1. INTRODUCTION:

Gypsum plaster boards are one of the main products that are widely used in the Infrastructure and other areas of constructions. According to The Future of Gypsum: Market Forecasts to 2026, the global gypsum market is valued at $1.49 billion in 2016, equivalent to 252 million tons, with 33.3% and 60.9% being consumed in the plasterboard and cement industries, respectively.

According to Smithers Apex, the gypsum market is forecast to grow at a CAGR of 9.9% to reach nearly $2.4 billion by 2018 and $3.8 billion by 2026. An initial market analysis revealed that the Indian gypsum market is poised to grow significantly in the coming years. India produces around 2.5% of world’s 150 million tons of natural gypsum. Government of India has been incentivizing this manufacturing sector by allowing up to 100% foreign direct investment (FDI) for setting up units to make gypsum products. In view of the increased focus on infrastructure development in the coming years the country as a whole anticipates huge growth in gypsum consumption. Gypsum board (not including lightweight board) accounts for about 50.4% of the industry's revenue. According to reliable information sources, Gypsum consumption in India is expected to grow at a compounded annual growth rate (CAGR) of around 4% during the period 2012-13 to 2017-18.

The manufacturing unit considered for the study is a semi- automated plant. It has installed capacity to produce 18 lakhs gypsum plaster boards per month. The unit has instituted practices that are part of world class manufacturing strategies leading to operational excellence. The preliminary study revealed that the unit manufactures about fifteen variants of boards and the major proportion includes Regular board. The entire process of manufacturing plaster boards comprises of six stages including Raw Material Handling, Calcination, Paper Preparation, Mixing, Drying and Finishing. The primary raw material is the paper whose consumption is to the tune of 2.026 square meters per gypsum plaster board. As per the data collected from the quality department, significant amounts of wastage in raw material were observed. It was estimated that the rejection rate was around 4% which led to losses accounting to 88,200 square meter of paper. The Quality losses in the unit were valued at Rs. 6, 91,488 per month. After detailed analysis of the existing process it was observed that. the paper preparation and splicing operation stages were critical. The study aimed at identifying various losses occurring in these two critical stages. The study as it evolved came out with recommendations to avoid such huge losses. Also included in the scope of the study was to document the revised standard operating procedure (SOP) for the above mentioned stages of the manufacturing processes to sustain the benefits of the study.

2. LITERATURE REVIEW:

As quality gained more and more importance over time, many quality initiatives and concepts have emerged. Inspection (100%), statistical quality control (SQC), total quality control (TQC), zero defects, total quality management (TQM), kaizen, ISO 9000 quality standards, quality award programs (Malcolm Baldrige, European Quality Award and so on), 6r, DFSS, lean six sigma have been among the most recognized ones (Fasser and Brettner, 2002; Montgomery, 2005). According to Waheeda Hanim binti Ab. Rahman(2009), the effort to reduce both the variability of a process and the production of nonconforming items should be ongoing, because quality improvement is never-ending process. Quality improvement must be distinguished from quality control. Improvements programmed seek to enhance actively the quality of a product; often through process improvement and reduction of process variability. Based on the study the author proposes a more effective quality control chart that is specifically applicable to occasions where the number of faults is limited. Dalgobind Mahto, Anjani Kumar (2013) identified the root-cause for quality and productivity related problems and they mentioned it as the key issues for manufacturing processes. It has been a very challenging engineering problem particularly in a multistage manufacturing, where maximum number of processes and activities are performed. However, it may also be implemented with ease in each and every individual set up and activities in any manufacturing process. Both the authors have adopted root-cause identification methodology to eliminate the dimensional defects in cutting operation in CNC oxy flame cutting machine and a rejection has been reduced from 11.87% to 1.92% on an average. Tanvir Ahmed, Raj Narayan Acharjee (2013) highlighted more on quality control tools applied in readymade garments sector in Bangladesh. The work represents a detail investigation on quality improvement of a garment factory by applying Pareto Analysis and Cause-Effect Diagram. The aim of their study was to minimize defects that will reduce rework and rejection rate. Lauee Shuang (2012) describes that Kaizen is a critical tool to eliminate or reduce waste from production processes. Seven quality control (7 QC) tools are one of the common methods and techniques of the kaizen. Attempts are made to improve product quality and performance of production using appropriate 7 QC tools and Standard Operation Procedure (SOP). A work on profit-related pay and continuous improvement by Deniels R.C (1996) describes that many industries can benefit from kaizen events because it results in increase of the productivity in the company and also it helps in producing high quality products. Benefits from kaizen activities can be achieved with minimum efforts. Fabio De Felice et.al., (2012) highlighted the formula for the ultimate productivity improvement strategy. Industries often suffer from the lack of a systematic and consistent methodology. In particular the manufacturing world has faced many changes throughout the years and as a result, the manufacturing industry is constantly evolving in order to stay ahead of competition. One in particular that has been gaining momentum is the idea of World Class Manufacturing (WCM) developed by Richard J. Schonberger (in the 80s) who collected several cases, experiences and testimonies of companies that had embarked on the path of continuous “Kaizen” improvement for excellence in production, trying to give a systematic conception to the various practices and methodologies examined. Some of the benefits of integrating WCM include increased competitiveness, development of new and improved technology and innovation, increased flexibility, increased communication between management and production employees, and an increase in work quality and workforce.

