Basics of Supply Chain Management : BSCM

Basics of Supply Chain Management : BSCM

Chapter 5. Capacity Management and Production Activity Control.

Main Issues :

· Discuss Objectives of Capacity Management and Characteristics of Capacity Planning.

· Understand how to determine Rated or Demonstrated Capacity (Capacity Available)

· Understand Capacity Requirement Planning. (Input & Output)

· Define Objectives of PAC and PAC Activities (Plan, Implement, and Control)

· Understand the Relationship between PAC and Manufacturing System.

· Understand PAC techniques : Scheduling, Loading, Bottleneck Management, Input/Output, Priority Rules.

1. Capacity Management.

□ Definition of Capacity.

- Capacity.

· The capability of a workers, machine, work center, plant, or organization to

produce output per period of time.

· Capacity required.

: The capacity of a system or resource needed to produce a desired output in                     : a particular time period.

: The system capability needed to make a given product mix (assuming

: technology, product specification, etc)

· Capacity available.

Figure 1. Capacity versus Load.

: The capability of a system or

: resource to produce a quantity of

: output in a particular time period.

Ch.5 Capacity Management & PAC.

2. Capacity Planning Process.

□ Capacity Planning.

- The process of determining the amount of capacity required to produce in the future.

- This process may be performed at :

1. An aggregate or product-line level (Resource Requirements Planning)

2. The master-scheduling level (Rough-Cut Capacity Planning)

3. The material requirements planning level (Capacity Requirement Planning)

Figure 2. Capacity Planning Levels.

		Priority		Capacity
		Production Plan		Resource Plan (Long range)
		Master Production Schedule		Rough-Cut Capacity Plan (Medium range)
Plan
		Material Requirement Plan		Capacity Requirement Plan (Short range)
Implement/ Control
		Production Activity Control		Capacity Control (Short range)

□ The Process of Capacity Planning.

Step 1. Determine the capacity available at each work center in each time period.

Step 2. Determine the load at each work center in each time period.

· Translate the priority plan into the hours of work required at each work

center in each time period.

· Sum up the capacities required for each item on each work center to

determine the load on each work center in each time period.

Step 3. Resolve differences between available capacity and required capacity.

If possible, available capacity should be adjusted to match the load. Otherwise,

the priority plans must be changed to match the available capacity.

3. Capacity Available

□ Measuring Capacity

- If a variety of products is made, a good common unit may not exist. In this case, the

unit common to all products is time.

- The work content of a product is expressed as the time required to make the product

using a given method of manufacture.

- Standard time provides a yardstick for measuring work content and a unit for stating

capacity.

□ Levels of Capacity

- Capacity needs to be measured on at least three levels.

· Plant, which can be considered as a group of different work centers.

· Work center, consisting of one or more people and/or machine with identical capabilities.

· Machine or individual worker.

□ Capacity Available.

- The capacity of a system or resource to produce a quantity of output in a given time period.

- Factors affecting capacity available.

· Product Specifications.

· Product Mix.

· Plant and equipment.

· Work effort.

- To calculate capacity available, identify

· Available Time.

· Utilization.

· Efficiency.

□ Rated Capacity.

- The expected output capability of a resource or system.

- Capacity is traditionally calculated from such data as planned hours, efficiency, and utilization.

- Factors for calculating Rated capacity

1. Available Time

· Depend on the number of machines, number of workers, and hours of operation.

· Number of machines (or number of workers) × hours of operation.

2. Utilization

· The percentage of time that the work center is actually active.

.· Utilization =	Hours actually worked	× 100 %
	Available hours

3. Efficiency

· A measure (as a percentage) of the actual output compared with the

standard expected output.

.· Efficiecy =	Standard hours of work	× 100 %
	Hours actually worked

· Example Problem.

Over a four-week period, a work center produced 540 standard hours of

work, was available for work 640 hours, and actually worked 480 hours.

Calculate the utilization and the efficiency of the work center.

Answer) Utilization =	480	× 100 % = 75%
	640

Answer) Efficiency =	540	× 100 % = 112.5%
	480

- Rated Capacity Example.

A work center consists of four machines and is operated eight hours per day for

five days a week. Historically, the utilization has been 85% and the efficiency 110%.

