Passenger Car Seat Quality Improvement Through Poka-Yoke Technique

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ISSN (Print): 2321-5747, Volume-1, Issue-2, 2013

82

Passenger Car Seat Quality Improvement Through Poka-Yoke Technique

Deshmukh D. B. & Mandale M. B.

Dept. of Mechanical, Rajarambapu Institute of Technology, Sakhrale Rajaramnagar415409 E-mail : [email protected]

Abstract - The Poka-Yoke entrance is promoted in the manufacturing industry as a way of improving productivity by reducing errors using often very simple modification. This paper gives that, as Poka-Yokes are designed to make process mistake proof and zero quality control. This paper provides a case study demonstrating the use of the Poka-Yoke approach in a Assembly line of Seat manufacturing process highlighting how they served to improve accessibility to work by fulfilling Universal Design principles.

Keywords - Poka yoke, Zero defects, Quality control I. INTRODUCTION

The Poka-Yoke (a Japanese word that means mistake proofing) technique was first invented in 1961 by Shigeo Shingo. Poka-Yoke uses devices on process equipment to prevent the human or machine errors that result in defects, or to inexpensively inspect each item produced to determine whether it is acceptable or defective. Poka- Yoke-designed manufacturing devices are one of the bases of Shingo’s zero quality control concepts, which mean that the defect rate in a production system is zero.

Poka-Yoke design can dramatically decrease the risk of producing defectives products (Shingo, 1986). The Poka- Yoke philosophy also aims to make work easier and prevent errors caused by monotony or other process related causes. In many productive environments, there is a tendency to equate speed with productivity. Traditional engineering processes are designed to increase the efficiency of an operation by enabling people and machines to work faster, and processes are usually complicated to achieve greater speed; yet it is these complications which cause many of the errors people and equipment make, resulting in more defective products. By contrast, the Poya-Yoke philosophy aims to increase productivity by simplifying processes, making them more efficient, reducing the number of errors that need to be

corrected, and increasing the overall efficiency of the system.

It is often assumed that adaptations to support the diversity of situations faced by disabled workers present a huge challenge for designers. In fact, the extra intellectual effort needed to overcome disability often results in a better final design for both the disabled and non-disabled users. In this paper Poka-Yoke represents a suite of simple and relatively inexpensive ways of improving access to work and the productivity and performance of disabled and non-disabled workers, and a powerful tool for implementing Universal Design in the workplace.

II. MANUFACTURINGPROCESS

This study was conducted at an automotive company of Seat manufacturing of passenger car.

Sl.

No .

Conveyor Total no of stations

Work Stations

Buffer stations

Testing stations

Replac ement Station

1 LH

Conveyor 12 6 4 1 1

2 RH

Conveyor 12 6 4 1 1

Seat assembly line is for assembling the seat of various models of passenger car. There are total 36 variants of Seats

There are two separate lines for LH and RH seats.

Each line has 12 nos. of station with two end lifters and return conveyor with two numbers of stoppers. Both lines have same schedule for seat manufacturing. Both lines have a same test station at station no. 9, Recliner and slider effort test station for RH & for LH.

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International Journal on Mechanical Engineering and Robotics (IJMER)

83 2.1 Recliner and slider effort test station for RH & for

LH (Station 9):

This is an automatic station. This station is used to measure the slider and reclining efforts of LH & RH seat. This station has load cell and PC for measure the slider effort & reclining effort. PC will measure the effort of slider & recliner movement through load cell.

LH and RH seat are not tested on same machine, i.e. On RH line test station only RH seat will get tested. If LH seat comes on RH line it will not get tested and station will bypass the test. Same is applicable for LH line; on LH line RH seat will not get tested.

Thumb wheel is provided at this station & system console is for selecting the manual action of station 9 actuators.

