Just In Time (JIT) Quality and Reliability Engg. (171906) H I T. Hit suyo na mono O Iru toki iru dake Tasukuran

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1 Just In Time (JIT) H I T Hit suyo na mono O Iru toki iru dake Tasukuran (What is needed) (When it is needed and in what quantity) (Make) The crux is, if you cannot use it now do not make it now. Quality and Reliability Engg. (171906) Assi. Professor, MED, S.S.A.S Insti. of Tech.,Surat

2 History 15-Aug-12 12:16:53 AM JIT is a Japanese management philosophy which has been applied in practice since the early 1970s in many Japanese manufacturing organisations. It was first developed and perfected within the Toyota manufacturing plants by Taiichi Ohno as a means of meeting consumer demands with minimum delays. Just-in-time production method is also called the Toyota Production System. Taiichi Ohno is frequently referred to as the father of JIT. Feb, 1912 May, 1990

3 Pull and Push Approach 15-Aug-12 12:16:53 AM Supply Chain, Procurement, Production and Distribution Push System Forecasted Pull System Demand-driven But it doesn't mean make-to-order

4 Que: what is MRP???

5 15-Aug-12 12:16:54 AM Que: what do u mean by customer here???

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7 Pull Vs Push 15-Aug-12 12:16:59 AM Pull Strategy Applied to that portion of the supply chain where demand uncertainty is high. Production and distribution are demand driven No inventory, response to specific orders Generally small production batches Difficult to implement Push Strategy Applied to that portion of the supply chain where demand uncertainty is relatively small. Production and distribution decisions are based on long term forecasts Based on past orders received from retailer's warehouse Large and variable production batches Easy to implement

8 15-Aug-12 12:16:59 AM Introduction - JIT The philosophy of JIT is simple: Inventory is Waste It originally referred to the production of goods to meet customer demand exactly, in time, quality and quantity, whether the customer is the final purchaser of the product or another process further along the production line. JIT revolves around the idea, Do not produce or assemble in anticipation. Produce or assemble only the right products in the required quantities at the right time. Here, inventory or stock is viewed as a waste of resources, blockage of working capital and an obstacle to improvement and flexibility. JIT is a management philosophy and not a technique.!!!

9 15-Aug-12 12:16:59 AM Implemented correctly, JIT focuses on continuous improvement and can improve a manufacturing organization's Return on Investment (ROI), quality, and efficiency. To achieve continuous improvement key areas of focus could be flow, employee involvement and quality. Quick notice that stock depletion requires personnel to order new stock, is critical to the inventory reduction at the center of JIT, which saves warehouse space and costs, but JIT relies on other elements in the inventory chain: for instance, its effective application cannot be independent of other key components of a lean manufacturing system or it can "end up with the opposite of the desired result. In recent years manufacturers have continued to try to hone forecasting methods for JIT planning; Que: what is Lean manufacturing???

10 15-Aug-12 12:16:59 AM JIT system is: Remember Produce and deliver finished goods just in time to be sold, sub-assemblies just in time to be assembled into finished goods, and purchased materials just in time to be transformed into fabricated parts. Definition by Schonberger; Oxford University Press 2007.

11 15-Aug-12 12:17:00 AM The primary elements of JIT are; (a)have only the required inventory when needed (b)improve quality to zero defects (c)reduce lead times by reducing setup times, queue lengths and lot sizes (d)incrementally revise the operations themselves (e)accomplish all the above at minimum cost. Que: what is Lead time & Setup time???

12 15-Aug-12 12:17:00 AM The Concept of JIT manufacturing requires Revise factory layouts Reduce set-up times Implement a pull system of production Better coordination with suppliers

13 15-Aug-12 12:17:00 AM Execution of JIT These are the requirements to implement TPM successfully. Respond to Customer Requirements and proper forecasting of demand Integrate all Processes in the Manufacturing System Employee Participation in Meeting Commitments Company wide Commitment to education Eliminate redundancy Reduce all Inventory Establish Continuous Improvement Goals Use a pull Production System Design products for Manufacturing Develop Controllable Production Processes Have a Defect Prevention Program Reduce Setup Times Build Products to Specification

14 Role of Inventory Reduction 15-Aug-12 12:17:01 AM

15 Uncovering Hidden Waste 15-Aug-12 12:17:04 AM Defective production / Rework Visible Waste Over production Inventory storage Redesign and Re-inspection Scrap/ excessive use of material Hidden Waste Unplanned preparation activities Unplanned Set up and adjustment Waiting (delay)