What is the rated capacity ?

Answer)

· Available Time = 4 × 8 × 5 = 160 hours per week.

· Rated Capacity = 160 × 0.85 × 1.10 = 149.6 standard hours.

□ Demonstrated Capacity.

- Proven capacity calculated from actual performance data, usually expressed as the

average number of items produced multiplied by the standard hours per item.

- Demonstrated Capacity Example.

Over the previous four weeks, a work center produced 120, 130, 150, and 140

standard hours of work. What is the demonstrated capacity of the work center ?

Answer)

.· Demonstrated Capacity =	120 + 130 + 150 + 140	= 135 standard hours
	4

4. Capacity Requirements Planning.

□ Elements of lead time

- Queue time : Time waiting before operation begins.

- Setup time : Time getting ready for operation.

- Run time : Time performing operation.

- Wait time : Time waiting after operation ends.

- Move time : Time physically moving between operations.

□ Inputs of CRP.

1. Planned order Release.

2. Open order file.

· A schedule receipt on the material requirement plan.

· It is a released order for a quantity of a part to be manufactured and completed

on a specific date.

· It shows all relevant information such as quantities, due date, and operations.

3. Routing file.

· A routing is the path that work follows from work center to work center as it is completed.

· Routing is specified on a route sheet or, in computer system, in a route file.

· The information contained.

1. Operation to be performed.

2. Sequence of operation.

3. Work centers to be used.

4. Possible alternate work centers.

5. Tooling needed at each operations.

6. Standard time : setup times and run times per piece.

4. Work center file.

· A work center is composed of a number of machines or workers capable of

doing the same work.

· A work center file contains information on the capacity and move, wait, and

queue times associated with the center.

5. Shop Calendar

· Another piece of information needed is the number of working days available.

· The Gregorian calendar has some serious drawbacks for manufacturing planning

and control.

· It is desirable to develop a shop calendar.

Figure 3. Routing and Open Order Status

Part Number	Shop Order Number	Quantity	Due Date	Operation Number	Work Center	Standard Setup Time	Standard Run Time per Piece	Status
A	101	20	415	010	100	2.0	0.2	Complete
				020	300	2.0	0.4	Complete
				030	400	4.0	0.2	Complete
				040	200	2.0	0.1
				050	400	2.0	0.3
B	106	40	419	010	400	2.0	0.3	Complete
				020	200	4.0	0.1	Complete
				030	300	2.0	0.2
				040	400	2.0	0.3
C	109	30	424	010	300	2.0	0.1	Complete
				020	100	4.0	0.4
				030	400	2.0	0.4
				040	100	2.0	0.2
				050	200	0.0	0.2

Figure 4. Work Center Data

Work Center No.	Description	No. of Machine	Machine Utilization	Efficiency	Planned Queue Time	Planned Wait Time
100	Saw	3	80%	110%	8.0	4.0
200	Glue	4	70%	90%	12.0	2.0
300	Drill	2	90%	100%	10.0	2.0
400	Smooth	3	95%	95%	8.0	4.0

Figure 5. Shop(Manufacturing) Calendar

Month	Week	Mon	Tues	Wed	Thurs	Frl	Sat	Sun
2002 August	32	29 123	30 124	31 125	1 126	2 127	3	4
	33	5 128	6 129	7 130	8 131	9 132	10	11
	34	12 133	13 134	14 135	15 136	16 137	17	18
	35	19 138	20 139	21 140	22 141	23 142	24	25
	36	26 143	27 144	28 145	29 146	30 147	31	1

□ Scheduling Orders.

- Scheduling is to calculate when orders must be started and completed on each work

center so the final due date can be met.

- The usual process is to start with the due date and, using the lead times, to work

back to find the start date for each operation. This process is called back scheduling.

- Requirements.

· The quantity and due date.

· Sequence of operations and work centers needed.

· Setup and run times for each operation.

· Queue, wait, and move times.

· Work center capacity available.

- Related file.

· Order file : Quantities and due dates.

· Route file : Sequence of operations, work centers needed, setup time, and runtime.

· Work center file : Queue, move, and wait times and work center capacity.

