A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are to be used on. Historically, humans have made blades from flaking stones such as flint or obsidian, and from various metal such as copper, bronze and iron. Modern blades are often made of steel or ceramic. Blades are one of humanity's oldest tools, and continue to be used for combat, food preparation, and other purposes.
Blades work by concentrating force on the cutting edge. Certain blades, such as those used on bread knives or saws, are serrated, further concentrating force on the point of each tooth.
During food preparation, knives are mainly used for slicing, chopping, and piercing.
In combat, a blade may be used to slash or puncture, and may also be thrown or otherwise propelled.The function is to sever a nerve, muscle or tendon fibers, or blood vessel to disable or kill the adversary. Severing a major blood vessel typically leads to death due to exsanguination.
Blades may be used to scrape, moving the blade sideways across a surface, as in an ink eraser, rather than along or through a surface. For construction equipment such as a grader, the ground-working implement is also referred to as the blade, typically with a replaceable cutting edge.
A simple blade intended for cutting has two faces that meet at an edge. Ideally, this edge would have no roundness but in practice, all edges can be seen to be rounded to some degree under magnification either optically or with an electron microscope. Force is applied to the blade, either from the handle or pressing on the back of the blade. The handle or back of the blade has a large area compared to the fine edge. This concentration of applied force onto the small edge area increases the pressure exerted by the edge. It is this high pressure that allows a blade to cut through a material by breaking the bonds between the molecules/crystals/fibers/etc. in the material. This necessitates the blade being strong enough to resist breaking before the other material gives way.
The angle at which the faces meet is important as a larger angle will make for a duller blade while making the edge stronger. A stronger edge is less likely to dull from fracture or from having the edge roll out of shape.
The shape of the blade is also important. A thicker blade will be heavier and stronger and stiffer than a thinner one of similar design while also making it experience more drag while slicing or piercing. A filleting knife will be thin enough to be very flexible while a carving knife will be thicker and stiffer; a dagger will be thin so it can pierce, while a camping knife will be thicker so it can be stronger and more durable. A strongly curved edge, like a talwar will allow the user to draw the edge of the blade against an opponent even while close to the opponent where a straight sword would be more difficult to pull in the same fashion. The curved edge of an axe means that only a small length of the edge will initially strike the tree, concentrating force as does a thinner edge whereas a straight edge could potentially land with the full length of its edge against a flat section of the tree. A splitting maul has a convex section to avoid getting stuck in the wood where chopping axes can be flat or even concave. A khopesh or falchion or kukri is angled and/or weighted at the distal end so that force is concentrated at the faster moving, heavier part of the blade maximizing cutting power and making it largely unsuitable for thrusting where a rapier is thin and tapered allowing it to pierce and be moved with more agility while reducing its chopping power compared to a similarly sized sword.
A serrated edge, such as on a saw or a bread knife, concentrates force onto the tips of the serrations which increases pressure as well as allowing soft or fibrous material (like wood, rope, bread, vegetables) to expand into the spaces between serrations. Whereas pushing any knife, even a bread knife, down onto a bread loaf will just squash the loaf as bread has a low elastic modulus (is soft) but high yield strain (loosely, can be stretched or squashed by a large proportion without breaking), drawing serrations across the loaf with little downward force will allow each serration to simultaneously cut the bread with much less deformation of the loaf. Similarly, pushing on a rope tends to squash the rope while drawing serrations across it sheers the rope fibers. Drawing a smooth blade is less effective as the blade is parallel to the direction draw but the serrations of a serrated blade are at an angle to the fibers. Serrations on knives are often symmetric allowing the blade to cut on both the forward and reverse strokes of a cut, a notable exception being Veff serrations which are designed to maximize cutting power while moving the blade away from the user. Saw blade serrations, for both wood and metal, are typically asymmetrical so that they cut while moving in only one direction. (Saws act by abrading a material into dust along a narrow channel, the kerf, whereas knives and similar act by forcing the material apart. This means that saws result in a loss of material and the serrations of a saw also serve to carry metal swarf and sawdust out of the cut channel.)
