The terms spoken on a surface treatment line, gathered with short definitions. Grouped by coating, bath control, lubricant and line; each definition written to stand on its own.
On a surface treatment line the same thing gets different names and different things get the same name, and that alone is enough to make a technical discussion go nowhere. This glossary gathers short, self-contained definitions of the terms used around phosphate coating and wire drawing lubricants. Each definition links on to the article that takes the subject further.
A coating that is not applied onto the metal but derived from it. Acid in the bath dissolves metal at the surface, and the resulting local chemical shift makes coating crystals precipitate directly on that surface. The layer is therefore chemically bonded to the metal and can deform along with it. More: what is phosphating.
The most common carrier layer in wire drawing and cold forming. Its porous, crystalline structure holds the lubricant and, at the moment of deformation, the pores spread apart and distribute that lubricant onto the newly exposed surface. Product side: phosphate coating.
A conversion coating harder and more wear-resistant than zinc phosphate. It is used mainly on sliding surfaces and parts needing run-in; it is not as widespread as zinc phosphate in wire drawing. Comparison: manganese or zinc phosphate.
The mass of coating per unit of surface. It is measured gravimetrically: the sample is weighed, the coating stripped with a selective solution, and the sample weighed again, with the difference divided by surface area. It is a measure of carrying capacity, not of thickness as such. More: coating weight measurement.
The step immediately before the phosphate bath that governs crystal nucleation. By creating many nucleation points on the surface it produces a fine, uniform crystal structure; skipped, the crystals come out coarse and irregular. More: the activation bath and crystal size.
The fineness of the crystals making up the phosphate layer. A fine, uniform structure means more pore surface and better soap pickup at the same coating weight; a coarse structure fractures under deformation and produces debris. This is why coating weight alone is not a sufficient target.
The titrated value of all acid components in the bath, usually expressed in points. It indicates the bath's overall concentration and its capacity to produce coating. More: phosphate bath maintenance.
A measure of the unbound acid in the bath. This is the part that starts the reaction by dissolving metal at the surface; too low and no coating forms, too high and the metal dissolves excessively so the coating will not hold.
The ratio of total acid to free acid. It summarises the bath's balance in a single number and is the parameter that actually governs crystal structure. When coating behaviour changes on a line, this ratio is the first place to look.
The solid that settles in the bath instead of becoming coating, mainly iron phosphate compounds. It is unavoidable, but its volume varies with how the bath is run; filtration and correct acid balance reduce it. More: phosphate sludge management.
A rinsing arrangement in which the wire passes through progressively cleaner stages of water flowing counter to it. It lowers both the carryover into the next bath and water consumption. More: phosphating wastewater management.
The dry powder lubricant applied to the wire surface before it enters the die in dry drawing. Chemically it is the metal salt of a fatty acid; it lodges in the pores of the phosphate layer and prevents metal-to-die contact. The same product is called <em>drawing soap</em>, <em>wire drawing lubricant</em>, <em>drawing powder</em> and <em>drawing compound</em> in different parts of the industry. Product side: drawing soaps.
A predominantly sodium-based soap that undergoes a displacement reaction with zinc in the phosphate layer. It forms a chemically bonded zinc soap film on the surface; film strength in heavy drawing is high, but its residue is difficult to clean.
A predominantly calcium-based soap that does not react appreciably with the phosphate layer. It leaves only a physical film held mechanically on the surface; its residue is largely removed by an alkaline wash. Comparison: wire drawing lubricant selection.
The base components of the soap. Sodium stearate is water-soluble, softens at lower temperature and takes up moisture; calcium stearate is insoluble in water, withstands higher temperature and does not take up moisture. A significant share of commercial products are blends of the two.
The container at the die entry through which the wire passes to pick the lubricant up onto its surface. Fill level, temperature and the moisture inside it directly affect how uniformly the film forms. More: dry drawing lubricant film stability.
The lubricant film staying continuous and thick enough throughout drawing. The moment the film tears, metal-to-die contact begins, and wear, galling and surface scoring arrive together.
The quantity of lubricant used per tonne drawn. It is not a quality indicator on its own; it is the joint result of coating weight, total reduction, wire diameter and soap box temperature. More: reducing wire drawing lubricant consumption.
The iron oxide layer that forms on steel when it meets air at high temperature. It is hard and brittle; left in place it blocks the phosphate bath from reaching the metal.
Removal of the oxide layer by mechanical means (reverse bending, brushing, shot blasting) or by acid. It is the precondition for phosphate coating. More: acid pickling and descaling.
Removal of oil, rolling residue and dust from the surface in an alkaline or neutral bath. A phosphate layer will not form properly on an oily surface. More: what is degreasing.
The heat treatment applied to high carbon wire before heavy drawing that gives it a fine lamellar structure. It leaves oxide on the wire coming out of the furnace, which is why it is the starting point of the surface preparation chain. More: PC strand and spring steel wire.
The proportional decrease in cross-sectional area at one die; total reduction is the cumulative decrease from rod to final diameter. The larger the total reduction, the longer the carrier layer is expected to endure.
The increase in surface area during deformation. In cold heading it can multiply at a single station, exposing unlubricated fresh metal underneath; the carrier layer has to stretch along with that expansion. More: the phosphate and lubricant chain for fastener wire.
How much a drawing die draws before it is changed, usually tracked in tonnes. It is the most directly measurable consequence of lubricant and coating performance.
Damage caused when the film tears and metal contacts the die face directly, micro-welding to it. It leaves material pick-up on the die and marks on the product. More: friction in cold forming.
Hydrogen released during acid pickling partly entering the steel lattice and causing delayed fracture under stress. It is a risk on high tensile and high carbon products; it may not show during production and appear instead in service.
This glossary covers the terms that appear in our own articles and is extended over time. If you cannot find the term you are looking for, or want to pin down what a concept on your own line corresponds to, get in touch; for technical data sheets see the document center.
An ordinary coating is applied or deposited onto the metal; a conversion coating derives from the metal itself. Acid in the bath dissolves metal at the surface, and the resulting local chemical shift makes coating crystals precipitate directly on it. The layer is therefore chemically bonded to the metal and can move with it during deformation.
Total acid measures all acid components in the bath and indicates its overall concentration. Free acid measures the unbound acid — the part that starts the reaction by dissolving metal at the surface. The ratio between the two summarises the bath's balance and is the parameter that actually governs crystal structure.
No, they are largely different names for the same product. The dry powder lubricant used in drawing is called drawing soap, wire drawing lubricant, drawing powder and drawing compound across different parts of the industry. The difference is regional and commercial naming rather than a technical one.
No. Coating weight measures carrying capacity, not quality. A layer heavier than needed and with a coarse crystal structure fractures under deformation rather than holding, produces debris and builds up on the die to mark the product. The right value is set by the part's deformation profile, and the fineness of the crystal structure matters at least as much as coating weight.
A zinc phosphate coating is a porous crystalline layer that grows on the steel surface through an acidic bath reaction. This guide explains how the layer forms, what coating weight actually means, and why the layer is indispensable in cold forming.
Read →Drawing soap is a metallic-soap based dry lubricant that forms a lubricating film between die and metal in wire and profile drawing. It is not a cleaning soap that dissolves in water; it is a consumable that keys into the phosphate layer and forms a film under pressure and heat.
Read →Phosphate coating is not a single tank but a connected chain: degreasing, rinsing, activation, phosphating, soap and drawing. This guide summarises each stage end to end — what it does, its typical parameters and how it affects the next one.
Read →