- The Process

1. For each work order, calculate the capacity required at each work center.

2. Starting the due date, schedule back to get the completion and start dates for

each operation.

□ Backward Scheduling & Loading : Example.

Suppose there is an order for 150 of gear shaft SG 123. The due date is day 135. The           route sheet, shown in Figure 6., gives information about the operations to be performed            and the setup and run times. The work center file, shown in Figure 6, give lead time              data for each work center. Calculate the start and finish dates for each operation. Use             the following scheduling rules.

1. Operation times are rounded up to the nearest eight hours and expressed as                     days on a one-shift basis. That is, if an operation takes 6.5 standard hours,                      round it up to eight hours, which represents one day.

2. Assume an order starts at the beginning of the day and finished at the end of a                   day. For example, if an order start on day 1 and is finished on day 5, it has                     taken five days to complete. If move time is one day, the order will be available                   to the next work station at the start of day 7.

Figure 6. Routing & Work center File for gear shaft SG 123.

Part Number : Gear shaft Drawing Number : D123X Part Number : SG 123
Operation No.	Work Center	Setup Time (Standard Time)	Run Time/piece (Standard Time)	Queue (days)	Wait (days)	Move (days)	Operation.
10 20 30 40 50	12 14 17 03 Stores	1.50 0.50 0.30 0.45	0.20 0.25 0.05 0.10	4 3 5 8	1 1 1 1	1 1 1 1	Turn Shaft Mill slot Drill 2 holes Grind Inventory

- Answer)

1. Calculate Standard hours (Setup time + Run time)

· Operation 10 (WC 12) :  1.50 + 0.20 × 150 = 31.5  standard hours (4 days)

· Operation 20 (WC 14) :  0.50 + 0.25 × 150 = 38.0  standard hours (5 days)

· Operation 30 (WC 17) :  0.30 + 0.05 × 150 =  7.8  standard hours (1 days)

· Operation 40 (WC 03) :  0.45 + 0.10 × 150 = 15.45 standard hours (2 days)

2. Backward Scheduling.

91	92	93	94	95 Start Date
96	97	98	99 - 100 Operation (12)
101 - 102 Operation (12)		103 Wait (12)	104 Move (12 -> 14)	105
106	107	108 - 110 Operation (14)
111 - 112 Operation (14)		113 Wait (14)	114 Move (14 -> 17)	115
116	117	118	119	120 Operation (17)
121 Wait (17)	122 Move (17 -> 03)	123	124	125
126	127	128	129	130
131-132 Operation (03)		133 Wait (03)	134 Move (03 -> store)	135 Due Date

Operation Number	Work center	Arrival Date	Queue (days)	Operation (days)	Wait (days)	Finish Date
10	12	95	4	4	1	103
20	14	105	3	5	1	113
30	17	115	5	1	1	121
40	03	123	8	2	1	133
50	Stores	135

3. Loading to Work centers.

· WC 12 :  99 - 102 (4 days)

· WC 14 : 108 - 112 (5 days)

· WC 17 : 120       (1 days)

· WC 03 : 131 - 132 (2 days)

□ Load Profile.

- A load profile shows the capacity requirements based on planned and released orders

for each time periods of the plan.

- Example :

· Work center load report.

Week	20	21	22	23	24	Total
Released Load	51.5	45	30	30	25	181.5
Planned Load	100.5	120	100	90	100	510.5
Total Load	152.0	165	130	120	125	692.0
Rated Capacity	140.0	140	140	140	140	700.0
(Over)/Under capacity	(12)	(25)	10	20	15	8

· Graph of a load profile.

Figure 7. Load Profile.

□ Resolving Difference.

- If available capacity is greater than required, there is a potential for not using resource

to the fullest.

- If available capacity is less than required, the priority plan cannot be met unless

changes are made.

- Alternatives for balancing required and available capacity.

· Change capacity.

1. Schedule overtime or under time.

2. Adjust the level of the workforce by hiring or layoffs workers.

3. Shift work force from underload to overload work center.

4. Use alternate routings to shift some load to another work center.

5. Subcontract work when more capacity is needed.

· Alter load.

1. Alter lot sizes.

2. Reschedule.

· Altering the load may complicate the schedule for other work centers.