Fullers are longitudinal channels either forged into the blade or later machined/milled out of the blade though the latter process is less desirable. This loss of material necessarily weakens the blade but serves to make the blade lighter without sacrificing stiffness. The same principle is applied in the manufacture of beams such as I-beams. Fullers are only of significant utility in swords. In most knives there is so little material removed by the fuller that it makes little difference to the weight of the blade and they are largely cosmetic.
Typically blades are made from a material that is about as hard, though usually harder, than the material to be cut. Insufficiently hard blades will be unable to cut a material or will wear away quickly as hardness is related to a material's ability to resist abrasion. However, blades must also be tough enough to resist the dynamic load of impact and as a general rule the harder a blade the less tough (the more brittle) a material. For example, a steel axehead is much harder than the wood it is intended to cut and is sufficiently tough to resist the impact resulting when swung against a tree while a ceramic kitchen knife, harder than steel, is very brittle (has low toughness) and can easily shatter if dropped onto the floor or twisted while inside the food it is cutting or carelessly stored under other kitchen utensils. This creates a tension between the intended use of the blade, the material it is to be made from, and any manufacturing processes (such as heat treatment in the case of steel blades that will affect a blade's hardness and toughness). A balance must be found between the sharpness and how well it can last. Methods that can circumvent this include differential hardening. This method yields an edge that can hold its sharpness as well as a body that is tough.
Prehistorically, and in less technologically advanced cultures even into modern times, tool and weapon blades have been made from wood, bone, and stone.Most woods are exceptionally poor at holding edges and bone and stone suffer from brittleness making them suffer from fracture when striking or struck. In modern times stone, in the form of obsidian, is used in some medical scalpels as it is capable of being formed into an exceedingly fine edge. Ceramic knives are non-metallic and non-magnetic. As non-metals do not corrode they remain rust and corrosion free but they suffer from similar faults as stone and bone, being rather brittle and almost entirely inflexible. They are harder than metal knives and so more difficult to sharpen, and some ceramic knives may be as hard or harder than some sharpening stones. For example, synthetic sapphire is harder than natural sharpening stones and is as hard as alumina sharpening stones. Zirconium dioxide is also harder than garnet sharpening stones and is nearly as hard as alumina. Both require diamond stones or silicon carbide stones to sharpen and care has to be taken to avoid chipping the blade. As such ceramic knives are seldom used outside of a kitchen and they are still quite uncommon. Plastic knives are difficult to make sharp and poorly retain an edge. They are largely used as low cost, disposable utensils or as children's utensils or in environments such as air travel where metal blades are prohibited. They are often serrated to compensate for their general lack of sharpness but, as evidenced by the fact they can cut food, they are still capable of inflicting injury. Plastic blades of designs other than disposable cutlery are prohibited or restricted in some jurisdictions as they are undetectable by metal detectors.
Native copper was used to make blades by ancient civilizations due to its availability. Copper's comparative softness causes it to deform easily; it does not hold an edge well and is poorly suited for working stone. Bronze is superior in this regard, and was taken up by later civilizations. Both bronze and copper can be work hardened by hitting the metal with a hammer. With technological advancement in smelting, iron came to be used in the manufacturing of blades. Steel, a range of alloys made from iron, has become the metal of choice for the modern age.
Various alloys of steel can be made which offer a wide range of physical and chemical properties desirable for blades. For example, surgical scalpels are often made of stainless steel so that they remain free of rust and largely chemically inert; tool steels are hard and impact resistant (and often expensive as retaining toughness and hardness requires expensive alloying materials, and, being hard, they are difficult to make into their finished shape) and some are designed to resist changes to their physical properties at high temperatures. Steels can be further heat treated to optimize their toughness, which is important for impact blades, or their hardness, which allows them to retain an edge well with use (although harder metals require more effort to sharpen).