3. DATA COLLECTION AND ANALYSIS:

Initial study involved a complete review of the manufacturing process of the plaster boards. Four types of plaster boards were manufactured in the plant namely Regular boards, Moisture resistance ultra, Square edge and Fire resistance boards. After studying the process it was observed that there was no standard data collection plan and also unnecessary material wastage was recorded at different phases of the process.

3.1 Pareto Analysis:

As the first stage of data collection, the yield losses including the defects observed during the production of gypsum plaster boards for a period of one year was gathered from the records of in house Quality division. In order to track the raw material consumption, papers consumed for producing reel of gypsum plaster board were collected over a period of one quarter. The main types of defects in the manufacturing process were wet scrap, dry scrap, production store, dispatch store, dispatch rejects. Pareto chart was plotted to identify the vital few defects causing rejections in the different stages of the manufacturing process. A sample Pareto plot of the wet scrap defects is shown in Fig. 1. Table. 1 indicates the stages of manufacturing and the critical defects observed along with the percentages of such defects at different stages. The focus in this study was limited to the two critical stages of paper preparation and Splicing operation during the gypsum plaster board manufacturing process.

Figure:1 Pareto Analysis for Wet scrap

Table 1: Percentage of critical defects at different stages

Sl. No	Stage	Critical Defects observed	Percentage
1.	Dry scrap board	Start up	54
1.	Dry scrap board	stacker	54
2.	B-store/Production store board	No taper bonding	53
3.	D-store	Edge groove	58
4.	Dispatch	Edge damage	19.7
5.	Wet scrap	Splicing	20

3.2 Study using existing Standard Operating Procedure (SOP) for Splicing:

Splicing is a manual process where a fresh paper reel is mounted on top of the aligned running paper reel for the purpose of continuous production of gypsum plaster boards. The SOP of existing splicing operation involved: Fixing the paper cutting rope above the in-process paper, Pulling the fresh paper towards splicing unit and passing above the cutting rope, Starting suction fans to lift the paper and align the paper on mantel roller, Aligning the paper properly with the in-process paper, Removing the double adhesive tape, Lowering the paper mantel roller, Tightening the paper cutting rope. As final step lifting the scorer while passing the splicing scorer unit and lowering it immediately. Intimation is then given to the knife associated to reject the scrap generated during paper splicing.

3.2.1 Analysis of the Splicing Operation:

It was also observed that the Splicing operation is carried out by three different operators during three shifts. It was observed that about 12 meters of paper was rejected during splicing.

Figure 2: Rejection during splicing operation.

As can be seen in the Fig 2, the spliced portion is around 3 meters in width i.e. 3 meters of the in-process paper gets attached with the 3 meters of the fresh paper and hence effective 6 meters width of paper get rejected during splicing operation so as to meet the gypsum plaster boards’ specifications. As per the existing system, 12 meters of paper is automatically rejected. Initially it was manual rejections before the process was automated. The reason that the process was eventually automated due to the negligence of operators during the night shift, improper alignment of the paper and tensioner issues.

Out of the above three reasons, it was seen that the first two reasons were the most critical ones. Due to negligence of the operators during night shift, the spliced portions of the boards were cut and passed on to the dryer where they caused blockages in the dryer. The operator has to align the paper accordingly and then switch on the splicing button present near the unit. Both these activities lead to human errors. Hence alignment was considered as a critical issue for proper paper splicing.

In order to further investigate the defects cause and effect diagrams were constructed based on the visual observations during the manufacturing process and brainstorming session was conducted involving the line personnel. The defects considered were wet scrap, dry scrap, P-store and D-store to trace and identify the possible causes for the defects occurring at each stage. Further from the root cause analysis carried out for wet scrap where splicing defects were observed, it was inferred that defects such as splicing, start-up, negligence of operators associated with SCADA software and initial set ups during production start were the main causes for wet scrap rejection.

