence as suggested in the in house process
2 2 6.06
6 Negligence 1 1 2 6.06 Total 18 14 1 33 100.00
% 54.55 42.42 3.03 100.00
Table 11 Types of unsafe conditions
Types of machine Sl. No
Types of Unsafe conditions GPM SPM CNC
Total %
1 Unguarded point of operation 12 9 21 28.38
2 Inadequately guarded point of operation 3 3 6 8.11
3 Unguarded pedal / unsafe design of operating control
2 1 3 4.05
4 Defective tool, die, other machine parts etc
5 1 6 8.11
5 Hazardous work arrangements at / around the machine
7 6 2 15 20.27
6 Non provision of proper hand tools, gloves etc
9 8 17 22.97
7 Improper layout 2 4 6 6.78
Total 40 32 2 74 100
6 Observations and Analysis
Safety in use and operation of machine tool depend mainly on design and maintenance of operating control system,i.e. example guards, feeding arrangement, loading and unloading of blanks, physical and environmental conditionsat and around the machine. The knowledge and adequate expertise is also the sole criteria for safety in CNCmachine tool.
The present status of some selected machine tools has been observed for six months (Tabulated in Tab. 12through Tab. 16) before implementation of the lean tools. It was done to assess and find the possible linkages, ifany, with past incidences.
Tab. 12: Analysis of safety features of operating control mechanisms
7
Table12 Analysis of safety features of operating control mechanisms
Safe design Unsafe design Sl
no Push button/ foot / automatic / switch lever/ handle etc type
No of safety
features
% No of safety
features
% Total Machine
investing-
ated in %
01 GPM
60 82.19 10 40.00 70 57.38
02 SPM
50 72.46 12 57.14 62 59.62
03 CNC
10 40.00 03 100 03 46.42
Total 120 - 25 - 145 % 82.76 - 17.24 - 100.00
Table 13 Analysis of safety features of cover guards and fixtures
7 Application of Lean Manufacturing tools and techniques
From the analysis of working environment it is evident that immediate attention is required to reduce or eliminatethe causes of accidents with suitable tools and techniques. Though many tools and techniques are available, leantools in today’s context come handy with scientific approach. As a result the tools like 5-S, TPM, OEE, KAIZENand FMEA were suggested to take up on need basis.
The detail action plan was undertaken as per the economics of safety suggested by {Dorman [1]}. It covers theaspects of basic safety, complex equipment and systems interaction tabulated in Tab. 18.
Tab. 18: Basic safety, complex equipment and systems interaction
7
Table12 Analysis of safety features of operating control mechanisms
Safe design Unsafe design Sl
no Push button/ foot / automatic / switch lever/ handle etc type
No of safety
features
% No of safety
features
% Total Machine
investing-
ated in %
01 GPM
60 82.19 10 40.00 70 57.38
02 SPM
50 72.46 12 57.14 62 59.62
03 CNC
10 40.00 03 100 03 46.42
Total 120 - 25 - 145 % 82.76 - 17.24 - 100.00
Table 13 Analysis of safety features of cover guards and fixtures
Analysis of data proves that it is quite essential to provide safety training to the employees. Management has tobe serious in providing necessary supports for the same. They should also provide the protective equipments andaids such as Hand Gloves, Protective Glasses, and Aprons etc.After conducting the above analysis, the training was to the employees. The training was mainly related to leantools and on the job training for safety measures. Fig. 3 shows the chart of number of training conducted duringthe month of March 2007 to September 2007.
11
Improvement Training
3 34
6
2 211
4
7
3
8
56
02468
10
Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07
Months
No
of T
rain
ing
Lean Tools Job Training
Fig.3 Number of training conducted during the month of March 2007 to September 2007
8. Design of Safety Features and Safety Measures
Design of safety features play an important role in reducing accidents and enhancing productivity. So, keeping in mind the safety aspect, the design of safety features have been introduced in machine tools. The problem of plant lay out has been verified and then modified, maintaining the relation with the overall plant design. It included many other functions such as selection of the production processes, equipment to job relation, adoption of new safety standards, introduction of new products (similar or dissimilar). It was noticed that newly properly designed covers and guards (nearly 25 % of total numbers) and its replacement resulted to no loss of even a single manpower after its implementation.