It is possible to combine different materials, or different heat treatments, to produce desirable qualities in a blade. For example, the finest Japanese swords were routinely made of up to seven sections of metals and even poorer quality swords were often made of two. These would include soft irons that could absorb the energy of impact without fracturing but which would bend and poorly retain an edge, and hard steels more liable to shatter on impact but which retained an edge well. The combination provided a sword that would resist impact while remaining sharp, even though the edge could chip if abused. Pattern welding involved forging together twisted bars of soft (bendable) low carbon and hard (brittle) higher carbon iron.This was done because furnaces of the time were typically able to produce only one grade or the other, and neither was well suited for more than a very limited use blade. The ability of modern steelmakers to produce very high-quality steels of various compositions has largely relegated this technique to either historical recreations or to artistic works. Acid etching and polishing blades made of different grades of steel can be used to produce decorative or artistic effects.
Japanese sword makers developed the technique of differential hardening by covering their sword blades in different thicknesses of clay before quenching. Thinner clay allowed the heated metal to cool faster, particularly along the edge. Faster cooling resulted in a finer crystal structure, resulting in a blade with a hard edge but a more flexible body. European sword makers produced similar results using differential tempering.
Blades dull with use and abuse. This is particularly true of acute blades and those made of soft materials. Dulling usually occurs due to contact between the blade and a hard substance such as ceramic, stone, bone, glass, or metal.
The more acute the blade, the more easily it will dull. As the blade near the edge is thinner, there is little material to remove before the edge is worn away to a thicker section. Thin edges can also roll over when force is applied it them, forming a section like the bottom part of a letter "J". For this reason, straight edge razors are frequently stropped to straighten the edge.
Drawing a blade across any material tends to abrade both the blade, usually making it duller, and the cut material. Though softer than glass or many types of stone used in the kitchen, steel edges can still scratch these surfaces. The resulting scratch is full of very fine particles of ground glass or stone which will very quickly abrade the blade's edge and so dull it.
In times when swords were regularly used in warfare, they required frequent sharpening because of dulling from contact with rigid armor, mail, metal rimmed shields, or other swords,for example. Particularly, hitting the edge of another sword by accident or in an emergency could chip away metal and even cause cracks through the blade. Soft-cored blades are more resistant to fracturing on impact.
Folding pocket knives often have a groove cut in the side of the blade near the spine. This is called a nail pull and allows the fingernail to be inserted to swing the blade out of the holder.
Some of the most common shapes are listed below.
(S1) A normal blade has a curving edge, and straight back. A dull back lets the wielder use fingers to concentrate force; it also makes the knife heavy and strong for its size. The curve concentrates force on a smaller area, making cutting easier. This knife can chop as well as pick and slice. This is also the best single-edged blade shape for thrusting, as the edge cuts a swath that the entire width of the knife can pass through without the spine having to push aside any material on its path, as a sheepsfoot or drop-point knife would.
(S2) A trailing-point knife has a back edge that curves upward to end above the spine. This lets a lightweight knife have a larger curve on its edge and indeed the whole of the knife may be curved. Such a knife is optimized for slicing or slashing. Trailing point blades provide a larger cutting area, or belly, and are common on skinning knives.
(S3) A drop point blade has a convex curve of the back towards the point. It handles much like the clip-point, though with a stronger point typically less suitable for piercing. Swiss army pocket knives often have drop-points on their larger blades.
(S4) A clip-point blade is like a normal blade with the back "clipped". This clip can be either straight or concave. The back edge of the clip may have a false edge that could be sharpened to make a second edge. The sharp tip is useful as a pick, or for cutting in tight places. If the false edge is sharpened it increases the knife's effectiveness in piercing. As well, having the tip closer to the center of the blade allows greater control in piercing. The Bowie knife has a clip point blade and clip-points are common on pocket knives and other folding knives.
(S5) A sheepsfoot blade has a straight edge and a straight dull back that curves towards the edge at the end. It gives the most control because the dull back edge is made to be held by fingers. Sheepsfoot blades were originally made to trim the hooves of sheep; their shape bears no similarity to the foot of a sheep.
(S6) A Wharncliffe blade is similar in profile to a sheep's foot but the curve of the back edge starts closer to the handle and is more gradual. Its blade is much thicker than a knife of comparable size.Wharncliffes were used by sailors, as the shape of the tip prevented accidental penetration of the work or the user's hand with the sudden motion of a ship.
