Alloy Steel

A combination of steel and other substances (called alloying elements) including carbon, nickel, vanadium, chromium, molybdenum, tungsten, and others to produce a required level of hardness, flexibility, or durability in a blade.

Anatomy of a Circular Blade

Anatomy of a Straight Blade

Arbor (or mandrel)

The shaft on which a circular blade turns.

Arbor hole

The center hole of a circular blade, also known as the bore hole, or inside diameter of a blade. These come in different shapes and sizes depending on the blade size, application, and manufacturer.

Bevel

An angled surface that has been ground to form one side of a sharp edge. Bevels can be applied in a number of configurations for both straight and circular blades.

Bevel angle

The angle to the original plane of the blade at which a bevel is ground.

Bevel width (bevel length-distance)

The distance from the beginning of the beveled surface to the sharpened edge.

Blade width

The total width of a straight knife from the sharp edge to the bottom edge, including any bevel or teeth.

Bolt circle

The circle described by the center of multiple mounting holes at the center of a circular slitter blade.

Bolt slots

Slots in a straight knife used to mount it to machinery.

Bore hole

See Arbor Hole.

Bottom edge

The non-sharpened edge of a straight blade.

Burr (or wire edge)

A small amount of metal left behind on the opposite side to a beveled edge or serration during grinding. Quality knife manufacture includes a deburring process.

Carbide

A mixture of tungsten and carbon that is pressed and formed in a high-temperature process called sintering to form an alloy with roughly twice the stiffness of cold-rolled steel. It is widely used in industrial cutting applications.

Carbon Steel

Carbon is added to iron to form steel. The higher the carbon content in carbon steel, the greater its hardness and ability to hold a sharpened edge without deformation.

Center Hole

See Arbor Hole.

Chromium

A metal added to steel to improve hardness and wear and corrosion resistance.

Circular blade (or slitter blade)

A rotating disk with a sharpened edge providing continuous cutting action. Circular blades come in a wide variety of configurations based on application.

Compound bevels

Two (or more) bevels with progressively higher angles applied to a blade to provide a more durable cutting edge.

Corrosion resistance

The ability of a metal to resist oxidation or rust. Steels with higher carbon or chromium content, such as stainless steel, are more resistant to corrosion.

Double bevel

A circular or straight blade that has had one or more bevels applied to both sides of its sharpened edge.

Drive holes (or pin holes)

Two or more off-center holes used to mount a circular blade to machinery and drive its rotation.

Edge

The sharpened, cutting side of a straight or circular blade. Edges can be applied in a wide range of configurations including beveled, scalloped, serrated, slotted, toothed, etc.

Edge retention

The ability of a knife to resist abrasion to maintain a sharp edge during cutting.

Face

On a single-beveled blade, the surface opposite the beveled edge is known as the face.

Hardness

An absolute measure of a steel’s resistance to deformation, usually measured by the Rockwell Hardness Scale. Material hardness is directly related to a blade’s resistance to wear.

Heat treatment

See Tempering.

High carbon steel

A steel with a carbon content of 0.5% or higher.

High-speed steel

Steels, often containing molybdenum, are designed to resist deformation when exposed to high heat, such as in high-speed industrial applications.

Hop

The extent to which a circular blade is not perfectly round.

Included bevel angle

The combined bevel angle of both ground surfaces on a double-bevel blade or knife.

Laser cutting

Laser technology can be used to cut knife forms precisely from sheets of material rather than individually forging blades.

Machine knives

TGW is a leading manufacturer of machine knives used in commercial packaging and food processing, including slitter, slicer, wrapper, and bagger knives. TGW is a proud supplier of quality blades to several leading OEM manufacturers.

Notched blades

Square-edged, notched, or slotted blades are used to produce partial cuts. These are often used to define where packaging materials can be separated or torn open.

Pitch

See Tooth Pitch.

Rockwell Hardness Scale

Any one of a system of scales that measures material hardness by how far an indenter is forced into the material by a standard load. For alloys used in blade making, Rockwell Hardness Scale C is normally used.

Run-out

When a circular blade does not rotate exactly in line with the axis of rotation of the machine. Run-out can be side or axial (caused by warping or twisting in the blade itself or by crooked mounting) or peripheral (caused by the blade being out of hop — not perfectly round).

Scalloped blades

Straight and circular blades with undulating edges formed from adjacent or overlapping semi-circular bevels on one or both sides of a blade, providing a combination of perforating and shear cutting actions.

Serrated knife

Any toothed blade.

Straight knife

Any blade with parallel sharpened and non-sharpened edges. Straight blades come in a wide variety of configurations based on application.

Strength, or toughness

The ability of a metal or alloy to withstand mechanical force without breaking, fracturing, or chipping. This is different from metal hardness, which measures resistance and abrasion.

Tang

A forged extension of some bagging knives that allow the blade to be mounted in a heat seal jaw.

Tear notch

A notch in a knife-cut plastic edge that allows consumer packaging to be torn open more easily.

Tempering

Heating a metal to a particular temperature and controlling the rate at which it cools to improve its toughness of hard, brittle steels. TGW tempers some blades up to three times.

Thickness

The total thickness of a sharpen-able blade edge.

Tooth back

The non-sharpened edge of a tooth on blades where only one side of the teeth are sharpened.

Tooth loading

Where product, sealant, or plastic packaging debris becomes caked on teeth. TGW recommends using a Titanium Nitride or Teflon non-stick coating to reduce this.

Tooth Pitch

The distance between the center of teeth on a tooth-edge straight blade, usually given as the number of teeth per inch.

Toughness

See Strength.

Twist

When a knife is not flat or straight.