MAE 364 Exam 1

manufacturing system

complex set of elements that include, machines (machine tools), people, materials-handling equipment, and tooling.

input

materials, information, energy

outputs

finished or semi-finished goods

physical elements

* machines for processing
* tooling
* material handling equipment
* people

measurable system parameters

* Throughput time
* production rate
* work-in-process inventory
* % on time delivery
* % defective
* daily weekly monthly volume
* cycle time or takt time
* total cost or unit cost

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production system; the enterprise

All aspects of workers, machines, and information, considered collectively, needed to manufacture parts or products; integration of all units of the system is critical.

Misrun

castings that solidify before completely filling the mold cavity. Typical causes include

Fluidity of the molten metal is insufficient \n Pouring temperature is too low \n Pouring is done too slowly \n And/or cross section of the mold cavity is too thin.

Cold Shut

they occur when two portions of the metal flow together but there is a lack of fusion between them due to premature freezing.  

Fluidity of the molten metal is insufficient \n Pouring temperature is too low \n Pouring is done too slowly \n And/or cross section of the mold cavity is too thin.

Cold Shot

These result from splattering during pouring, causing the formation of solid globules of metal that become entrapped in the casting.  

Pouring procedures and gating system designs that avoid splattering can prevent this defect. \n

Shrinkage category

This is a depression in the surface of an internal void in the casting, caused by solidification shrinkage that restricts the amount of molten metal available in the last region to freeze.  

It often occurs near the top of the casting, in which case it is referred to as a “pipe”.  The problem can often be solved by proper riser design. \n

Microporosity

This consists of a network of small voids distributed throughout the casting caused by localized solidification shrinkage of the final molten metal in the dendritic structure. 

The defect is usually associated with alloys, because of the protracted manner in which freezing occurs in these metals.  Therefore materials with large solidification range, as well as castings that are not properly risered.

Hot Tearing

manifested as a separation of the metal (hence the term tearing or cracking) at a point of high tensile stress caused by the metals inability to shrink naturally

occurs when the casting is restrained from contracting by an unyielding mold during the final stages of solidification or early stages of cooling after solidification. 

general casting defects

misrun

cold shut

cold shot

shrinkage category

microporosity

hot tearing

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sand casting defects

sand blow

pinholes

sand wash

scabs

penetration

mold shift

core shift

mold crack

Manufacturing system

All aspects of workers, machines, and information, considered collectively, needed to manufacture parts or products; integration of all units of the system is critical.

Machine or machine tool or manufacturing process

A specific piece of equipment designed to accomplish specific processes, often called a machine tool; machine tools linked together to make a manufacturing system.

Job (station)

A collection of operations done on machines or a collection of tasks performed by one worker at one location on the assembly line.

operation (process)

A specific action or treatment, often done on a machine, the collection of which makes up the job of a worker.

Tools or tooling

Refers to the implements used to hold, cut, shape, or deform the work materials; called cutting tools if referring to machining; can refer to jigs and fixtures in workholding and punches and dies in metal forming.