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This document and the information contained herein, is the exclusive property of R&M Materials Handling Inc. and represents a non-public, confidential and proprietary trade
secret that may not be reproduced, disclosed to third parties, altered or otherwise employed in any manner whatsoever without the express written consent of R&M Materials
Handling Inc. Copyright 2020 © R&M Materials Handling Inc. All rights reserved.
APPENDIX: DESIGNED WORKING PERIOD (DWP) CALCULATION
The end of the Designed Working Period (DWP) must be calculated in accordance with the ISO 12482-1 standard
during each recurring inspection and service. If the component does not have a condition monitoring unit, use the
following method to calculate the remaining DWP%.
Note:
The values used in each DWP calculation, as well as the result and the date, must be carefully recorded
in the log book. Each DWP calculation requires the use of figures recorded during previous calculations.
Step 1: Calculate the motor operating hours (running hours) per inspection interval,
T
i
Check the following values for this inspection interval:
J = the number of working days during the inspection interval [days]
H = the average hoisting height [m]
N = the average number of work cycles per hour [cycles/h]
T = the average daily working time [h]
V = the maximum hoisting speed [m/min] (as shown on the data plate)
Use the following formula to calculate
T
i
, the motor operating hours (total lifting time) per inspection interval:
60
2
=
V
J
T
N
H
T
i
For example
, if we use:
J
= 180 [days],
H
= 5 [m],
N
= 20 [cycles/h],
T
= 12 [h],
V
= 5 [m/min]
1440
60
5
180
12
20
5
2
=
=
i
T
Step 2: Calculate the actual load spectrum factor per inspection interval,
K
mi
1. Divide the total lifting time in proportion to the actual load spectrum during the inspection interval. For example, if
the product has lifted full loads (100%) for half of the time and no load (0%) for half of the time then record 50 for
each of these in the “Lifting time %” column of the table below.
Load %
Lifting time %
Factor k
3
Load spectrum factor
100 %
*
1
=
80 %
*
0.51
=
60 %
*
0.22
=
40 %
*
0.06
=
20 %
*
0.01
=
0 %
*
0
=
Total:
100%
Sum:
Divide by 100:
Sum / 100 =
Load spectrum factor, Kmi:
2. The sum of the figures in the “Lifting time %” column must always be 100.
3. Multiply each entry in the “Lifting time %” column by the multiplier in the “Factor k3” column. Write the results in
the “Load spectrum factor” column.
4. Add up the numbers in the “Load spectrum factor” column and record the result of this sum.
5. Divide the sum of the “Load spectrum factor” column by 100 to get the Kmi
For example
, if we use: 100% load for 10% of the time, 40% load for 30% of the time and 20% load for 60% of the
time:
