A knife

A knife (plural knives) is a cutting tool with a cutting edge or blade, hand-held or otherwise, with or without a handle. Knife-like tools were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools.[1][2] Originally made of rock, bone, flint, and obsidian, knives have evolved in construction as technology has, with blades being made from bronze, copper, iron, steel, ceramics, and titanium. Many cultures have their unique version of the knife. Due to its role as humankind's first tool, certain cultures have attached spiritual and religious significance to the knife.[3]

Most modern-day knives follow either a fixed-blade or a folding construction style, with blade patterns and styles as varied as their makers and countries of origin.

Contents [hide]

1 Materials, features, and construction

1.1 Parts of a knife

1.2 Blade

1.2.1 Fixed blade features

1.2.2 Folding blade features

1.2.3 Sliding blade features

1.3 Handle

2 Types of knives

2.1 Knives as weapons

2.2 Knives as sports equipment

2.3 Knives as utensils

2.4 Knives as tools

2.5 Knives as a traditional or religious implement

3 Rituals and superstitions

4 Legislation

5 Further reading

6 See also

7 References

8 External links

Materials, features, and construction[edit]

Main article: Knife making

Characteristic parts of a knife

Today, knives come in many forms but can be generally categorized between two broad types: fixed blade and folding blade knives.

Parts of a knife[edit]

A modern knife consists of:

a blade

a handle

the point – the end of the knife used for piercing

the edge – the cutting surface of the knife extending from the point to the heel

the grind - the cross section shape of the blade

the spine – the thickest section of the blade

the fuller - the groove added to make the blade lighter

the ricasso - the flat section of the blade located at the junction of the blade and the knife's bolster or guard

the guard - the barrier between the blade and the handle which prevents the hand from slipping forward onto the blade and protects the hand from the external forces that are usually applied to the blade during use

the hilt or butt - the end of the handle utilized for blunt force

the lanyard - a strap used to secure the knife to the wrist

The blade edge can be plain or serrated, or a combination of both. Single edged knives may have a reverse edge or false edge occupying a section of the spine. These edges are usually serrated and are used to further enhance function.

The handle, used to grip and manipulate the blade safely, may include the tang, a portion of the blade that extends into the handle. Knives are made with partial tangs (extending part way into the handle, known as a "stick tang") or full tangs (extending the full length of the handle, often visible on top and bottom). The handle may include a bolster, a piece of heavy material (usually metal) situated at the front or rear of the handle. The bolster, as it's name suggests, is used to mechanically strengthen the knife.

A Gerber made full tang survival knife. Notice how the metal from the blade extends beyond the handle.

Blade[edit]

Main article: Blade

Knife blade mass production.

Knife blades can be manufactured from a variety of materials, each of which has advantages and disadvantages. Carbon steel, an alloy of iron and carbon, can be very sharp. It holds its edge well, and remains easy to sharpen, but is vulnerable to rust and stains. Stainless steel is an alloy of iron, chromium, possibly nickel, and molybdenum, with only a small amount of carbon. It is not able to take quite as sharp an edge as carbon steel, but is highly resistant to corrosion. High carbon stainless steel is stainless steel with a higher amount of carbon, intended to incorporate the better attributes of carbon steel and stainless steel. High carbon stainless steel blades do not discolor or stain, and maintain a sharp edge. Laminate blades use multiple metals to create a layered sandwich, combining the attributes of both. For example, a harder, more brittle steel may be sandwiched between an outer layer of softer, tougher, stainless steel to reduce vulnerability to corrosion. In this case, however, the part most affected by corrosion, the edge, is still vulnerable. Pattern-welding is similar to laminate construction. Layers of different steel types are welded together, but then the stock is manipulated to create patterns in the steel. Titanium is a metal that has a better strength-to-weight ratio, is more wear resistant, and more flexible than steel. Although less hard and unable to take as sharp an edge, carbides in the titanium alloy allow them to be heat-treated to a sufficient hardness. Ceramic blades are hard, brittle, and lightweight: they may maintain a sharp edge for years with no maintenance at all, but are as fragile as glass and will break if dropped on a hard surface. They are immune to common corrosion, and can only be sharpened on silicon carbide sandpaper and some grinding wheels. Plastic blades are not especially sharp and typically serrated. They are often disposable.[4]

Knife-blades have different profiles.

Steel blades are commonly shaped by forging or stock removal. Forged blades are made by heating a single piece of steel, then shaping the metal while hot using a hammer or press. Stock removal blades are shaped by grinding and removing metal. With both methods, after shaping, the steel must be heat treated. This involves heating the steel above its critical point, then quenching the blade to harden it. After hardening, the blade is tempered to remove stresses and make the blade tougher. Mass manufactured kitchen cutlery uses both the forging and stock removal processes. Forging tends to be reserved for manufacturers' more expensive product lines, and can often be distinguished from stock removal product lines by the presence of an integral bolster, though integral bolsters can be crafted through either shaping method.

Knives are sharpened in various ways. Flat ground blades have a profile that tapers from the thick spine to the sharp edge in a straight or convex line. Seen in cross section, the blade would form a long, thin triangle, or where the taper does not extend to the back of the blade, a long thin rectangle with one peaked side. Hollow ground blades have concave, beveled edges. The resulting blade has a thinner edge, so it may have better cutting ability for shallow cuts,

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