One
established industry or a factory measure of productivity is overall equipment
effectiveness. OEE (OVERALL EQUIPMENT EFFECTIVENESS) in simple form is a measure of Productivity of an asset. If
a machine has a planned production of 5 hours ,with the expectation that it can
produce 5000 units during that time, but the machine only produces 2500 during
the shift, that machine has an OEE of ( 2500/5000=.5).
The
components of OEE (OVERALL EQUIPMENT EFFECTIVENESS):
To
answer this, we should understand the three components that makeup OEE. These components are:
- Availability
- Performance
- Quality
Availability:
It measures how frequently machine is
available for its intended use. Events that stop machine production result in a
downtime loss. Availability can be affected by equipment failure, unplanned
maintenance and downtime, material shortages, and machine changeover time.
Performance:
It
is more difficult to assess, but is defined as a speed loss. If a machine is
rated to produce a certain amount of units per hour, and runs uninterrupted for
that hour, producing fewer units than the machine rating is called as
performance loss. These losses can be a contribution of machine wear, operating
person’s efficiency, bad materials.
Quality:
It
can be calculated very easily among three. It is a measure of amount of scrap a
machine produces. Any reject material that doesn’t meet quality standards, and
rework all contributes to quality losses.
Measuring OEE:
Availability
is calculated as a ratio between actual operating time and planned production
time
Availability
= Operating time/Planned production time
Performance
is the ratio of the ideal cycle time to the operating time divided by total
pieces produced
Performance
= Ideal cycle time/ (operating time/total pieces produced)
This
can also be defined as a ratio of net operating time to operating time.
Quality
is measured as the ratio of good pieces to total pieces
Quality=
Good pieces/ total pieces.
OEE Example:
Through
this example I want to explain the OEE calculation.
The
plant shift is 8 hours, with two breaks 15 min tea break,30 minutes lunch. The
machine can produce 60pieces per hour at its ideal cycle time. For suppose if
the machine is down for 15 minutes, but produces 400 pieces during its uptime.
Out of which 20 pieces are rejected and sent for reworking. Based on this ..
8
hours 480 minutes
Breaks 45 minutes
Down
time 15 minutes
Parts
produced 400 pieces
Rejection 100 pieces
Planned
production time 480-45=435
Operating
time 435-15=420
Availability 420/435=.96
Performance 400/420=.95
Quality 380/ 400=.95
OEE .95*.95*.96=.86
The
machine is having OEE of 86%.
Date: 11/02/2016
Date: 11/02/2016