4 - OEE (Performance+Measurement+of+Production+Systems)

Question 1

What is Productivity?

Answer 1

Productivity is an AVERAGE MEASUREMENT OF THE EFFICIENCY of a production and logistic system

Question 2

**Show the key times in the “waterfall” of the reference framework for internal performance

Answer 2

Ts (Solar Time)
T (Opening Calendar Time)
TtU (Theoretical Utilization Time) 
TaU (Actual Utilisation Time)
TaP (Actual Productive Time)
Ttr (Machining Time)
TPb (Time of good Production)

Question 3

Standard vs Actual ?

Answer 3

In the real life, actual performances are always lower than the expected

This is happening also in production systems

• An actual status (and an actual time registration) of a production system is the collection of what happened in the system
• A standard status (or planned, or expected) of a production system is an a priori definition, based on previous knowledge and experience

Question 4

What is the OEE?

Answer 4

It is the ratio b/w:

• Fully productive time: (Sum of Tpb) + (Sum of Tps)
• Planned Productive time : T-TSc-TMo-TM-TPr

Question 5

In practice how is it possible to calculate OEE?

Answer 5

By means of three (3) mains contributors:

OEE = Availability * Performance * Quality

Question 6

What does Availability consider?

Answer 6

Availability: considers the impacts of Down Time losses (only breakdowns), and is calculated as:
A = Operating Time / Planned Operating Time

Question 7

What does Performance consider?

Answer 7

Performance takes into account Speed Losses, and it is calculated as:
P = Ideal Cycle Time /
(Operating Time / Total produced pieces)

Question 8

What does Quality consider?

Answer 8

Quality(OEE) takes into account Quality losses

Y = Good Pieces / Produced Pieces (in standard time)

Question 9

What does Ideal Cycle Time mean?

Answer 9

Ideal Cycle Time is the minimum cycle time that your process can be expected to achieve in optimal circumstances.
It is sometimes called Design Cycle Time, Theoretical Cycle Time (or Nameplate Capacity

Question 10

The states of a plant (a machine or in general a productive resource) ?

Answer 10

Ts solar time

T opening (calendar) time (potentially productive)

TSc strikes

TO organizational causes

TMo idle time due to lack of orders

TMm idle time due to lack of materials

TM idle time due to maintenance

TG idle time due to breakdown

TPr time for tests

TS time of setup

TPs time of waste (non-compliant) production

TPb time of good (compliant) production