BM 605 การจัดการการดําเนินงาน การผลิตแบบทันเวลา (Just-in-Time)
รศ. ดร. ประสงค ปราณีตพลกรัง 16-1
What is Just-in-Time (JIT)? ♦Management philosophy of continuous and forced problem solving ♦Supplies and components are ‘pulled’ through system to arrive where they are needed when they are needed. ♦Toyota Manufacturing systemsÎระบบการผลิตแบบญี่ปุน ♦ผลิตเฉพาะของที่จําเปนซึ่งลูกคาตองการ ♦ผลิตในจํานวนที่จําเปน ♦ผลิต ณ เวลาที่จําเปน 16-2
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Push versus Pull ♦ Push system: material is pushed into downstream workstations regardless of whether resources are available ♦ Pull system: material is pulled to a workstation just as it is needed
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Principle of JIT ♦ Produce product that customer desires ♦ Produce product only at the rate the customer want ♦ Produce with perfect quality ♦ Produce instantaneous ♦ Produce with no wastes ♦ Produce by method that allow people to develop themselve
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Types of Waste ♦ Overproduction ♦ Waiting ♦ Transportation ♦ Inefficient processing ♦ Inventory ♦ Unnecessary motion ♦ Product defects © 1995 Corel Corp.
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JIT Contribution to Competitive Advantage ♦Suppliers ♦ supportive supplier relationships ♦ quality deliveries on time
♦ Layout ♦ movable, changeable, flexible machinery ♦ reduced space for inventory
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JIT Contribution to Competitive Advantage - Continued ♦Inventory ♦ small lot sizes ♦ low setup times
♦Scheduling ♦ zero deviation from schedules ♦ suppliers informed of schedules ♦ Kanban techniques
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JIT Contribution to Competitive Advantage - Continued ♦ Preventive Maintenance daily routine ♦ operator involvement ♦
♦ Quality Production statistical process control ♦ quality by suppliers ♦
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JIT Contribution to Competitive Advantage - Continued ♦ Employee Empowerment empowered and cross-trained employees ♦ training support ♦
♦ Commitment ♦
support of management, employees, and suppliers
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Just-in-Time Success Factors Employee Empowerment
Quality
Suppliers Layout
JIT
Preventive Maintenance
Inventory
Scheduling 16-10
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Suppliers ♦ Incoming material and finished goods involve waste ♦ Buyer and supplier form JIT partnerships ♦ JIT partnerships eliminate ♦ ♦ ♦ ♦
Unnecessary activities In-plant inventory In-transit inventory Poor suppliers
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Characteristics of JIT Partnerships Suppliers
♦ Few ♦ Nearby ♦ Repeat business ♦ Analysis and support to enable desirable suppliers to
become or stay price competitive ♦ Competitive bidding mostly limited to new purchases ♦ Buyer resists vertical integration and subsequent wipeout of supplier business ♦ Suppliers encouraged to extend JIT to their suppliers (2nd and 3rd tier suppliers) 16-12
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Characteristics of JIT Partnerships Quantities
♦ Steady output rate ♦ Frequent deliveries in small-lot quantities ♦ Long-term contract agreements ♦ Minimal
or no paperwork (use EDI or internet) ♦ Delivery quantities fixed for whole contract term ♦ no permissible overage or underage ♦ Suppliers package in exact quantities
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Characteristics of JIT Partnerships Quality ♦ Minimal product specifications imposed on
suppliers ♦ Help suppliers meet quality requirements ♦ Close relationship between buyers’ and suppliers quality assurance people ♦ Suppliers use poka-yoke and process control charts instead of lot-sampling techniques
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Goals of JIT partnerships Elimination of unnecessary activities Elimination of in-plant inventory Elimination of in-transit inventory ³Elimination of poor suppliers
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Inventory ♦ Traditional: inventory exists in case problems arise ♦ JIT objective: eliminate inventory ♦ JIT requires ♦ ♦ ♦
Small lot sizes Low setup time Containers for fixed number of parts
♦ JIT inventory: Minimum inventory to keep system running 16-16
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JIT Inventory Tactics ♦ Use a pull system to move inventory ♦ Reduce lot size ♦ Reduce setup time ♦ Develop Just-in-Time delivery systems with suppliers ♦ Deliver directly to point of use ♦ Perform-to-schedule ♦ Reduce setup time ♦ Use group technology 16-17
Scheduling ♦ Involves timing of operations ♦ JIT requires Communicating schedules to suppliers ♦ Level schedules ♦ Small lots ♦ Kanban techniques ♦
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Kanban=Visible record ♦ Japanese word for card ♦
Pronounced ‘kahn-bahn’ (not ‘can-ban’)
♦ Authorizes production from downstream operations ♦
‘Pulls’ material through plant
♦ May be a card, flag, verbal signal etc. ♦ Information include: item, quantity, storage location ♦ Used often with fixed-size containers ♦
Add or remove containers to change production rate 16-19
Kanban= คัมบัง ♦คัมบัง – ใชในการควบคุมสินคา หรือ ควบคุมการสั่ง ของโดยใชบัตร ♦Two type of Kanban in a two – card system 1.Withdrawal card Î บัตรหมุนเวียนระหวางชั้นวาง ของกับคลังพัสดุ( Store) 2.Production–order card Îบัตรหมุนเวียนระหวางผู สงสินคากับคลังพัสดุ( Store) 16-20
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Average demand during lead plus safety stock K=
Size of container d ( w + p ) (1 + α) K =
C
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♦K = Number of production-order/withdrawal card sets ♦ d = Expected daily demand ♦w = Average waiting and materials handling time ♦p = Average processing time ♦C = Container size ♦α = efficiency policy variable 16-22
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Example Item has an average daily demand of 1,000 units. The average waiting time per container of part (which holds 100 units) is 0.5 day.The processing time per container is 0.1 day.If the policy variable Is set at 10%. How many KANBAN card sets are required ?
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Diagram of Outbound Stockpoint with Warning-Signal Marker
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Kanban Signals “Pull” Material Through the Process
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Kanban: Additional Points ♦ When producer and user are not in visual contact, a card may be used; otherwise, a light, flag, or empty spot on the floor may work. ♦ Because a pull station may require several resupply components, several kanban pull techniques can be used at the same station. ♦ Usually, each card controls a specific quantity of parts, although multiple card systems can be used if the producing cell produces several components or the lot size is different from the move size. ♦ In an MRP system, the schedule can be thought of as a “build” authorization and the kanban as a type of “pull” system that initiates the actual production. 16-26
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Kanban: Additional Points Continued ♦ The kanban cards provide direct control (limit) on the amount of work-in-process between cells. ♦ If there is an intermediate storage area, a twocard system may be used; one card circulates between user and storage area, and the other circulates between the storage area and the producing area.
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Quality ♦ JIT exposes quality problems by reducing inventory ♦ JIT limits number defects with small lots ♦ JIT requires TQM ♦ ♦
♦
Statistical process control Worker involvement ♦ Inspect own work ♦ Quality circles Immediate feedback
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JIT Quality Tactics ♦ Use statistical process control ♦ Empower employees ♦ Build failsafe methods (poka-yoke, checklists, etc.) ♦ Provide immediate feedback
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Employee Empowerment ♦ Get employees involved in product & process improvements ♦
Employees know job best!
♦ JIT requires
© 1995 Corel Corp.
Empowerment ♦ Cross-training ♦ Training support ♦ Few job classifications ♦
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