Comparative study on the relationship between just-in-time production practices and operational performance in manufacturing plants

Abstract

This study analyzes the differences in approaching JIT production across countries in order to identify alternative paths to high manufacturing performance. We applied ANOVA and regression techniques to the database of High Performance Manufacturing Project to examine the similarities and differences across countries in JIT implementation and the effect of JIT production practices on operational performance. The results indicated that JIT production practices were implemented in different ways across the countries. We found that the relationship between JIT production practices and plant performance is contingent on the national context and infrastructure practices in quality and workforce management. JIT delivery by suppliers, JIT layout, and setup time reduction were found to be the most effective approaches to improve cost, delivery, and flexibility. This study highlights the important role of shop-floor communication and information sharing, which should be focused for maximizing the benefits of JIT implementation.

Appendices

Appendix A: Description of Survey Respondents

Table 5 Characteristics of survey respondents

Table 6 Survey respondents

Appendix B: Survey Questionnaire

Question Items of JIT Scales, Quality Management Scales, and Workforce Management Scales (Factor loadings are given in parentheses following each item)

Just-in-Time Delivery by Suppliers

• 1. Our suppliers deliver to us on a just-in-time basis (.79)

• 2. We receive daily shipments from most suppliers (.68)

• 3. We can depend upon on-time delivery from our suppliers (.76)

• 4. Our suppliers are linked with us by a pull system (.65)

• 5. Suppliers frequently deliver materials to us (removed)

Just-in-Time Link with Customers

• 1. Our customers receive just-in-time deliveries from us (.87)

• 2. Most of our customers receive frequent shipments from us (removed)

• 3. We always deliver on time to our customers (removed)

• 4. We can adapt our production schedule to sudden production stoppages by our customers (removed)

• 5. Our customers have a pull type link with us (.73)

• 6. Our customers are linked with us via JIT systems (.88)

Leveled Master Schedule

• 1. Our master schedule repeats the same mix of products, from hour to hour and day to day (.84)

• 2. The master schedule is level-loaded in our plant, from day to day (.77)

• 3. A fixed sequence of items is repeated throughout our master schedule (.75)

• 4. Within our schedule, the mix of items is designed to be similar to the forecasted demand mix (removed)

• 5. We use a repetitive master schedule from day to day (.81)

• 6. Our master schedule does not facilitate JIT production (removed)

Pull system

• 1. Suppliers fill our kanban containers, rather than filling purchase orders (.76)

• 2. Our suppliers deliver to us in kanban containers, without the use of separate packaging (.76)

• 3. We use a kanban pull system for production control (.82)

• 4. We use kanban squares, containers or signals for production control (.82)

Setup Time Reduction

• 1. We are aggressively working to lower setup times in our plant (.71)

• 2. We have converted most of our setup time to external time, while the machine is running (.60)

• 3. We have low setup times of equipment in our plant (removed)

• 4. Our crews practice setups, in order to reduce the time required (.78)

• 5. Our workers are trained to reduce setup time (.80)

• 6. Our setup times seem hopelessly long. (.55)

JIT Layout

• 1. We have laid out the shop floor so that processes and machines are in close proximity to each other (.73)

• 2. We have organized our plant floor into manufacturing cells (.57)

• 3. Our machines are grouped according to the product family to which they are dedicated (.51)

• 4. The layout of our shop floor facilitates low inventories and fast throughput (79)

• 5. We have located our machines to support JIT production flow (.79)

• 6. We have located our machines to support JIT production flow (.66)

Multi-Functional Employees

• 1. Our employees receive training to perform multiple tasks (.78)

• 2. Employees at this plant learn how to perform a variety of tasks (.82)

• 3. The longer an employee has been at this plant, the more tasks they learn to perform (.66)

• 4. Employees are cross-trained at this plant, so that they can fill in for others, if necessary (.78)

• 5. At this plant, each employee only learns how to do one job (.66)

Process Control

• 1. Processes in our plant are designed to be “foolproof” (.75)

• 2. A large percent of the processes on the shop floor are currently under statistical quality control (.84)

• 3. We make extensive use of statistical techniques to reduce variance in processes (.81)

• 4. We use charts to determine whether our manufacturing processes are in control (.70)

