Perencanaan Kapasitas
Produksi
D0394 Perancangan Sistem Manufaktur
Pertemuan XI - XIV
Goal of Business
Turn Sales into Profits
Use Minimum Resources to Max Profits
Produce to Demand
No Over Production
No Under Production
Capacity Management
• Capacity
– APICS Definition
• “The capability of a worker, machine, work center, plan, or
organization to produce output per period of time.”
– Is the amount of work that can be done in a specified
time period.
– Capacity is the rate of doing work, not the quantity of
work done.
Capacity Management
•
Two Types of Capacity
1. Capacity Available
•
The capacity of a system or resource to produce a quantity
of output per time period
2. Capacity Required
•
•
The capacity of a system or resource needed to produce a
desired output in a given time period.
Load
•
The amount of released and planned work assigned to a
facility for a particular time period.
Capacity Management
• Capacity Management
– APICS Definition:
• “The function of establishing, measuring, monitoring and
adjusting limits or levels of capacity in order to execute all
manufacturing schedules”
• CM is responsible for determining the capacity needed to
achieve the priority plans
• CM also serves by providing, monitoring, and controlling
that capacity such that the priority plan can be met.
Capacity Management
• Capacity Control
– Is the process of monitoring production output,
comparing it with capacity plans, and taking
corrective action when needed.
Capacity Management
• Capacity Planning
– The process of determining the resources required to
meet the priority plan and the methods needed to
make that capacity available.
– The priority plan cannot be implemented unless the
firm has sufficient capacity to fulfill demand.
– Capacity planning links priority schedules to
manufacturing resources.
Capacity Management
• Capacity versus Load
LOAD
CAPACITY
AVAILABLE
OUTPUT
Capacity Tracking
Day
Available
Time
Press Performance
Run Time Down Time
Pieces Produced
Target
Actual
13-Nov-00
8:50:00
5:02:00
3:48:00
100,170
40,617
6,617
16%
6,617
16%
57%
41%
84%
14-Nov-00
5:30:00
4:07:00
1:23:00
62,370
37,197
4,197
11%
3,450
9%
75%
60%
91%
15-Nov-00
8:47:00
6:04:00
2:43:00
99,603
44,190
3,342
8%
3,342
8%
69%
44%
92%
16-Nov-00
9:00:00
7:17:00
1:43:00
102,060
64,998
8,773
13%
8,773
13%
81%
64%
87%
17-Nov-00
8:45:00
7:06:00
1:39:00
99,225
56,043
1,855
3%
1,855
3%
81%
56%
97%
18-Nov-00
0:00:00
0:00:00
0:00:00
-
-
-
0%
-
0%
0%
0%
0%
Weekly Totals
40:52:00
29:36:00
11:16:00
24,784
10.2%
24,037
9.9%
72.4%
52.4%
90.1%
463,428
243,045
Total Scrap Loss
(pcs)
(%)
Zed #1 Daily OEE
1.2
Quality Loss
(pcs)
(%)
Availability Performance Quality
0:00:00
0:00:00
29:36:00
11:16:00
-
-
463,428
243,045
-
0%
-
0%
0%
0%
0%
24,784
10.2%
24,037
9.9%
72.4%
52.4%
90.1%
Capacity Tracking
Zed #1 Daily OEE
1.2
1
Percentage
0.8
Availability
Performance
0.6
Quality
OEE
Target OEE
0.4
0.2
0
13-Nov-00 14-Nov-00 15-Nov-00 16-Nov-00 17-Nov-00 18-Nov-00
Day
Weekly
Totals
Capacity Management
• Capacity Planning
– Priority plans are stated in units of product or some
standard unit of output.
– Capacity can usually be stated in similar units.
– If there exists no common unit then capacity must be
expressed in terms of hours available.
Capacity Management
• The Process of Capacity Planning
– Determine the capacity available at each work center
in each time period
– Determine the load at each work center in each time
period
– Resolve differences between available capacity and
required capacity
• If possible, adjust available capacity to match the load.
