Instruct: Given a question, retrieve relevant documents that answer the question.
Query: What are screws most commonly made of?
A screw is a type of fastener, in some ways similar to a bolt (see "Differentiation between bolt and screw" below), typically made of metal, and characterized by a helical ridge, known as a "male thread" (external thread). Screws are used to fasten materials by digging in and wedging into a material when turned, while the thread cuts grooves in the fastened material that may help pull fastened materials together and prevent pull-out. There are many screws for a variety of materials; those commonly fastened by screws include wood, sheet metal, and plastic.
Cabinets may be finished with opaque paint, opaque lacquer and transparent finishes such as lacquer or varnish. Decorative finishes include distressing, glazing, and toning. The choice of finish can affect the cabinet's color, sheen (from flat to high gloss), and feel.Hardware is the term used for metal fittings incorporated into a cabinet extraneous of the wood or engineered wood substitute and the countertop. The most basic hardware consists of hinges and drawer/door pulls, although only hinges are an absolute necessity for a cabinet since pulls can be fashioned of wood or plastic, and drawer slides were traditionally fashioned of wood. In a modern kitchen it is highly unusual to use wood for a drawer slides owing to the much superior quality of metal drawer slides/sides.
There are four basic types of knitting needles (also called "knitting pins"). The first and most common type consists of two slender, straight sticks tapered to a point at one end, and with a knob at the other end to prevent stitches from slipping off. Such needles are usually 10-16 inches long but, due to the compressibility of knitted fabrics, may be used to knit pieces significantly wider. The most important property of needles is their diameter, which ranges from below 2 mm to 25 mm (roughly 1 inch). The diameter affects the size of stitches, which affects the gauge of the knitting and the elasticity of the fabric. Thus, a simple way to change gauge is to use different needles, which is the basis of uneven knitting. Although knitting needle diameter is often measured in millimeters, there are several different size systems, particularly those specific to the United States, the United Kingdom and Japan; a conversion table is given in the knitting needle article. Such knitting needles may be made out of any materials, but the most common materials are metals, wood, bamboo, and plastic. Different materials have different frictions and grip the yarn differently; slick needles such as metallic needles are useful for swift knitting, whereas rougher needles such as bamboo are less prone to dropping stitches. The knitting of new stitches occurs only at the tapered ends, and needles with lighted tips have been sold to allow knitters to knit in the dark.
Many sculptors seek new ways and materials to make art. One of Pablo Picasso's most famous sculptures included bicycle parts. Alexander Calder and other modernists made spectacular use of painted steel. Since the 1960s, acrylics and other plastics have been used as well. Andy Goldsworthy makes his unusually ephemeral sculptures from almost entirely natural materials in natural settings. Some sculpture, such as ice sculpture, sand sculpture, and gas sculpture, is deliberately short-lived. Recent sculptors have used stained glass, tools, machine parts, hardware and consumer packaging to fashion their works. Sculptors sometimes use found objects, and Chinese scholar's rocks have been appreciated for many centuries.
The view of most scholars (see organology) is that the term "brass instrument" should be defined by the way the sound is made, as above, and not by whether the instrument is actually made of brass. Thus one finds brass instruments made of wood, like the alphorn, the cornett, the serpent and the didgeridoo, while some woodwind instruments are made of brass, like the saxophone.
Wire has many uses. It forms the raw material of many important manufacturers, such as the wire netting industry, engineered springs, wire-cloth making and wire rope spinning, in which it occupies a place analogous to a textile fiber. Wire-cloth of all degrees of strength and fineness of mesh is used for sifting and screening machinery, for draining paper pulp, for window screens, and for many other purposes. Vast quantities of aluminium, copper, nickel and steel wire are employed for telephone and data cables, and as conductors in electric power transmission, and heating. It is in no less demand for fencing, and much is consumed in the construction of suspension bridges, and cages, etc. In the manufacture of stringed musical instruments and scientific instruments, wire is again largely used. Carbon and stainless spring steel wire have significant applications in engineered springs for critical automotive or industrial manufactured parts/components. Pin and hairpin making; the needle and fish-hook industries; nail, peg, and rivet making; and carding machinery consume large amounts of wire as feedstock.
Until the twentieth century, the materials used for building were limited to brick, stone, timber and steel to form structures, slate and tiles for roof coverings, lead and sometimes copper for waterproofing details and decorative roofing effects. The Romans used concrete, but it was virtually unknown as a building material until the invention of reinforced concrete in 1849. Modern construction is much more complex, with walls, floors and roofs all built up from many elements to include structure, insulation and waterproofing often as separate layers or elements.
316 stainless steel, also referred to as marine grade stainless steel, is a chromium, nickel, molybdenum alloy of steel that exhibits relatively good strength and corrosion resistance. Along with the titanium alloy Ti6Al4V, 316 stainless is a common choice of material for biomedical implants. Although Ti6Al4V provides greater strength per weight and corrosion resistance, 316 stainless components can be more economical to produce. However, immune system reaction to nickel is a potential complication of 316. 
Implants and equipment that are put under pressure (bone fixation screws, prostheses, body piercing jewelry) are made out of austenitic steel, often 316L and 316LVM compliant to ASTM F138.
