Partnering in Lean Manufacturing Equals Savings

The Who, What, Where, When, How and Why
of Lean Manufacturing
By Agnieszka Perlinska and James Chapados

At the heart of our manufacturing operation lies the fundamental practice of Lean Manufacturing. Through the use of tools, such as Value Stream Mapping, Spaghetti Diagrams and Total Productive Maintenance (TPM), Interplex thinks lean right from the beginning. Our use of cellular manufacturing and single piece flow assembly allows us to maximize operational efficiencies with the flexibility of immediate line changeovers. Our Six Sigma DMAIC approach to problem solving and the use of experimental designs (DOE’s) for process development ensure robust and validated processes. We take great steps to make sure that our measurement systems reliably monitor and control our processes and your products. Use of process control charts and process capability indices ensure consistent and reliable products through the elimination and control of process variation.

What is Lean Manufacturing?

A company using Lean Manufacturing methods makes its product or delivers its service while working to:

  • Eliminate Waste which includes:
    • Process design flaws
    • Overproduction or service effort
    • Excess Work in Process (WIP)
    • Waiting
    • Unnecessary movement
    • Rework or scrap
    • Defects in product or service
    • Reduce Cycle Time (the time from order to ship)
    • Improve the Quality of processes and product or service

These three main components of Lean Manufacturing are interrelated. If one is improved, the other two are also positively impacted.

  • A company that machines pump parts worked at significantly reducing its scrap rate. In so doing, it improved its manufacturing processes that resulted in better quality while reducing cycle time. Both were the result of less rework and reduced need for inspection.
  • A company that builds wire harnesses for medical equipment worked to reduce its cycle time. It did this by cross training and certification of workers and making them responsible for inspecting their own work. Workers were more competent, and the increased skills allowed workers to assist each other when one got behind. The increased competency and ability to assist each other allowed them to make harnesses in almost half the time as before, with fewer mistakes, meaning less rework and scrapped material. Self inspection also reduced mistakes and the amount of time a harness had to be inspected by quality assurance.
  • A steel foundry worked to find ways to improve their quality by better controlling their processes. The result was more predictable material and a higher yield of poured parts. Yield increased from 85% to 98%. In doing so, they reduced the number of pours they had to do to fill an order, reducing their cycle time. By standardizing, their improved processes made it easier for people to be trained and to tell when they were doing a task properly.
  • A mortgage company was taking up to six weeks getting information processed after sales had been closed. It was also taking over a thousand pages of paper for each processed mortgage. By rethinking how they processed their paperwork, they were able to reduce the handoffs and paperwork queues by more than 90%. Their processing time was cut by five weeks. They were also able to cut the amount of actual paper used to one quarter of that used previously. Reducing the number of handoffs and stacks of paper, mistakes were also significantly reduced.

Who Makes a Company Lean?

Every person working in a company is involved with helping a company become a lean company. Implementing and sustaining lean is a change in a company's culture that involves three key components:

  • Workers need to understand and commit to becoming more flexible in their jobs so that they can help the company respond more quickly to changing demand.
  • People doing the work need to have responsibility to make the immediate decisions that impact quality, cycle time, and waste.
  • All the people in the company need to understand that they are working together to successfully respond to market demands and customer needs.

Why is Lean Manufacturing Important?

Implementing lean methods helps a company become customer responsive, that is: provide customers with what they want, in the manner they want it, at the time they demand it, at the price they are willing to pay, and do so in a way that makes a profit.

Where Should Lean Principles Be Applied?

Lean principles and tools should be applied throughout the whole supply chain, from the time the product is ordered to the time the product is shipped. Thus lean methods are applicable not only on the manufacturing floor but in all the other areas that support the manufacturing process: sales, purchasing, planning, engineering and product development, and shipping.

Lean principles and tools apply to and affect both physical and human processes and focusing them upon continuously improving product or service quality and speed.

When Should Lean Be Implemented?

Lean implementation program focuses on both the long and short term planning objectives. Before implementing lean, a company needs to define and analyze both their current and future business strategic planning objectives. Lean can be used as a proactive measure to reach strategic objective during times of stability or growth. Lean can be also used as a reactive measure to address issues of inefficiencies during times of crisis.

How Does a Company Become Lean?

There is no one lean method. Instead, there are several core principles and a set of basic tools used for becoming and continuing to be a "lean" company.

The key principles are:

  • Making product or delivering service must be the central organizing point for determining the flow of the work or service with all other activities supporting the manufacturing or service delivery.
  • Material flow and information flow is integrated, matching how it is made, be kept constant to the demand of the customer, and is simple and visible.
  • A product or service can only be provided as fast as the slowest part of the material or information flow.
  • The people who make the product or deliver the service are the main drivers of productivity.
  • The quality of a product or service depends upon the knowledge, skills and commitment of the people responsible for manufacturing the product or delivering the service.
  • True excellence and competitive advantage result from merging physical and human process and focusing them upon continuously improving product or service quality and speed.

Lean Tools

There are basic tools and methods used to address each of the three areas of lean manufacturing initiative:

Tools for Eliminating Waste:

Process Mapping and Redesign (also known as Value Stream Mapping)

  • Process mapping and redesign involves examining physical work, human process, and information. It is done by workers first describing the process "as is" and documenting it. Second, workers analyze each step and figure out ways to simplify the work, while identifying and determining ways to eliminate waste. Third, workers develop and implement ways to integrate changes into the system, document and automate them.
  • Process mapping and redesign allows workers to identify which steps do not add value and eliminate unnecessary hand-offs, which results in eliminating waste, reducing cycle-time and indirectly improving quality.

