Just In Time Manufacturing Push Manufacturing vs. Pull Manufacturing Push System: Traditional production system as parts are processed based on the master production schedule (MPS). Materials are pushed on the next process regardless of whether they are required at the time or not. Pull System (=JIT): The system designed to build parts only what is required by the next operation. Uses kanban tools such as cards, containers, etc.

P Push System CS Sp P P PP Plant C : customers S (1)(2) (3) (4) (5)(6) (7) (1)-(7): sequence of “PUSH” : flow of products (or parts, or raw materials, etc.) P Sp : process : shipping/delivery : suppliers

P Pull System CS P P PP Plant C : customers S (1) (2) (3) (4)(6) (5) (7) (1)-(12): chain reaction sequence : flow of products (or parts, or raw materials, etc.) P Sp : process : shipping/delivery : suppliers Sp (8) (7) (8) (9) (10) (11) (12) (11) : request for products (or parts, or raw materials, etc.) This action is called “PULL.”

Characteristics of Push System: Regardless of a large size stock inventory, goods customers want are not always available since the Push system may produce goods without knowing what customers want. Defective products are likely to be shipped since a Push plant is not so organized that defective parts are hidden in a big pile of inventory and the cause of a problem is not easily found. Few product selections and long lead time are realized by customers since in the Push system people are not trained and layout/machines are not designed to respond to a sudden process change request. An unorganized Push plant gives a poor impression to visitors (including customers) since they naturally think that the way people treat the plant is also the way they treat the products.

Characteristics of Pull System: Regardless of a small size stock inventory, goods customers want are always available since the JIT system produces goods knowing what customers want. Only high quality products are made since a JIT plant is well organized that defective parts are easily located/rejected/reworked and the cause of a problem is quickly found. Variety of product selections and quick design changes are provided to customers since in the JIT system people are well trained and layout/machines are designed to provide any necessary parts/products in timely manner. An clean/organized JIT plant gives a good impression to visitors (including customers) since they naturally think that the way people treat the plant is also the way they treat the products.

Inventory hides many problems. Source: / /

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Principles Behind JIT Manufacturing System 5 S 3 Ms –7 wastes Visual Control Kanban Continuous Improvement (Kaizen)

5 S: Level 1: Sort (Seiri) –Sort out necessary from unnecessary items Level 2: Straighten (Seiton) –Everything should be placed in order. –Everything should be easy to use. –Shouldn’t take time to locate or reach anything. Level 3: Sweep (Seiso) –Keep your shop (office) clean. –Should be easy to identify trouble with equipment.

Level 4: Sanitize (Seiketsu) –Maintain the first three guidelines (Sort, Straighten, and Sweep) –Maintain and improve neatness. Level 5: Sustain (Shitsuke) –Maintain the first four guidelines (Sort, Straighten, Sweep, and Sanitize). –Discipline all people to maintain those 5 S and make it as habit.

3 M: To improve manufacturing efficiencies, it is necessary to eliminate the following 3 Ms. Waste (Muda): Any work that does not add value to the product. Unevenness (Mura): For example, are work load of all manufacturing cells balanced? Overburden (Muri): For example, do workers work too many hours?

7 Wastes (Mudas) in Manufacturing: Muda for correction: When we must correct problems after mistakes. Example: Repackaging after knowing a missing part. Muda for overproduction: When we make more products than customers require. Muda for processing: When we perform more processes than it is actually needed. Muda for transportation: When we move materials and parts for more long distance than it is needed.

Muda for inventory: When we have more inventory that it is needed. Muda for motion: When we are not efficient in walking and using our hands to do our work. Muda for waiting: When we have to wait before we can continue to work on a job.

Visual Control: Make it easy for everyone to identify the state of normal or abnormal conditions. Housekeeping Organization Consistency

Disorganized Work Place

Organized Work Place

Kanban: Kanban is a fundamental tool to make people participating in manufacturing activities visualize manufacturing status so that those people can pursue the work to accomplish “Pull” production in the most effective manner. (In some sense, Kanban is like a controller for Pull system.)

There are two major types of Kanbans. Withdrawal Kanban (Pull Kanban): It authorizes the movement of parts from one workstation to another. Production Kanban: It specifies the type and quantity of product which the earlier process must produce.

Withdrawal (Pull) Kanban: Example

Production Kanban: Example

Comparing Push system and JIT system in terms of Original Equipment Manufacturers (OEMs) and Their Suppliers ItemPush SystemJIT Lot size of parts/product LargeSmall Supplier selectionMultiple sourcingNear to the plant. Good long-term relationship. A small number of suppliers. Supplier evaluationQuality. Delivery performance. Price. Same

ItemPush SystemJIT Receiving inspectionResponsibility of the buyer Responsibility of both the buyer and the supplier Bidding processEmphasis on low price (after satisfying quality checks) Emphasis on quality with a fair price for both the buyer and the supplier Mode of transportation CostOn-Time delivery Product specificationThe supplier makes products based on the buyer’s design specification. The supplier and the buyer work together to produce product.

ItemPush SystemJIT PaperworkFormal (a lot of paper work) In-formal (telephone calls, s, etc.) PackagingLarge size containersSmall standard size containers.

Other Notes: Implementing JIT is not only to train people to pursue JIT principles but also to pursue a lot of technical work (such as automating material handling system, implementing a computer controlled process monitoring system, etc.) JIT system has proven to work in variety of industries including automobile, aerospace, and computers.

The Continuous Improvement Cycle (Deming Cycle): Source: