Surface finish in the context of "Honing (metalworking)"

Machinability is the ease with which a metal can be cut (machined) permitting the removal of the material with a satisfactory finish at low cost. Materials with good machinability (free-machining materials) require little power to cut, can be cut quickly, easily obtain a good finish, and do not cause significant wear on the tooling. Factors that typically improve a material's performance often degrade its machinability, presenting a significant engineering challenge.

Machinability can be difficult to predict due to the large number of variables involved in the machining process. Two sets of factors are the condition and physical properties of the work materials. The condition of the work material includes at least eight factors: microstructure, grain size, heat treatment, chemical composition, fabrication, hardness, yield strength, and tensile strength. Physical properties are those of the individual material groups, such as the modulus of elasticity, thermal conductivity, thermal expansion, and work hardening. Other important factors are operating conditions, cutting tool material and geometry, and the parameters of the specific machining process being performed.

Polymetallic nodules, also called manganese nodules, are mineral concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core. As nodules can be found in vast quantities, and contain valuable metals, deposits have been identified as a potential economic interest. Depending on their composition and authorial choice, they may also be called ferromanganese nodules. Ferromanganese nodules are mineral concretions composed of silicates and insoluble iron and manganese oxides that form on the ocean seafloor and terrestrial soils. The formation mechanism involves a series of redox oscillations driven by both abiotic and biotic processes. As a byproduct of pedogenesis, the specific composition of a ferromanganese nodule depends on the composition of the surrounding soil. The formation mechanisms and composition of the nodules allow for couplings with biogeochemical cycles beyond iron and manganese. The high relative abundance of nickel, copper, manganese, and other rare metals in nodules has increased interest in their use as a mining resource.

Nodules vary in size from tiny particles visible only under a microscope to large pellets more than 20 centimetres (8 in) across. However, most nodules are between 3 and 10 cm (1 and 4 in) in diameter, about the size of hen's eggs. Their surface textures vary from smooth to rough. They frequently have botryoidal (mammillated or knobby) texture and vary from spherical in shape to typically oblate, sometimes prolate, or are otherwise irregular. The bottom surface, buried in sediment, is generally rougher than the top due to a different type of growth.

Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened tool steel dies which have been machined into shape and work similarly to an injection mold during the process. Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter, and tin-based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used.

The casting equipment and the metal dies represent large capital costs and this tends to limit the process to high-volume production. Manufacture of parts using die casting is relatively simple, involving only four main steps, which keeps the incremental cost per item low. It is especially suited for a large quantity of small- to medium-sized castings, which is why die casting produces more castings than any other casting process. Die castings are characterized by a very good surface finish (by casting standards) and dimensional consistency.

Surface roughness or simply roughness is the quality of a surface of not being smooth and it is hence linked to human (haptic) perception of the surface texture. From a mathematical perspective it is related to the spatial variability structure of surfaces, and inherently it is a multiscale property. It has different interpretations and definitions depending on the disciplines considered.

In surface metrology, surface roughness is a component of surface finish (surface texture). It is quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is smooth. Roughness is typically assumed to be the high-frequency, short-wavelength component of a measured surface. However, in practice it is often necessary to know both the amplitude and frequency to ensure that a surface is fit for a purpose.