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Definitions
Glossary
Clear, practical definitions for wire, tube, strip, cable, and profile processing.
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Technical dictionary
All terms
95 technical terms
A
Adjustment
The positioning of straightening rolls relative to each other — measured from a defined zero line — so that alternating forming on the straightener changes the material's characteristics as intended.
Analysis of straightened material production
The first of three analyses behind a correct straightening process set-up: tracing the stress history a material accumulates during its production, separating avoidable from unavoidable stresses, and countering them with selective corrective measures.
Analysis of the final product
Defining what the straightened product must actually achieve — tolerance fields such as final curvature, helicity, stretching limit and tensile strength — and setting those requirements realistically rather than tighter than justified.
Analysis of the product to be straightened
Recording the geometrical parameters of the incoming material — its directions and zones of curvature — before straightening; only material with constant curvature on one plane gives good conditions for a constant follow-up process.
Automatic roll positioner
A WITELS-ALBERT innovation that positions straightening rolls objectively, exactly and reproducibly using a single actuator and sensor — across one or several straighteners — while automatically documenting positions and process data.
Automation
A closed information loop of offline and online data, a basic automation system, at least one straightener, and geometry, stretching-limit and adjustment operators — positioning the rolls automatically so quality holds despite fluctuations in diameter or stretching limit.
B
Bauschinger effect
A metal-forming phenomenon in which reversing the loading direction (e.g. tension to compression) lowers the onset of flow — central to straightening, since alternating bending is exactly such a load reversal.
Bend
The strain produced in long bodies by external forces, creating internal bending moments over the cross section that change the body's straightness or curvature elastically or plastically.
Bending roll
A rotating roll (pulley) on which the product to be straightened is plastically deformed during a partial or complete wrap; the product should only be bent in the direction of its initial curvature to avoid helicity.
Bending test
A static test in which bending test-pieces are loaded to record a force-bend curve — yielding the modulus of elasticity, bending limit and bending strength — and which mirrors the loading in roll-type straightening far better than a tensile test.
Burnishing
A chemical surface-coating process in which iron and steel parts are dipped in heated oxidizing solutions to form dark brown to black iron-oxide layers that are decorative and give limited corrosion protection.
C
Caliber
A gauge-type measuring instrument placed between the open straightening rolls to align all adjustable rolls on one line and set a reproducible zero line for the product to be straightened.
Carbon content
The carbon content of a steel wire governs many of its properties: higher carbon raises tensile strength but lowers elongation to fracture; spring steel wire typically contains 0.4 to 1.0 percent carbon.
Cassette
WICAS, the WITELS Cassette Straightening System, encloses the rolling elements of a straightening roll in a sealed housing with a labyrinth seal — extending useful life up to 30-fold and enabling higher speeds and freely designed straightening sheaves.
Causes of stress
Stress is a material's reaction to external load — an internal resistance force per unit area; plastic deformation leaves internal stresses in a workpiece, and the type of load (tensile, bending) determines the type of stress produced.
Chain-link shirt
A protective garment of iron rings worn by knights in combat — an early large-scale application of drawn wire that replaced the coat of mail in the early 12th century.
Checklist
A blueprint for preventing mistakes: a checklist ensures nothing is forgotten and that set-up steps — such as the TMAA sequence of Testing, Maintenance, Adjustment, Action — are performed in the essential order.
Circular pulling through
A pull-off method in which the material is pressed against a driven pulley by a partial or full wrap, with movement produced by the interference fit between pulley and material.
Coarse wire drawing
The historical craft of drawing heavy steel wire, remembered through Johan Gerdes of Altena — the first manufacturer of steel wire there, credited with accidentally discovering the first lubricant for drawing steel wire.
Coil
A coil is a wound bundle of endless material (wire, strip, rope) prepared for logistics — how it is laid and later pulled off directly affects helicity and the quality of the straightened product.
Coiler
A coiler is a device for winding or unwinding a lengthy process material; it can also create tensile stress and guide the material through the process.
Curvature
Curvature is a deviation from the straight — the reciprocal of the radius of curvature, with the dimension 1/mm.
Curvature course during straightening
The correct sequence of curvatures the process material passes through during straightening: initial curvature, counter-curvature, and the final curvature remaining after spring back.
D
Danger area
Zones on straighteners and wire processing lines where operators risk crushing or clamping injuries — identified in the documentation and guarded by hoods, covers, paneling, or enclosures.
