7. Require supplier quality assurance and implement a zero defects quality program: errors leading to defective items must be eliminated, since there are no buffers of excess parts.

A quality at the source (jidoka) program must be implemented to give workers the personal responsibility for the quality of the work they do, and the authority to stop production when something goes wrong. Techniques such as "JIT lights" (to indicate line slowdowns or stoppages) and "tally boards" (to record and analyze causes of production stoppages and slowdowns to facilitate correcting them later) may be used.

8. Small-lot (single unit) conveyance:

use a control system such as a kanban (card) system to convey parts between work stations in small quantities (ideally, one unit at a time).

In its largest sense, JIT is not the same thing as a kanban system, and a kanban system is not required to implement JIT (some companies have instituted a JIT program along with a MRP system), although JIT is required to implement a kanban system and the two concepts are frequently equated with one another.

Kanban Production Control System

A kanban is a card that is attached to a storage and transport container. It identifies the part number and container capacity, along with other information.

There are two main types of kanban (some other variations are also used):

1. Production Kanban (P-kanban): signals the need to produce more parts

2. Conveyance Kanban (C-kanban): signals the need to deliver more parts to the next work center (also called a "move kanban" or a "withdrawal kanban")

A kanban system is a pull-system, in which the kanban is used to pull parts to the next production stage when they are needed; a MRP system (or any schedule-based system) is a push system, in which a detailed production schedule for each part is used to push parts to the next production stage when scheduled.

The weakness of a push system (MRP) is that customer demand must be forecast and production lead times must be estimated.

Bad guesses (forecasts or estimates) result in excess inventory, and the longer the lead time, the more room for error.

The weakness of a pull system (kanban) is that following the JIT production philosophy is essential, especially concerning the elements of short setup times and small lot sizes.

Dual-card Kanban Rules

1. no parts made unless P-kanban authorizes production

2. exactly one P-kanban and one C-kanban for each container (the number of containers per part number is a management decision)

3. only standard containers are used, and they are always filled with the prescribed (small) quantity

Productivity Improvement With Kanban

1. deliberately remove buffer inventory (and/or workers) by removing kanban from the system

2. observe and record problems (accidents, machine breakdowns, defective products or materials, production process out of control)

3. take corrective action to eliminate the cause of the problems

JIT Just in time