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Fixture offsets (in G codes):

This compensation type is used on machining centers, wire EDM equipment, turret punch presses, and laser equipment. Fixture offsets, also called work coordinate system multiple sttings, allow the user to work with several coordinate systems from within the same program.

Fixture offsets also relieve the programmer from the burden of assigning the program zero point in the program.

The Standard six work offsets G54 to G59 are generally available for both the milling and turning control systems. However, due to the unique machining requirements, they are normally associated with the milling controls. Their programming format is the same for both control types:

G10 L2 P- X- Y- Z- (Machining centers)

G10 L2 P- X- Y- (Turning centers)

The L2 word is a mandatory ofset group number that identifies the ofset input type as the work coordinate settings. The P adres in this case can have a value from 1 to 6, assigned to the G54 to G59 selection respectively:

P1=G54, P2=G55, P3=G56, P4=G57, P5=G58, P6=G59

For example,

G90 G10 L2 P1 X-450.0 Y-375.0 Z0

will input X-450.0 Y-375.0 Z0 coordinates into the G54 work coordinate offset register.

G90 G10 L2 P3 X-630.0 Y-408.0

will input X-630.0 Y-408.0 coordinates into the G56 work coordinate offset register. Since the Z-value has not been programmed, the current value of Z-offset will be retained.

(Lynch M., Computer numerical control for machining, 1992, p. 160

Smid P., Fanuc CNC custom macros: programming resources for Fanuc Custom Macro B users, 2005, p.51)

Erosion corrosion:

Erosion corrosion is the acceleration or increase in the rate of deterioration or attack on a metal because of mechanical wear or abrasive contributions in combination with corrosion with corrosion. The combination of wear or abrasion and corrosion results in more severe attack that would be realized with either mechanical or chemical corrosive action alone. Metal is removed from the surface as dissolved ions, as particles of solid corrosion products, or as elemental metal. The spectrum of erosion corrosion ranges from primarily erosive attack, such as sandblasting, filling, or grinding of a metal surface, to primarily corrosion failures where the contribution of mechanical action is quite small. This section focuses on those instances where there is a fairly well-defined contribution from both mechanical and corrosive factors. Erosion corrosion resulting from relative movement between a corrosive fluid and the metal surface is discussed first, followed by a discussion of two special forms of erosion corrosion, namely cavitation and fretting corrosion.

(Davis J. R., Corrosion: understanding the basics, 2000, p. 134,135)

Intergranular corrosion:

Intergranular corrosion is defined as the selective dissolution of grain boundaries, or closely adjacent regions, without appreciable attack of the grains themselves. This dissolution is caused by potential differences between the grain boundary region and any precipitates, intermetallic phases, or impurities that form at the grain boundaries. The actual mechanism differs with each alloy system.

(Davis J. R., Corrosion: understanding the basics, 2000, p. 151)

Uniform corrosion:

Uniformor general corrosion, as the name implies, results in a fairly uniform penetration (or thinning) over the entire explosed metal surface. The general attack results from local corrosion-cell action; that is, multiple anodes and cathodes are operating on the metal surface at any given time. The location of the anodic and cathodic areas continues to move about on the surface, resulting in uniform corrosion.

(Davis J. R., Corrosion: understanding the basics, 2000, p. 100)