Capacity Management
Planning Levels
Plan
Implementation/
Control
Production
Plan
Resource
Plan
Master
Production
Schedule
Rough-cut
Capacity
Plan
Material
Requirements
Plan
Capacity
Requirements
Plan
Production
Activity
Control
Capacity
Control
Short Range
Capacity Management
• Capacity Requirements Planning (CRP)
– It is the process of determining in detail the
amount of labor and machine resources
needed to achieve the required production.
– CRP occurs at the level of the MR plan
– CRP is the most detailed, complete, and
accurate of the capacity planning techniques.
Capacity Management
• Capacity Requirements Planning Inputs
*Open shop orders
*Planned order releases
*Routings
*Time standards
*Lead times
*Work center capacities
• Sources of Information
*Open order file
*MR plan
*Routing file
*Work center file
Capacity Management
• Open Order File
– A record of all active shop orders
– Shows all relevant information such as quantities,
due dates, and operations
• Planned Order Releases
– Determined by the MRP logic based upon the gross
requirements for a part
– Inputs to the CRP process in assessing the total
capacity required in future time periods.
Capacity Management
• Routing File
– A routing is the path that work follows from work
center to work center as it is completed
• Shown on route sheets or route files
– Routing files contain the following:
•
•
•
•
•
Operations performed
Sequence of operations
Work centers to be used
Tooling needed at each operation
Standard, setup, and run times per piece
Capacity Management
• Work Center File
– A work center consists of a number of machines or
workers capable of doing the same work.
• No differences in the kind of work or capacity
– A work center file contains information on:
•
•
•
•
Capacity
Move time
Wait time
Queue time
Capacity Management
•
Shop Calendar used to assist in
determining the
number of work
days in a period.
S
T
F
S
1
Calendar Day
2
3
4
1
9
Manufacturing
Day
M
Jan-00
W
T
16
23
30
10
5
2
11
6
3
12
7
4
13
8
5
14 15
6
7
8
9 10
17 18 19 20 21 22
11 12 13 14 15
24 25 26 27 28 29
16 17 18 19 20
31
21
Capacity Management
• Capacity Available
– Is the capacity of a system or resource to produce a
quantity of output in a given time period.
– Capacity available is affected by:
•
•
•
•
Product specifications
Product mix
Plant and equipment
Work effort
Capacity Management
• Measuring Capacity
– Units of Output
• If a variety of products produced is not large, a common
unit of output can be used such as:
–
–
–
–
Tons of material
Gallons
Barrels
Number of units…etc.
• Where a variety of products exists a common unit may not
be feasible, so time becomes the unit
– Standard times
Capacity Management
• Levels of Capacity
– Capacity should be measured on three levels:
• Machine or Individual Worker
• Work Center
• Plant
Capacity Management
• Determining Capacity Available
– Demonstrated Capacity
• An average obtained from historical data
– Calculated Capacity
• Based on available time, utilization and efficiency
– Available Time
• Is the number of hours a work center can be used
• Depends on the number of machines, number of workers and
the hours of operation.
Demonstrated Capacity Example:
#5.6, pg. 137
Q: Over a period of four weeks, a work center produced
50, 45, 35, and 55 standard hours of work. What is the
demonstrated capacity of the work center?
A: Demonstrated capacity = (50 + 45 + 35 + 55) / 4 = 46.25 standard hours
Capacity Formulas
• Utilization=(actual hours worked/available hours)
x 100%
• Efficiency=(std. hrs. of work/actual hours worked)
x 100%
• Rated Capacity = available time x utilization x
efficiency
Available Time Example:
A work center has three machines and is operated for
two eight hour shifts a day, five days a week. What is
the available time?
Available Time = 3 machines x 16 hrs. x 5 days
= 240 hrs/wk
Utilization Example:
A work center is available 80 hours, but actually
produced goods for 70 hours. What is the utilization
of the work center?
Utilization = (hours actually worked/available hours) x 100%
= (70/80) x 100%
= 87.5%
Capacity Management
•
Capacity Required (Load)
–
Translation of priorities into hours required
at each work center in each time period.
–
Two-step process:
1. First determine the time required for each order
at each work center
2. Second, add up the capacity required for the
individual orders to obtain the load.
Capacity Management
• Time Needed per Order
– The time needed for each order is the sum of
the setup time and the run time.