Prioritizing the production requirement and urgent need to upgrade the safety vis–a-vis production efficiency, a Core Functional Team (CFT) team has been formed to look into the safety aspects of the machine tools and fixtures. Some of the latest initiatives in design of jigs and fixtures are presented in Fig.4 through Fig.7.
Figure 4 shows the arrangement of toggle clamps. It is worth mentioning that the toggle clamps are used for fastening the job. The toggle clamps are comparatively simple to hold the job tightly and easy to remove.
FIG. 3: Number of training conducted during the month of March 2007 to September 2007.
8 Design of Safety Features and Safety Measures
Design of safety features play an important role in reducing accidents and enhancing productivity. So, keeping inmind the safety aspect, the design of safety features have been introduced in machine tools.
The problem of plant lay out has been verified and then modified, maintaining the relation with the overall plantdesign. It included many other functions such as selection of the production processes, equipment to job relation,adoption of new safety standards, introduction of new products (similar or dissimilar). It was noticed that newlyproperly designed covers and guards (nearly 25 % of total numbers) and its replacement resulted to no loss of evena single manpower after its implementation.
Prioritizing the production requirement and urgent need to upgrade the safety vis–a-vis production efficiency,a Core Functional Team (CFT) team has been formed to look into the safety aspects of the machine tools andfixtures. Some of the latest initiatives in design of jigs and fixtures are presented in Fig.4 through Fig.7.
Fig. 4 shows the arrangement of toggle clamps. It is worth mentioning that the toggle clamps are used forfastening the job. The toggle clamps are comparatively simple to hold the job tightly and easy to remove.
Similarly, Fig. 5 shows an arrangement made for welding of the jobs. This arrangement made possible to keepthe working environment clean and achieve better welding quality as well as higher productivity
Fig. 6 is related to provision of idlers for smooth movement of assembled beams for welding. It works as amechanical feeding device. The same operation was done earlier in the plane surface and for advancement andpositioning crane was utilized. Now with the provision of idlers no crane is required and positioning of the job alsobecome very easy. The main purpose of this was to minimize movement effort, protecting the spoiling of workingsurface and improving the working condition.
Like wise Fig.7 is a poka-yoke drilling jig. The jig was made in order to eliminate the frequent dimensionalproblem of center-to-center distance between the drill holes and 100% inspection. The job was ?shape bended inthe CNC press brake and then drilled using a Radial drill machine. There were four drill holes in the product. Thetwo holes were in x axis and another two holes were in y-axis. The center-to-center dimension was most important.
Improvements in Product Quality and Productivity Through Pragmatic. . . 89
12
Fig.4 Provision of toggle clamps
Similarly, Figure 5 shows an arrangement made for welding of the jobs. This arrangement made possible to keep the working environment clean and achieve better welding quality as well as higher productivity
Figure 6 is related to provision of idlers for smooth movement of assembled beams for welding. It works as a mechanical feeding device. The same operation was done earlier in the plane surface and for advancement and positioning crane was utilized. Now with the provision of idlers no crane is required and positioning of the job also become very easy. The main purpose of this was to minimize movement effort, protecting the spoiling of working surface and improving the working condition.
Fig. 5 Development of a welding fixture
FIG. 4: Provision of toggle clamps.
FIG. 5: Development of a welding fixture.
It has a tolerance of ±0.1mm in a basic prescribed dimension of 312 mm i.e. the job was acceptable, if it wasfound within the range 311.9 to 312.1. The Jig was designed in such perfection that the problem has completelyeliminated and the inspection-sampling plan has been changed from 100 % to 1 in every 50 processed pieces.
To instill safety habits and awareness among employees a safety committee was formed taking representativefrom each unit. They have to take the responsibility to enforce and implement the safety measures. Safety cam-paigning was done through posters at certain important locations. Annual rewarding system was also introduced.