• 5. We monitor our processes using statistical process control (.87)

Information Feedback

• 1. Charts showing defect rates are posted on the shop floor (.71)

• 2. Charts showing schedule compliance are posted on the shop floor (.71)

• 3. Charts plotting the frequency of machine breakdowns are posted on the shop floor (.68)

• 4. Information on competitive performance is readily available to employees (.81)

• 5. Information on productivity is readily available to employees (.76)

Housekeeping

• 1. Our plant emphasizes putting all tools and fixtures in their place (.69)

• 2. We take pride in keeping our plant neat and clean (.85)

• 3. Our plant is kept clean at all times (.86)

• 4. Employees often have trouble finding the tools they need (.57)

• 5. Our plant is disorganized and dirty (.79)

Preventive Maintenance

• 1. We upgrade inferior equipment, in order to prevent equipment problems (.71)

• 2. In order to improve equipment performance, we sometimes redesign equipment (.55)

• 3. We estimate the lifespan of our equipment, so that repair or replacement can be planned (.74)

• 4. We use equipment diagnostic techniques to predict equipment lifespan (.75)

• 5. We do not conduct technical analysis of major breakdowns (.55)

Supplier Quality Involvement

• 1. We strive to establish long-term relationships with suppliers (.64)

• 2. Our suppliers are actively involved in our new product development process (.72)

• 3. Quality is our number one criterion in selecting suppliers (.55)

• 4. We use mostly suppliers that we have certified (.61)

• 5. We maintain close communication with suppliers about quality considerations and design changes (.80)

• 6. We actively engage suppliers in our quality improvement efforts (.77)

• 7. We would select a quality supplier over one with a lower price (removed)

Customer Involvement

• 1. We frequently are in close contact with our customers (.69)

• 2. Our customers seldom visit our plant (removed)

• 3. Our customers give us feedback on our quality and delivery performance (.70)

• 4. Our customers are actively involved in our product design process (.58)

• 5. We strive to be highly responsive to our customers’ needs (.72)

• 6. We regularly survey our customers’ needs (.71)

Task-Related Training for Employees

• 1. Our plant employees receive training and development in workplace skills, on a regular basis (.87)

• 2. Management at this plant believes that continual training and upgrading of employee skills is important (.76)

• 3. Employees at this plant have skills that are above average, in this industry (.58)

• 4. Our employees regularly receive training to improve their skills (.89)

• 5. Our employees are highly skilled, in this plant (removed)

Shop Floor Contact

• 1. Managers in this plant believe in using a lot of face-to-face contact with shop floor employees (.68)

• 2. Engineers are located near the shop floor, to provide quick assistance when production stops (.65)

• 3. Our plant manager is seen on the shop floor almost every day (.64)

• 4. Managers are readily available on the shop floor when they are needed (.66)

• 5. Manufacturing engineers are often on the shop floor to assist with production problems.(.63)

Small Group Problem Solving

• 1. During problem solving sessions, we make an effort to get all team members’ opinions and ideas before making a decision (.64)

• 2. Our plant forms teams to solve problems (.80)

• 3. In the past three years, many problems have been solved through small group sessions (.78)

• 4. Problem solving teams have helped improve manufacturing processes at this plant (.78)

• 5. Employee teams are encouraged to try to solve their own problems, as much as possible (.65)

• 6. We don’t use problem solving teams much, in this plant (.72)

Employee Suggestions—Implementation and Feedback

• 1. Management takes all product and process improvement suggestions seriously (.82)

• 2. We are encouraged to make suggestions for improving performance at this plant (.77)

• 3. Management tells us why our suggestions are implemented or not used (.76)

• 4. Many useful suggestions are implemented at this plant (.82)

• 5. My suggestions are never taken seriously around here (.72)

• 6. The plant has an informal strategy, which is not very well defined (.67)

Appendix C: Measurement Test

Table 7 Measurement analysis of JIT measurement scales

Appendix D: Chow Test Results

Table 8 Impact of JIT production practices on manufacturing cost

Table 9 Impact of JIT production practices on on-time delivery

Table 10 Impact of JIT production practices on volume flexibility

Table 11 Impact of JIT production practices on inventory turnover

Table 12 Impact of JIT production practices on cycle time