LOADING JOBS, AND METHODS

Chapter 5

David de la Cruz BailénJorge Moreno Fuentes

LOADING JOBSLoading means the assignment of Jobs to

work or processing centers.

Operations Managers assign jobs to work centers so that cost and completion times are kept to a minimum

Loading work centers

Oriented to Capacity

Related to assigning specific jobs.

Work centers are areas in a business in which productive resources are organized and work is completed.

It may be a single machine, a group of machines, or an area where a particular type of work is done.

The work centers can be organized in a variety of ways including by function in a job-shop configuration; or by product in a flow, assembly line, or group-technology-cell configuration

A characteristic that distinguishes one scheduling system from another is how capacity is considered in determining the schedule.

The scheduling systems can use

LOADING JOBS

Infinite Loading

Finite Loading

Infinite loading:

Ignores capacity constraints, but helps identify bottlenecks in a proposed schedule to enable proactive management

With infinite loading jobs are assigned to work centers without regard for capacity of the work center.

Jobs are loaded at work centers according to the chosen priority rule.

LOADING JOBS

Priority rules are appropriate for use under the infinite loading approach.

This is known as vertical loading.

Finite loading:

Allows only as much work to be assigned as can be done with available capacity – but doesn’t prepare for inevitable slippage

Finite loading considers the capacity of each work center and compares the processing time so that process time does not exceed capacity.

With finite loading the scheduler loads the job that has the highest priority on all work centers it will require.

LOADING JOBS

Then the job with the next highest priority is loaded on all required work centers, and so on.

This process is referred to as horizontal loading

Characteristics of High-Volume OperationsHigh-volume aka flow operations, like

automobiles, bread, gasoline can be repetitive or continuous

High-volume standard items; discrete or continuous with smaller profit margins

Designed for high efficiency and high utilizationHigh volume flow operations with fixed routingsBottlenecks are easily identifiedCommonly use line-balancing to design the process

around the required tasks

Low-volume, job shop operations, are designed for flexibility.

Use more general purpose equipment Customized products with higher margins Each product or service may have its own routing

(scheduling is much more difficult)Bottlenecks move around depending upon the products

being produced at any given time

Characteristics of Low-Volume Operations

What an Input-Output Process is?

It is a technique that allows operation personnel to manage facility work flows.

The idea of this process is to know how much work is carrying out in order to adjust it

to the objective.

The advantages of Input-Output Control

Identifies overloading and underloading conditions

Prompts managerial action to resolve scheduling problems

Can be maintained using ConWIP cards that control the scheduling of batches.

F.e. In the case we need 120 hours

IDENTIFY THE BEST CONDITION

UNDERLOADING OVERLOADING

50 HOURS

50 HOURS

50 HOURS

50 HOURS

50 HOURS

The work is arriving faster than it is being processed

Inefficiency

Quality problems

The work is lower than it is being processed

Idle capacity

Wasted Resources

AIRBUS COMPANY

Input-Output Exercise

1º Week 2º Week 3º Week 4º Week

Planned Input 200 200 200 200

Actual Input 160 230 210 200

C. Deviation -40 -10 0 -0

Planed Output 220 220 220 220

Actual Output 200 260 190 180

C. Deviation -20 -60 -30 +10

C. Change in BackLog

? ? ? ?

CarCar, Ltd is a car enterprise which desires to develop an Input-Output Control for the Wheels Department for 4 weeks. The time stipulated per week is 200 hours for the Input, for the Output is 220. The real Input-Output is between 150-260 hours per week.

How much is the Cumulative Change in BackLog? What does this result mean?

Input-Output Exercise

1º Week 2º Week 3º Week 4º Week

Planned Input 200 200 200 200

Actual Input 160 230 210 200

C. Deviation -40 -10 0 -0

Planed Output 220 220 220 220

Actual Output 200 260 190 180

C. Deviation -20 -60 -30 +10

C. Change in BackLog

-40 -70 -50 -30

CarCar, Ltd is a car enterprise wich desires to develop an Input-Output Control for the Wheels Department for 4 weeks. The time stipulated per week is 200 houres. The real Input-Output is between 150-210 hours per week.