90 D. Mahto & A. Kumar
13
Fig.6 Provision of mechanical feeding device
Like wise Fig.7 is a poka-yoke drilling jig. The jig was made in order to eliminate the frequent dimensional problem of center-to-center distance between the drill holes and 100% inspection. The job was ∟shape bended in the CNC press brake and then drilled using a Radial drill machine. There were four drill holes in the product. The two holes were in x axis and another two holes were in y-axis. The center-to-center dimension was most important. It has a tolerance of ±0.1mm in a basic prescribed dimension of 312 mm i.e. the job was acceptable, if it was found within the range 311.9 to 312.1. The Jig was designed in such perfection that the problem has completely eliminated and the inspection-sampling plan has been changed from 100 % to 1 in every 50 processed pieces.
Fig.7 Poka yoke drilling jig
FIG. 6: Provision of mechanical feeding device.
13
Fig.6 Provision of mechanical feeding device
Like wise Fig.7 is a poka-yoke drilling jig. The jig was made in order to eliminate the frequent dimensional problem of center-to-center distance between the drill holes and 100% inspection. The job was ∟shape bended in the CNC press brake and then drilled using a Radial drill machine. There were four drill holes in the product. The two holes were in x axis and another two holes were in y-axis. The center-to-center dimension was most important. It has a tolerance of ±0.1mm in a basic prescribed dimension of 312 mm i.e. the job was acceptable, if it was found within the range 311.9 to 312.1. The Jig was designed in such perfection that the problem has completely eliminated and the inspection-sampling plan has been changed from 100 % to 1 in every 50 processed pieces.
Fig.7 Poka yoke drilling jig
FIG. 7: Poka yoke drilling jig.
Considering the background, educational level, age, skill, attitude, level of risk at workplace, and job require-ments, an in depth data collection has been carried out considering each and every employee and a skill matrixhas been made to know their strong and weak points, so that their ability may be utilized properly or they may betrained for any specific job, if required.
The comparative data about product rejection are given in Fig. 8
Further, to enforce safety at work a rating procedure has been developed and is introduced. The house keepingand safe practice rating are presented in Tab. 19. On the basis of the obtained scored points, the average value ofHouse Keeping and Safe Practices Rating was calculated as 74%.
The machine up keep rating has been presented in Tab.20; and it was continuously monitored. Similarly, thesummary of monthly progress in working environment can be seen in Fig 9. In the Tab. 20 legends used were P
Improvements in Product Quality and Productivity Through Pragmatic. . . 91
14
To instill safety habits and awareness among employees a safety committee was formed taking representative from each unit. They have to take the responsibility to enforce and implement the safety measures. Safety campaigning was done through posters at certain important locations. Annual rewarding system was also introduced. Considering the background, educational level, age, skill, attitude, level of risk at workplace, and job requirements, an in depth data collection has been carried out considering each and every employee and a skill matrix has been made to know their strong and weak points, so that their ability may be utilized properly or they may be trained for any specific job, if required.
The comparative data about product rejection are given in Fig 8
Product Rejections due to Working Environment
148
101 89
176
121
54
97
18 15 24 19 936 25
0
50
100
150
200
Apr May Jun Jul Aug Sep Oct
Month
Num
ber o
f Pro
duct
Before Lean at 2006 After Lean at 2007
Fig. 8 Product rejections trend due to working environment
Further, to enforce safety at work a rating procedure has been developed and is
introduced. The house keeping and safe practice rating are presented in Table 19. On the basis of the obtained scored points, the average value of House Keeping and Safe Practices Rating was calculated as 74%.
The machine up keep rating has been presented in Table20; and it was continuously monitored. Similarly, the summary of monthly progress in working environment can be seen in Fig 9. In the Table 20 legends used were P for Poor, G for Good, VG for Very Good and Ex for Excellent. Total Marks was 1600. The scale for marking was determined and assigned. It was decided that excellent and very good condition would carry 4 marks and 3 marks. Similarly, Good and poor were assigned 2 and 1 marks respectively. From the Table 20 the total score was 1336 yielding a machine upkeep rating of 83.50%.
