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Electrical ground securing is a critical operation in ensuring safety and reliability within electrical systems. However, inefficiencies in this process can lead to increased risk of electrical hazards and operational disruptions. This paper presents a comprehensive application of the Six Sigma methodology to improve the efficiency and effectiveness of electrical ground securing operations. The study begins with a thorough analysis of the current state of the ground securing process, identifying key performance metrics, and pinpointing areas of inefficiency and potential improvement. Utilizing Six Sigma Define, Measure, Analyze, Improve, and Control (DMAIC) framework, a structured approach is employed to systematically address the identified issues. Through rigorous data collection and analysis, root causes of inefficiencies such as variability in grounding procedures, inadequate training, and inconsistent equipment maintenance are identified.

Fahad M. Sharique, Nithin K. Aili, Sibin Mathew and Ahad Ali

A. Leon Linton Department of Mechanical, Robotics and Industrial Engineering, Lawrence Technological University, Michigan, USA

xxx@ltu.edu, xxxx@ltu.edu, xxxx@ltu.edu and sali@ltu.edu

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Abstract

Conclusion

References

Methodology

Johnson, L. (2019). “Six Sigma Fundamentals and Its Application in Manufacturing,” Quality Control & Applied Statistics, 64(4), 334-340.

Zhao, F., et al. (2022). “Improving Ground Nut Securing in Automotive Assembly through Six Sigma Methodology,” Operations Management Research, 15(3), 203-219. 

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Introduction

In today's competitive industrial environment, cost-effectiveness, efficiency, and quality can only be guaranteed by operational process optimization. A critical component of assembly line operations is the proper attaching of ground nuts, particularly when constructing electrical components. The effectiveness of this process, as well as the caliber of the final product, affects the dependability and safety of electrical systems. Assembly lines can speed up the ground nut securing procedure and promote continuous improvement across the whole manufacturing process by implementing Six Sigma methodologies.

The purpose of this study is to investigate how applying the Six Sigma approach to the electrical ground nut securing process in an assembly line setting can improve its effectiveness and efficiency. This study aims to identify current process deficiencies, establish sustainable control mechanisms, analyze root causes of variation, establish performance metrics, and implement targeted improvements using an organized. By implementing the Six Sigma principles, businesses can ultimately reach greater standards of quality, dependability, and customer satisfaction, setting them up for success in today's fast-paced industrial environment.

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To sum up, there are several advantages to changing the tool angle specifications from 5–1200 degrees to 50–370 degrees, including a decreased risk of cross-threading and nut stripping. You can improve the integrity and dependability of threaded fastening connections and guarantee their performance and durability in a variety of applications by concentrating on optimal thread engagement, decreased material deformation, improved thread form, improved thread quality, and optimized machining parameters.

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Process Improvement of an Electrical Ground Nut Securing Operation in an Assembly Plant Using Six Sigma

Project Objectives

Phase 1: Define 

The issue of ground nut looseness in an assembly process refers to a situation where the nut used for grounding purposes becomes loose within the assembly, leading to electrical failures or malfunctions. This issue can occur due to various factors such as improper tightening during assembly, vibration or movement during operation, inadequate torque specifications, or degradation over time.

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Factors such as the materials used, the mechanism of torque transmission, and the precision of components can significantly impact the tool's performance. Additionally, environmental conditions, including temperature, humidity, and vibration, can affect the friction and resistance encountered during tool operation, thereby influencing both the angle and torque applied. Figure below shows a fishbone diagram of the main factors that can affect the process of securing ground by an operator in an assembly line.

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Figure 4. Process capability report of Angle 1

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Phase 3: Analyze

• When analyzing angle and torque measurements for a ground securing tool, the data that has been gathered is carefully examined to draw out important conclusions and trends.
• First, the distribution of angle and torque measurements is investigated using statistical analysis techniques.
• To evaluate the central tendency and variability of the data, calculations for measures like mean, median, standard deviation, and range must be made.
• Correlation analysis is then performed to investigate the relationship between torque measurements and angle.
• To acquire a thorough grasp of a ground securing tool's performance characteristics, it is imperative to analyze the angle and torque measurements.

• The Lower Specification Limit (LSL) and Upper Specification Limit (USL) for angle specifications on a ground securing tool can significantly impact the occurrence of stripping and cross-threading of a nut.
• If the angle specification falls below the LSL, there's a risk of insufficient torque being applied during the tightening process.
• This insufficient torque can result in loose connections, leaving the nut vulnerable to stripping, where the threads on the nut or bolt become damaged or worn out due to excessive force.
• Conversely, if the angle specification exceeds the USL, there's a risk of excessive torque being applied during tightening.
• This excessive torque can lead to cross-threading, where the threads on the nut and bolt fail to align properly, causing them to become misaligned or damaged.
• To further investigate the relationship between torque measurements and other pertinent variables, like angle or fastener size, correlation analysis is carried out.

