Just – In – Time (JIT)
Quality and Reliability Engg. (171906)
Prof. K. M. Joshi Assi. Professor, MED,
S.S.A.S Insti. of Tech.,Surat
H – I – T –
(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.”
Hit suyo na mono O
Iru toki iru dake
Tasukuran
History
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.
Prof. K. M. Joshi
15-Aug-12 12:16:53 AM
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
Pull and Push Approach
Prof. K. M. Joshi
15-Aug-12 12:16:53 AM
Supply Chain,
Procurement,
Production and
Distribution
Pull System Demand-driven But it doesn't mean make-to-order
Push System Forecasted
Que: what is MRP…???
Prof. K. M. Joshi
15-Aug-12 12:16:54 AM
Que: what do u mean by customer here…???
Pull Vs Push
Pull Strategy Push Strategy
Applied to that portion of the supply chain where demand uncertainty is high.
Applied to that portion of the supply chain where demand uncertainty is relatively small.
Production and distribution are demand driven
Production and distribution decisions are based on long term forecasts
No inventory, response to specific orders
Based on past orders received from retailer's warehouse
Generally small production batches
Large and variable production batches
Difficult to implement Easy to implement
Prof. K. M. Joshi
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.
Prof. K. M. Joshi
15-Aug-12 12:16:59 AM
JIT is a management philosophy and not a technique.!!!
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;
Prof. K. M. Joshi
15-Aug-12 12:16:59 AM
Que: what is Lean manufacturing…???
JIT system is:
“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”.
Remember
© Definition by Schonberger; Oxford University Press 2007.
Prof. K. M. Joshi
15-Aug-12 12:16:59 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.
Prof. K. M. Joshi
15-Aug-12 12:17:00 AM
Que: what is Lead time & Setup time…???
Revise factory layouts
Reduce set-up times
Implement a pull system of production
Better coordination with suppliers
The Concept of JIT
manufacturing requires
Prof. K. M. Joshi
15-Aug-12 12:17:00 AM
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
Execution of JIT
These are the requirements to implement TPM successfully….
Prof. K. M. Joshi
15-Aug-12 12:17:00 AM
Role of Inventory Reduction
Prof. K. M. Joshi
15-Aug-12 12:17:01 AM
Defective production / Rework
Hidden Waste
Visible Waste
Waiting (delay)
Scrap/ excessive use of material
Redesign and Re-inspection
Unplanned preparation activities
Unplanned Set up and adjustment
Uncovering Hidden Waste
Over production
Prof. K. M. Joshi
15-Aug-12 12:17:04 AM
Inventory storage
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
Wastes
Prof. K. M. Joshi
15-Aug-12 12:17:05 AM
(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
Common Causes of Waste
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
Prof. K. M. Joshi
15-Aug-12 12:17:05 AM
© Oxford University Press 2007. All rights reserved.
Heightened awareness of problems &
causes
Reduced buffer stocks and/or
operators
Fast feedback on defects
Ideas for improving JIT delivery performance
Ideas for controlling
defects
Lot size reductions
JIT production
Scrap/ quality control
Smoother output rates
Less material
waste
Less stock in the system
Less indirect cost
Fewer rework hours
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
Benefits of JIT
Ideas for cutting lot sizes
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
JIT- Advantages
Prof. K. M. Joshi
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.
KANBAN system
Prof. K. M. Joshi
15-Aug-12 12:17:05 AM
KANBAN Card
Prof. K. M. Joshi
15-Aug-12 12:17:05 AM
KANBAN Post
Prof. K. M. Joshi
15-Aug-12 12:17:05 AM
How KANBAN Works..??
Prof. K. M. Joshi
15-Aug-12 12:17:05 AM
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.
CALCULATION FOR NUMBER OF KANBAN
Prof. K. M. Joshi
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.
Example
Given: d = 250 parts per hour L = 25 minutes = 25/60 hours = 0.4167hour S = 0.15 (250 × 0.4167) = 15.6 C = 30 parts Now, since number of Kanban is N = DL + s/c = (250 x 0.4167) + 15.6 / 30 = 3.993 kanbans or container ~ 4 kanbans or containers30
Prof. K. M. Joshi
15-Aug-12 12:17:05 AM
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.
JIT- Overview
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.
Prof. K. M. Joshi
www.joshikandarp.webs.com
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.
JIT- Overview
Prof. K. M. Joshi
www.joshikandarp.webs.com
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 on-time delivery.
High availability and reliability of machines and flexible multifunctional workers, (Shojinka) and built-in quality.
Limited number of geographically close and dedicated suppliers.
You can not change the direction of the wind , but you can always adjust your sails