FIG. 8: Product rejections trend due to working environment.
for Poor, G for Good, VG for Very Good and Ex for Excellent. Total Marks was 1600. The scale for marking wasdetermined and assigned. It was decided that excellent and very good condition would carry 4 marks and 3 marks.Similarly, Good and poor were assigned 2 and 1 marks respectively. From the Tab. 20 the total score was 1336yielding a machine upkeep rating of 83.50%.
Tab. 19: House keeping and safe practice rating
11
Table 19 House keeping and safe practice rating
Description Points Allowe
d
Area A
Area B
Area C
Area D
I. House Keeping (60 Points)
1.1 Binds and racks in order 1.2 Material On floor (including jig & fixture) 1.3 Clean shop floor (excluding gang way) 1.4 Machine cleaning 1.5 Material in specified area (any material) 1.6 Gangway clear and clean 1.7 Cycle parking
10 10 10 10 08 08 04
7 7 5 7 6 5 4
8 7 6 7 5 8 4
8 7 9 9 6 7 3
6 6 7 6 5 4 3
Total points for (I) 41 45 49 37 II. Safe Practices (40 Points)
2.1 Use of safety appliances 2.2 Shoes 2.3 Uniform 2.4 Safety publicity
07 05 02 02
4 3 1 1
3 2 1 1
4 3 1 1
3 2 1 1
2.5 Machine guards 2.6 Paint booth, grinding dust, coolant 2.7 Operator platforms, conveyors and conveyors trolleys, bins & trolleys overloaded 2.8 Use of improper tools, worn out parts and electrical points
06 06 06
06
6 6 5
6
6 6 3 6
6 6 6
6
5 6 6
6
Sub -Total points for (II) 24 23 21 24 23 Total points for (I+II) 40 32 28 33 30 Total points 100 73 73 82 67
On the basis of above calculated total points, the average value of House Keeping and
Safe Practices Rating may be calculated as 74%.
On the basis of above calculated total points, the average value of House Keeping and Safe Practices Ratingmay be calculated as 74%.
92 D. Mahto & A. Kumar
Tab. 20: Machine upkeep rating
12
Table 20 Machine upkeep rating
Parameter
Tool condition
Job location
and clamping
Electric wiring
Cleanliness Lubrication Oil / Air
leakage
Total
Area Sample points
10 4 13 18 35 20 100 1 (VG)
3*10 (G) 2*4
(EX) 4*13
(VG) 3*18
(EX) 4*35
(VG) 3*20
344
A 2 (VG)
3*10 (G) 2*4
(G) 2*13
(G) 2*18
(EX) 4*35
(VG) 3*20
300
Sub Total A 60 16 78 90 280 120 644 1 (VG)
3*10 (G) 2*4
(G) 2*13
(VG) 3*18
(EX) 4*35
(EX) 4*20
338
B 2 (G)
2*10 (G) 2*4
(EX) 4*13
(VG) 3*18
(EX) 4*35
(EX) 4*20
354
Sub Total B 50 16 78 108 280 160 692 Grand Total 110 32 156 198 560 280 1336
Analysis Total Score = 1336 Full marks = 1600 Hence, Machine Upkeep Rating = (1336 / 1600) X 100 = 83.50 %,
17
Quality environment monitoring from April 2007 - January 2008
53 58 51 55 56 53 62 71 68 6970 72 73 73 75 75 74
84 80 8075 80
70 75 75 7080 80 85 86
0102030405060708090
Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Month
%
Quality Environment %Machine Upkeep Rating %House Keeping and Safe Practice Rating %
Fig. 9 Quality environment monitoring from April 2007 - January 2008
Table 21 shows the improvement on various heads achieved through design of safety
features and safety initiatives; and over and above by improving working environment.
