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Jack H.Integration and automation of manufacturing systems.2001.pdf
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page 514

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.

Operation

 

 

 

 

 

 

 

Cell status and

 

 

 

 

 

 

 

 

 

plans

 

 

 

 

 

 

 

quality reports

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cell

 

 

 

 

Controller

 

 

 

(IBM PC)

 

 

 

NC

NC

 

Quality

 

Programs

Status

 

Measurements

CNC

Actuators,

CNC

Actuators,

Gauges

Controller

Structure,

Controller

Sensors

and Meters

 

Sensors

 

 

 

18.3 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

page 515

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

 

 

Operator or

Operator or

Operator

Recipe Hold at

Recipe Bypass

Abort

Completion

Command

Command

Command

 

Yes

 

 

 

 

Previous

No

Perform Step

Hold

No

Next

at step

Step

Bypass Step

Operation

completion

 

Step

 

 

 

 

 

Yes

 

 

 

 

Fault Detected

 

 

 

 

 

or Operator Abort

 

 

Fault Exit to pre-defined step

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18.4 PRACTICE PROBLEMS

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

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.

ans.

The lab equipment (right now) only satisfies the first couple of levels. You can

3. Information drives an automated factory from the initial entry of geometry in CAD, to the final production of parts with CAM. Discuss how data networks support this and the impact of open network standards.

4.

18.5 LABORATORY - WORKCELL INTEGRATION

Purpose:

All of the components explored in the laboratories of previous weeks will be integrated into a final working cell.

Overview:

Pre-Lab:

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To be determined.

In-Lab:

1. To be determined.

Submit (individually):

1. To be determined.