Operations Management Chapter 16 - Scheduling

Primary goals of flow-shop scheduling

1. Achieve and maintain smooth rate of flow through process for products, services or customers.

General approaches to service scheduling

1. Demand management. -Customers, employees. 2. Capacity management -Employees, equipment, facilities.

Key success factors for flow-shop scheduling

1. Design products, services and processes that promote smooth flow of work through a system. 2. Use optimal mix of products or services to make best use of inputs to create minimal cost output.

operations using job shop scheduling

1. Processing or material requirements. 2. Process times, steps or sequencing.

Challenges when scheduling services

1. Random nature of service requests. 2. Inability to inventory process output.

Ways to minimize scheduling challenges

1. Set realistic due dates for work completion. 2. Variability in setup and processing times. 3. Reduce the impact of constraints by increasing those resource's capacity or scheduling them first.

Primary goals of flow-shop scheduling

2. Achieve and maintain high levels of utilization for employees, equipment and facilities

Key success factors for flow-shop scheduling

3. Minimize probability of quality problems to avoid process disruptions and wasted resources. 4. Improve reliability and timing of components by maintaining optimal levels of inventory.

Key success factors for flow-shop scheduling

5. Use preventive maintenance to minimize process breakdowns and disruptions. 6. Use rapid repair program to quickly respond to breakdowns with on-hand stores of critical part.

Johnson's Rule

a sequencing technique that seeks to minimize makespan when scheduling a group of jobs or orders that has to be processed by two machines or successive work centers

Gantt Chart

a type of tool used for both job shop scheduling and work center loading. organizes and visually displays intended or actual use of resources in a time framework. useful for evaluating alternative arrangements for loading and scheduling using trial and error.

Cyclical scheduling

assigns employees to time slots or shifts with days off on a repeating basis to have capacity as needed

Appointment systems

control customer demand for service to maximize resource use

Job lateness

difference between date that job is expected to be completed and the date it was due or promised to a customer

Forward scheduling

from a point in time

Backward scheduling

from some due date

Priority rules

heuristics used to select which jobs will be processed first and next

Three basic issues addressed by intermediate-volume scheduling

job run size, timing, and sequence

Line balancing

method of allocating tasks so that each work station is allocated equal total task times and sequencing requirements are met

scheduling

process of establishing the operational timing for activities and the use of resources

Highly balanced flow-shop process

results in high levels of resource and capacity utilization and highest possible rate of output

Drum

schedule entire operation to maximize utilization of the capacity of its constraints

Intermediate-volume scheduling

scheduling for operations that create relatively moderate volumes of relatively standardized products or services on intermittent basis

Yield management

scheduling tool that seeks to maximize revenue for a fixed service capacity that is perishable using variable pricing

Theory of Constraints

seeks to avoid complexity of scheduling systems by focusing on operation's bottlenecks or constraints. Uses drum-buffer-rope approach to scheduling. Maximizes through the system instead of output of every resource.

Rope

sequence the release of jobs to process to maximize utilization of constraint

Finite loading

taking into account current center capacity and job processing times

Average number of jobs

that are started and considered to be work-in-process inventory

Job flow time

time it takes from when a job arrives until it is completed

flow-shop scheduling

tools and systems tend to be specific to a product, service or industry

Makespan

total time needed to complete a group of jobs from beginning of first job to completion of the last job

Assignment models

use linear programming to determine optimal assignment of tasks and resources to work centers

Yield management

used for scheduling operations that have both walk-in customers who are not price sensitive and price-sensitive customers who can be incentivized to make reservations. also used for aggregate capacity planning

Loading

used to assign jobs to work centers by minimizing one or more of: 1. setup and processing costs. 2. work center idle times. 3. Job completion times.

Sequencing

used to determine work flow or the order in which jobs will be processed at a work center using priority rules

Reservation systems

used to generate an estimate of customer demand for a given time period to use for service scheduling

Input - Output Controls

used to manage work flow in a way that maximizes utilization of work centers and minimizes queues

Load charts

used to schedule jobs and display loaded and idle times of work centers

Scheduling chart

used to schedule sequence of tasks or activities required to complete a job. Completed charts can also be used to track progress and monitor if a job is on schedule.

Buffer

uses small amounts of inventory or time to minimize risk of constraint being idle

Infinite loading

without regard to capacity