ดาวน์โหลด All Proceeding - AS Nida

unit time, for preventive replacements at time t p, denoted as D(t p). From
equation (3) and (4) we show the sample calculations for:
Pump bearing give the value of β = 5.26308 and η = 10.2572
(see Table 7). Let T f = 0.071 wk, T p = 0.036 wk. The sample calculations
illustrated in Table 9 and gives values of D(t p) for various of t p. Here it
can be seen that the optimal preventive replacement interval is t p = 8
weeks.
Table 9 Optimal preventive replacement interval - Pump bearings (wk)
t p 5 6 7 8 9 10 11
D(t p) 0.00743 0.00653 0.00610 0.00603 0.00628 0.00684 0.00771
Packing give the value of β = 5.49178 and η = 3.86463 (see
Table 7). Let Tf = 0.024 wk, Tp = 0.006 wk. The sample calculations
illustrated in Table 10 and gives values of D(tp) for various of tp. Here it
can be seen that the optimal preventive replacement interval is tp = 2
weeks.
245
Table 10 Optimal preventive replacement interval - Packing (wk)
t p 1 2 3 4 5 6
D(t p) 0.00599 0.00384 0.00559 0.01134 0.02268 0.04163
4.6 Implement and Refine the maintenance plan
According to section 4.5 we defined the appropriate task
intervals and optimization for all Pulp Pump. At this stage we will
implement the maintenance plan for machine MC1, MC2 and MC3, for
example motor has failure mode is motor burn within the β = 1.42682
that shown has constant failure rate (β~1) thus the appropriate
maintenance task should be PM and the mean time to fail (MTTF) is
62.6639 wks, so we will scheduled inspection at week of 60 th or month
15 th . For other components scheduled PM intervals and optimization
maintenance are shown as Table 11.
Table 11 Scheduled PM Interval and Optimization for Pulp Pump components of Stock preparation unit
Components Failure Mode
Parameters
β η
Maintenance
Task
FFI
(months)
Replacement /
Overhaul (wk)
1. Motor Motor burns. 1.42682 62.6639 PM 15 -
2. Belt Damaged or broken belt. 1.37027 23.5603 PM 5 -
3. Shaft & Shaft sleeve Shaft wear or bend. 1.12241 26.0567 PM 6 -
4. Pump bearings Bearing broke 5.26308 10.2572 PdM - 8
5. Motor bearings Bearing broke 1.20565 56.2784 PM 14 -
6. Packing Wear, pulp and water leaks 5.49178 3.86463 PdM - 2
7. Flange Wear, water splashes into the bearing 1.42214 15.9930 PM 3 -
8. Impeller Wear due to a hotchpotch 1.30804 111.277 PM 27 -
9. Body Wear due to friction 1.18374 113.604 PM 28 -
10. Pulley Pulley loose off 1.01427 82.1241 PM 20 -
11. Pump base Base loose due to rust 1.01035 137.051 PM 34 -
5. Overall Operation
After implementation of maintenance plan per table 11
within the paper machine and collecting data in order to compare
with the result after applied maintenance action. By using operation
indicator which is machine downtime and machine availability, the
result is as follow Table 12 shown that when implementing
preventive maintenance to establish maintenance plans the machine
downtime for machine MC1 is 19.80%, MC2 is 19.98% and MC3 is
19.00% and machine availability for MC1 is 80.20%, MC2 is
80.02% and MC3 is 81.00% respectively.
Table 12 Downtime of machine breakdown after maintenance
improvement
Month
Operating Time
(min)
Downtime (%)
MC1 MC2 MC3
Availability (%)
MC1 MC2 MC3
Oct-10 44,640 22.52 24.39 23.33 77.48 75.61 76.67
Nov-10 43,200 21.64 21.19 19.61 78.36 78.81 80.39
Dec-10 41,760 20.09 19.93 19.38 79.91 80.07 80.62
Jan-11 41,760 19.68 18.60 18.19 80.32 81.40 81.81
Feb-11 40,320 15.08 18.19 16.83 84.92 81.81 83.17
Mar-11 44,640 19.83 17.59 16.69 80.17 82.41 83.31