Chapter 6 - Process Design and Facility Layout
Process selection: deciding on the way production of goods or services will be organized
Process Design: how production of goods or services is to occur. It has major implications for;
- Capacity planning
- Layout of facilities
- Design of work systems
Process Design occurs when new product or services are being planned, but also periodically due to
technological changes in equipment
The first step is process planning is to consider whether to make or buy (outsource), some or all of products
The choice of operations used depends on nature, shape, size, quantity, variety, & other attributes of the product
Process type is selected based on variety (how much), flexibility (what degree) and volume, expected output
There are five basic process types;
1. Project: unique, non routine operations with a limited time frame to complete
- Ex. Buildings, Dams, Bridges, Ships, Crisis Management (Columbine Shootings, Hurricane Recovery)
2. Job Shop: used when a low volume of high variety customized goods or services is needed
- Processes may change from job to job. Highly flexible workforce and equipment
- Ex. Tool & Die Shop, Custom Car Painting, Beauty Solon, Hospital, Veterinarians Office
3. Batch Processing: used when a moderate volume or variety of goods or services is desired
- H as job shop flexibility but runs batches usrepetitive techniques. Flexible Automation
- Easy to set-up processes
- Ex. Small Bakery, PIP style printing, TV Show Production, Airline baggage handling
4. Repetitive: used when higher volumes of more standardized goods or services are needed
- Processes are very constant with little change.
- Lower skilled workers needed – Fixed Automation
- Auto Assembly, High Volume Electronics, Cafeteria Lines, Ticket Takers
4. Continuous: used when a high volume of highly standardized output is required
- Frequently totally automated. Fixed (hard) automation - Making Steel, Fiberglass, Petrochemicals, Generating Electricity, Internet, Air Quality Monitoring,
Job Shop Batch Repetitive Continuous
Product Variety Customized Semi-Standardized Standardized Highly Standardized
Volume Low Low-Moderate High Very High
Equipment Flexibility Very High Moderate Low Very Low
Automation: Using machinery that has sensing and control devices that enable it to operate automatically
(ATMs, automated heating/air conditioning)
Advantages reduced human variation, improved quality (consistency), safety, and productivity
Disadvantages it is costly, much less flexible than human labour, support personnel are needed
Fixed Automation – designed to do a specific task.
Specialized equipment – high volume at low cost, inflexible.
Programmable Automation – may be reprogrammed to do many different tasks.
General purpose equipment – lower volume/ higher variety, very flexible.
Flexible Automation – evolved from programmable automation
Uses equipment that is more customized than programmable. Requires less changeover time than programmable
Numerically Controlled (N/C) Machines: machines that perform operations by following mathematical
processing instructions. These require higher skill levels
Robot: a machine consisting of a mechanical arm, a power supply, and a controller
Level 1 – robots that follow a fixed set of instructions
Level 2 – programmable robots, which repeat movements after being led through the sequence (“play back”)
Level 3 - follow instructions from a computer
Level 4 – recognize objects and make certain simple decisions
Flexible Manufacturing System (FMS): A group of machining centers that include supervisory computer
control, automatic material handling, and robots or other automated processing equipment
Advantages: reduced labor costs and more consistent quality, lower capital investment and higher flexibility,
quick change-over time. Used by managers who wish to achieve both the flexibility of job shop processing and
the productivity of repetitive processing systems
Disadvantages: can handle only a narrow range of part variety, requires longer planning & development times
due to its increased complexity and cost.
Computer Integrated Manufacturing (CIM): A system for linking a broad range of manufacturing activities
through an integrating computer system
The overall purpose of CIM is to link various parts of an organization to achieve rapid response to customer
orders and/or product changes, to allow rapid production, and to reduce indirect labour costs
Process Design: how production of goods or services is to occur. It involves identifying the activities, resources, and controls needed in the production/service process.
Methodology for Process Design
We assume that this is a new process for a new product. When a process is being redesigned, only some of the
following steps need to be performed
1. Define the production process (process planning)
- Determine how completed the input materials should be. (make or buy decisions)
- Set production system objective based on:
- Capacity, flexibility, type of process, cost (fixed/variable), process quality capability,
extend of automation, production start date
- Determine the nature of process in general
2. Conceptualize the design
How do you get from inputs (materials) to output? What is the sequence of major operations (activities) needed?
- Develop a few alternative process concepts (sketches). Two approaches can be used
(a) Incremental: do one step at a time from start to end
(b) Hierarchical (top down): break the whole job into two operations, then into sub operations,
etc, until desired level of detail is reached
- Create a process flow diagram to show the operations and movement of materials
- Evaluate each alternative process concept and choose the best
3. Make an embodiment of the Design
- Choose one process concept and complete the design
- Build a prototype process (can use computer modeling) and test it
- Determine the resources needed and estimate the costs, quality, etc, and compare with the objectives
- Refine the process and reevaluate
- Choose the best process
4. Create a detailed design
Finalize the process specifications
- Determine the machines, equipment (their capacities and make), and labor
- Design the plant layout and work centers
Process Flow Diagram: a diagram used to identify process boundaries and the level of detail required
Service Process Design
The difference with service process design is that instead of material, the flow of the customer or something belonging to the customer is followed.
Suggestions to improve customer perception in services are;
- Do not raise customer’s expectations too high in the beginning.
- End the service positively b/c customers remember the end more
- If the service is pleasurable, divide it into segments, If the service is painful, combine the segments
- Let customers control part or all of the process (self service: atm machines)
- Communicate the evidence of quality to customers
Layout: the configuration of departments, work centers, and equipment, with particular emphasis on movement
of work (customers or materials) through the system.
- Concepts applicable to factories, retail, airports, etc.
- Goal: Efficient & Safe FLOW!
Layout decisions are important for 4 basic reasons:
(1) require substantial investment of money and effort
(2) involve long-term commitment
(3) significant impact on the cost and efficiency of operations
(4) Planning is critical – down time to implement
Poor layout = poor flow = higher cost
TYPES OF LAYOUT
There are two types of layout, product layout (assembly, continuous) and process layout (job shop, batch)
Product Layout: uses standardized processing operations to achieve smooth, rapid, high-volume flow.
Used to achieve a smooth and rapid flow of large volume of goods or services through a system
Used for Repetitive or Continuous Processing
Optimizing Product FLOW.
Without high standardization, many of the benefits of repetitive processing are lost Product layouts achieve a high degree of labour and equipment utilization, which tends to offset their high
Because items move quickly form operation to operations, the amount of Work In process is often minimal.
Operations are so closely tied to each other that the entire system is highly vulnerable to being shut down b/c of
mechanical failure or absenteeism.
• High rate of output • Creates dull, repetitive jobs
• Low unit cost • Poorly skilled / motivated workers may not
• Labor specialization maintain equipment or quality of output
• Low material handling cost • Fairly inflexible to changes in volume
• High utilization of labor and equipment • Highly susceptible to shutdowns
• Established routing and scheduling • Needs preventive maintenance
• Routine accounting and purchasing
Process Layout: A layout that is designed to handle varied processing requirements through specialized areas
Used for Intermittent processing - Job Shop or Batch
Optimize Processes rather than product.
The variety of jobs that are processed requires frequent adjustments to equipment. This causes a discontinuous
work flow, which is referred to as intermitted processing.
The use of general-purpose equipment provides the flexibility necessary to handle a wide range of processing
Process layouts are quite common in service environments, example - Hopsitals