Fastener system with enhanced wear resistance features for abrasive environments

A fastener configured to fasten one part to another part, the fastener being elongated along a longitudinal axis, the fastener including:

• a shank being elongated along the longitudinal axis, the shank having a base end and a free end, the shank having a shank surface with a portion of the shank surface forming threads;
• a head positioned on the base end of the shank, the head having:
• a crown having a crown surface, the crown surface defining a crown plane, the crown surface having a central portion and a peripheral portion;
• and
• a perimeter configured to be engaged by a tool for manipulating the fastener, the perimeter and the crown converging at a peripheral edge, the peripheral edge surrounding the crown;
• and
• a protective coating positioned on the head, the coating being positioned on the peripheral portion of the crown of the head, the coating extending from the peripheral edge inwardly toward the central portion of the crown;
• wherein the head and the shank are formed of a first material having a first hardness measurement, the protective coating being formed of a second material having a second hardness measurement,
• wherein the second material is different than the first material and a magnitude of the second hardness measurement is greater than the magnitude of the first hardness measurement;
• wherein the perimeter of the head has a plurality of flats, the flats each being substantially planar and extending in a respective flat face plane, the flat face planes of the flats being oriented substantially perpendicular to the plane of the crown surface, adjacent said flats of the perimeter converging at point edges, the point edges extending substantially parallel to the longitudinal axis of the fastener;
• and
• wherein the flats of the perimeter of the head are free of the coating.

A fastener configured to fasten one part to another part, the fastener being elongated along a longitudinal axis, the fastener including:

• a shank being elongated along the longitudinal axis, the shank having a base end and a free end, the shank having a shank surface with a portion of the shank surface forming threads;
• a head positioned on the base end of the shank, the head having:
• a crown having a crown surface, the crown surface defining a crown plane the crown surface having a central portion and a peripheral portion, the peripheral portion substantially surrounding the central portion;
• and
• a perimeter configured to be engaged by a tool for manipulating the fastener, the perimeter and the crown converging at a peripheral edge, the peripheral edge surrounding the crown, the perimeter of the head having a plurality of flats, the flats each being substantially planar and extending in a respective flat face plane, the flat face planes of the flats being oriented substantially perpendicular to the plane of the crown surface, adjacent said flats of the perimeter converging at point edges, the point edges extending substantially parallel to the longitudinal axis of the fastener;
• and
• a protective coating positioned on the head, the coating being positioned on the crown of the head, the coating being positioned on the peripheral portion of the crown, the coating extending from the peripheral edge inwardly toward the central portion of the crown, the coating extends along a continuous path along the perimeter of peripheral portion of the crown surface about the central portion of the crown surface, the central portion of the crown surface being free of the protective coating and the flats of the perimeter of the head being free of the protective coating;
• wherein the head and the shank are formed of a first material having a first hardness measurement, the protective coating being formed of a second material having a second hardness measurement,
• wherein the second material is different than the first material and a magnitude of the second hardness measurement is greater than the magnitude of the first hardness measurement.

A system comprising:

• a harvester having a cutterhead configured to cut plant materials received by the harvester, the cutterhead having a central drum, a plurality of knife mounting bases on an exterior of the central drum, and a plurality of knives each removably mounted on one of the knife mounting bases;
• and
• a plurality of fasteners, each fastener fastening a said knife to a said knife mounting base, the fastener being elongated along a longitudinal axis, each fastener including:
• a shank being elongated along the longitudinal axis, the shank having a base end and a free end, the shank having a shank surface with a portion of the shank surface forming threads;
• a head positioned on the base end of the shank, the head having:
• a crown having a crown surface, the crown surface defining a crown plane, the crown surface having a central portion and a peripheral portion;
• and
• a perimeter configured to be engaged by a tool for manipulating the fastener, the perimeter and the crown converging at a peripheral edge, the peripheral edge surrounding the crown;
• and
• a protective coating positioned on the head, the coating being positioned on the crown of the head, the coating being positioned on the peripheral portion of the crown, the coating extending from the peripheral edge inwardly toward the central portion of the crown;
• wherein the head and the shank are formed of a first material having a first hardness measurement, the protective coating being formed of a second material having a second hardness measurement,
• wherein the second material is different than the first material and a magnitude of the second hardness measurement is greater than the magnitude of the first hardness measurement;
• wherein the peripheral portion substantially surrounds the central portion;
• and
• wherein the protective coating does not extend to the central portion of the crown surface of the crown of the head.

A system comprising:

• a harvester having a cutterhead configured to cut plant materials received by the harvester, the cutterhead having a central drum, a plurality of knife mounting bases on an exterior of the central drum, and a plurality of knives each removably mounted on one of the knife mounting bases;
• and
• a plurality of fasteners, each fastener fastening a said knife to a said knife mounting base, the fastener being elongated along a longitudinal axis, each fastener including:
• a shank being elongated along the longitudinal axis, the shank having a base end and a free end, the shank having a shank surface with a portion of the shank surface forming threads;
• a head positioned on the base end of the shank, the head having:
• a crown having a crown surface, the crown surface defining a crown plane, the crown surface having a central portion and a peripheral portion;
• and
• a perimeter configured to be engaged by a tool for manipulating the fastener, the perimeter and the crown converging at a peripheral edge, the peripheral edge surrounding the crown;
• and
• a protective coating positioned on the head, the coating being positioned on the crown of the head, the coating being positioned on the peripheral portion of the crown, the coating extending from the peripheral edge inwardly toward the central portion of the crown;
• wherein the head and the shank are formed of a first material having a first hardness measurement, the protective coating being formed of a second material having a second hardness measurement,
• wherein the second material is different than the first material and a magnitude of the second hardness measurement is greater than the magnitude of the first hardness measurement;
• wherein the perimeter of the head has a plurality of flats, the flats each being substantially planar and extending in a respective flat face plane, the flat face planes of the flats being oriented substantially perpendicular to the plane of the crown surface, adjacent said flats of the perimeter converging at point edges, the point edges extending substantially parallel to the longitudinal axis of the fastener;
• and
• wherein the flats of the perimeter of the head are free of the coating.

A fastener configured to fasten one part to another part, the fastener being elongated along a longitudinal axis, the fastener including:

• a shank being elongated along the longitudinal axis, the shank having a base end and a free end, the shank having a shank surface with a portion of the shank surface forming threads;
• a head positioned on the base end of the shank, the head having:
• a crown having a crown surface, the crown surface defining a crown plane the crown surface having a central portion and a peripheral portion;
• and
• a perimeter configured to be engaged by a tool for manipulating the fastener, the perimeter and the crown converging at a peripheral edge, the peripheral edge surrounding the crown;
• wherein the head of the fastener includes a perimeter recess positioned between the crown and the perimeter of the head;
• and
• a protective rim positioned in the perimeter recess of the head, the protective rim extending substantially continuously about the crown of the head;
• wherein the head and the shank are formed of a first material having a first hardness measurement, the protective rim being formed of a second material having a second hardness measurement,
• wherein the second material is different than the first material and a magnitude of the second hardness measurement is greater than the magnitude of the first hardness measurement.