3.9 Part X requires machining on a milling machine (operations A and B are required). Find the number of machines required to produce 3500 parts per week.
Assume the company will be operating 5 days per week, 18 hours per day. The following information is known:
Operation Standard Time Efficiency Reliability Scrap
A 2 min. 95 % 95% 2%
B 4 min. 95% 90% 5% note: The milling machine requires tool changes and preventive maintenance after every lot of 400 parts. These changes require 30 min.
OB = 2500 parts per week
I B =
1 0.05
2500
−
=2632 parts per week
O A =I B
I A =
1 0.02
2632
−
=2686 parts per week
H= available time – maintenance
Operation
A
Operation
B
2% 5%
I A O A
O B
available time = 5days/week*18 hours/day*60 min/hour = 5400 min/week maintenance time = *30
400
2686 =201.45 min/week
H = 5400 min/week – 201.45 min/week = 5198.55 min/week
F A=
HRE
Q SA A =
5189.55* 0.95* 0.95
2686 * 2 = 1.145 machines
F B =
HRE
Q SB B =
5198.55* 0.95* 0.90
2632 * 4 = 2.369 machines
F=F A + F B = 1.145+2.369 = 3.51 ≅ 4 Milling Machines
3.11 Given the following, what