Facility Layout Chapter 6

Facility Layout

• Refers to the configuration of departments, work centers, and equipment, with emphasis on movement of work (customers or materials) through the system.
• Involves an optimum arrangement of facilities, including man, machine, equipment, materials, etc.
• Critical due to substantial investments, long-term commitments, and significant impact on operational costs and efficiency.

The Need for Layout Decisions

• Inefficient operations, high costs, and bottlenecks.
• Changes in product or service design, introduction of new products or services, accidents, and safety hazards.
• Changes in environmental or legal requirements, output volume, or product mix.
• Changes in methods and equipment, and morale problems.

Facility Layout Requirements

• Specification of objectives in terms of output and flexibility.
• Estimation of product or service demand.
• Processing requirements in terms of operations and flow between departments and work centers.
• Space requirements for elements in the layout.
• Space availability within the facility.

Basic Layout Types

1. Product Layout

• Used with product-focused (repetitive) processes.
• Facility organized around product.
• Achieves smooth and rapid flow of large volumes of goods or customers through the system.
• Advantages:
  • High output, faster processing, and less unproductive time.
  • Low unit cost due to high volume and low material-handling cost.
  • Fairly routine accounting, purchasing, and scheduling.
  • High utilization of labor and equipment.
• Disadvantages:
  • Breakdown in a machine can cause shutdown.
  • Little satisfaction to workers.
  • Difficult to avoid machine interference.
  • Difficulty of applying individual-based incentive plans.
  • The system is fairly inflexible.

2. Process Layout

• Used with process-focused processes; low volume, high variety.
• Designed to process items or provide services that involve a variety of processing requirements.
• Causes discontinuous work flow, referred to as intermittent processing (non-repetitive processing).
• Place departments with large flows of material or people close together.
• Similar processes and equipment are located in close proximity.
• Advantages:
  • Flexibility: Allows wide variety of products.
  • Low fixed costs for general-purpose equipment.
  • Breakdown of a machine or worker does not stop processing.
  • Can handle a variety of processing requirements.
  • Possible to use individual incentive plans.
  • More satisfaction to workers.
• Disadvantages:
  • In-process inventory costs can be high.
  • Challenging routing and scheduling.
  • Equipment utilization rates are low.
  • Material handling slow and inefficient.
  • Complexities often reduce span of supervision.
  • Special attention for each product or customer.
  • Employees more loyal to their department than to the company.

3. Fixed-Position Layout

• Used for projects in which the product can't be moved.
• Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed.
• Workers and equipment come to the site.
• Widely used in farming, firefighting, road building, home building, and drilling for oil.

Combination Layouts

• A combination of the three basic layout types to satisfy the needs of a particular situation.
• Hospitals, for example, use a combination of process and fixed-position layouts.

Service Layouts

• Different types of service layouts, including:
  • Warehouse Layout
  • Storage Layouts
  • Retail Layouts
  • Office Layouts
  • Restaurant Layouts
  • Hospital Layouts, etc.

Scheduling

• Scheduling is the process of determining the starting and completion times for jobs, and allocating resources (labor, equipment, and facilities) to produce a product or provide a service.
• It specifies the timing and sequence of production, and must be realistic and clearly differentiated from aggregate planning.

Work Loading

• Loading is the assignment of work to specific resources/machines, and can be classified into two types:
  • Finite loading: assigns only as much work as can be done with available capacity, but doesn't prepare for inevitable slippage.
  • Infinite loading: ignores capacity constraints, but helps identify bottlenecks in a proposed schedule to enable proactive management.

Forward and Backward Loading

• Forward loading: starts processing when a job is received.
• Backward loading: begins scheduling the job's last activity so that the job is finished on the due date.

Job Sequencing

• Sequencing is concerned with developing an exact order (or sequence) of job processing.
• It determines the order in which jobs at a work center will be processed, taking into account the workstation, job time, and setup and processing time.

Gantt Charts

• Developed by Henry Gantt in the early 1900's, load charts illustrate the workload relative to the capacity of a resource, and are used as a visual aid for loading and scheduling.
• They show today's job schedule by employee, and help determine which jobs should be scheduled first.

Priority Rules for Allocating Jobs

• Priority rules are used to select the order in which jobs will be processed, and can be simple or complex, using one or more pieces of information.
• Commonly used priority rules include:
  • First Come, First Served (FCFS): orders are run in the order they arrive in the department.
  • Shortest Processing Time (SPT): run the job with the shortest completion time first.
  • Earliest Due Date (EDD): run the job with the earliest due date first.
  • Critical Ratio (CR): calculated as the difference between the due date and the current date divided by the work remaining.
  • Random Order: the supervisors or operators select which job to run based on their preference.
  • Last Come, First Served (LCFS): orders are placed on top of the stack, and the operator usually picks up the order on top to run first.
  • Slack Time Remaining (STR): calculated as the difference between the time remaining before the due date minus the processing time remaining.

Service Scheduling

• Service scheduling is encountered in manufacturing systems, and is complex due to the inability to store or inventory services, and the random nature of customer requests.
• Scheduling the workforce involves managing capacity for service, while scheduling multiple resources involves coordinating the use of more than one resource.

This quiz covers the concept of facility layout, including the configuration of departments, work centers, and equipment, and the importance of layout decisions.