Table 21 Comparison of improvement status in key result area
Sl No Description U O M Past Present 01
Man days lost Hour /Man / Year 2.19 1 .09
02
Fulfillment of schedule % 83 94
03
Machine break down Hour /day 1.35 0.53
04
Utilization of the plant area % 89 67
05 Material handling time % 32.7 24.8
06
Throughput time from raw material to finish stage on major items A, B, C and D
Hour A – 56 B - 47 C – 59 D - 51
A - 43 B - 40 C – 47 D - 35
07 Cleanliness
% 53.45 % 74.00 %
FIG. 9: Quality environment monitoring from April 2007 - January 2008.
Tab. 21 shows the improvement on various heads achieved through design of safety features and safety initia-tives; and over and above by improving working environment.
Tab. 21: Comparison of improvement status in key result area
13
Table 21 Comparison of improvement status in key result area
Sl No Description U O M Past Present 01
Man days lost Hour /Man / Year 2.19 1 .09
02
Fulfillment of schedule % 83 94
03
Machine break down Hour /day 1.35 0.53
04
Utilization of the plant area % 89 67
05 Material handling time % 32.7 24.8
06
Throughput time from raw material to finish stage on major items A, B, C and D
Hour A – 56 B - 47 C – 59 D - 51
A - 43 B - 40 C – 47 D - 35
07 Cleanliness
% 53.45 % 74.00 %
Table 22 Break down per hour and respective frequencies
Sl No Breakdown per hour Frequency %
1 7 and less 5 2 8 12 3 9 25 4 10 30 5 11 20 6 12 and above 8
Table 23 Service time in minutes and respective frequencies
Sl. No Service time (Minutes) Frequency % 1 10 5 2 20 25 3 30 40 4 40 25 5 50 5
Improvements in Product Quality and Productivity Through Pragmatic. . . 93
9 Simulation of the Maintenance department
It has been observed during study and as reported earlier, the maintenance area was the worst resourced area withno adequate manpower.
Therefore, a simulation model has been developed to assess the requirement of actual manpower (Crew Size)for maintenance shop. The data available for simulation is presented in Tab. 22 and Tab. 23. The wages to theservicemen given as per existing norms of the company is Rs 20 per hour per serviceman and machine loss due tonon-functioning is Rs 430 per hour.
Tab. 22: Break down per hour and respective frequencies
13
Table 21 Comparison of improvement status in key result area
Sl No Description U O M Past Present 01
Man days lost Hour /Man / Year 2.19 1 .09
02
Fulfillment of schedule % 83 94
03
Machine break down Hour /day 1.35 0.53
04
Utilization of the plant area % 89 67
05 Material handling time % 32.7 24.8
06
Throughput time from raw material to finish stage on major items A, B, C and D
Hour A – 56 B - 47 C – 59 D - 51
A - 43 B - 40 C – 47 D - 35
07 Cleanliness
% 53.45 % 74.00 %
Table 22 Break down per hour and respective frequencies
Sl No Breakdown per hour Frequency %
1 7 and less 5 2 8 12 3 9 25 4 10 30 5 11 20 6 12 and above 8
Table 23 Service time in minutes and respective frequencies
Sl. No Service time (Minutes) Frequency % 1 10 5 2 20 25 3 30 40 4 40 25 5 50 5
Tab. 23: Service time in minutes and respective frequencies
13
Table 21 Comparison of improvement status in key result area
Sl No Description U O M Past Present 01
Man days lost Hour /Man / Year 2.19 1 .09
02
Fulfillment of schedule % 83 94
03
Machine break down Hour /day 1.35 0.53
04
Utilization of the plant area % 89 67
05 Material handling time % 32.7 24.8
06
Throughput time from raw material to finish stage on major items A, B, C and D
Hour A – 56 B - 47 C – 59 D - 51
A - 43 B - 40 C – 47 D - 35
07 Cleanliness
% 53.45 % 74.00 %
Table 22 Break down per hour and respective frequencies
Sl No Breakdown per hour Frequency %
1 7 and less 5 2 8 12 3 9 25 4 10 30 5 11 20 6 12 and above 8
Table 23 Service time in minutes and respective frequencies
Sl. No Service time (Minutes) Frequency % 1 10 5 2 20 25 3 30 40 4 40 25 5 50 5
Knowing this much of input data, the machine breakdown and service time frequencies is converted into cu-mulative frequencies. The detail conversion is tabulated in Tab. 24 and Tab. 25.
