7. Integration Issues

7.1 Corporate Structures

• First consider the major functions within a company,

Production

Materials

Process Planning

Design

Customer Orders / Service

Marketing

Accounting

Management

• All of these functions generate and use common information which must be communicated between departments.

• Since computers handle information, we must be aware of what we get, and what we produce.

7.2 Corporate Communications

• Previous paper based systems provided support for data transfer between departments, and provided a good basis for the introduction of computers

• ASIDE: Computers can make a good system better, but they will always make a bad system worse. This is because a system which is not well defined and poorly understood cannot be programmed, or optimized.

• Characteristics of paper based manufacturing systems,

Multiple copies of same information.

Revising information is hard when multiple copies exist.

Delays for the transfer of paper.

Easy to lose paper.

Paper is not interactive.

Paper requires bulky storage.

• Computers overcome and reduce the problems above, but introduce some technological challenges,

Creating programs to support corporate functions.

Software to support interdepartmental communication and data sharing.

Hardware to support the software.

• This figure below shows various departments, and the information flow [source: ???

• Requirements for interfacing corporate management and staff functional entities to the factory [source: find]

• Assumed functional hierarchy computer system structure for a large manufacturing complex [source: find]

• Report interfacing to corporate management and staff functional entities from the factory [source: find]

• The Shop Floor Production Model (SFPM):

[ source: find]

	Level	Sub-Activity	Responsibility
4	Section/Area	Supervise shop floor production process	Supervising and coordinating the production and supporting the jobs and obtaining and allocating resources to the jobs.
3	Cell	Coordinate shop floor production process	Sequencing and supervising the jobs at the shop floor production process
2	Station	Command shop floor production process	Directing and coordinating the shop floor production process
1	Equipment	Execute shop floor production process	Executing the job of shop floor production according to commands

The ISO Reference Model for Factory Automation adds a couple of layers

[ source: find]

Level/Hierarchy	Area of Control	Responsibility	Basic Functions
6 / Enterprise	Managing the corporation	Achieving the enterprise’s mission and managing the corporation	Corporate management Finance Marketing and sales Research and Development
5 / Facility or plant	Planning Production	Implementing the enterprise functions and planning and scheduling production	Product design and production engineering Production management (upper level) Resource management (upper level) Procurement (upper level) Maintenance management (upper level)
4 / Section or area	Allocating and supervising materials and resources	Coordinating production and obtaining and allocating resources to jobs	Production management (lower level) Procurement (lower level) Resource management (lower level) Maintenance management (lower level) Shipping Waste material treatment
3 / Cell	Coordinating multiple machines and operations	Sequencing and supervising shop floor jobs and supervising various supporting services	Shop floor production (cell level)
2 / Station	commanding machine sequences and motion	Directing and coordinating the activity of the shop floor equipment	Shop floor production (station level)
1 / Equipment	Activating sequences and motion	Taking action on commands to the shop floor equipment	Shop floor production (equipment level)

• A LAN (Computer Network) Hierarchy for Shop Floor Control [source: find]

• Typical Architecture for Manufacturing Components [ update]

Item	Equipment	Workstation	Cell
EXAMPLES   Hardware	Lathe, Mill, T-10 Bridgeport Series I IBM 7545 Robot	Robot tended Machine Center, Cartrac Material Handling System	Variable Mission System, Several Integrated workstations
Controller Hardware	Mark Century 2000, Accuramatic 9000, Custom-single-board system.	Allen-Bradley PLC-5, IBM-PC, etc.	Windows NT, SUN workstation, etc.
Type Controller	Single-board processors, Machine tool controller, Servo-Controller, etc	PLC, PC, Minicomputer	PC, Microcomputer, Super-MiniComputer
Language Application	Assembler, Part programming, Robot programming, etc.	C, Ladder logic, Pascal and other sequential languages	C, LISP, FORTRAN, and other high level languages
Memory/Size Requirements	8k-128k RAM plus custom ROM, EPROM, etc.	32M RAM, >1M Hard Drive	128M RAM, >1Gigabyte Hard drive
Response Time	< 10-3 sec	< 1 sec	< 20 sec
Machines/ Interconnects	1-1 connect	1-many 1-[1,8] Machine tools, 1-[1-50] Material handling	1-many 1-[1-15] workstations

• Functional Breakdown of Control Architecture

 

	Equipment	Workstation	Cell
Planning	Tool selection, parameter specification, tool path refinement, GMT code, tool assignment to slots, job setup planning	•Resource allocation jobs •Batch splitting and equipment load balancing	Batching, Workload balancing between workstations, Requirements planning Task allocation to workstations
Planning Horizon	Milliseconds: Minutes	Minutes: Hours/Days	Hours: Days/weeks
Scheduling	•Operation sequencing at individual equipment	•Sequence equipment level subsystems •Deadlock detection and avoidance •Gantt chart or E.S. based scheduling •Buffer management	•Assignment of due dates to individual workstations •Look ahead ES/simulation based scheduling •Optimization based tech •Batch sequencing
Control	•Interface to workstation controller •Physical control (motion control at NC and robot pick and place level) •Execution of control programs (APT, AML, etc.)	•Monitor equipment states and execute part and information flow actions based on states •Synchronize actions between equipment (eg. robot & machine while loading/unloading parts) • Ladder logic execution	Organizational control of workstations, Interface with MPS, generation of reports, etc.

• In all of these models we must consider the value of the information being passed. At the low level control stages, information that is more than a few seconds old may be completely worthless, while the same information at the higher level may be valuable for quality tracking months later.

• We can draw part of a simple flow chart that illustrates a simple CIM system. The elements shown include a PLC, NC machine, and stand alone sensors. These are all integrated by a single computer running cell control software.

 

7.3 Computer Controlled Batch Processes

• The nature of Batch processes,

Batch processes deal with discrete quantities of raw materials or products.

batch processes allow the tracking of these discrete quantities of materials or products

batch processes allow more than one type of product to be processed simultaneously, as long as the products are separated by the equipment layout.

Batch processes entail movement of discrete product from processing area to processing area

Batch processes have recipes (or processing instructions) associated with each load of raw material to be processed into product.

Batch processes have more complex logic associated with processing than is found in continuous processes

Batch processes often include normal steps that can fail, and thus also include special steps to be taken in the event of a failure.

• The nature of steps in a batch process,

Each step can be simple or complex in nature, consisting of one or more operations

Generally, once a step is started it must be completed to be successful.

It is not uncommon to require some operator approval before leaving one step and starting the next.

There is frequently provision for non-normal exits to be taken because of operator intervention, equipment failure or the detection of hazardous conditions.

Depending on the recipe for the product being processed, a step may be bypassed for some products.

The processing operations for each step are generally under recipe control, but may be modified by operator override action.

• A typical process step

7.4 Problems

Problem 7.1 List 5 industries that are well suited to integration, and 5 that are not. Indicate why you think so.

Problem 7.2 In an automated factory there as many as six levels of control. Discuss the equipment available in the lab and how this relates to the 6 level model of factor floor control.