III. PROBLEM IDENTIFICATION

The next step in this project involved identifying problems that occur in the station no.9. The problem identification methodology employed in this study is shown in Table 1. At station no. 9 Seat testing equipment is mounted for testing the sliding effort and reclining effort. It is essential to have proper position of seat at particular station. The main types of defects found were mis-location, and half insert. Some possible causes for these three problems are workers not able to follow or are not following the standard operation procedure (SOP),

From observations and detailed interviews with the operators, it is believed that human error is a major issue in this production line. Since human cause is the major factor in this problem, as well as method and machine factor, attempt will be made to employ Poka Yoke or a mistake proofing technique.Problem identification has been conducted by following activities

Table 1 Step Main activities

1 Observation of the current operations at station no 9 and production line:

Observation at Seat testing station and entire production line. Observation have made considering worker, working method , layout and working condition

2 Company documentation study:

Documents of company such as Operation standards, process flow layout, worker complaint, customer complaint, process flow chart. investigation report, procedure documentation etc.

3 Unstructured interview:

Discussions were carried out in to get a rough idea on how a problem occurs. This process is conducted at collecting useful experiences, opinions and explanations from experienced personnel who works in the particular field, for example, supervisors, the Station workers, Quality assurance executive and senior engineers. It has given various opinions and views from different perspectives and level of expertise of the interviewees were gained.

4 Data collection and analysis:

Applicable data regarding problem identification was gathered and analyzed.

The Cause and Effect diagram is made to identify possible reasons to the problem faced in the assembly line. The four major reasons being studied included material factor, human factor, machine and method factor

The results obtained through activities in table 1 are given below.

Quality problem occur because of following reasons 1. Improper orientation of pallet on conveyor.

2. Wrong position mounting of seat on pallet.

3. Loose mounting of seat on pallet

5. Loss of orientation of seat or pallet because of vibration

6. Loss of orientation of seat or pallet because of foreign disturbance

7. Failure of recliner lever of seat IV. POKA-YOKE DEVICE

Poka yoke device is designed in such a way that at all conditions seat will pass in standard defined orientation into the station no. 9 for that simple fencing assembly has been designed according to the shape of seat and standard orientation of seat. This fencing device is mounted on conveyor before the station no 9. All the seats pass through fencing device in only proper orientation. If off standard seat comes, it does not pass through the fencing assembly. Schematic views with its part names have been shown in fig. below.

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84 Fig.1: Poka-yoke device

Fig. 2 : Isometric view of poka-yoke device

SR.NO DESCRIPTION QTY

1 Aluminium Extrusion 60x60 1 2 Aluminium Extrusion 60x60 1

3 Supporter 2

4 Screw Button Head M5x20 8

5 Extrusion Cover plate 5

6 M.S. Sheet 1

7 Connecting Plate 9

8 Screw Button Head M5x16 40

9 Aluminium Extrusion 60x60 1 10 Aluminium Extrusion 60x60 1 11 Aluminium Extrusion 60x60 1 12 Aluminium Extrusion 60x60 1

13 Foundation Bolt M10x75 2

14 Hexagonal NutM10 2

15 Aluminium Extrusion 60x60 1

16 Support structure 1

17 Bracket-1 1

18 Bracket-2 1

21 Rework Support 1

The main function at station no. 9 is to check the sliding action of seat, measurement of force for sliding the track of the seat , check the reclining action of the seat, measurement of force to reclining action. All the testing are carried out putting the weigh equal to average man on the seat .

Fig. 3: Seat testing machine at station no 9.with poka- yoke device

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85 V. RESULTS AND DISCUSSIONS

The main selection criteria to be considered is the efficiency of the proposed Poka-yoke device in eliminating the defect, and more importantly, it has eliminated all the bad orientations seats and it results in increases overall quality and productivity performance.

If false orientation seat comes on conveyor near fencing device it is stopped by the fencing device due to mismatching of seat shape or orientation to the shape of fencing device.

VI. CONCLUSION

This paper has presented the findings of quality improvement using Poka Yoke technique for a Passenger car seat assembly process. This study has identified the problems affecting the quality at Seat testing station. The problem has been overcome by using a fencing device where a mistake proofing device has been proposed and tested.

VII. REFERENCES

[1] Lee Ing Yi, Sha’ri Mohd Yusof, Product Quality Improvement Through Poka Yoke Technique Journal Mechanical June 2007, No. 23, 74 – 82 [2] Cristóbal Miralles, Raymond Holt, Universal

design of workplaces through the use of Poka- Yokes: Case study and implications, Universidad Politécnica de Valencia (SPAIN) September 2011.

[3] Michael Fisher,Process Improment by Poka- yoke,Volume48. Number7.199 pp 264-266ISSN 0043-8022.

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