antaac jan. 2009 · 2019. 11. 16. · - 4 - antaac jan. 2009 the lisciani rod preparation system....

ANTAAC Jan. 2009

The mechanical descaling in the low carbon wires production. Marco Graziani R. Lisciani Trafilerie s.r.l ITALY

Table of contents

1. Technical notes about low carbon rods scale.

2. Low carbon rods fit for mechanical descaling.

3. The Lisciani rod preparation system.

4. Technical data of the Lisciani rod preparation.

5. Advantages of the Lisciani rod preparation.

Since 1953 Lisciani has specialized in the production of bright and annealed low carbon wires having diameters going from 4,5mm up to 0,6mm for building and agricultural use.

Our machines and auxiliaries for the wire industry are designed on the base of our practical experience as wire drawers.

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Technical notes about low carbon rods scale.

Rod scale and its characteristics.

The rod scale characteristics influence the rod preparation. With reference to the rod cooled in coils, the calamine that forms on the rod surface during the cooling process after the lamination is made up by a mix of three oxides with different characteristics:

• FeO Wustite with hardness 270 / 350 Hv and grey – black colour • Fe3O4 Magnetite with hardness 420 / 500 Hv and black colour • Fe2O3 Hematite with hardness about 1030 Hv and red – black colour

Rod structure with the three oxides that make up the scale.

The quantity of each depends on the permanence of the rod at the different temperatures and on the presence of oxygen. Since oxidation kinetics is determined by temperature and time, an extended period at elevated temperatures results in the formation of a thicker calamine. Laying ahead temperatures around 800°C - 850°C and more extended permanence at these temperatures during the cooling process originate thicker scales - made up mainly by Wustite - that can be easily removed. Lower laying ahead temperatures generally result in the formation of thinner scales. Moreover cooling processes initially fast followed from long permanence around 600°C in presence of oxygen aid the Wustite decomposition and the formation of scales having higher percentage of Magnetite often coupled with red oxide layer - Hematite - on surface, that are more adherent and more difficult to remove. This is the case of rod subjected to slow cooling processes finalized to get in-line annealing effects. The hardness of the oxides, if these are not completely removed by chemical or mechanical cleaning process, concurs to cause an anomalous wear of the dies in the rod drawing. Under this point of view, the Wustite is less hard and consequently less harmful than Magnetite and Hematite.

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Hematite (Fe2O3)

Air (O2)

Metal (Fe)

Wustite (FeO)

Magnetite (Fe3O4)


Rod scale and mechanical descaling.

Following what said above an increase in scale thickness improves the mechanical descaleability. More in particular the drawing experience indicates that rods with a good mechanical descaleability present typically a percentage of scale included between 0,6% - 1% of their weight. Lower percentages generally are characterized by the presence of more elastic oxides more difficult to remove by the mechanical descaling. On the base of these considerations we can connect this classification to the relative scale thickness:

Scale thickness Type of scale

< of 10 Micron Scale for chemical pickling

From 10 up to 15 Micron Scale for both chemical and mechanical cleaning

> of 15 Micron (1) Scale for mechanical descaling

(1) A scale layer of 15 Micron is about 0,6% of the rod weight.

A uniform scale improves the quality of the mechanical descaling, so it is important the control of the rod cooling. A bad laying of the rod waps on the cooling bad, can give rise to a rod surface that presents sections - in correspondence of the waps overlaps - with a different scale. During the cooling the loss of scale in some sections of the rod surface can cause the oxidation of the lower layers of these sections - typical dark spots visible on the rod surface also after the mechanical descaling -.

The roughness of the rod surface is an other factor that has influence on the quality of the mechanical descaling process. The smoother the interface metal-scale, the better the action of the mechanical descaling. A control of the rolling process can improve this characteristic.


