Basic Factory PhysicsProf. Hyun Chung

Mar. 17 2015

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Definitions

Manufacturing system: A manufacturing system is an objective-oriented network of processes through which entities flow.

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GT revisited

Classification: arranging items into groups according to some principles or system where by similar things are brought together by virtue of their similarities and then separated according to their differences

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GT revisited

Code: A system of symbol (alpha-numeric) used in information processing in which a combination of numbers and letters have a certain meaning

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Applying GT

Direct Clustering Algorithm

Similarity Index

Dendrogram

McAuleys single linkage cluster analysis

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Definitions

Workstation: A workstation is a collection of one or more machines or manual stations that perform (essentially) identical functions.

Synonyms: station, workcenter, process center

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Definitions

Part: A part is a piece of raw material, a component, a subassembly, or an assembly that is worked on at the worstations in a plant

Synonyms: intermediate product, interim product

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Definitions

End item: A part that is sold directly to a customer

Synonyms: product

The relationship between end items and their constituent parts (raw materials, components, and subassemblies) is maintained in the bill of materials (BOM)

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Definitions

Consumable: for the most part, consumables are materials such as bits, chemicals, gases, and lubricants that are used at workstations but do not become part of a product.

What about glue and solder?

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Definitions

Routing: A routing describes the sequence of workstations passed through by a part.

Order: A customer order is a request from a customer for a particular part number, in a particular quantity, to be delivered on a particular time

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DefinitionsJob: A job refers to a set of physical materials that traverses a routing, along with the associated logical information (e.g., drawings, BOM)

Every job is triggered by

an actual customer order

anticipation of a customer order (forecasted demand)

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Definitions

Throughput: The average output of a production process (machine, workstation, line, plant) per unit time

can be defined at various levels

Synonyms: throughput rate

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Definitions

Capacity: An upper limit on the throughput of a production process

Raw material inventory (RMI): the physical inputs at the start of a production process

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Definitions

Finished goods inventory (FGI): The stock point at the end of a routing

used to gather different parts within the plant before further processing or assembly

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Definitions

Work in process (WIP): the inventory between the start and end points of production routing

Synonyms: inventory

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Definitions

Inventory turns: a commonly used measure of the efficiency with which inventory is used

Synonyms: turnover ratio = the ratio of throughput to average inventory

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Definitions

Cycle time: The cycle time of a given routing is the average time from release of a job at the beginning of the routing until it reaches an inventory point at the end of the routing

Synonyms: average cycle time, flow time, throughput time, sojourn time

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Definitions

Lead time: the lead time of a given routing is the time allotted for production of part on that routing

Synonyms: build time

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Definitions

Utilization: the utilization of a workstation is the fraction of time it is not idle for lack of parts.

includes the fraction of time that workstation is working on parts or has parts waiting and is uable to work on them due to a machine failure, setup, or other detractor.

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Parameters

Bottleneck rate: the bottleneck rate of the line is the rate (part per unit time or jobs per unit time)of the workstation having the highest long-term utilization

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Parameters

Raw process time: the raw process time of the line is the sum of the long-term average process time of each workstation in the line.

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Parameters

Critical WIP: the critical WIP of the line is the WIP level for which a line with given value of bottleneck rate and raw process time but having no variability achieves maximum throughput with minimum cycle time.

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