16 Wastes 15-Aug-12 12:17:05 AM Waste is defined as any activity that increases cost but does not add value to the product. The end result should be a manufacturing process with no wasteful actions. The goal of JIT manufacturing is to identify the perfect process, making the process as simple and efficient as possible. It is a philosophy that focuses on identifying and elimination all types of wastes on a continuous basis. The seven wastes are (a)over production (b)waiting (delay) (c) Transportation (d)stock (inventory) (e)waste of motion; Set up and adjustment, preparation activities (f) Defective products (g)inspection

17 Common Causes of Waste 15-Aug-12 12:17:05 AM Layout (distance) Long setup time Incapable processes Poor maintenance Poor work methods Lack of training Inconsistent performance measures Ineffective production planning Lack of workplace organization Poor supply quality/reliability

18 Benefits of JIT Heightened awareness of problems & causes Reduced buffer stocks and/or operators Ideas for cutting lot sizes Lot size reductions Ideas for improving JIT delivery performance Less stock in the system JIT production Ideas for controlling defects Less indirect cost Fast feedback on defects Scrap/ quality control Fewer rework hours Smoother output rates Less material waste Less material, labor, and indirect inputs for the same or higher output = higher productivity Less inventory in the system = faster market response, better forecasting, less administration Oxford University Press All rights reserved.

19 JIT- Advantages 15-Aug-12 12:17:05 AM Reduce the inventory to optimal level Unpleasant surprises eliminated Less computerization visual control Improved quality WIP reduced Better communications Less pressure on receiving docks and incoming inspection areas Lower costs Change in attitude Defects are treasures

20 KANBAN system 15-Aug-12 12:17:05 AM To meet JIT objectives, the process relies on signals or Kanban ( 看板 ) between different points in the process, which tell production when to make the next part. Kanban are usually 'tickets' but can be simple visual signals, such as the presence or absence of a part on a shelf.

21 KANBAN Card 15-Aug-12 12:17:05 AM

22 KANBAN Post 15-Aug-12 12:17:05 AM

23 How KANBAN Works..?? 15-Aug-12 12:17:05 AM

24 15-Aug-12 12:17:05 AM CALCULATION FOR NUMBER OF KANBAN Kanban system attempts at continual reduction of inventory. The number of kanbans are calculated as follows: N = d L + s / C Where, N : Number of kanban (or containers) d : Demand units (average number over a given period of time) L : Lead time (time to replenish an order, expressed in the same time unit as expressed in demand) S : Safety stock (as a percentage of demand during lead time), based on service level and variance of demand during lead time C : Container size Container size should be kept much smaller (say 10 to 16%) than the average demand during the lead time, as this will force a continuous improvement process.

25 Example 15-Aug-12 12:17:05 AM A production manager is working in a cellular manufacturing system for an automobile parts. He has to process an average of 250 parts per hour in the cell. The capacity of each container is 30 parts and one kanban is attached to all the containers. The time to receive new parts from the previous workstation is 25 minutes. Factory maintains a safety stock factor of 15%. Determine the kanbans needed for the plant. Given: d = 250 parts per hour L = 25 minutes = 25/60 hours = hour S = 0.15 ( ) = 15.6 C = 30 parts Now, since number of Kanban is N = DL + s/c = (250 x ) / 30 = kanbans or container ~ 4 kanbans or containers30

26 JIT- Overview The Essence A Production philosophy whose objective is to produce quality goods, as needed by customers, economically, quickly and safely. A philosophy, which believes in Pull, rather than Push. An intelligent and simplified way to address inventory in purchasing, production and distribution pipelines. The real challenge is not only to reduce inventory but also to keep it visible. An approach advocates for waste [Muda] elimination at all levels. The Role Ties production to actual demand and maintains flow. Exposes root causes, problems, bottlenecks and all types of wastes, which are usually not evident in the inventory-dependent production scenario. Attacks wastes such as excessive set up time, quality rejects, non-availability of machine, transportation, inspection, overproduction and scrap. Improves productivity and helps reduce costs drastically.

27 JIT- Overview Requirements Simplification of product design, processes, communication and managerial activities. This is achieved by embracing concepts such as Andon, Kaizen, Kanban, 5S and SMED. Exposure of wastes and complexity and sharing right information through involvement. Industrial engineering basics viz., work study, standardization and SMED. Involvement of all parties at all levels. Ongoing TQM and TPM activities for maintaining quality at source, high reliability and availability of machines. Management that believes in simplicity, visibility and is prepared to expose problems and waste areas, with a willingness to improve. Assumptions Stable environment and lesser product variety. Trust and commitment between the parties concerned, whether it is between management and employees, company and vendors, or any other partners involved. Inventory is an evil and wasteful liability without merit. Defect-free raw materials and parts from vendors in right quantity, quality and ontime delivery. High availability and reliability of machines and flexible multifunctional workers, (Shojinka) and built-in quality. Limited number of geographically close and dedicated suppliers.

28 You can not change the direction of the wind, but you can always adjust your sails