Fred Taylor and Henry Ford sought to address the weaknesses of craft production. Taylor’s scientific management and Ford’s factory innovations laid the foundation for mass production. Alfred Sloan’s managerial innovations and the role of organized labor in controlling work tasks and job assignments completed the system. Mass production rolled to victory after victory for decades.
Toyota faced daunting financial, technological, and labor relations challenges 50 years ago. Eiji Toyota concluded that mass production would not work in Japan. He and his production genius, Taichi Ohno, created a system that made a virtue of necessity. For example, the unavailability of capital spurred the development of flexible, right-sized machinery and quick changeovers. The legal restrictions on worker layoffs created the company’s image as a community and laid the foundation for intense employee involvement and problem-solving.
It took almost 30 years to perfect and drive his system through Toyota. He established the Operations Management Consulting Division (OMCD) to support Lean thinking in Toyota plants and suppliers. The system would have been remarkable under any circumstances. But today, we face the same daunting problems that Toyota faced half a century ago. Ohno’s approach is more relevant than ever.
A central goal of the lean system is to eliminate waste to improve profitability, the only effective strategy under the new economics. Lean activities are interrelated, mutually supportive, and informed by the same thinking.
The eight different kinds of muda (“waste”) are core lean attributes, as are the related concepts of mura (“imbalance”) and muri (overburden). Overproduction is the most severe waste. But Lean production is more than a scavenger hunt for muda. The positive goals of Lean production include creating flow so that the customer can pull and involving our workers in improvement activities.
5S and TPM are two keys to achieving production stability. 5S is a workplace optimization and standardization process aiming to support visual management. Visual management is managing by exceptions in a visual Gemba. Out-of-standard conditions are apparent and can be quickly corrected by countermeasures.
5S typically leads to Total Productive Maintenance (TPM), where production team members become involved in basic maintenance activities. TPM suggests the six significant losses that afflict equipment. The Machine Loss Pyramid concept highlights the importance of identifying hidden and minor failures. We harvest substantial benefits by involving our production team members in checking and improving equipment performance.
Standardized work is a process whose goal is to identify muda so that we can continually improve through team member involvement. Lean production and methods engineering differ substantially in their approach to standardized work. Through standardized work, we can enhance labor density by increasing the amount of value-added work in each process. We also seek to improve efficiency by reducing the workforce. Workers freed up by kaizen activity are redeployed. The implicit goal of standardized work is Kaizen.
JIT means producing the right part in the correct quantity at the right time. The objective of JIT is to create a constant flow of value so that the customer can pull. JIT supports quick response to customers, a better sense of takt time, and abnormality control. The JIT system comprises Kanban and production leveling or heijunka—the six Kanban rules.
Rule 1 – Never Ship Defective Items
Rule 2 – The Customer Withdraws Only What Is Needed
Rule 3 – Produce Only the Quantity Withdrawn by the Customer
Rule 4 – Level Production
Rule 5 – Use Kanban to Fine-Tune Production
Rule 6 – Stabilize and Strengthen the Process
And the three types of pull systems.
Type “A” Pull Systems are the most common and require replenishing or plugging gaps created in the finished goods or parts store when the customer withdraws an amount or product.
Type “B” Pull Systems are used when order frequency is low and customer lead time is long (e.g., custom producers). The pacemaker is usually farther upstream than in Type A systems. Downstream work proceeds sequentially through FIFO (first in, first out).
Type “C” Pull Systems are a combination of types A + B running in parallel. High-frequency orders are put through an A system, and low-frequency orders are placed through a B system. Type C systems work best for manufacturers producing both high and low-frequency items.
Conveyance takes on greater importance in the Lean system. Both fixed time and fixed quantity conveyance are possible. Value stream mapping is a language that helps us grasp our current condition and identify Kaizen opportunities.
The Jidoka concept was invented by Sakichi Toyota and developed and expanded by Shigeo Shingo. Jidoka is essential to achieve our best quality targets at the lowest cost in the shortest lead time. Jidoka requires a fundamental rethinking of quality management, away from statistical quality control and toward 100% inspection and poka-yoke. A poka-yoke is a simple, inexpensive, and robust tool that inspects 100% of items, detects errors that might lead to defects, and provides quick feedback to take countermeasures. Team members are the best source for polka-yolks.
Poka-yokes either shut down equipment or warn when an error has been detected. Poka-yokes typically identify abnormalities in product characteristics, differences concerning a fixed value, or missing process steps. Sensor technology is a rich field that produces unlimited support for poke-yoke development. Sensors can be contact or noncontact type.
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