5. Production Activity Control : Introduction.

□ Objectives.

- The function of routing and dispatching the work to be accomplished through the

production facility and of performing supplier control.

- Production activity control (PAC) is responsible for executing the MPS and the MRP.

- It also must make good use of labor and machines, minimize work-in-process

inventory, and maintain customer service.

- The MRP authorizes PAC :

· To release work order to the shop for manufacturing.

· To take control of work orders and make sure they are completed on time.

· To be responsible for the immediate detailed planning of the flow of orders

through manufacturing, carrying out the plan, and controlling the work as it

progresses to completion.

· To manage day-to-day activity and provide the necessary support.

□ PAC Activities : Planning.

- Ensure that resources are available to manufacture the components when needed.

(Resources : Materials, Personnel, Tooling, Information)

- Schedule start and completion dates for each shop order at each work center so the

scheduled completion date of the order can be met.

- This will involve the planner in developing a load profile for the work centers.

- Main Activities.

1. Order Preparation.

· PAC is responsible for planning and preparing its release to the shop floor.

· The order should be reviewed to be sure that :

: The necessary tooling.

: Material. (if not used in MPR program)

: Capacity. (if not used in CRP system)

2. Scheduling.

· Consideration for Scheduling.

: Manufacturing Lead time.

: Scheduling Techniques.

: Overlapping & Lot Splits.

3. Load Leveling.

· Spreading orders out in time or rescheduling operations so that the amount

of work to be done in sequential time periods tends to be distributed

evenly and is achievable.

4. Documentation(Shop Information Packet).

· A package of documents used to plan and control the shop floor

movement of an order.

· The packet may include a manufacturing order, operation sheets,

engineering blueprints, picking lists, move tickets, inspection tickets, and

time tickets.

Figure 8. Order Release Process

□ PAC Activities : Implementation (Execution).

- Gather relevant information for the shop order to make the product.

- Release shop orders as authorized by the material requirements plan. This is called

dispatching.

- Main Activities.

1. Staging/Kitting.

· Staging : Pulling material for an order from inventory before the material is

required. This action is often taken to identify shortages, but it can

lead to increased problems in availability and inventory accuracy.

· Kit : The components of a parent item that have been pulled from stock

and readied for movement to a production area.

· Kitting : The process of constructing and staging kits.

2. Dispatching.

· The selecting and sequencing of available jobs to be run at individual

workstations and the assignment of those jobs to workers.

3. Expedite/de-expedite.

· Expedite : To rush or chase production or purchase orders that are

needed in less than the normal lead time ; To take extraordinary

action because of an increase in relative priority.

· De-expedite : The reprioritizing of jobs to lower level of activity. All

extraordinary actions involving these jobs stop.

□ PAC Activities : Control.

- Establish and maintain order priority, and establish a dispatch list based on this information.

- Track actual performance of work orders and compare it to planned schedules. Where

necessary, PAC must take corrective action by replanning, rescheduling, or adjusting

capacity to meet final delivery requirements.

- Monitor and control WIP, lead times, and queue.

- Report work center performance such as efficiency, operation times, order quantities,

and scrap.

- Main Activities.

1. Input/Output Control.

· A techniques for capacity control where planned and actual inputs and

planned and actual outputs of a work center are monitored.

· Production monitoring.

2. Operation Sequencing.

· A techniques for short-term planning of actual jobs to be run in each work

center based on capacity (i.e., existing workforce and machine availability)

and priorities.

· The result is a set of projected completion times for the operations and

simulated queue levels for facilities.

□ PAC reporting

- PAC reporting provides feedback of what is actually happening on the plant floor.

- It allows PAC to maintain valid records of on-hand and on-order balances, job status,

shortage, scrap, material shortages, and so on.

- Types of information needed for the various reports :

· Order status.

· Weekly input/output by department or workcenter.

· Exception reports on such things as scrap, rework, and late shop orders.

· Inventory status.

· Performance summation on order status, work center and department efficiencies,

and so on.

5. Manufacturing Systems and PAC Techniques.

□ Manufacturing Systems and PAC.

- Manufacturing processes can be conveniently broken down into three categories :

· Flow manufacturing.

· Intermittent manufacturing.

· Project manufacturing.