Tab. 24: Conversion of Breakdown frequency to cumulative frequency
14
Table 24 Conversion of Breakdown frequency to cumulative frequency
Breakdown per hour
Frequency% Cumulative frequency
Range Random Number fitted
7 and less 5 5 00-05 8 12 17 06-17 12(2) 9 25 42 18-42 21 (1), 21(4)
10 30 72 43-72 69(3) 11 20 92 73-92
12 and above 8 100 93-100
Table 25 Conversion of service time frequency to cumulative frequency
It was noticed that at certain times, when a breakdown occurs, both the members of the repair crew becomesbusy at the same time to attend it. If in the mean time some other break down occurs, then it will have to wait untilone of them has finished his previous task. At some other times, due to no breakdown, both the said crewmembersmay become idle. Thereafter, it was felt to simulate the system.
First four hours of machine repair time was simulated and simultaneously, repairmen’s waiting time and themachine waiting time have been calculated. For making these computations, it is assumed that each repairman willwork effectively for only 55 minutes in an hour allowing 5 minutes for personal allowances.
94 D. Mahto & A. Kumar
Simulation has been done manually for a crew size consisting of 5 members and for 6 members as well(Tab. 26). Tab. 26 clearly indicates that machine waiting time has reduced from 65 minutes to 10 minutes, ifthe crewmember size is chosen as 6 instead of 5. The 10 minutes time is sufficient for switching over to anotherbreak down. It also considerably reduces the cost involved from Rs. 7250/− to Rs. 855/− . Therefore, the bestcrew size is of six repairmen.
For more accurate and reliable results, the study should be carried out over a much longer period on a computer.The above calculation is an indication that with proper maintenance plan it is possible to reduce unnecessarywastages such as machine idle time, optimized crew size. Further, the rate of incidents can be minimized if propermaintenance is taken up on the machines.
Tab. 26: Simulation of machine repair time and repairmen’s waiting time and cost optimization
15
Table 26 Simulation of machine repair time and repairmen’s waiting time and cost Optimization
Total idle time ∑880 ∑10 Cost in Rupees for idle time (Machine + Repairman)
6600 75
Wages for Repairmen for 8 hours (Rupees)
650 780
Total cost (Rupees) 7250 855 Table 27 Productivity related data for 8 days before and after the application of lean tool
including improvement in working environment
Days 1 2 3 4 5 6 7 8 Total Before (x) 49 53 51 52 47 50 52 53 407 After (y) 52 55 52 53 50 54 54 53 423
10 Productivity Improvement due to Improvement in Working Environment
The effectiveness of working environment on productivity has been tested in CNC Horizontal Boring Machine.The productivity related data before and after the application of lean tool including improvement in workingenvironment is tabulated in Tab. 27.
Tab. 27: Productivity related data for 8 days before and after the application of lean tool including improvement in workingenvironment
1
27 Productivity related data for 8 days before and after the application of lean tool including improvement in working environment
Days 1 2 3 4 5 6 7 8 Total Before (x) 49 53 51 52 47 50 52 53 407 After (y) 52 55 52 53 50 54 54 53 423
Table 28 Statistical Calculations of productivity (x and y) before and after the application of lean tool including improvement in working environment
The student’s t test (one tail t-test) has been carried out with the help of tabulated data (Tab. 27). The followingassumptions were considered:
– The parent production from which the sample has been drawn is normal.– The sample observations are independent i.e. the sample is random.– The population standard deviation is unknown.
Let the productivity before and after the application of lean tool including improvement in working environmentbe x and y respectively as tabulated in Tab. 27.
Then according to hypothesis,H0 : µx = µy, there is no significant difference in productivity due to environmental change.Alternate Hypothesis H0 : µx < µy (Left tailed),
Improvements in Product Quality and Productivity Through Pragmatic. . . 95
If the samples of productivity were assumed to be independent then t test for difference of means will be appliedto test H0.