Low carbon rods fit for mechanical descaling. AISI / SAE (ASTM A510M - 1996) low carbon rods classification:

Designation AISI / SAE

C% Mn% Si% P% S%

1005 <= 0.06 <= 0.35 <= 0.10 <= 0.040 <= 0.050

1006 <= 0.08 0.25 ÷ 0.40 <= 0.10 <= 0.040 <= 0.050

1008 <= 0.10 0.30 ÷ 0.50 <= 0.10 <= 0.040 <= 0.050

1010 0.08 ÷ 0.13 0.30 ÷ 0.60 <= 0.10 <= 0.040 <= 0.050

1011 0.08 ÷ 0.13 0.60 ÷ 0.90 <= 0.040 <= 0.050

1015 0.10 ÷ 0.15 0.30 ÷ 0.60 <= 0.040 <= 0.050

Generally we can say that the low carbon rods fit for the mechanical descaling process are employed in the production of the following categories of wires:

Bright wire for general use

Bright wire for structural use (electro-welded meshes, etc)

Bright wire for white and black annealing

Bright wire plating quality (electrolytic galvanizing, electrolytic chromium-plating, etc)

Bright wire for hot galvanizing

Bright wire for concrete reinforcement fibers

Bright wire for nails and fasteners

Bright wire for low resistance chains

Bright wire for cold rolling (wire bands, flat bars, etc)

Welding wires (electrodes, CO2 wire, sub-arc wire)

Not included low carbon rods employed in the production of:

Bright wire for screws, nuts, bolts and in general cold-stamping

Free-cutting wire (for parts machined by high-speed tools)

that require the phosphate coat necessary for the following cold stamping or cutting process. In these cases the rod is generally prepared by chemical pickling + phosphate coat process.

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The Lisciani rod preparation system. An efficient rod preparation is at the basis of a competitive drawing process. The Lisciani Mechanical Descalers SC55b and SC90b (patented) are designed for the most simple and effective rod preparation at lower operating costs.

Modular design for a rod preparation in three stages.

The Mechanical Descalers SC55b and SC90b prepare the rod in three stages by three specific Modules:

• Stage No.1: rod bending and scale breaking by the Modules SC55bA and SC90bA. • Stage No.2: rod cleaning by the Modules SC55bB and SC90bB. • Stage rod lubrication and first drawing step by Rotary Dieholder Modules SC55bC, FR4CSB

and FR5CSB type.

Stage No.1: rod bending and scale breaking by the Modules SC55bA and SC90bA.

These Modules dimensioned according to the rod diameter: • SC55bA fit for low carbon rods up to 8,0mm; • SC90bA fit for low carbon rods up to 14,0mm, are equipped by inlet and bending rolls. - The inlet rolls guide with precision and without abrasions the rod in entrance. - The following group of integral tungsten carbide rolls break the scale through an alternate rod

bending. Both bending design and rolls dimension allow to get an effective scale break all around the rod surface. The bending is on two orthogonal planes and is adjustable by hydraulic regulation of the central bending rolls position. For low carbon rods up to 6,5mm is also available the not adjustable bending on four bending planes. Rod entrance and rod exit are coaxial in order to allow easier rod threading operations.

SC55b - Adjustable bending in operation SC55b - Not adjustable bending in operation

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The scale collection and removal is by boxes that equips the Modules frame. Automatic scale removal systems are available as option.

SC55b - Scale removal system in operation (particular)

Stage No.2: rod cleaning by the Modules SC55bB and SC90bB.

These Modules dimensioned according to the rod diameter: • SC55bA fit for rods up to 8,0mm; • SC90bA fit for rods up to 14,0mm, are equipped by patented wiping devices that remove in succession the more adherent and dusty residues of scale. - Air blower in entrance, that removes the scale broken by the rod bending. - Static Press (patented). Interpenetrating blades driven by pneumatic cylinder push commercial steel

wool on the rod surface. The abrasive action - produced by the rod advance into the steel wool - is uniform and constant thanks to the continuous compensation of the steel wool wear.

- Rotary Press (patented). Functionally same type of press but rotating around the rod surface. In this case the clenching of the steel wool inside the interpenetrating blades is obtained by centrifugal force. The rotary action of the steel wool amplifies the cleaning effect marking the rod surface with helical micro-furrows that facilitate the lubricant pick-up.

SC90b - Static press SC90b - Rotary press

One or two Rotary Presses can follow the Static Press according to the characteristics of the rod processed. The rotation speed of the Rotary Presses follows the speed of the rod and can be set according to rod and drawing process characteristics. The decisive advantage of these wiping devices consists in the use of cheap consumable abrasives and their almost total exploitation.