3.3 Studies on consumption of raw material:

Data pertaining to the consumption of paper during the process of manufacturing gypsum plaster boards was gathered from the manufacturing line. It was noted that two methods were deployed namely knife counter reading and take off method. However, this work elaborates only the knife counter method. The knife counter is a computer controlled special purpose machine which cuts the gypsum plaster boards according to the given dimensions based on the pre programmed logic. The counter has a display screen which displays the number of the boards cut, area of the boards and the error during cutting. Data was collected for one month period. The amount of paper consumption was calculated using the formula as follows:-

Gross production=Knife counter reading final- Knife counter reading initial + uncut scrap:

Detailed analysis indicated that 10 kilograms of paper was being wasted due to preparation of the paper reel, 12 kilograms due to edge damages present in the reel and 1 kilogram due to set up stages of production .The actual paper consumption from the data collected was found to be 2.053 square meters against the standard set for paper consumption for unit gypsum plaster board of 2.024 square meters. In order to account for the gap of 0.005 square meters, further data on the number of boards produced per paper reel was collected.

Based on the process study and analysis, it was seen that splicing, preparation waste and edge damages were the main causes leading to raw material wastage. The paper consumption in terms of Input–Output ratio is determined as follows. Top paper (Grey paper) - 180 gram square meters (GSM) and Bottom paper (Ivory paper)-190 gram square meters (GSM). are used to manufacture gypsum plaster boards. Paper consumption per square meter of board=4.5176/2.2296=2.026 square meter. However, present paper I/O is 2.05 square meter. This is leading to a total loss of about 88200 square meters.

3.4 Study and Analysis of existing standard operating procedure for paper preparation:

Based on the analysis it was observed that a huge amount of losses were occurring in the unit during paper preparation and hence it was considered as a critical quality issue. As the target was to reduce the wastage occurring during the paper preparation stage, the standard operating procedure (SOP) in practice for paper preparation was studied. The SOP for paper preparation included: Checking for visual defects while taking paper from stores, inform the shift in-charge for any observed damages and keep aside the damaged reel with an appropriate mark, removing the shaft assembly from the core of the used reel and mounting the same shaft assembly for the fresh reel, Removing the damaged portion of the reel by cutting the paper upper piles with sharp knife, weighing the paper scrap quantity using the weighing scale, placing the scrapped reel in the paper scrap allotted area, applying seven strips of double side adhesive tape at the splicing end, cutting the paper accordingly at the edges and mounting the paper reel on the paper stand.

Paper preparation was being carried out by three different operators during the three shifts operations. During the gemba study in the manufacturing unit it was noticed that, the way of preparing the paper reel adapted by each of the operators was different. Based on the data collected per reel, it was seen that 10-15 kilograms of paper was being removed irrespective of the damages present. This led to deviation from the standard operating procedures. Using the cause and effect diagram it was infer that, method of carrying the process, tool used for cutting the paper, foreign particles, unskilled operators and edge damages caused during transportation were the main causes for losses during paper preparation stage of manufacturing.

4.0 APPLICATION OF FOCUSSED IMPROVEMENT (FI) TOOLS:

Training on Focussed Improvement tools which are part of world class manufacturing was given to the project team prior to the application of the tools. Tools like 5W+1H (What, When, Where, Who, Which + How), root cause analysis and quick kaizen were used for carrying out a thorough analysis of the two critical stages of manufacturing namely splicing and paper preparation. The 5W and 1 H technique helped in tackling the root causes. These tools were applied covering the three shifts operations: in the paper preparation area, at the mixer area, knife counter area and stacker area. Log sheets for carrying out 5W+1H analysis were prepared for all the 9 operators in three different shifts.

5.0 RECOMMENDATIONS AND PROPOSALS OFFERED:

Several proposals and recommendations have been put forth to the operations group of the manufacturing organization. Significant among them is the re design of knife/cutter for paper preparation and design of paper guide for splicing operation. Revisions in the standard operating procedures for paper preparation and splicing stages have also been proposed. Few of the Quick kaizens and poke yokes proposed are described in the subsections to follow.

5.1 Recommendations Made Based On Quick Kaizen:

The following recommendations were made based on the verification and analysis done on the causes for wastages during paper preparation-

· Due to presence of foreign particles on the shop floor, cleaning of the shop floor for every two hours by spreading wasted paper reel on the floor was recommended.

