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