316 surgical steel is used in the manufacture and handling of food and pharmaceutical products where it is often required in order to minimize metallic contamination. 
ASTM F138-compliant steel is also used in the manufacture of body piercing jewellery and body modification implants.
Jewellery (British English) or jewelry (American English) consists of small decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a western perspective, the term is restricted to durable ornaments, excluding flowers for example. For many centuries metal, often combined with gemstones, has been the normal material for jewellery, but other materials such as shells and other plant materials may be used. It is one of the oldest type of archaeological artefact – with 100,000-year-old beads made from "Nassarius" shells thought to be the oldest known jewellery. The basic forms of jewellery vary between cultures but are often extremely long-lived; in European cultures the most common forms of jewellery listed above have persisted since ancient times, while other forms such as adornments for the nose or ankle, important in other cultures, are much less common.
They are also produced commercially. Simple whistles may cost less than 1 USD in bulk; expensive ones may be quite ornate. They are commonly made of plastic, aluminum, stainless steel, silver, brass, titanium, Corian, jade, buffalo horn and other materials.
The Copper Age is the early part of the Bronze Age. Bronze is made when tin is added to copper and brass is copper with zinc. Copper came into use before 5,000 BC and bronze around 3,100 BC, although the times vary by region. Copper and bronze were used for the same types of tools as stone such as axes and chisels, but the new, less brittle, more durable material cut better. Bronze was cast into desired shapes and if damaged could be recast. A new tool developed in the copper age is the saw. Other uses of copper and bronze were to "harden" the cutting edge of tools such as the Egyptians using copper and bronze points for working soft stone including quarrying blocks and making rock-cut architecture.
Cabinet doors may feature a variety of materials such as wood, metal or glass. Wood may be solid wood ("breadboard" construction) or engineered wood or may be mixed (e.g. engineered wood panel in a solid wood frame)
Somewhat less common are surface anchors, commonly made from surgical implant-grade titanium. A surface anchor has two parts: a base or foot which is inserted under the dermis during the piercing process and which incorporates a stem exposed to the surface, and a decorative disc or ball of jewelry which typically appears flush with the surface of the skin. Surface anchor nape piercings are most commonly found placed symmetrically on either side of the spine at the nape.
The term "asbestos ware" refers to vessels containing 90% asbestos and 10% clay. Asbestos ware can resist heat up to 900–1000 °C. The clay made shaping of the vessel possible, but the high amount of asbestos does not classify it as pottery in a formal sense. It is believed that the asbestos ware was used in iron production such as spearheads, arrowheads and artefacts. The vessel is also drilled with many holes. The fact that the reduction of iron ore (FeO) with abundant carbon generates large amounts of carbon monoxide (CO) may suggest that the drilled holes were used to increase the influx of air (oxygen) required for proper glowing process. Iron ore is abundant in lakes e.g. in Finland.
Stainless steel was invented in 1913 by Harry Brearley of Sheffield, working for Firth Brown Steels (now called Sheffield Forgemasters). SAE 304 stainless steel is the most common stainless steel today, invented by Dr William Herbert Hatfield FRS in 1924 at Firth-Vickers known as Staybrite 18/8, a chromium-nickel steel. Many Swiss watches were mostly made out of Staybrite.
Longships for the most part used two different kinds of anchors. The most common was a natural wood yoke formed from a tree branch. The weight was supplied by a stone passing laterally through the U of the yoke. The top of the yoke was closed by either a length of hardwood or a curved iron head, which kept the stone in place. One side of the head stuck out so it could dig into mud or sand. In the Ladby ship burial in Denmark, a unique iron anchor has been found, resembling the modern fisherman's anchor but without the crossbar. The cross bar may have rusted away. This anchor—made of Norwegian iron—has a long iron chain to which the hemp warp was attached. This construction has several advantages when anchored in deep waters or in rough seas.
Once the preliminary wool preparation steps are completed, knitting can begin. Early materials for needles included whale bone, deer bone, telephone wire, bamboo chopsticks, and wood. Today, knitters primarily use readily available and inexpensive plastic or metal needles. No matter which material is used for needles, the sizes vary from 4-7.5mm depending on the weight of the hand spun yarn.
The "scorpio" is a torsion catapult powered by torsion springs, a kind of ballista. It used a system of torsion springs to propel the projectiles. Scorpions could be designed to fire stones or arrow-shaped missiles of various sizes. Scorpions could be large enough to damage city walls during sieges, but the term typically refers to the smaller battlefield artillery, which were manoeuvrable enough to be taken on campaign, were light enough to be deployed in numbers on the top levels of wooden siege towers, and compact enough to be used on parapets, earthworks, and palisades. Depictions of this kind depicted are on Trajan's Column. Though the scorpion, like other ballistae, could resemble large crossbows, their design and propulsion is quite different.
The silicon content leads to a strengthening of the metal matrix. The appearance is similar to ordinary brass. Silicon tombac has good friction bearing characteristics and is corrosion resistant but is not resistant to ammonia atmosphere. The strength properties are largely retained at application temperatures up to 200 °C.
