Alpay Teoman YILDIZ 030050014 - 10th Week

Operating Hazard Analysis:

The Operating Hazard Analysis (OHA) is normally started and sometimes completed during this phase, even though, if adequate information is available, the OHA may be initiated in the design phase. Hazards associated with the human interface and with operating and maintenance producers should be identified at this time. Project evaluation tree (PET) analysis is the preferred technique for performing OHAs.

Stephans R.A., System Safety for the 21st Century, p.66

Electrochemical Grinding (Electro Chemical Grinding):

This modification of electrochemical machining has been widely used for grinding carbide tools, since conventional methods can produce burrs, poor-quality finish and even cracking. It is also used to grind stainless steel and titanium honeycomb material and other surfaces. In electrochemical grinding the tool is a rotating and conducting circular stone or wheel composed of diamond abrasive bonded to copper. The electrolyte is pumped more slowly than in machining over the whole surface of the wheel which is moved slowly across the surface of the workpiece with a gap as low as 0.025 mm. The workpiece is again the anode and the wheel, the catode.

Walsh F., Pletcher D., Industrial Electrochemistry, p.465


Breakout Board:

These boards are also referred to as a BOB, which is short for breakout board. One of the primary functions of any breakout board is to provide some form of electrial isolation between the computer and the controller. This is critical as any anomalies in wiring or spikes in voltage will isolate the damaging electricity from migrating back to the physical port on the computer. These types of boards also provide convenient connections for the user to interface with the components. Some breakout boards have more features than others, but all provide basic connectivity required for step and direction signaling for each axis and phased output signaling for each motor -all via a db- 25 input port.

Overby A., CNC Machining Handbook: Building, Programming, and Implementation, p.72

Grain Boundary Strengthening:

Metals normally contain huge numbers of randomly oriented grains, or crystals, seperated by grain buondries. Whereas a single crystal has a free surface and can deform by dislocation glide on a single active slip system, grains in a polycrystal with differing orientations of their lattice and slip systems are forced to conform to the overall strain. In general, for a given plastic strain the dislocation density will be higher in a polycrstal than in a single crystal due to the presence of geometrically necessary dislocations that result from nonuniform strains in the polycrystal. A polycrstal is deformed by disassembling it into its constituent grains and allowing aech to slip according to Schmid's Law, thereby introducing statistical dislocations. When the crystal are subsequently  reassembled, they are no longer fit together.

Lee K. L., Russell M.A., Structure-Property Relations in nonferrous Metals, p.28