· Paper preparation is carried out by three different operators per shift. Operation carried out by each operator is different and hence violating the SOP. It was recommended to give skill improvisation training for every 3 months along with regular training program.

· Handling the paper reel involves huge amount of manual power. It was suggested to introduce a reel holder that lifts the paper reel and hence eliminating the extra manual force needed.

· Due to the thickness and sharpness of the cutter, the study suggested to change the cutter. A new design for knife was proposed for the same.

· The paper reel is transported from Chennai port to Bangalore plant. These paper reel are wrapped in a polythene reel cover. Edge damages are mostly seen during transportation and hence it was suggested to coordinate with the supplier to wrap the paper reel with Kraft cardboard instead of polythene reel.

5.2 Design of Knife/Cutter for Paper Preparation:

It was observed that with the existing cutter, more amount of paper was being wasted due to the thickness and sharpness of the cutter. It was observed that fresh layers along with the initial layers were cut leading to more wastage. Fig. 3 depicts the proposed design of knife/cutter for paper preparation, a small curve at the tip of the cutter was incorporated which helped the operators to remove the initial 5 layers at a single stretch without cutting the remaining fresh layers. Using the old cutter along with this proposed design would reduce the paper preparation wastage from 10 kilograms to 5 kilograms. The proposed design was accepted and approved by the plant manager and operators at the paper preparation area. This cutter was considered as the standard cutter and was mentioned in the revised Standard operating procedures. By implementing the proposed tool a savings to the tune of Rs. 85,613/- was estimated to accrue per month during the paper preparation stage.

Fig. 3 Proposed design of knife/cutter for paper preparation.

5.3 Design of Paper Guide for Splicing Operation:

During splicing operation, operators are supposed to mount the fresh paper on to the in-process paper with proper alignment. Since it is a manual process and dependent on operators experience alignment issues were being encountered and process engineers were not able to maintain the standards. Due to this alignment issue lot of rejections and defects occur such as edge damage, bad edge and open edge. Hence paper alignment is considered as a critical issue during splicing operation.

Figure 4: Proposed design of paper guide for splicing operation

The occurrence of alignment issues was addressed by SCADA and FIFE unit Due to the time lag in correct alignment and line process, considerable amount of boards were being rejected. With the introduction of new poka-yoke technique that is installation of “paper guides” to guide the paper in correct direction at the splicing unit making the whole splicing process fool-proof by eliminating human error in adjusting the paper alignment. The proposed designs are shown in Fig.4 and 5.

Figure 5: Paper guides on Splicing unit

5.4 Establishing Standard Data Collection Plan:

After studying the existing process, it was seen that the plant had no standard data collection plan for calculating the paper consumption. The data collection was started with the implementation of the new standard data collection plan. The standard data collection plan was reviewed and accepted by the plant manager and other workers in the plant. Before the implementation of the standard data collection plan, number of boards per stack was being noted individually for every reel by marking the initial board and final board. The marked boards were collected at the bundler unit and stack number was noted. This involved a lot of physical work. In order to reduce the burden of the operators in collecting data, a new sensor as shown in Fig:6 was installed at the bundler unit which collected the data of number of boards per stack by having a total count of boards and stack number. This was automatically noted in the Supervisory Control and Data Acquisition software. The encircled portion in the Fig:6 shows a count of gypsum plaster boards, a sensor at bundler unit and stacker number respectively.

Figure 6 : Sensor at bundler unit.

5.5 Revised Standard Operating Procedure (SOP) for Paper Preparation:

As a measure of instituting good practices a revised standard operating procedure for paper preparations was proposed. The main objective of the revision was to avoid excess paper wastage during paper preparation. The procedure comprised the following task lists:

a. The operator is required to wear the safety equipment prior to the operation

b. Clean the paper preparation area for every 2- 3 hours irrespective of the shift to avoid the foreign particles

c. With the help of forklift transport the fresh paper reel from the paper warehouse (store) to the paper preparation area

d. Check for any damages along the thickness of the reel, If the paper reel is damaged to an extent, then replace it with another fresh paper reel

e. With the help of normal cutter, cut the polythene reel

f. Weigh the paper reel before paper preparation and note down, If any damages are seen after removing the polythene reel then Inform the shift Engineer/ Mark the paper reel as “DO NOT USE”/ Note down the reel no. , weight and type of defect /Replace the old reel by a fresh one.

g. Using curve tipped knife peel the first layer and check for damages, repeat the same for initial 5 layers and weigh the peeled layers and enter it in the preparation waste column in the log book maintained

h. Place the peeled off layers in the paper scrap area, If any edge damages are seen, using the standard knife cutter cut the layers with damage and weigh the peeled layers and enter it in the edge damage column in the log book maintained,

i. If any stone push marks and grooves are seen on the paper reel, cut the layers, weigh them and enter the same in the log book, Using double adhesive tape, stick 7 stripes of tape for about 3 meters on the beginning of the paper reel,

j. Remove the shaft assembly from the old reel and place it on the fresh reel,

k. With the help of paper hoist lift the paper reel from the paper preparation area and place it on the paper stand.