Figure 9. Job Shop and Flow Manufacturing.

1. Flow manufacturing.

· It is concerned with the production of high-volume standard products.

· If the units are discrete, the process is called repetitive manufacturing.

· If the goods are made in a continuous flow, continuous manufacturing.

· Characteristics.

: Routing are fixed, and work centers are arranged according to the routing.

: Work centers are dedicated to producing a limited range of similar products.

: Material flow from one workstation to another.

: Capacity is fixed by the line.

· PAC in flow manufacturing.

: PAC concentrates on planning the flow of work and make sure that the right

: material is fed to the line as stated in the planned schedule.

: Since work flows from one workstation to another automatically,

: implementation and control are relatively simple.

2. Intermittent manufacturing.

· It is characterized by many variations in product design, process requirements,

and order quantities.

· Characteristics.

: Flow of work through the shop is varied and depends on the design of a

: particular product.

: Machinery and workers must be flexible enough to do the variety of work.

: Throughout time are generally long. Scheduling work to arrive just when

: needed is difficult, the time taken by an order at each work center varies,

: and work queues before work centers, causing long delays in processing.

: The capacity required depends on the particular mix of products being built

: and is difficult to predict.

· PAC in intermittent manufacturing.

: PAC in this system is complex, because of the number of product made, the

variety of routings, and scheduling problems.

: PAC is a major activity in this type of manufacturing.

: Planning and control are typically exercised using shop orders for each batch

: being produced.

3. Project Manufacturing.

· It usually involves the creation of one or a small number of uints.

· Because the design of a product is often carried out or modified as the project

develops, there is close coordination between manufacturing, marketing,

purchasing, and engineering.

□ PAC Data Requirements.

- PAC must have the following information :

· What and how much to produce.

· When parts are needed so the completion date can be met.

· What operations are required to make the product and how long the operation will take.

· What the available capacities of the various work centers are.

- Usually the data needed to answer these questions are organized into database. The

files contained in the database are of two types : Planning and Control file.

1. Planning files : Item master file, Product structure file, Routing file, Work center master file.

- Item master file.

· Part number, a unique number assigned to a component.

· Part description.

· Manufacturing lead time, the normal time needed to make this part.

· Quantity on hand.

· Quantity available.

· Allocated quantity, quantities assigned to specific work orders but not yet

withdrawn from inventory.

· On-order quantities, the balance due on all outstanding orders.

· Lot-size quantity, the quantity normally ordered at one time.

- Product structure file (Bill of material file)

· A list of the single-level components and quantities needed to assemble a parent.

· It forms a based for "pick list" to be used by storeroom personnel.

- Routing file.

· The operations required to make the product and the sequence in which

those operations are performed.

· A brief description of each operation.

· Equipment, tools, and accessories needed for each operation.

· Setup times, the standard time required for setting up the equipment for

each operation.

· Run times, the standard time to process one unit through each operations.

· Lead times for each operation.

- Work center master file.

· Work center number.

· Capacity.

· Number of shifts worked per work.

· Number of machine hours per shift.

· Efficiency.

· Utilization.

· Queue time, the average time that a job waits at the work center before

work is begin.

· Alternate work centers, work centers that may be used as alternatives.

2. Control files : Shop order master file, Shop order detail file.

- Shop order master file.

· Each active manufacturing order has a record in this file.

· The purpose is to provide summarized data on each shop order.

: Order quantity.

: Quantity completed.

: Quantity scrapped.

: Quantity of material issued to the order.

: Due date, the date the order is expected to be finished.

: Priority, a value used to rank the order in relation to others.

: Balance due, the quantity not yet completed.

: Cost information.

- Shop order detail file.

· Each shop order has a detail file that contains a record for each operation

needed to make the item.

: Operation number.

: Setup hours, planned and actual.

: Run hours, planned and actual.

: Quantity reported complete at that operations.

: Quantity reported scrapped at that operations.

: Due date or lead time remaining.

□ PAC Technique 1 : Scheduling.

- Objectives of Scheduling.

· To meet delivery lead time and to make the best use of manufacturing resources.

· It involves establishing start and finish dates for each operation required to

complete an item.

