Chapter 29

Waste Elimination

Objectives

• Select and apply techniques for eliminating or preventing waste.

• Pull systems, Kanban, 5S, standard work, & poka yoke.

Kanban

• Kanban is a system that signals the need to replenish stock or materials or to produce more of an item.

• Kanban is also known as a pull approach.• If process inputs arrive before they are needed,

unnecessary confusion, inventory, and costs generally occur.

• If process outputs are not synchronized with downstream processes, the result is delays, disappointed customers, and associated costs.

Pull & Push Systems

• In a pull system, the customer order process withdraws the needed items (from a supermarket), and the supplying process produces to replenish what was withdrawn.

• Many manufacturing enterprises operate in the push system. Raw material and sub assemblies are pushed through the production process with the anticipation that they will be needed by the customers.

5S• Derives its name from the 5 Japanese terms beginning with “s”

utilized for lean production.• 5S’s create a workplace that is visibly organized, free of clutter,

neatly arranged, and clean.• 1. Serti (sort): To separate needed tools, parts, and instructions

from unneeded materials and remove the latter.• 2. Seiton (set in order): to neatly arrange and identify parts and

tools for ease of use.• 3. Seiso: (scrub): to clean up.• 4. Seiketsu (standardize): to maintain workplace in perfect

condition.• 5. Shitsuke (self discipline): to form a habit of following the first

four Ss.

Standard Work

• Each activity is organized around human motion to minimize waste.

• Standard Work: Each work activity is described specifying cycle time, task time, task sequence, and minimum inventory required to conduct activity.

• Work is performed the same way every time.

Poka (error) Yoke (avoid)

• Poka Yoke (Japanese): Mistake proof a process by building safeguards into the system to immediately find errors.

• Automatically eliminate sources of variation.• Example: using different colors for different

jobs.• With an increase in flexible work assignments

and cross trained personnel, poka-yoke becomes even more important.

Kaizen

• Kaizen means improvement by doing things better and setting and achieving higher standards.

• Process control can be enhanced by reducing non value added activities.

• The resulting work is more productive.

Summary• Kanban is a system that signals the need to replenish stock or

materials or to produce more of an item.• In a pull system, the customer order process withdraws the needed

items, and the supplying process produces to replenish what was withdrawn.

• 5S’s create a workplace that is visibly organized, free of clutter, neatly arranged, and clean.

• Standard Work: Each work activity is described specifying cycle time, task time, task sequence, and minimum inventory required to conduct activity.

• Poka Yoke (Japanese): Mistake proof a process by building safeguards into the system to immediately find errors.

• Kaizen means improvement by doing things better and setting and achieving higher standards.

Home Work

• 1. What is a Kanban system?• 2. What is the advantage of 5S?• 3. What does poka-yoka help accomplish?• 4. What is Kaizen?