8/2/2019 13 JIT, CAM

1/27

Click to edit Master subtitle style

4/17/12

Just In Time (JIT)

8/2/2019 13 JIT, CAM

2/27

4/17/12

The Just In Time concept of production wasintroduced in Japan under the nameKanban. According to this concept,materials and components are supplied to

the work station just at the time when theyare required for use

This means the production unit andvendors have to be in close proximity andliasion

JIT is a logistic approach, wherein, the levelof inventory is kept at the minimum

because these are made to arrive just intime when they are needed to be used

8/2/2019 13 JIT, CAM

3/27

4/17/12

The success of JIT depends on thefollowing things:-

Customer orientation

Focus on long term objectiveAll departments work as one team

It is common knowledge that in majority oforganizations, both in developed anddeveloping countries, the prevailingworking conditions are not conducive topromote the concept of JIT

8/2/2019 13 JIT, CAM

4/27

4/17/12

Elements of JITmanufacturing

8/2/2019 13 JIT, CAM

5/27

4/17/12

Eliminating the waste

JIT is a management philosophy thateliminates sources of manufacturingwaste by producing the right art at theright place at the right time

Waste results from any activity that addscost without adding value

In a JIT system, underutilized (excess)

capacity instead of buffer inventories tohedge against problems that may arise

JIT concept applies to repetitivemanufacturing processes in which the

same products and components are

8/2/2019 13 JIT, CAM

6/27

4/17/12

There are six major sources of waste

Over production

Time spent waiting

Transportation

Processing time

Inventory

Defects

Under the JIT system, the waste is aimed atto be eliminated by the application of thefollowing steps

8/2/2019 13 JIT, CAM

7/27

4/17/12

Material handling and shipping is reduced orvirtually eliminated

All the un- needed production steps areeliminated

Set up times are reduced and the productionrates are increased

All the unnecessary human motions are

eliminated or avoidedThe defects are eliminated. This also

eliminates the inspection

8/2/2019 13 JIT, CAM

8/27

4/17/12

Enforced Problem Solving &Continuous ImprovementIn traditional manufacturing, in process

inventories allow production to continueeven if production problem occurs

JIT, on the other hand is system of enforcedproblem solving

The approach in JIT is to lower inventorygradually to expose problems and find their

solutionWith no buffer inventories to offset

production interruptions, problems arehighly visible and cannot be ignored

8/2/2019 13 JIT, CAM

9/27

4/17/12

There are a few safety factors in JIT

Every material is expected to meet qualitystandards

Every part is expected to arrive exactly at thetime promised and precisely at the expectedplace

Every machine is expected to function as

intended without breakdownsHowever the job of eliminating production

problems is never finished. Therefore,Kaizen is central to the philosophy of JIT

The purpose of Kaizen is to eliminate

8/2/2019 13 JIT, CAM

10/27

4/17/12

Parallel Processing

JIT believes in parallel processing ratherthan series processing

This helps in saving the time, which isconsidered the most significant asset in

Japanese manufacturing

OP 1 OP 2 OP 3 OP 4

Series ProcessingSuppose, Cycle time for each

operation=1 hour

8/2/2019 13 JIT, CAM

11/27

4/17/12

OP 2

OP 1

OP 4

OP 3

OP 5

OP 6 OP 7

Parallel Processing

8/2/2019 13 JIT, CAM

12/27

4/17/12

Kanban Production System

Kanban is the means of signaling to theupstream workstation that the downstreamworkers are ready for the upstreamworkstation to produce another batch of

parts

There are two types of Kanban cards. Theseare

A conveyance card (C- Kanban)A production card (P- Kanban)

8/2/2019 13 JIT, CAM

13/27

4/17/12

The process of Kanban will involve thefollowing steps

The worker takes the C- Kanban from thecontainer he just emptied

He finds a full container of the needed part instorage

He places the C- Kanban in the full container

and removes the P- Kanban from the fullcontainer and places it on a post at theprevious work centre

He takes the full container parts with its C-

Kanban back to his own work center

8/2/2019 13 JIT, CAM

14/27

4/17/12

JIT Purchasing

Is an approach to purchasing that requireslong term agreements with few suppliers

Aims at building co-operative and longterm relationship between customer andsupplier