Decoil-straightener
A combination of a decoiling/unspooling unit and a straightening unit with a material store, in which the material is paid off dynamically at constant pull-off force to avoid torsional stresses and helicities.
Deflecting
Redirecting the process material during production and processing — deflection must remain elastic and follow the direction of the initial curvature, which sets a permissible minimum deflecting roll diameter.
Deflection
The deflection h of a product to be straightened is the maximal distance between the chord and the arc of the product, expressed as mm per reference length.
Diagnosis unit
A device that determines select material parameters of a wire (elongation limit, modulus of elasticity, modulus of hardening, Bauschinger modulus, etc.) through bending tests, providing the inputs a simulation program needs to describe a straightening process virtually.
Drawing direction in the straightening process
The direction in which a wire was drawn leaves a directional microstructure ('drawing texture'); straightening tests show final curvatures differ by pull-through direction, so difficult wires are best straightened in the drawing direction.
Drawing iron
A historical forged tool with several conical drawing holes, used to draw iron before modern drawing dies existed.
Drawing process
The forming of a process material by drawing, based on the wedge principle: the normal force at the drawing hole — four to seven times the drawing force — performs the forming mainly through radial and tangential compressive stresses.
Drawing shoe
An old device that applied lubricant to the material before it entered the drawing iron, reducing wear and the force needed for drawing.
Drive unit
A feeding device that clamps endless material between pairs of driven rolls or caterpillars and uses motor power to pull or push it through the process — with contact force set high enough to prevent slippage but low enough to avoid plastic deformation and surface damage.
E
Empiricism
Gaining knowledge through experience without the aid of theory — the historical driver of straightener set-ups, whose extreme wire deflections of the 1950s-70s gave way to modern designs that combine empirical knowledge with scientific theory.
Errors
Errors result from avoidable and unavoidable processes or actions; the simplest correction is to avoid them or minimize their repercussions, and unavoidable errors should be corrected as soon as they occur rather than at the end of a process chain.
F
Final curvature
The curvature of the product as it leaves the straightening process — the target being either zero (straight within tolerance) or a defined non-zero value, and above all as constant as possible to guarantee final products of constant quality.
Fine wire drawing
The historical drawing of thin brass, copper and later iron and steel wires through dies made from reinforced birch wood — a set-up still in use at wire drawing mills at the end of the 19th century.
Friction
The inhibition of relative movement between touching bodies. In straightening it occurs mainly in the straightening rolls, converts kinetic energy into losses, and should be kept as low as possible through acceptable bearing loads and optimal lubrication.
G
Guide rolls
Cylindrical rolls with rolling bearings that guide and support endless material — withstanding high loads and speeds while the material runs tangentially along them without additional plastic deformation.
H
Hammer forge
A water-powered forge of the type illustrated in the book, dating from the end of the 19th century and remaining in use until late in the 1950s.
Helicity
A curvature course adopted by wire radially rather than axially as it leaves the curvature plane — intentional in rope, cable and spring making (lay length, pitch), but an undesirable defect for follow-up processes when it arises unintentionally.
Helix straightener
A straightener whose straightening rolls can additionally be adjusted in height, forcing the wire unilaterally from its zero line into a second curvature plane — allowing helicities to be removed or deliberately created.
I
Initial curvature
The curvature the product to be straightened displays before entering the straightener — in practice a range of curvatures rather than a single value, arising for example from spooling, incorrect processing or deflecting.
Internal stresses
The internal forces and moments that remain in equilibrium inside a workpiece after external loading ends — in drawn wire, tensile in the core and compressive at the edge — which straightening changes and, with the right technology, can minimize.
K
Killing-straightening
Severe alternating bending with small radii that "kills" a wire's fluctuating initial parameters, reducing curvature fluctuations and forcing the final curvature into a single plane before conventional straightening.
L
Life-time equation
A set of three bearing life equations — nominal life-time per ISO, modified nominal life-time, and modified nominal life-time per the SKF life theory — used to determine how long a straightening roll will last under known operating conditions.
Location of the straightener
The distance between pay-off (or last deflection) and straightener strongly affects the result: keeping it within A ≤ π · d prevents the wire from turning and twisting out of the curvature plane before it enters the straightener.