• The run time is equal to the run time per piece
multiplied by the number of pieces in the order.
Capacity Management
•
Load
–
The load is the sum of the required times for all the
planned and actual orders to be run on the work
center in a specified period.
–
Calculating the load:
1. First, determine the standard hours of operation time for
each planned and released order to each work center by
time period.
2. Second, add all the standard hours together for each work
center in each period.
Capacity Required Example:
#5.11, pg. 137
Q: How many standard hours are needed to run an order of 200
pieces if the setup time is 1.3 hours and the run time is 0.3 hours
per piece? How many actual hours are needed at the work center
if the efficiency is 130% and the utilization is 70%?
A: Time Required = setup time + (run time X no. of pieces)
= 1.3 + (.3 X 200)
= 61.3 standard hours
Actual Hours = standard hours/(efficiency X utilization)
= 61.3/(1.3 X 0.7)
= 67.36 hours
Capacity Management
• Work Center Load Report
– Shows future capacity requirements based on
released and planned orders for each time period of
the plan.
– Undercapacity
• Means the work center is underloaded
– Overcapacity
• Means the work center is overloaded
Work Center Load Example:
#5.14, pg. 138
5.14 A work center has the following open and planned
orders for week 4. Calculate the total standard time
required (load).
Order
Quantity
Released Orders 125
150
345
50
Planned Orders
565
75
785
35
Total Time (standard hours)
Released Orders 125
345
Planned Orders 565
785
Setup Time
(hrs)
0.25
0.40
1.00
0.50
Run Time
(hrs/pc)
0.10
0.05
0.20
0.15
Total Time
(hrs)
15.25
2.90
16.00
5.75
39.90
Total time = 0.25 + (150 x 0.10) = 15.25
Total time = 0.40 + (50 x 0.05) = 2.90
Total time = 1.00 + (75 x 0.20) = 16.00
Total time = 0.50 + (35 x 0.15) = 5.75
Capacity Management
• Scheduling Orders
– Calculation of when orders must be started
and completed on each work center so the
final due date can be met.
• Back Scheduling
– Start with the due date, and using the lead
times, work back to find the start date for
each operation.
Capacity Management
• Scheduling Orders
– Information Needed:
•
•
•
•
•
Quantity and due date
Sequence of operations and work centers
Setup and run times for each operation
Queue, wait and move times
Work center capacity available
– Information obtained from:
• Order file
• Route file
• Work center file
Capacity Management
•
Scheduling Process
1. First, calculate for each work order the
capacity required (time) at each work center.
2. Second, starting with the due date, schedule
back to get the completion and start dates for
each operation.
Capacity Management
• Making the Plan
– At this step the objective is to compare the load
to available capacity to identify any
imbalances.
– Two ways of balancing capacity and load:
• Alter the load
• Change the capacity available
Capacity Management
• Making the Plan
– Altering the load
• Shifting orders ahead or back so that the load is
leveled.
• Other components may have to be rescheduled
• The MPS may need to be changed
Capacity Management
• Making the Plan
– Changing the Capacity Available
• Schedule overtime or under time.
• Adjust the level of the workforce by hiring or laying off
workers.
• Shift workforce from underloaded to overloaded work
centers.
• Use alternate routings to shift some load to another work
center.
• Subcontract work when more capacity is needed or bring in
previously subcontracted work to increase required capacity.
Capacity Management
MRP and CRP Closed-Loop System
MPS
NO
Capacity OK?
(Rough Cut)
Feedback
YES
MRP
NO
Capacity OK?
(CRP)
YES
Purchasing
Production Activity
Control
Performance Measures
Scheduling Example:
#5.18, pg. 140
5.18 Back schedule the following shop order. All times are given in
days. Move time between operations is one day, and wait time is
one day. Due date is day 200. Assume orders start at the beginning
of a day and finish at the end of a day.
Operation
Number
Work
Center
10
20
30
110
120
130
Stores
Operation
Queue
Arrival Date Finish Date
Time (days) Time (days)
4
2
3
3
4
2
176
185
193
200
Finish Date – Operation Time – Queue Time
197 – 2 - 3
182
190
197
199 – 1 – 1
Finish Date - Wait Time - Move Time