Supplier section is based not only on price,but also on delivery schedules, product

quality and mutual trustJIT is known as the purchase of goods or

materials such that a delivery immediatelyprecedes demand or use

8/2/2019 13 JIT, CAM

15/27

4/17/12

JIT PurchasingTraditionalPurchasing

1. Smaller lot sizes

2. More frequentdeliveries

1. No rejection fromthe supplier

2. Long termcontracts

1. Buyer decidesdelivery schedule

1. Relatively largelot sizes

2. Less deliveries athigher quantities

3. 2% rejection fromsupplier

4. Lowest price is

the mainobjective

5. Time consuming,formal framework

8/2/2019 13 JIT, CAM

16/27

4/17/12

7. Minimal paperwork

8. Less formalcommunication

8/2/2019 13 JIT, CAM

17/27

4/17/12

Reducing inventories throughset up reductionUnder JIT manufacturing, set up times and

lot sizes are reduced in order to reduceinventories

Factory outlay is changes to allowstreamlined flows

This is called installation of FlexibleManufacturing Systems (FMS)

In JIT, it is aimed to reduce the lot size toreduce the carrying inventory level

However, this could increase the set upcost

8/2/2019 13 JIT, CAM

18/27

4/17/12

For successfulimplementation of JIT

Manufacturing followingpoints are to be kept in mind

8/2/2019 13 JIT, CAM

19/27

4/17/12

Reduce or eliminate set up times donethrough better planning, process redesign,and product redesign

Reduce lot sizes (manufacturing andpurchasing)

Reduce lead times (production anddelivery)- production lead times can be

reduced by moving work station closertogether, applying group technology,reducing queue length

Preventive maintenance

Flexible work force

8/2/2019 13 JIT, CAM

20/27

4/17/12

Just-in-Time (JIT) involves inventory andquality control, industrial relations andsupplier-manufacturer practices that differfrom traditional business practices

Japanese business practices tend toemphasize long term business relationships

The main objective of JIT manufacturing is

to reduce manufacturing lead times

A central feature of JIT is the ability tooperate with minimal levels of inventory

8/2/2019 13 JIT, CAM

21/27

Click to edit Master subtitle style

4/17/12

Factories of Future

Computer Aide Design (CAD)/Computer Aided Manufacturing

(CAM)

8/2/2019 13 JIT, CAM

22/27

4/17/12

Computer Aided Design(CAD)Is the use of a wide range of computer

based tools that assist engineers,architects and other design professionals intheir design activities

It is the main geometry authoring toolwithin the Product Lifecycle Managementprocess and involves both S/W andsometimes special purpose hardware

Also known as computer assisted ,computer aided drafting, CADD(computer aided design and drafting), CAID(computer aided industrial design) or asimilar phrase

8/2/2019 13 JIT, CAM

23/27

4/17/12

CAD is used to design and developproducts which can be goods used by endconsumers or intermediate goods used inother products

Also extensively used in the design of toolsand machinery used in the manufacture ofcomponents

8/2/2019 13 JIT, CAM

24/27

4/17/12

Areas of use

1. Architectural design

2. Civil engineering and infrastructure

3. Roads & highways

4. Water & sewer systems

5. Mapping & surveying

6. Mechanical (MCAD)

7. Automotive

8. Aerospace

9. Consumer goods

10. Machinery

11. Ship building

12. Electronic and electrical (ECAD)

13. Manufacturing process planning

14. Digital circuit design

15. Software applications

16. Apparel and Textile CAD

8/2/2019 13 JIT, CAM

25/27

4/17/12

Computer AidedManufacturing (CAM)Is the use of a wide range of Product

Lifecycle Management computer basedsoftware tools that assist engineers in themanufacture of product component

This involve the engineer in selecting whattype of tool, machining process of pathsthat are to be used

Machining Process- most MachiningProgresses through three stages, each ofwhich is implemented by a variety of basicand sophisticated strategies, depending uponthe material and software available. These

stages are:-

8/2/2019 13 JIT, CAM

26/27

4/17/12

Roughing- rough model of the final project

Semi finishing- this process begins with aroughed part that unevenly approximates themodel and cuts to within a fixed offset

distance from the model

Finishing- the excess material from semifinishing is left at a constant thickness overthe final surface, so during this process there

is little change in the metal removal rate,following the results to be accurate

8/2/2019 13 JIT, CAM

27/27

4/17/12

Areas of usage- In

Mechanical engineering

In electronic design automation, CAM tools

prepare printed circuit board (PCB) andintegrated circuit design data formanufacturing

CAE or Computer Aided Engineering used for

testing the model whether it is workingproperly or not

DMU or Decision Making Unit is often referredto as a group of people involved in the process

of making a decision (eg purchasing a productor service)