OM Ch.16
Toyota Production System
*Continuous improvement* - Build an organizational culture and value system that stresses improvement of all processes, kaizen - Part of everyone's job *Respect for people* - People are treated as knowledge workers - Engage mental and physical capabilities - Empower employees
The 5Ss
- *Sort/segregate* - when in doubt, throw it out - *Simplify/straighte*n - methods analysis tools - *Shine/sweep* - clean daily - *Standardize* - remove variations from processes - *Sustain/self-discipline* - review work and recognize progress Additional S's: - *Safety* - built in good practices - *Support/maintenance* - reduce variability and unplanned downtime
TPS Elements
- Andon - Pull System / Kanban - Standard Work Practices - Minimal Machines - Kaizen Area - Jidoka - Level Schedules - JIT - Respect for People / Empowered Employees - Assembly Components
Lean Operations
- Broader than JIT in that it is externally focused on the customer - Starts with understanding what the customer wants - Optimize the entire process from the customer's perspective
Increased Flexibility
- Cells designed to be rearranged as volume or designs change - Applicable in office environments as well as production settings - Facilitates both product and process improvement
Supermarket - Pull system
- Customers choose exactly what they want - Supply merchandise in a simple, efficient, timely manner - Each production line is the customer for the preceding line - Following line comes and chooses the items it needed and only those items - Preceding line would replace only the replacement items for the ones that the following had selected
Impact on Employees
- Employees may be cross trained for flexibility and efficiency - Improved communications facilitate the passing on of important information about the process - With little or no inventory buffer, getting it right the first time is critical
Reduce Setup Costs
- High setup costs encourage large lot sizes - Reducing setup costs reduces lot size and reduces average inventory - Setup time can be reduced through preparation prior to shutdown and changeover
Just-In-Time, TPS, and Lean Operations
- JIT focuses on continuous forced problem solving - TPS emphasizes continuous improvement, respect for people, and standard work practices in an assembly-line environment - Lean operations emphasize understanding the customer
Remove Variability
- JIT systems require managers to reduce variability caused by both internal and external factors - *Variability* is any deviation from the optimum process - Inventory hides variability - Less variability results in less waste
Kanban
- Japanese word for "card" - The card is an authorization for the next container of material to be produced - A sequence of kanbans pulls material through the process - Many different sorts of signals are used, but the system is still called a kanban
Distance Reduction
- Large lots and long production lines with single-purpose machinery are being replaced by smaller flexible cells - Often U-shaped for shorter paths and improved communication - Often using group technology concepts
Eliminate Waste (2)
- Other resources such as energy, water, and air are often wasted - Efficient, sustainable production minimizes inputs, reduces waste - Traditional "housekeeping" has been expanded to the 5Ss
Sources of Variability
- Poor production processes resulting in improper quantities, late, or non-conforming units - Unknown customer demands - Incomplete or inaccurate drawings, specifications, or bills of material -> Both JIT and inventory reduction are effective tools in identifying causes of variability
Just-In-Time (JIT)
- Powerful strategy for improving operations - Materials arrive where they are needed when they are needed - Identifying problems and driving out waste reduces costs and variability and improves throughput - Requires a meaningful buyer-supplier relationship
Level Schedules
- Process frequent small batches rather than a few large batches - Make and move small lots so the level schedule is economical - Freezing the schedule closest to the due dates can improve performance
Reduce Inventory
- Reducing inventory uncovers the "rocks" - Problems are exposed - Ultimately there will be virtually no inventory and no problems - Shingo says "Inventory is evil"
Building a Lean Organization
- Use JIT techniques - Build systems that help employees produce perfect parts - Reduce space requirements - Develop partnerships with suppliers - Educate suppliers - Eliminate all but value-added activities - Develop employees - Make jobs challenging - Build worker flexibility
Eliminate Waste
- Waste is anything that does not add value from the customer point of view - Storage, inspection, delay, waiting in queues, and defective products do not add value and are 100% waste
Kanban (2)
- When the producer and user are *not in visual contact*, a card can be used; otherwise, a light or flag or empty spot on the floor may be adequate - Usually each card controls a specific quantity or parts although multiple card systems may be used if there are several components or if the lot size is different from the move size
Reduced Space and Inventory
- With reduced space, inventory must be in very small lots - Units are always moving because there is no storage
JIT Inventory
-> Inventory is at the *minimum level* necessary to keep operations running
JIT Partnerships
-> exist when a supplier and purchaser work together to remove waste and drive down costs Four goals of JIT partnerships are: - Removal of unnecessary activities - Removal of in-plant inventory - Removal of in-transit inventory - Improved quality and reliability
Ohno's Seven Wastes
1) Overproduction 2) Queues 3) Transportation 4) Inventory 5) Motion 6) Overprocessing 7) Defective products
JIT/TPS/Lean Operations
Good production systems require that managers address three issues that are pervasive and fundamental to operations management: eliminate waste, remove variability, and improve throughput
CHAPTER 16
JIT, TPS, and Lean Operations
JIT Scheduling
Schedules must be communicated inside and outside the organization Level schedules - Process frequent small batches - Freezing the schedule helps stability Kanban - Signals used in a pull system
JIT Quality
Strong relationship: - JIT cuts the cost of obtaining good quality because JIT exposes poor quality - Because lead times are shorter, quality problems are exposed sooner - Better quality means fewer buffers and allows simpler JIT systems to be used