Lean Production Quiz 1

Question 1

Process Capability

Answer 1

is a measure of how good metric is performing against established standard.

Question 2

statistics to measure process capability

Answer 2

Cp and Cpk

Question 3

Cp

Answer 3

Capability ratio measures potential capability.

Question 4

Cpk

Answer 4

Capability index measures actual capability.

Question 5

Cp > 1

Answer 5

The process spread is less and all products fal within specification limit.

Question 6

Cpk > 1

Answer 6

The center of the process may be shifted from the target but still the process is capable of meeting design specifications.

Question 7

Cp formula and requirement

Answer 7

cp = (usl - lsl)/6sigma

companies require cp = 1.33 or greater

Question 8

cpk formula and requirement

Answer 8

cpk = min (u - lsl/ 3 sigma , usl - u/3sigma)

Question 9

Variation

Answer 9

variability is anything that causes the system to depart from predictable behavior.

Question 10

Variation Causes

Answer 10

1. causes degradation in the performance of the system
2. Impacts WIP, cycle time and TH of the system
3. causes buffer with additonal inventory, capacity and time.

Question 11

Controlled Variation

Answer 11

This type of variation stays steady and follows consistent pattern over time.

Question 12

Uncontrolled variation

Answer 12

This type of variation changes over time and is hard to predict. It usually has some kind of pattern to it.

Question 13

Sources/ causes of Variability and example

Answer 13

Setup - workplace
Machine breakdown - different skills levels
Worker not available - different customer needs
Running out of material - changes in design or engineering

Question 14

Variation Law

Answer 14

• Law (variation)
• Law (Variability Buffering)
• Variability Placement

Question 15

Define Law variation

Answer 15

Increasing variability always degrades the performance of a production system.

Question 16

Define Variability Buffering

Answer 16

Variability in production system will be buffered by some combination of inventory, capacity and time.

Question 17

Variability Placement

Answer 17

Early variability increases CT more than later variability.

Question 18

Variability Buffering

Answer 18

• Inventory Buffer
• Capacity Buffer
• Time Buffer

Question 19

Inventory Buffer

Answer 19

If supplier take long time to deliver or if the customer place unpredictable orders, it is good to have extra products in stock

example: pen

Question 20

Capacity Buffer

Answer 20

if you don’t keep extra inventory and your supplier delivers late, it is better to pay for faster shipping or pay for extra production line. This cost more than keeping inventory.

example: ambulance

Question 21

Time Buffer

Answer 21

If you don’t keep extra product or extra capacity, and when the demand is higher than expected, the customer will have to wait longer.

example: heart transplant

Question 22

Define Natural variability and causes

Answer 22

variability inherient in natural process time

causes: operator pace, equipment

Question 23

preemtive outages and example

Answer 23

downtime that occurs whether we want it or not.

example: power outages, machine breakdown

Question 24

variability and flow

Answer 24

low variability give smooth flow and vice versa

Question 25

High Utilization station and variability

Answer 25

flow variability out of high utilization station is determined by flow variability at that station

Question 25

Non-preemptive outages and example

Answer 25

downtimes that will inevitably occur but for which we have some control as to exactly when example: setups

Question 26

low utilization station

Answer 26

flow variability of out of low utilization station is determined by flow variability into that station.

Question 27

LV (low variation) MV (moderate variation) HV (high variation)

Answer 27

* c<0.75 * 0.75 <= c <= 1.33 * c>1.33