Lubrication plan
A schedule for relubricating straightening rolls with lubrication points and WICAS cassette systems — daily at high speeds and loads, weekly at low speeds and loads — using special and long-life greases.
M
Maintenance and wear
Maintenance delays wear and keeps a straightener in good operating condition — on roll-type straighteners the straightening roll groove and rolling-element faces wear fastest, and worn parts must be replaced before they degrade product quality.
Material characteristics
The mechanical parameters — modulus of elasticity, stretching limit, modulus of hardening, carbon content and alternating-forming parameters — that describe a process material and largely determine its forming behavior in elastic-plastic cold forming.
Material model/material behavior
A mathematical-physical model that produces a virtual image of a process material's behavior — verified by tests, used to forecast stresses under forming forces, and essential for simulating the straightening process.
Mechanical model / straightening
An idealization of the straightening triangle as an end-fixed beam under a central straightening force — a statically indeterminate substitute system that permits simplified calculations and predictions about the product being straightened.
Modulus of elasticity
A material parameter from the tensile test describing the proportionality between load and elastic elongation (Hooke's law); it varies by material and processing — drawn wire never reaches the 210,000 MPa typical of hot-rolled steel.
N
Number of straightening rolls
The roll count is governed by the initial curvature range, the permissible final curvature and the material parameters; rules of thumb apply — bigger curvature ranges and stronger materials need more rolls — with the guiding strategy "as little as necessary".
P
Parallel-axis straightening
Arranging the first straightener with its roll axes parallel to the spool, coiler or deflecting-roll axis so straightening happens in the plane of the initial curvature — avoiding the common errors of a 90-degree turn or rolls contacting the wrong side.
Postforming apparatus
A straightener-like device used solely on multi-wire materials such as strands and ropes, positioned downstream of the stranding point to minimize the recovery efforts of individual elements and the internal stresses of the final product.
Preforming head
A rotating head of radially applied bending rolls that pre-forms wires, strands or legs into their spiral shape ahead of the stranding point, so the finished rope carries as little stress as possible — sometimes called the "Trulay" process.
Process forces
The forces at work during straightening — straightening forces at the roll/material interface and the tensile forces (pull-off and reverse) that transport the material — which together govern the process.
Pull-off force
The force needed to pull the material to be straightened through a line, machine or tooling — made up of acceleration, friction and bending-related tensile force components.
R
Reproducibility of straightening roller positions
The ability to return straightening rolls to documented positions — the precondition for constant straightening results, shorter line stoppages and less wasted material during repeat set-ups.
Roll-type straightener
A straightening device whose bending tools are straightening rolls arranged in two parallel, mutually offset rows, subjecting the material to alternating bends to change one-plane initial curvatures into defined final curvatures.
Roller crosses/guides
Guide units placed between spool or coil, straightener, pull-off unit or processing machine to support endless material, prevent sagging and surface damage, and feed it centrally into the next machine.
Rotary straightening
A straightening process that subjects the material to alternating bends with a revolving bending axis, used mainly for rods and bars — more aggressive to the material than roll straightening.
S
Semi-automatic straightening
Straightening that uses offline and online data plus basic automation equipment to set straightening roll positions with high precision, enabling reproducible roll adjustment at any time.
Simulation
Representing the straightening process in a computational model to pre-calculate the straightening roll positions needed for a defined final curvature, based on the elastic-plastic material behavior under alternate bending.
Speed
The rate at which the process material moves relative to the tooling; straightening results stay essentially unchanged up to about 10 m/s, above which the same roll adjustment produces a different deformation.
Spool
A carrier for the safe transport of endless material, wound layer by layer; its minimal inner and maximal outer diameters cause differences in speed and in curvature across the wound material.
Status quo
Latin for "the existing state" — the documented starting point of a straightening process, especially the positions of the straightening rolls relative to the process material, from which reproducible results can be produced.
Steam engine
A drive unit that runs on steam power — presented in the book with a tongue-in-cheek definition quoted from Heinz Ruehmann in the German film "Die Feuerzangenbowle".
Straightened material
The workpiece whose properties — above all straightness or final curvature, but also internal stress condition — have been changed by the straightening process. It can be finite (rails, sheets) or endless (wire, cable, rope).
Straightened material parameter
The characteristics of the straightened material — its material, cross-sectional geometry, and initial curvature — which determine the type, design, and size of straighteners and their supporting equipment.
