Capacity planning and control

 

they have occurred because of the market and technical demands on the operation.

 

The actual capacity after such losses are accounted for = Effective capacity of operation.

 

Actual output < Effective capacity

(due to quality problems, machine breakdowns, absenteeism and other avoidable problems)

 

Actual Output/ Design capacity = Utilization

 

Actual Output/ Effective capacity = Efficiency of the plant

WORKED EXAMPLE

 

Suppose the photographic paper manufacturer  has a coating line with a design  capacity of 200 square meters per minute

 

The line is operated on a 24-hour day, 7 days per week (168 hours per week) basis.

 

Design capacity is 200 × 60 × 24 × 7 = 2.016  million square metres per week. 

 

The records for a week’s production  show the following lost production time:

 

1 Product changeovers (set-ups)  20 hrs

2 Regular preventative maintenance   16 hrs

3 No work scheduled     8 hrs

4 Quality sampling checks   8 hrs

5 Shift change times     7 hrs

6 Maintenance breakdown    18 hrs

7 Quality failure investigation    20 hrs

8 Coating material stockouts   8 hrs

9 Labour shortages    6 hrs

10 Waiting for paper rolls    6 hrs

During this week the actual output was  only 582,000 square metres.

 

The first five categories of lost production  occur as a consequence of reasonably unavoidable, planned occurrences and amount to a total of 59 hours.

 

The last five categories are unplanned, and avoidable, losses and amount to 58 hours.

 

Design capacity = 168 hours per week

 

Effective capacity = 168 – 59 =  109 hrs

 

Actual output = 168 – 59 –  58 = 51 hrs

 

                    actual output 51 hrs

Utilization = ––––––––––––––  = –––––– = 0.304 (30%)

                 design capacity 168hrs

 

                   actual output 51 hrs

Efficiency = –––––––––––––––  = –––––– = 0.468 (47%)

                 Effective capacity 109 hrs

 

OVERALL EQUIPMENT EFFECTIVENESS

 

The overall equipment effectiveness (OEE) measure is a method of judging the effectiveness of operations equipment.

 

 It is based on 3 aspects of performance:

 

•  the time that equipment is available to operate;

 

•  the quality of the product or service it produces;

 

•  the speed, or throughput rate, of the equipment.