(S7) A spey point blade (once used for neutering livestock) has a single, sharp, straight edge that curves strongly upwards at the end to meet a short, dull, straight point from the dull back. With the curved end of the blade being closer to perpendicular to the blade's axis than other knives and lacking a point, making penetration unlikely, spey blades are common on Trapper style pocketknives for skinning fur-bearing animals.
(C1) Leaf blade with a distinctive recurved "waist" adding some curved "belly" to the knife facilitating slicing as well as shifting weight towards the tip meaning that it is commonly used for throwing knives as well as improving chopping ability.
(C2) A spear point blade is a symmetrically-shaped blade with a point aligned with the centerline of the blade's long axis. True spear-point blades are double-edged with a central spine, like a dagger or spear head. The spear point is one of the stronger blade point designs in terms of penetration stress, and is found on many thrusting knives such as the dagger. The term spear point is occasionally and confusingly used to describe small single-edged blades without a central spine, such as that of the pen knife , a small folding-blade pocket knife formerly used in sharpening quills for writing. Pen-knife may also nowadays refer to a knifelike weapon blade pattern of some of larger pocket knife blades that would otherwise be termed drop-point designs.
(C3) A needle point blade has a sharply-tapered acuminated point. It is frequently found on daggers such as the stiletto (which had no sharpened edges) and the Fairbairn-Sykes fighting knife. Its long, narrow point reduces friction and increases the blade's penetrative capabilities, but is liable to stick in bone and can break if abused. When the needle point is combined with a reinforced 'T' section running the length of the blade's spine, it is called a reinforced tip. One example of a knife with a reinforced tip is the pesh-kabz .
(C4) Kris or flame-bladed sword. These blades have a distinct recurved blade form and are sharpened on both sides, typically tapering to (or approximating) a symmetrical point.
(C5) Referred to in English speaking countries as a "tanto" or "tanto point" (a corruption of the Japanese word tantō though the tip bears no resemblance to a tantō) or a chisel point. ("Chisel point" refers to the straightness of the edge that comprises the end of the blade,whereas "chisel grind" usually refers to a blade ground on only one side even though chisels can be ground on one or both sides. ) It is similar to, but not the same as, some early Japanese swords that had kamasu kissaki ("barracuda tip"), a nearly straight edge at the tip whereas the typical "tanto point" as found in the west has a straight edge. The barracuda tip sword was sharp but also fragile whereas modern tanto points are often advertised as being stronger at the tip for having nearly the whole thickness of the blade present until quite close to the end of the knife. The geometry of the angle under the point gives tanto blades excellent penetration capabilities. For this reason, tanto blades are often found on knives designed for combat or fighting applications, where the user may need to pierce heavy clothing or low-level soft body armor.
The lower illustration is a modified tanto where the end is clipped and often sharpened. This brings the tip closer to the center of the blade increasing control of the blade and improves penetration potential by having a finer point and a sharpened back edge.
(C6) A hawkbill blade is sharpened on the inside edge and is similar to carpet and linoleum knives. The point will tear even if the rest of the knife is comparatively dull. The karambit from Far South-East Asia is a hawkbill knife which is held with the blade extending from the bottom of the fist and the tip facing forward. The outside edge of a karambit may be sharp and if so may also feature a backward-facing point.
(C7) An ulu (Inuit woman's knife) knife is a sharpened segment of a circle. This blade type has no point, and has a handle in the middle. It is good for scraping and sometimes chopping. The semi-circular version appears elsewhere in the world and is called a head knife. It is used in leatherworking both to scrape down leather (reducing thickness, i.e. skiving), and to make precise, rolling cuts for shapes other than straight lines. The circular version is a popular tool for slicing pizzas. One corner is placed at the edge of the pizza and the blade is rolled across in a diameter cut.
The sharp edges of a sword may be either curved or straight. Curved blades tend to glide more easily through soft materials, making these weapons more ideal for slicing. Techniques for such weapons feature drawing the blade across the opponent's body and back. For straight-edged weapons, many recorded techniques feature cleaving cuts, which deliver the power out to a point, striking directly in at the target's body, done to split flesh and bone rather than slice it. That being said, there also exist many historical slicing techniques for straight-edged weapons. Hacking cuts can be followed by a drawing action to maximize the cut's effectiveness. For more information see Western Martial Arts or kenjutsu.