The work is arriving faster than it is being processed, so it means bad qualities and inefficiency.

How can be the Input-Output improved?

Through Go-Look-See Management, being the process in which managers actively move around the business engaging with their teams, their products, and the processes they operate.

Go to the source, observe and deeply understand the actual situation for yourself.

Gantt ChartsDeveloped in the late 1800’s by Henry

GanttLoad charts illustrate the workload

relative to the capacity of a resource

It shows the use of resources such working centers and labor

It also shows today’s job schedule by employeeWhen used in loading, Gannt Charts show the

loading and idle times of several departments, machines or facilities.

The display the relative workloads in the system so that the manager knows what adjustments are appropriated.

If a work center comes overloaded employees from other a low-loaded center can be transferred temporarily to increase work force.

Versatile equipment may also be transferred among centers.

Gantt Charts

Gantt ChartsShows relative workload in facilityDisadvantages

Does not account for unexpected eventsMust be updated regularly

DayWork Center

Monday Tuesday Wednesday Thursday Friday

Metalworks Job 349 Job 350

Mechanical Job 349 Job 406

Electronics Job 408 Job 349

Painting Job 295 Job 408 Job 349

Processing

Unscheduled

Center not available (for example, maintenance time, repairs, shortages)

Description  Decemb

erJanuary

February

March April May June July

A. Train Project Team                                                                                                                                  

B. Project Management Paperwork

                                                                                                                                  

C. Modify Purchased Package                                                                                                                                  

D. Manual systems Flow                                                                                                                                  

E. Modify In-House Procedures

                                                                                                                                  

F. Test and Implement Modifications to Purchased Package

                                                                 

                                                                 

G. Test and Implement Manual Systems Flow

                                                                                                                                  

H. Test and Implement Modifications to In-House Procedrues

                                                                 

                                                                 

Gantt Charts Exercise Answer key

What an Assignment Method is? It is a method of allocating organizational resources.

The Assignment Method involves assigning task or jobs to the resources.

To avoid the subactivity.

Optimize Workload capacity balance.

What is the objective of this method?

Minimize Total Costs Minimize the time required Maximize the production

The characteristics of the Assignment Method

Just one job or work is assigned to one project or machine.

It is used for production allocation.It is called as well The Hungarian method is

a combinatorial optimization algorithm that solves the assignment problem in polynomial time and which anticipated later primal-dual methods.

Models

JOB Wheels Airbag Lights

Worker 1 30 hours 35 hours 25 hours

Worker 2 15 hours 20 hours 19 hours

Worker 3 10 hours 13 hours 11 hours

Assignment Method ExerciseThe CarCar, Ltd. Co. wants to start the year with the following project: Assign Wheels, Airbag, and Lights, looking for the one with lower opportunity cost.

W A LJob 1 5 10 0 2 0 5 4 3 0 3 1

Typesetter

Step One - Rows¹

W A LJob 1 5 7 0 2 0 2 4 3 0 0 1

Typesetter

Step Two – Columns²

Assignment Method Exercise

Create zero opportunity costs by repeatedly subtracting the lowest costs from each row¹ and column².

Models

JOB Wheels Airbag Lights

Worker 1 30 hours 35 hours 25 hours

Worker 2 15 hours 20 hours 19 hours

Worker 3 10 hours 13 hours 11 hours

W A LJob1 5 7 02 0 3 43 0 0 1

Typesetter

Step Three – Lines

Because three lines is needed, the solution is optimal.

Draw the minimum number of vertical and horizontal lines necessary to cover all the zeros.

We take the Zeros to the Original Table

We repeat the creation of Zero opportunity Cost resting the low number outside the line to the other numbers.

Enough

Not enough

W A LJob1 5 7 02 0 3 43 0 0 1

Typesetter

Step Four - Assignments ORIGINAL COST TABLE

WheelsAirbagLightsJobWorker 1 30 35 25Worker 2 15 20 19Woker 3 10 13 11

Typesetter

MINIMUM COST: 25+15+13=53

David de la Cruz BailénJorge Moreno Fuentes