· To develop a reliable schedule, the planner must have information on routing,

required and available capacity, competing jobs, and manufacturing lead time

(MLT) at each work center.

- Considerations of Scheduling

· Manufacturing Lead time.

· Scheduling Techniques : Backward & Forward Scheduling.

· Loading Techniques : Infinite & Finite Loading.

1. Manufacturing Lead time.

· The total time required to manufacture an item, exclusive of lower level

purchasing lead time.

· For make-to-order.

: It is the length of time between the release of an order to the production

: process and shipment to the final customer.

· For make-to-stock.

: It is the length of time between the release of an order to the production

: process and receipt into finished goods inventory.

· Elements of MLT.

: Setup time and run time are straightforward, and determining them is the

responsibility of the industrial engineering department.

: The largest of the five elements is queue time. Typically, in an intermittent

manufacturing operation, it accounts for 85 -95% of the total lead time.

Figure 10. Manufacturing Lead Time.

· PAC vs. MLT.

: Queue, wait, and move times are under the control of manufacturing and PAC.

: PAC is responsible for managing the queue by regulating the flow of work

: into and out of work centers.

: PAC must manage both the input of orders to the production process and

: the available capacity to control queue and WIP.

2. Scheduling Techniques.

· Forward scheduling.

: Material procurement and operation scheduling for a component start when

: the order is received.

: Whatever the due date, and operations are scheduled forward from order

: received date.

: The technique is used for purposes such as developing promise dates for

customers or figuring out whether an order behind scheduling can be caught up.

· Backward scheduling.

: The last operation on the routing is scheduled fist and is scheduled for

: completion at the due date.

: This schedules items to be available as needed and is the same logic as

: used in the MRP system.

: Backward scheduling is used to determine when an order must be started.

: This is common in industry because it reduces inventory.

2. Loading Techniques.

· Infinite loading.

: The assumption is made that the workstations have capacity available when

: required.

: It does not consider the existence of other shop orders competing for

: capacity at these work center.

· Finite loading.

: It assumes there is a defined limit to available capacity at any workstation.

: If there is not enough capacity available at a workstation because of other

: shop orders, the order has to be scheduled in a different time period.

Figure 13. Infinite and Finite load profile.

□ PAC Technique 2 : Overlapping & Lot Splits.

- Operation Overlapping.

· In operation overlapping, the next operation is allowed to begin before the entire

lot is completed on the previous operation.

· This reduces the total manufacturing lead times because the second operation

starts before the first operation finishes all the part in the order.

· Operation overlapping is a method of expediting an order, there are some cost

involved.

: Move cost are increased.

: The queue and lead time for other orders may be increased.

Figure 14. Operation Overlapping.

- Operation Splitting.

· The order is split into two or more lots and run on two or more machines

simultaneously.

· If the lot is split in two, the run-time component of lead time is effectively cut in

half, although an additional setup is incurred.

Figure 15. Operation Splitting.

□ PAC Technique 3 : Bottleneck Management.

- In intermittent manufacturing, some workstations are overloaded and some underloaded.

The overloaded workstations are called bottlenecks.

- A bottleneck is defied as "a facility, function, department, or resource whose capacity is

equal to or less than the demand placed upon it."

- Bottlenecks control the throughput of all products processed by them.

- Workcenters feeding bottlenecks should be scheduled at the rate the bottleneck can process.

- Workcenters fed by the bottleneck have their throughput controlled by the bottleneck.

- Some bottleneck principles.

1. Utilization of a non-bottleneck resource is not determined by its potential, but by

another constraint in the system.

2. Using a non-bottleneck 100% of the time does not produce 100% utilization.

3. The capacity of the system depends on the capacity of the bottleneck.

4. Time saved at a non-bottleneck saves the system nothing.

5. Capacity and priority must be considered together.

6. Loads can, and should, be spilt.

- Managing bottleneck.

1. Establish a time buffer before each bottleneck. A time buffer is an

inventory(queue) place before each bottleneck.

2. Control the rate of material feeding the bottleneck.

3. Do everything to provide the needed bottleneck capacity.

4. Adjust loads.

5. Change the schedule.

□ PAC Technique 4 : Input/Output Control.