Some weapons are made with only a single leading edge, such as the saber or dusack. The dusack has a "false edge" near the tip, which only extends down a portion of the blade's backside. Other weapons have a blade that's entirely dull except for a sharpened point, like the épée or foil, which prefer thrusts over cuts. A blade cannot perform a proper cut without an edge, and so in competitive fencing such attacks reward no points.
Some variations include:
Blades are sometimes marked or inscribed, for decorative purposes, or with the mark of either the maker or the owner. Blade decorations are often realized in inlay in some precious metal (gold or silver).
Early blade inscriptions are known from the Bronze Age, a Hittite sword found at Hattusa bears an inscription chiseled into the bronze, stating that the blade was deposited as an offering to the storm-god by king Tuthaliya.
Blade inscriptions become particularly popular in the 12th century knightly sword, based on the earlier, 9th to 11th century, the tradition of the so-called Ulfberht swords.
A knife is a tool or weapon with a cutting edge or blade, often attached to a handle or hilt. One of the earliest tools used by humanity, knives appeared at least 2.5 million years ago, as evidenced by the Oldowan tools. Originally made of wood, bone, and stone, over the centuries, in step with improvements in both metallurgy and manufacturing, knife blades have been made from copper, bronze, iron, steel, ceramic, and titanium. Most modern knives have either fixed or folding blades; blade patterns and styles vary by maker and country of origin.
A chisel is a tool with a characteristically shaped cutting edge of blade on its end, for carving or cutting a hard material such as wood, stone, or metal by hand, struck with a mallet, or mechanical power. The handle and blade of some types of chisel are made of metal or of wood with a sharp edge in it.
Differential heat treatment is a technique used during heat treating to harden or soften certain areas of a steel object, creating a difference in hardness between these areas. There are many techniques for creating a difference in properties, but most can be defined as either differential hardening or differential tempering. These were common heat treating techniques used historically in Europe and Asia, with possibly the most widely known example being from Japanese swordsmithing. Some modern varieties were developed in the twentieth century as metallurgical knowledge and technology rapidly increased.
A tantō is one of the traditionally made Japanese swords (nihonto) that were worn by the samurai class of feudal Japan. The tantō dates to the Heian period, when it was mainly used as a weapon but evolved in design over the years to become more ornate. Tantō were used in traditional martial arts (tantojutsu). The term has seen a resurgence in the West since the 1980s as a point style of modern tactical knives, designed for piercing or stabbing.
A Japanese kitchen knife is a type of a knife used for food preparation. These knives come in many different varieties and are often made using traditional Japanese blacksmithing techniques. They can be made from stainless steel, or hagane, which is the same kind of steel used to make Japanese swords. Most knives are referred to as hōchō or the variation -bōchō in compound words but can have other names including -kiri. There are four general categories used to distinguish the Japanese knife designs: handle, blade grind, steel, and construction.
Usuba bōchō is the traditional vegetable knife for the professional Japanese chef. Like other Japanese professional knives, usuba are chisel ground, and have a bevel on the front side, and have a hollow ground urasuki on the back side. Usuba characteristically have a flat edge, with little or no curve, and are tall, to allow knuckle clearance when chopping on a cutting board. Usuba literally means "thin blade" indicating its relative thinness compared to other knives, required for cutting through firm vegetables without cracking them. Due to its height and straight edge, usuba are also used for specialized cuts such as katsuramuki, shaving a vegetable cylinder into a thin sheet.
A file is a tool used to remove fine amounts of material from a workpiece. It is common in woodworking, metalworking, and other similar trade and hobby tasks. Most are hand tools, made of a case hardened steel bar of rectangular, square, triangular, or round cross-section, with one or more surfaces cut with sharp, generally parallel teeth. A narrow, pointed tang is common at one end, to which a handle may be fitted.
