Industrial and Construction Basics One

Allowance

The prescribed difference between the design size and the basic size.

Angled Bottom

Bottom of the slot is angled.

Axis of Thread

The axis of the thread pitch cylinder.

Bearing Surface Radial Slots

Slots that are milled perpendicular to the axis of the part into the bearing surface.

Body Thickness

A reference dimension measured from the bearing surface to the base of the collar on the top of a part.

Broken Corner

Slight chamfer at slot corners.

Case-hardened

A process by which only the surface area of the part is hardened to a specified depth.

Case Depth

Depth to which Rc 58 minimum is maintained.

Chamfer

An external angular feature emanating perpendicular to the axis of the part.

Class of Thread

An alphanumerical designation to indicate the standard grade of tolerance and allowance specified for a thread. (see also Thread Fit)

Colla

A circular boss on the bearing surface or the top surface of a nut.

Concentricity

The permissible variation in the location of the axis (exact center) of a characteristic to the axis of another characteristic. The axis of the controlled characteristic must remain within a circular zone of a diameter equal to the concentricity limit.

Core Hardness

The measurement of the hardness of the center of the wall of a part.

Counterbore

A concentric diametric enlargement of a hole for part of its depth which forms an angular, radial or flat surface at the bottom.

Countersink

An angular beveling or flaring of the end(s) of a hole, outer edge of a counterbore, or at the bottom of a counterbore, that does not extend to the OD or counterbore diameter.

EAU

Estimated annual usage.

External Groove

A circular continuous channel cut into an external feature of a part.

Face Groove

A circular continuous channel cut into the bearing or top surface of a part.

Finish

The type of coatings, platings or treatments applied to the final product.

Flange

A circular projection forming the outside diameter of a part.

Flange Thickness

The distance as measured from the flange bottom or bearing surface of a part to the top of the flange, including the chamfer or radii.

Flatness

The permissible variation of the flatness of a surface or characteristic.

Hardness

The property of metals and their alloys relating to strength, elasticity, and toughness and defined as the measurement of its resistance to indentation. Through-hardened parts are typically measured by the Rb, Rc or Brinell scales. Case-hardened parts usually have a hardness specified to a specific depth.

Horizontal Slots on the OD

Slots that are milled parallel to the bearing surface of the part into the OD.

Induction Hardened

A process by which only a designated surface, usually the bearing surface, is hardened.

Internal Groove

A circular continuous channel cut into an internal feature of a part.

Lead

The axial distance between two consecutive points of intersection of a helix by a line parallel to the axis of the cylinder on which it lies, i.e., the axial movement of a threaded part rotated one turn in its mating thread.