JIT

Question 1

JIT (Just-In-Time) is a philosophy of

Answer 1

production and a set of techniques that emphasize elimination of waste through continuous improvement and demand-driven production. JIT is also referred to as lean production.

Question 2

JIT Principles

Answer 2

Elimination of waste

Continuous improvement
Continually seek ways to improve processes
Demand-driven production
Produce products only as needed

Question 3

Elimination of Waste

Answer 3

Waste is anything that does not add value from the customer’s perspective

Seven types of wasteOverproductionInventory Waiting TransportationProcessingMotionDefects

Question 4

Overproduction

Answer 4

Producing more than needed  increased inventory and leadtimes

Question 5

Inventory

Answer 5

Inventory  costs of capital, space, hiding problems, increased leadtimes

Question 6

Waiting

Answer 6

Waiting time Increased leadtimes and WIP

Question 7

Transportation

Answer 7

Unnecessary movement of materials or equipment materials handling costs, increased leadtimes and WIP

Question 8

Processing

Answer 8

Unnecessary production steps (over-processing) or the use of inappropriate tools or equipment (inappropriate processing) less productivity, waste of resources

Question 9

Motion

Answer 9

Inefficient work methods, wasteful motion  less productivity

Question 10

Defects

Answer 10

Defects  rework, disposal, waste of resources, loss of customer goodwill

Question 11

JIT Elements

Answer 11

Pull system
Kanban system

Uniform plant loading (Heijunka)
Small lot sizes and setup time reduction
Flexible resourcese.g.) cross-trained workers, general-purpose machines 
Cellular manufacturing 
Group technology, U-shaped cells
Close relationship with suppliers
Frequent deliveries, better quality 
Preventive maintenance
Automation

Question 12

pull system

Answer 12

is a demand-driven production system, in which all the production and procurement activities are triggered by actual consumptions

Question 13

Pull vs. push system

Answer 13

In a push system, production and procurement are triggered by plans

Pull and push systems can be used together
e.g.) push system for final assembly and pull system for production of sub-assemblies and components

Question 14

Kanban SyStem

Answer 14

is a pull system that uses kanbans to control production and material movement

Question 15

niform plant loading (or Heijunka)is the

Answer 15

leveling of production by mixed-model scheduling and small-batch production to achieve uniform workloads on all workstations

This scheduling concept is used for rate-based MPS for end products

Question 16

Small Lot Sizes & Setup Time Reduction

Answer 16

Benefits of small lot sizes
Less average inventory
Helping achieve uniform workloads 
Less rework when defects occur
Increased production flexibility

Small lot sizes require short setup times

Setup times can be reduced by:
Simplifying and automating setup processes
Preparing for changeovers while current job is still being processed

Question 17

Impact of JIT on MPC

Answer 17

Rate-based MPSPull systems for production of components
Shop-floor scheduling and reporting systems are not necessary
Simplified product structure
Shorter manufacturing leadtime and less work-in-process inventories

Question 18

Rate-based MPS

Answer 18

Production rates are specified for end products, rather than quantities to be completed in each period