Phase 4: Implementation

• Optimal Thread Engagement: The cutting edge will align with the thread profile more precisely and the nut and bolt threads will engage better if the tool angle is adjusted to a smaller range (50-370 degrees).
• Decreased Material Deformation: The integrity of the threads may be compromised by excessive material removal or displacement caused by a tool angle that is either too steep or too shallow.
• Better Thread Form: The dimensions and form of the threads, such as the pitch, crest, and root, are referred to as the thread form. This reduces the possibility of stripping, which occurs when the threads are unable to provide enough strength and grip.
• Improved Thread Quality: Threads with greater quality and consistency can be produced by narrowing the tool's angle range. The overall reliability of the fastening connection can be increased by producing threads with better mechanical qualities and tighter tolerances by optimizing the tool angle specifications.
• Optimized Machining Parameters: Cutting speed, feed rate, and depth of cut can all be optimized by reducing the range of possible tool angles. This will also improve thread accuracy, surface finish, and chip formation.

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Phase 5: Control

• Operator Grabs the Tool: The first step in the process is for the operator to grab the appropriate tool needed for the task.
• Loosen the Nut: After grabbing the tool, the operator proceeds to the nut that needs adjustment. Using the tool, they loosen the nut to prepare it for the subsequent steps.
• Secure the Ground on Stud: With the nut loosened, the operator then secures the ground on the stud. This may involve positioning a grounding wire or cable onto the designated stud or terminal to establish a secure electrical connection.
• Tighten the Nut: Once the ground is secured, the operator proceeds to tighten the nut using the same tool used to loosen it. Tightening the nut effectively completes the electrical connection and ensures stability.
• Quality Check: After tightening the nut, the operator performs a quality check to verify that the operation has been completed successfully. Additionally, the operator may use a torque wrench or other measuring devices to confirm that the nut is properly tightened.
• Operation Passed: If the quality check confirms that the nut is securely tightened and the ground is properly established, the operation is considered successful. The process flow diagram indicates that the operation has passed, and the equipment or system is ready for further use or operation.

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The objective of the project is to increase the electrical ground nut securing process's efficiency and effectiveness on a manufacturing line by applying Six Sigma methodology. The study aims to decrease errors, boost efficiency, and uphold consistent quality standards by thoroughly evaluating and improving the ground nut securing procedure. Ultimately, this would increase consumer trust and commitment to the produced goods.

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Implementing a knockdown station to track the tool angle specification and verify its compliance can be a proactive approach to reduce failure modes in manufacturing processes. By integrating a knockdown station into the production line, components can be systematically inspected for adherence to the specified tool angle parameters before proceeding further.

Figure 1 : Process flow diagram of ground nut secure operation

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Figure 2 : Block diagram for Electrical failures in a week

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Problem Statement

In the context of vehicle maintenance and operation, there exists a recurring issue where groundnuts within the vehicle's electrical system become loose, resulting in vehicle non-starting instances. This problem poses significant inconvenience and potential safety hazards for vehicle operators, leading to operational disruptions and potentially stranded vehicles. The challenge is to develop effective strategies or solutions to prevent ground nut loosening and mitigate its impact on vehicle functionality and reliability.

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Process Layout

Phase 2: Measurements

This phase is to verify the validity of data through the evaluation of the measurement system. The beginning step is the normality test of the data collected and an analysis of the process capability. For this phase data of all the Torque and Angle specification of the tools used to secure the groundnut is collected for the analysis. Table 1 shows the data of Torque and Angle data of the tool.

Table 1: Angle and Torque measurements of the tool

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Figure 3. Factors affecting the process of securing a ground nut

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Figure 5. Process capability report of Angle 2

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Figure 6. Process capability report of Torque

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Table 2: Angle and Torque measurements of the tool after knockdown added in the station

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Figure 7. Block diagram for Electrical failures in a week after implementation

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• In summary, there have been notable gains from using the Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) methodology to enhance the ground nut securing process by modifying the tool's angle specification.
• We have successfully decreased failure rates, minimized the risks of cross-threading and stripping, and improved the overall reliability of the fastening process by carefully analyzing and optimizing the tool angle specifications.
• In addition to producing observable benefits in terms of process dependability and efficiency, this effective Six Sigma initiative also cultivates an innovative and continuous improvement culture within the company, setting us up for long-term success in satisfying industry standards and customer expectations.

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Results

Data and Analysis