Test Statistic t = (x− y)/√
S2( 1n1
+ 1n2
) ∼ tn1 +n2−2
Where,
–– Mean value of x = x,– Mean value of y = y,– No. of data of mean values of x = n1,– No. of data of mean values of y = n2,
S2 =1
n1 +n2−2[∑(x− x)2 +∑(y− y)2] (1)
Where, S represents an unbiased estimate of the common population Variance σ2.
The statistical calculations are tabulated in Tab. 28
Tab. 28: Statistical Calculations of productivity (x and y) before and after the application of lean tool including improvementin working environment
1
27 Productivity related data for 8 days before and after the application of lean tool including improvement in working environment
Days 1 2 3 4 5 6 7 8 Total Before (x) 49 53 51 52 47 50 52 53 407 After (y) 52 55 52 53 50 54 54 53 423
Table 28 Statistical Calculations of productivity (x and y) before and after the application of lean tool including improvement in working environment
x = 50+7/8 = 50.875 and y = 52+7/8 = 52.875,n1 = 8,n2 = 8.
Now,
∑(X− x)2 =[∑δ
21− (∑δ 1)2/n1
]= 30.875, (2)
∑(Y − y)2 =[∑δ
22− (∑δ 2)2/n2
]= 16.875 (3)
S2 =1
n1 +n2−2x2[∑(X− x)2 +∑(Y − y)2]= 3.41 (4)
Therefore,
t = (x− y)/√
S2(1n1
+1n2
)∼ tn1 +n2−2 =−2.17 (5)
Tabulated t0.05, for (8+8−2) = 14 degree of freedom, for one tail test is 1.76. The critical region for the left tailtest t <−1.76. Since calculated t is less than −1.76, H0 is rejected at 5% level of significance. It is concluded thatthe productivity X and productivity differ significantly as regards their effect on increase in productivity.
Further, since y > x, productivity Y is superior to productivity X .
96 D. Mahto & A. Kumar
11 Conclusions
All the figures and tables presented in this chapter are self-explanatory. However following conclusions may bedrawn.
1. Injuries resulted in the accidents were due to sharp edges and corners. Better tool design, accurate tool setting,and defects elimination could overcome the situation.
2. It is seen from Tab. 8 that average number of man days lost per accident were highest in Single PurposeMachine tools (5.5 days) followed by General Purpose Machine tools (4 days) and Special Purpose and CNCMachine tools (3.2 days). The maximum no of man-days lost in a single case was highest at CNC Machine tool(70 days), followed by SPM (57 days) and GPM (36 days). It can, therefore, be concluded that SPM accidentsare more disabling as compared to others.
3. The accidents could be controlled to a great extent by on the job training and supervision, certain improvementsin machine tool design, provision of proper gripping in machine tool, use of lifting aids and adoption of safeclamping practices.
4. It was observed that in most of the cases point of operation was not provided with a guard permitting freeaccess to the danger zone. It would be seen from Tab. 11 that on an average 28.38% of the accidents occurreddue to absence of guards at the point of operation and 8.11 % were due to “Inadequately guarded point ofoperation “. Therefore, altogether 36.49% of accidents occurred due to absence of proper safety guards at theoperating point. Certainly control of such accidents entirely depends on provision of appropriate safety guardsat the point of operation. In the absence of guards no amount of training and motivation could be successful tocontrol these accidents. Non-provision of proper hand tools gloves, safety shoes etc to workmen contributedto causation of 22.97% of the accidents.
5. Further, 8.11% accidents were accounted on the heading defective tool, die, other machine parts etc. Hazardouswork arrangements contributed to 20.27% of accidents on unsafe conditions.
6. 6.78% accidents were reported due to improper layout.7. It can be concluded from Tab. 7 that almost all accidents may be avoided if safety measures are taken properly,
and the working environment in engineering industries are improved.8. It justifies the need of Lean manufacturing tools and techniques with reference improve working environment
and ultimately improving the product quality and productivity.
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