A blade's grind is its cross-sectional shape in a plane normal to the edge. Grind differs from blade profile, which is the blade's cross-sectional shape in the plane containing the blade's edge and the centre contour of the blade's back. The grind of a blade should not be confused with the bevel forming the sharpened edge; it more usually describes the overall cross-section of the blade, not inclusive of the beveled cutting edge which is typically of a different, less acute angle as the bevel ground onto the blade to give it a cross-sectional shape. For example, the famous Buck 110 hunting knife has a "hollow ground" blade, with concave blade faces, but the cutting edge itself is a simple, flat-ground bevel of lesser angle. It would be difficult, if not impossible, to put a "hollow grind" onto the actual cutting edge of the blade itself, which is a very narrow and small bevel.
A razor strop is a flexible strip of leather, canvas, denim fabric, balsa wood, or other soft material, used to straighten and polish the blade of a straight razor, a knife, or a woodworking tool like a chisel. In many cases stropping re-aligns parts of the blade edge that have been bent out of alignment. In other cases, especially when abrasive polishing compound is used, stropping may remove a small amount of metal. Stropping can also burnish the blade.
A kitchen knife is any knife that is intended to be used in food preparation. While much of this work can be accomplished with a few general-purpose knives – notably a large chef's knife, a tough cleaver, a small paring knife and some sort of serrated blade – there are also many specialized knives that are designed for specific tasks. Kitchen knives can be made from several different materials.
In cooking, a chef's knife, also known as a cook's knife, is a cutting tool used in food preparation. The chef's knife was originally designed primarily to slice and disjoint large cuts of beef. Today it is the primary general-utility knife for most western cooks.
The Santoku bōchō or Bunka bōchō (文化包丁) is a general-purpose kitchen knife originating in Japan. Its blade is typically between 13 and 20 cm long, and has a flat edge and a sheepsfoot blade that curves down an angle approaching 60 degrees at the point. The term Santoku may refer to the wide variety of ingredients that the knife can handle: meat, fish and vegetables, or to the tasks it can perform: slicing, chopping and dicing, either interpretation indicating a multi-use, general-purpose kitchen knife. The Santoku's blade and handle are designed to work in harmony by matching the blade's width and weight to the weight of the tang and the handle.
Japanese carpentry was developed more than a millennium ago through Chinese architectural influences such as Ancient Chinese wooden architecture and uses woodworking joints. It involves building wooden furniture without the use of nails, screws, glue or electric tools.
Sharpening stones, water stones or whetstones are used to sharpen the edges of steel tools and implements through grinding and honing.
Sharpening is the process of creating or refining a sharp edge of appropriate shape on a tool or implement designed for cutting. Sharpening is done by grinding away material on the implement with an abrasive substance harder than the material of the implement, followed sometimes by processes to polish the sharp surface to increase smoothness and to correct small mechanical deformations without regrinding.
A cleaver is a large knife that varies in its shape but usually resembles a rectangular-bladed hatchet. It is largely used as a kitchen or butcher knife and is mostly intended for splitting up large pieces of soft bones and through thick pieces of meat such as a steak. The knife's broad side can also be used for crushing in food preparation and can also be used to scoop up chopped items.
Knife sharpening is the process of making a knife or similar tool sharp by grinding against a hard, rough surface, typically a stone, or a flexible surface with hard particles, such as sandpaper. Additionally, a leather razor strop, or strop, is often used to straighten and polish an edge.
A tomato knife is a small serrated kitchen knife designed to slice through tomatoes. The serrated edge allows the knife to penetrate the tomatoes’ skin quickly and with a minimum of pressure without crushing the flesh. Many tomato knives have forked tips that allow the user to lift and move the tomato slices after they have been cut.
A cheese knife is a type of kitchen knife specialized for the cutting of cheese. Different cheeses require different knives, according primarily to hardness. There are also a number of other kitchen tools designed for cutting or slicing cheese, especially the harder types. These include the cheese cutter, cheese slicer, cheese plane and others.
A fillet knife is a kitchen knife used for filleting. It gives good control and aids in filleting. It is a very flexible member of the boning knife family that is used to filet and prepare fish. Fillet knife blades are typically 15 to 28 cm long. This allows them to move easily along the backbone and under the skin of meat.