It is a special alloy in terms of the combination of casting process and casting temperature. In most cases, parts made of silicon tombac, are produced through the high pressure die casting process, which is normally specialized on metals with relatively low melting temperatures. But in this case the temperature melting range of silicon tombac is in the area of 950 to 1000 °C, which is relatively high for casting into permanent moulds. The advantage is the productivity of this highly automated casting process. The disadvantage is the temperature stress of the surface of the permanent mould, so that the lifetime of these moulds is limited.
The Bronze Age was the period in human cultural development when the most advanced metalworking (at least in systematic and widespread use) included techniques for smelting copper and tin from naturally-occurring outcroppings of copper ores, and then combining those ores to cast bronze. These naturally-occurring ores typically included arsenic as a common impurity. Copper/tin ores are rare, as reflected in the fact that there were no tin bronzes in western Asia before 3000 BC. In some parts of the world, a Copper Age follows the Neolithic and precedes the Bronze Age.
The stainless steel production in China accounts for more than 50% of the world production in 2017Breakdown of production by families of stainless steels in 2017:This breakdown is quite stable over the yearsStainless steel is used for buildings for both practical and aesthetic reasons. Stainless steel was in vogue during the art deco period. The most famous example of this is the upper portion of the Chrysler Building (pictured). Some diners and fast-food restaurants use large ornamental panels and stainless fixtures and furniture. Because of the durability of the material, many of these buildings still retain their original appearance. Stainless steel is used today in building construction because of its durability and because it is a weldable building metal that can be made into aesthetically pleasing shapes. An example of a building in which these properties are exploited is the Art Gallery of Alberta in Edmonton, which is wrapped in stainless steel.
The Unified Thread Standard (UTS) is most commonly used in the United States, but is also extensively used in Canada and occasionally in other countries. The size of a UTS screw is described using the following format: X-Y, where X is the nominal size (the hole or slot size in standard manufacturing practice through which the shank of the screw can easily be pushed) and Y is the threads per inch (TPI). For sizes inch and larger the size is given as a fraction; for sizes less than this an integer is used, ranging from 0 to 16. The integer sizes can be converted to the actual diameter by using the formula 0.060 + (0.013 × number). For example, a #4 screw is 0.060 + (0.013 × 4) = 0.060 + 0.052 = 0.112 inches in diameter. There are also screw sizes smaller than "0" (zero or ought). The sizes are 00, 000, 0000 which are usually referred to as two ought, three ought, and four ought. Most eyeglasses have the bows screwed to the frame with 00-72 (pronounced double ought – seventy two) size screws. To calculate the major diameter of "ought" size screws count the number of 0's and multiply this number by 0.013 and subtract from 0.060. For example, the major diameter of a 000-72 screw thread is .060 – (3 x .013) = 0.060 - 0.039 = .021 inches. For most size screws there are multiple TPI available, with the most common being designated a Unified Coarse Thread (UNC or UN) and Unified Fine Thread (UNF or UF). Note: In countries other than the United States and Canada, the ISO Metric Screw Thread System is primarily used today. Unlike most other countries the United States and Canada still use the Unified (Inch) Thread System. However, both are moving over to the ISO Metric System. It is estimated that approximately 60% of screw threads in use in the United States are still inch based.[67]
Propellers (as well as screws, fans and rotors) are used to move through a fluid. Propellers have been used as toys since ancient times, however it was Leonardo da Vinci who devised what was one of the earliest propeller driven vehicles, the "aerial-screw". In 1661, Toogood & Hays adopted the screw for use as a ship propeller. Since then, the propeller has been tested on many terrestrial vehicles, including the Schienenzeppelin train and numerous cars. In modern times, propellers are most prevalent on watercraft and aircraft, as well as some amphibious vehicles such as hovercraft and ground effect vehicles. Intuitively, propellers cannot work in space as there is no working fluid, however some sources have suggested that since space is never empty, a propeller could be made to work in space.
The #6-32 UNC is a UTS screw specifying a major thread diameter of which is defined as ; and (threads per inch) which equates to a thread pitch of . The optional UNC specification indicates the standard coarse thread is used which is defined for #6 screws as 32 tpi rendering 'UNC' redundant, however it may be seen when other specifications such as plating or other treatments are also specified. It is by far the most common screw found inside computer cases. It commonly appears in lengths of () and () or less often (). Non-standard metricized lengths such as are also sometimes encountered. Nearly every brand new computer case comes with a bag of these. They are commonly used for the following purposes, however there are many exceptions:
The most commonly known screw press of this design is said to have been invented by famous Greek mathematician Archimedes and is known as the screw conveyor. The screw conveyor consists of a shaft, which is surrounded by a spiral steel plate, similar in design and appearance to a corkscrew. This design is used in a multitude of screw presses. There are some machines of this and also of similar design that are not screw presses at all - they do not separate solids from liquids but are instead used to fuse them together. An example of this is a mold-filling machine. Plastic pellets are inserted at one end and heat is applied, melting the pellets and discharging them into a mold. Another example is known as a cooker-extruder and is used in the production of snack foods such as pretzels and more.