Straightener / set-up
The precise, modular constructive design of a straightener: load-bearing "A" parts sized to the number of rolls carry standard "B" parts, with the wear-exposed straightening rolls as the final block of the modular chain.
Straightener/accessories
The range of add-on elements and devices for a straightener or straightening system — from guide blocks to micrometer screws and actuators — classified by application, safety, handling, design, and maintenance.
Straightening / definition
Straightening covers all actions and measures needed to eliminate process-induced curvatures in the process material, producing straightness, levelness, or a defined curvature.
Straightening plane
The plane defined by the axial position of the straightening rolls — not by the straightener body — in which curvature is processed; a constant straightening plane can only produce constant final curvatures from constant curvatures in that same plane.
Straightening process set-up
The structured procedure — based on analyses of the product to be straightened, its production process, and the final product — for choosing the correct straightening system, number of rolls, and straightener location so that constant input parameters yield a constant final curvature.
Straightening roll
The last link in a straightener's modular design chain and the component exposed to the greatest wear — a bearing-mounted grooved roll whose materials, bearing arrangement, load ratings, life-time, lubrication, and tolerances all demand special attention.
Straightening roll brushes
Stationary brushes held by a cross arm that continuously wipe the straightening roll groove clean, preventing dirt deposits that would change the effective diameter and zero line, alter final curvature, and damage the straightened material.
Straightening roll groove
The profile cut into the outer ring of a straightening roll to accommodate and guide the product to be straightened — angular grooves of 90°, 100° or 110° for round solid material, adapted profiles for profiled, soft or tubular material, and smooth rolls for strip.
Straightening roll life-time
The useful life of a straightening roll, determined by rolling-bearing methods but allowing for elastic deformation of the outer ring, and governed by external factors (material contact, speed, slip, soiling) and internal factors (bearing lubrication, type, load, seals).
Straightening system
A combination of straighteners, adapted to the product to be straightened, that transforms difficult and sometimes alternating initial material parameters into constant values — the constant process transition needed for controlled follow-up processes.
Stretch-bend-straightening
A straightening process that bends material around small-diameter rolls while simultaneously applying tensile stress, stretching the product in steps to produce a defined final curvature in wire or a flatness profile in strip.
Stretch-straightening
A straightening process in which the product is subjected to a tensile force strong enough to produce plastic deformation, superimposing tensile stress on the existing internal stresses.
Stretching limit
A material parameter from the tensile test: the stress at which elongation continues to increase even though the inner resistance stays constant or decreases. For drawn wires it cannot be read from the stress/strain diagram, so the 0.2% elongation limit is used instead.
Swelling
The elastic deformation of a straightener under straightening forces, which reduces the effective roll adjustment and enlarges the straightening gap — each machine's force/swelling characteristic must be known to achieve constant results.
T
Tensile strength
A material parameter from the tensile test: the maximal endurable stress, derived from the quotient of the maximal load and the cross-sectional area prior to loading, at which the specimen begins to constrict locally.
Tensile test
The static test method per DIN EN 10 002 — the most important test for determining a material's mechanical parameters, in which a clamped test bar is loaded in tension until failure and a stress/strain diagram is derived.
Tolerance
The difference between the permissible maximum and minimum value of a measurable property; in straightening, dimensional tolerance matters especially in straightener geometry and product curvature.
U
Unspooling/unwinding
Paying off material to be straightened from a spool or reel, either statically (spool fixed, material removed axially, creating twist) or dynamically (spool rotated, material paid off without torsion).
W
Water wheel
A drive unit which runs on hydropower, historically used to power wire-making machinery.
Windmill
A mill with a drive system which uses wind energy, historically among the power sources for wire production.
Wire catch
An old-fashioned measuring instrument — a wire blade with two opposing rows of jaw-shaped notches — used like today's external gauges to check wire diameters and geometrical tolerances.
Wire drawer
The historical craftsman (German "Drahtzieher") who drew metal wires; the word later came to mean anyone "drawing the wires" in the background, like the English "pulling strings".
Wire washing
The historical practice of washing wire coils in flowing river water, then pickling and liming them, to reduce frictional losses and wear on the drawing die in the next drawing pass.
Z
Zero line
Used in two senses: the zero line of the processing system, along which the product runs without additional bending, deflecting or guiding, and the zero line in the straightener, where all straightening rolls touch the product without bending it.