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Buffer

The purpose of the buffer is the smooth handling of works for unmanned manufacturing, and TAKT balance is very important for automated lines. If not balanced, the production line may suffer considerable line distturbance. The control of connecting a few assembly processes cen introduce the ‘PULL MODE’ operation, which is optimum WIP. The whole process is dynamically controlled using the shop-floor control system and a so-called ‘IC’ cardwhich is a small memory unit for the information controlling the operation. All production information will be retained and used to control the next process. If required, the information will be transferred to a host system and distributed to people required to take quick actions. The assembly production line is fully automated by the computers: this is computer-integrated assembly. Normally th buffer sizes are optimized by computer simulation of the production process. Recently, cell-type production has been applied to specific processes in mixed production in Japanese enterprises.

(Asai K., Takashima S., Edwards P. R., Manufacturing, Automation Systems, and CIM Factories, 1994, pg.125)

Thermal Shock

The common use of some inherently brittle materials, especilly ceramics and glasses at high temperatures leads to a special engineering problem called thermal shock. Thermal shock can be defined as the fracture (partial or complete) of the material as a result of a temperature change (usually a sudden cooling).

The mechanism of thermal shock can involve both thermal expansion and thermal conductivity. Thermal shock follows from these properties in one of two ways. First, a failure stress can be built up by constraints of uniform thermal expansion. Second, rapid temperature changes produce temporary temperature gradients in the material with resulting internal residual stress. Even without external constraints, thermal shock can occur due to temperature gradients created because of a finite thermal conductivity.

(Shackelford J. F., Introduction to materials science for engineers, 3rd Edition, 2009, pg.221)

Thermal Fatigue

Thermal fatigue characterization has been the area of the most testing for tin – leas as well as lead – free solders. There have been numerous studies on this mechanism for lead – free solders, as seen in many journal and conference proceedings. The driving force for damage in thermal fatigue is the coefficient of thermal expansion (CTE) mismatch between the different materials that make up an electronics assembly, along with the fact that solder plastically deforms to accommodate a portion of that strain mismatch. Damage accumulates within the solder joint with each temperature cycle, and eventually a crack is nucleated that will propagate through the joint and create an electrical open.

(Bradley E., Handwerker C. A., Bath J., Lead-free electronics: iNEMI projects lead to successful manufacturing, 2007, pg.218)

The Vacuum Sensor

Vacuum sensor is designed as a gauge pressure sensor, but the output terminals are reversed as compared to a gauge configuration to provide an increasing output with the increasing vacuum (decreasing pressure). At ambient pressure, the vacuum sensor indicates a zero output with a full-scale output produced at a full vacuum. Output is not dependent on a baromatric pressure.

(Soloman S., Sensors Handbook, pg.1064)