Perencanaan Kapasitas Produksi

D0394 Perancangan Sistem Manufaktur

Pertemuan XI - XIV

Turn Sales into ProfitsTurn Sales into Profits

Goal of Business

Use Minimum Resources to Max ProfitsUse Minimum Resources to Max Profits

Produce to DemandProduce to Demand

No Over ProductionNo Over Production No Under ProductionNo 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 Capacity1. 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

Capacity Tracking

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

Capacity Requiremen

ts Plan

Production Plan

Master Production Schedule

Material Requiremen

ts Plan

Production Activity Control

Resource Plan

Rough-cut Capacity

Plan

Capacity Control

Implementation/ Control

Plan

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 *Time standards

*Planned order releases *Lead times

*Routings *Work center capacities

• Sources of Information*Open order file *Routing file

*MR plan *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.

Calendar DayCalendar Day

Manufacturing Manufacturing DayDay

Jan-00S M T W T F S

1

2 3 4 5 6 7 81 2 3 4 5

9 10 11 12 13 14 156 7 8 9 10

16 17 18 19 20 21 2211 12 13 14 15

23 24 25 26 27 28 2916 17 18 19 20

30 3121

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:

Available Time = 3 machines x 16 hrs. x 5 days

= 240 hrs/wk

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?

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 center2. 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

Setup Time (hrs)

Run Time (hrs/pc)

Total Time (hrs)

Released Orders 125 150 0.25 0.10345 50 0.40 0.05

Planned Orders 565 75 1.00 0.20785 35 0.50 0.15

Total Time (standard hours)

Released Orders 125 Total time = 0.25 + (150 x 0.10) = 15.25

15.25

345 Total time = 0.40 + (50 x 0.05) = 2.90

2.90

Planned Orders 565 Total time = 1.00 + (75 x 0.20) = 16.00

16.00

785 Total time = 0.50 + (35 x 0.15) = 5.75

5.7539.90

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 Process1. 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 ManagementMRP and CRP Closed-Loop

SystemMPS

Capacity OK? (Rough Cut)

MRP

Capacity OK? (CRP)

Purchasing Production Activity Control

Performance Measures

Feed

back

NO

YES

YES

NO

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

Operation Time (days)

Queue Time (days)

Arrival Date Finish Date

10 110 4 320 120 2 430 130 3 2

Stores 200197193190185182176

197 – 2 - 3Finish Date – Operation Time – Queue Time 199 – 1 – 1

Finish Date - Wait Time - Move Time