-  A method of managing queues and work-in-process lead times by monitoring and

controlling the input to, and output from, a facility.

-  The input rate is controlled by the release of orders to the shop floor.

-  The output rate is controlled by increasing or decreasing the capacity of a workcenter.

-  Input/Output report : For comparing what actually occurs against what was planned, to

control input and output.

Figure 16. Input/Output Control

Work Center : 201

Capacity per Period : 40 standard hours

Period	1	2	3	4	5	Total
Planned Input	38	32	36	40	44	190
Actual Input	34	32	32	42	40	180
Cumulative Variance	-4	-4	-8	-6	-10	-10

Planned Output	40	40	40	40	40	200
Actual Output	32	36	44	44	36	192
Cumulative Variance	-8	-12	-8	-4	-8	-8

Figure 18. Input/Output Report

Planned Backlog	32	30	22	18	18	22
Actual Backlog	32	34	30	18	16	20

□ PAC Technique 5 : Operation Sequencing.

-  A technique for short-term planning of actual jobs to be run in each workcenter

based on capacity and priorities. Priority, in this case, is the sequence in which jobs

at workcenter should be worked on.

-  Dispatching is a function of selecting and sequencing available jobs to be run at

individual workcenters.

-  The information of dispatching list.

1. Plant, department, and workcenter.

2. Part number, shop order number, operation number, and operation description of

jobs at the workcenter.

3. Standard hours.

4. Priority information.

5. Jobs coming to the work center.

-  Dispatching rules.

1. First come, first served (FCFS).

2. Earliest job due date (EDD).

3. Earliest operation due date (ODD).

4. Shortest process time (SPT).

5. Critical ratio (CR).

CR =	due date - present date	=	actual time remaining
	lead time remaining		lead time remaining

Figure 20. Application of sequencing list.

Job	Process Time(days)	Arrival Date	Due Date	Operation Due Date	Sequencing Rule
					FCFS	EDD	ODD	SPT
A	4	223	245	233	2	4	1	3
B	1	224	242	239	3	2	2	1
C	5	231	240	240	4	1	3	4
D	2	219	243	242	1	3	4	2

■  Performance Check.

1. A work center consist of two machines working eight hours a day and five days a week. Historically, utilization has been 80%, and efficiency has been 90%. To the nearest hour, what is the rated capacity ?

A. 80 hours.          B. 58 hours.          C. 40 hours.        D. 30 hours.

2. What term indicates the percentage of time the work center is active compared to the available time ?

A. Efficiency.         B. Effectiveness.        C. Utilization.       D. Uptime.

3. What item is used for the ratio of standard hours of work produced to hours actually worked ?

A. Efficiency         B. Effectiveness          C. Utilization        D. Uptime.

4. What term is used for calculating (available time) × (utilization) × (efficiency) ?

A. Effectiveness

B. Useful capacity

C. Demonstrated Capacity

D. Rated capacity

5. Which of the following shows the capacity required at each workcenter based on planned and released orders for each time period of the plan ?

A. Workcenter profile

B. Load profile

C. Scheduled order profile

D. Work-to-be-done report

6. Which of the following must production activity control do when planning the flow of work ?

A. Be sure the material and tooling needed are available.

B. Advise the plant supervisor of future orders.

C. Refer to the production plan for what orders to run.

D. Complete a material requisition plan.

7. Which of the following is concerned with very short-term detailed planning of the flow of orders through manufacturing ?

A. Production planning.

B. Master production scheduling.

C. Material requirement planning.

D. Production activity control.

8. Which of the following is an element of manufacturing lead time ?

A. Design time

B. Delivery lead time

C. Wait time

D. Purchase lead time

9. What is the name given to a scheduling system in which the last operation on a routing is scheduled first and for completion on the due date ?

A. Forward scheduling.

B. Backward scheduling.

C. Infinite scheduling.

D. Finite scheduling

10. Which of the following statements is most accurate ?

A. Work centers located after a bottleneck should work at full capacity.

B. A time buffer should be established after a bottleneck.

C. Work centers feeding a bottleneck should work at full capacity.

D. A bottleneck will control the throughput of all products processed by it.

Solutions :

1  2  3  4  5  6  7  8  9  10

B C A D B A D C B D