5.6 Revised Standard Operating Procedure (SOP) for Splicing Operation:

This was done with an objective of reducing splicing failures. This procedure included the following tasks:

a. The operator is required to wear safety equipments prior to the splicing operation

b. Remove the running paper reel from the paper stand 1 and mount it on the paper stand 2,

c. Mount the fresh paper reel on the paper stand 1 and lock the clamps,

d. Pull the fresh paper reel towards the alignment bars above the cutting rope,

e. Lift the paper by switching on the suction fans,

f. Remove the double adhesive tape, Lower the paper manger,

g. When the running reel is about to end press the green switch near the splicing unit such that initial three meters of the fresh reel gets stuck to the final three meters of the running reel,

h. Lift the scorer while the splicing part is passing through it and release it immediately,

i. Guide the spliced part to fold near the extruder in order to avoid the breakage of the paper due to thickness variation,

j. Lift the ironing bar when the spliced part approaches it and lower it immediately,

k. Intimate the operator at the knife to reject the spliced part for about 8 meters.

6.0 CONCLUSION:

The study to identify and eliminate waste and improve the overall quality of outputs was conducted in a major gypsum plaster board production unit. The raw material consumed was to the extent of 2.026m2 per board. Stage rejections in the manufacturing process were resulting in revenue losses due to poor quality to the tune of Rs. 6, 91,488. Data Collection and Investigative analysis revealed that the paper preparation and splicing stages contribute to major portion of losses. After deploying focused quality improvement tools, several kaizens the redesign of paper cutters and paper guiding mechanisms have been proposed as solutions to solve the quality problems. Major revisions in the standard operating procedures have been proposed for the paper preparation and splicing operation stages of the manufacturing process.

Implementing the kaizens and poke yokes can result in reduction of wastages and losses in paper, thereby leading to substantial savings in the cost of manufacturing of gypsum plaster boards. The project study has therefore been successful in the waste reduction and defect prevention in the two critical stages of paper preparation and splicing operations. The

work also involved successfully proposing revised standard operating procedures for paper preparation and splicing operation stages with an aim to minimize wastages. A standard plan is also proposed for effective

data collection regarding the number of boards per stack as a further strategy for waste minimization.

7.0 REFERENCES:

1. Fasser, Y., and Brettner, D. Management for quality in high-technology enterprises. New York: Wiley-Interscience 2002.

2. Montgomery, D. Introduction to statistical quality control. Hoboken, NJ: John Wiley 2005.

3. WaheedaHanimbinti Ab. Rahman, Quality Improvement in Manufacturing Industries, International Journal for Quality research, 2009: 3, (4), pp-512-605.

4. DalgobindMahto, Anjani Kumar, Application of root cause analysis in improvement of product quality and productivity, National Institute of Technology (INDIA), Journal of Industrial and Engineering and Management, 2013: 1, (2), pp-16-53.

5. Tanvir Ahmed, Raj Narayan Acharjee, An Application of Pareto Analysis and Cause-Effect Diagram for Minimizing Defect Percentage in Sewing Section of a Garment Factory in Bangladesh, International Journal of Modern Engineering Research (IJMER), 2013: 3, (6), pp- 3700-3715.

6. Lauee Shaung. Implementation of 7 QC tools by using kaizen approach for sme manufacturing industry, University of Malaysia Pahangh, 2012

7. Deniels, R.C. Profit-related pay and continuous improvement: the odd couple, Engineering Management Journal. 1996: 6, (6), pp-233–236

8. Fabio De Felice, Antonella Petrillo, Stanislao Monfreda, Improving Operations Performance with World Class Manufacturing Technique, International Journal of Industrial and Engineering and Management, 2009 1, (5), pp 512-569.

Received on 21.02.2018 Modified on 22.03.2018

Asian Journal of Management. 2018; 9(2):947-953.

DOI: 10.5958/2321-5763.2018.00150.6