Process Config - Line Balancing/Little's Law/SF & LT/DBR

Question 1

Give 5 negative things that will occur if you don’t optimise the flow of resources through an operation.

Answer 1

1) Queues
2) Long process times
3) High costs
4) Inflexible operations
5) Unpredictable and confused flow patterns

Question 2

The nature of any process is influenced by what and what

Answer 2

The volume and variety of what it has to process

Question 3

Define long and thin processes

Answer 3

A process designed to have many sequential stages, each performing a relatively small part of the task

Question 4

Define short and fat processes

Answer 4

A process with relatively few sequential stages, each of which performs a relatively large part of the total task

Question 5

Define WIP

Answer 5

Number of units in the queue of a process - i.e. number of units waiting to be processed.

Question 6

Define line balancing

Answer 6

The attempt to equalise the load on each station or part of a line layout or mass process.

Question 7

Define bottle neck

Answer 7

the capacity constraining stage in a process - it acts as the drum and governs the output of the whole process

Question 8

Define balancing loss

Answer 8

The percentage of time used for non-productive purposes compared to the total time invested in making a product.

Question 9

Define Little’s law

Answer 9

The mathematical relationship b/w Through Put time, WIP and Cycle time

Question 10

Define Work Content

Answer 10

The total amount of time required to produce a unit of output

Question 11

Define through put time

Answer 11

The time for a unit to move through a process

Question 12

Define through put efficiency

Answer 12

WC/Throughput time * 100

Question 13

What is one of the most important design decisions in product layout?

Answer 13

Line balancing

Question 14

What happens if the line is unbalanced?

Answer 14

It increases effective cycle time of the operation. The effectiveness of the line balancing activity is measured by balancing loss.

Question 15

What does balancing loss measure?

Answer 15

The time wasters through the unequal allocation of work as a percentage

Question 16

Name the 5 advantages of Long and Thin processes

Answer 16

1) Controlled Flow
2) Simple materials handling
3) Lower capital requirement
4) Greater efficiency
5) Higher space utilisation

Question 17

Name the 4 disadvantages of Long and Thin processes

Answer 17

1) Exposed to breakdowns
2) Non-flexible
3) Too much standardisation can cause high turnover

Question 18

What are the 4 advantages of short and fat processes?

Answer 18

1) higher mix flexibility
2) higher volume flexibility
3) greater robustness
4) less monotonous

Question 19

What are the 4 disadvantages of short and fat processes?

Answer 19

1) Training times
2) Equipment needs
3) Duplication of resources
4) Reliant on employees

Question 20

What does DBR concept do in operations?

Answer 20

Helps to decide exactly where in a process control should occur.

Question 21

What should be the control point in a process?

Answer 21

The bottle neck

Question 22

What is the bottleneck usually called?

Answer 22

The drum because it sets the beat for the rest of the process to follow

Question 23

Why is the buffer meant to be kept in front of the bottleneck?

Answer 23

To ensure that the bottleneck always has something to work on

Question 24

What impact does a bottle neck have on a process?

Answer 24

Affects the output of the whole process.

Question 25

Is it worthwhile for parts of the process before the bottle neck to work to their full capacity?

Answer 25

No.

Question 26

What does the rope do?

Answer 26

Communicates to the stages before the bottle neck to ensure that they don’t produce work that will accumulate at the point where the bottle neck is constraining the flow.

Question 27

What does the DBR concept do for operations managers?

Answer 27

Helps managers to realise that the speed at which the system can produce is limited by the slowest link

Question 28

What is SPC?

Answer 28

It is about measuring whether you have variation in the process. This variation maybe common cause variation (normal) or special cause variation (abnormal and needs to be investigated further).

Question 29

Define capable process

Answer 29

Where the control limits fit within the process specification

Question 30

Define incapable process

Answer 30

Where either or both the control limits exist outside the process specification

Question 31

Define natural variation

Answer 31

The variation that exists in the process without any adjustment

Question 32

Define special event

Answer 32

A recorded data point that falls outside the control limits - needs to be investigated

Question 33

Define a run of seven

Answer 33

A statistically significant series of data points that indicate that the process has changed it’s performance - either negatively or positively

Question 34

Why do we use SPC?

Answer 34

To understand variation in the process. If we don’t understand variation and respond inappropriately we can exacerbate the problem.

Question 35

What is the purpose of a control chart?

Answer 35

To detect the change in the performance of a process. It provides a dynamic view of the both the change in the absolute level of performance (average, mean, measure of central tendency) and the level of variation within a process (the deviation).

Question 36

The standard deviation in a CC assumes what?

Answer 36

That the process is normally distributed.

Question 37

What axis is time on a CC chart?

Answer 37

X axis

Question 38

Describe the 5 exception rules in SPC

Answer 38

1) Is there a point which falls above or below our control limits (UCL/LCL) 2) Is there a run of 7 consecutive points above or below the mean? This indicates the process is slowly changing over time. At this point it is worth splitting the data set and recalculate on the points after the change in process. 3) 2 consecutive points in UWL/LWL. Needs investigation but not recalculation of the warning/control limits 4) Is there a cyclical pattern? Seasonality may explain the variation. 5) Peaks and troughs may indicate a process out of control.