Work Standardization

Work standardization is the making of clear written and illustrated descriptions that help people understand how to make or do something right the first time, quickly, cost effectively, and safely.

    

Mistake Proofing

  • Mistake proofing is a quality assurance approach that prevents defects by catching errors and non-standard conditions before they turn into defects.
  • Mistake proofing relies on sensing mechanisms called paka-yoke that are installed where defect-causing conditions usually arise and prevent these conditions to occur by signaling when problems occur.

Visibility Management Tools

  • The visibility management tools allow people to communicate with simple signals or pictures rather than sheet of texts or complex computer screens. For example, instead of having to read an order form to check if you are low on parts, a single card system in the pull/kanban system will automatically trigger a restocking order.
  • Visibility management tools include: kanbans, andon lights, color coded pipes, machine parts or floor spaces, min-max bins, cross-training and certification boards and many others. These are designed tools to integrate material flow and information flow, and match how product is made.

Inventory Management

Besides visibility management tools such as min-max bins for inventory control, the "point of use inventory" is the most important lean tool for inventory management. At "point of use inventory" raw materials are moved from a central stockroom to the point of consumption. Point of use inventory has many benefits:

  • Reduced handling
  • Reduced number of hand-offs
  • Higher inventory accuracy
  • Lower stock levels

Continuous Improvement Methods and Tools

  • Continuous improvement has its foundation in the tool called Plan-Do-Check-Act Cycle. Effective change is incremental and depends on the organization's ability to continuously incorporate feedback into all activities. Successful initiatives consists of those four stages: Planning, Doing, Checking and then Acting on the data and feedback.
  • Using a Plan-Do-Check-Act Cycle for addressing quality and process improvements involves the use of data collection and cause analysis tools, specifically run chart, pareto charts, and cause analysis tools such as the fishbone diagram.
    

Tools for Reducing Cycle Time:

Process Mapping and Redesign

Work Station Organization

Disorganized work stations are one of the biggest problems that affect waste, efficiency and quality. Work station organization strives to organize the workplace so that everything has its place and is in its place. Emphasis should also be placed on keeping the tools within easy reach.

Quick set-up and Changeover

Quick set-up and Changeover principle is about finding ways of reducing set-up and changeover times on machines. To produce economically in smaller lots, a company must learn how to reduce the time required for changeovers. This can be achieved by:

  • Figuring out what steps of changeover can be done while the machine is still running the previous job
  • Transport all the necessary tools and parts to the machine while it is still running the previous job
  • Prepare operating conditions in advance
  • Standardize functions to eliminate the need for adjustments
  • Use devices that automatically position the parts without measurement
  • Use parallel operations with a few people working simultaneously
  • Use clamps instead of nuts and bolts
  • Use numerical settings to eliminate trial and error adjustments

Total Preventive Maintenance

TPM is a comprehensive, company-wide approach for reducing equipment-related losses by involving operators in maintaining and cleaning their machines on a daily basis.

Cellular Manufacturing or One Piece Flow

  • Cellular manufacturing is a method of moving one piece at a time through each manufacturing step, in an environment where the raw materials start at one end of the cell and move from one station to another in a continual flow to emerge as a finished product at the other end.
  • Reorganizing work and workers into product or product family groups allow for the most efficient use of space, machines, and workers. It significantly speeds throughput, improves quality, and helps reduce costs.
  • This method is different from the traditional manufacturing where parts move in batches from one process step to another, often sitting until they are queued up for further assembly. This kind of process of large-lot production builds delays because no item can move on to the next set up until all the items in the lot have been processed.

Cross-training and Certification / People Sharing

  • Cross-training and certification enables employees to perform different functions within a process and lets the team take full responsibility for their work. The People who make the product or deliver the service are the main drivers of productivity. The quality of a product of service depends upon the knowledge, skills and commitment of the people responsible for manufacturing the product or delivering the service.
  • The use of certification boards provide people in teams with a clear understanding of the teams skills and abilities, encourages people to cross train, and allows teams to decide who can work on what and share resources throughout the company.

Continuous Improvement Methods and Tools

Tools for Improving Quality:

  • Process Mapping and Redesign
  • Work Standardization
  • Cellular Manufacturing / One Piece Flow
  • Mistake Proofing
  • Visibility Management Tools
  • Cross-training and Certification
  • Continuous Improvement Methods and Tools
  • Cell-centered Support Activities

References:

  • World Class Manufacturing by Richard Schonberger
  • Lean Thinking by James P. Womack and Daniel T. Jones
  • Cycle Time Management by Patrick Northey and Nigel Southway
  • One Piece Flow by Keniche Sekine
  • JIT Implementation Manual by Hirouki Hirano
  • The Shingo System: Modern Approaches to Manufacturing Improvement by Alan Robinson
  • A Revolution in Manufacturing: The SMED System by Shigeo Shingo
  • TPM Total Productive Maintenance by Seiichi Nakajima
  • Making the Numbers Count by Brian Maskell
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