Lisciani can supply its own abrasives packaged in standard sponges fit for the static and rotary wiping devices that gives excellent results both for life and rod surface cleaning.

SC55b - Lisciani abrasive into the Static press SC90b - Lisciani abrasive into the Rotary press

- Air blower in exit that that removes the residual and dustier particles completing the cleaning process. Two guide rolls (or four in the case of the Descalers SC90b) allow a perfect alignment of the rod with the wiping devices axis. Moreover these are transducer devices that detecting the passage of the rod allow the operation of the Rotary Presses and the setup of their speed without any connection the drawing machine electrical cabinet.

SC55b - Exit air blower in operation SC90b - Exit air blower

The scale collection and removal is by boxes that equips the Modules frame. It is possible the connection to external vacuum systems for the scale and dust removal.

Stage No.3: rod lubrication and first drawing step by Rotary Dieholder Modules SC55bC, FR4CSB and FR5CSB.

These Modules dimensioned according to the rod diameter: • SC55bC and FR4CSB fit for low carbon rods up to 8,0mm; • SC90bC and FR5CSB fit for low carbon rods up to 14,0mm, are equipped by a lubricant holder box and a Rotary Dieholder Lisciani (patented). The lubricant holder box presents: - lubricant applicator sheaves; - hand grip to lift the central lubricant applicator sheave for an easier rod threading; - lubricant feeding tank that allows a comfortable charge of the lubricant and an its proper distribution

inside the box; - openable bottom to discharge the lubricant into the removable box of the Module.


SC55b - Lubricant holder box and Die holder SC55b - Wire in exit after 1st drawing step

The combined action lubricant applicator sheaves - Rotary Dieholder (that can be equipped by Direct or Indirect cooling cartridges, for single or pressure dies) allows a perfect and wide regulation of the wire lubrication according to the following drawing process and to the final product characteristics. In the case of the Rotary Dieholder Modules FR4CSB and FR5CSB type the lubricant holder box is designed to be assembled directly on the bench of the drawing machine.

Several configurations available.

The Modules SC55b and SC90b are available in several configurations with different technical characteristics in order to make up complete or partial units specific for the production requirements of the User. To know Modules and relatives technical details please refer to our Catalogue.


Technical data of the Lisciani rod preparation. Please find two technical reports concerning low carbon rods - the first one SAE 1005, the second one SAE 1010 - prepared by the Lisciani Mechanical Descalers.

Low carbon rod for deep drawing.

Low carbon rod RIVA G3V5 type (SAE 1005) - Ø 5,5mm having the following characteristics:

C Mn Si Tensile strength

0,04 % 0,30 % 0,05 % 370 N/mm2

Rod used at Lisciani plant for the production - by dry drawing - of bright wires for bright and annealed wire products included in the range Ø 1,8mm - Ø 1,0mm.

Rod before descaling and cleaning.

- Scale thickness: 0,015mm (0,54% of the rod weight) - Scale chemical composition: Fe3O4

Fig.1

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Fig.2

Fig.3

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Fig.4

Rod after descaling and cleaning.

Fig.5

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Fig.6

Fig.7

In general the analyzed sample presents negligible residual scale with a maximum value of 0,0019mm in thickness - 0,07% of the rod weight, into the groves where the roughness of the interface metal-scale is accentuated (Fig.6 and Fig.7).

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Wire after lubricant application and first drawing step.

- First working die on the Mechanical Descaler: Ø 4,60mm / high pressure die - Life of the Ø 4,60mm die: over 200 Tons - Lubricant on first drawing step: calcium or calcium - sodium mix

Two sections A and B from the same wire sample:

Data A B

Wire diameter in exit (mm) 4,58 4,58

Residual lubricant (g/m2) 25,20 21,77

Residual lubricant (g/Ton) 2791,82 2413,10

The Cartridge that equips the Rotary Dieholder of the Descaler is very “flexible” because it is possible to regulate the wire surface lubrication through the length of the channel dies - spacers and through the dies diameter. In this specific case the High Pressure Die has been set to get a plentiful lubricant application.

Main data of the following drawing process.

Bright wire fit for black annealing:

Outlet wire 1,80 mm

Drawing steps 8

Inlet speed into the descaler 2,25 m/sec

Final speed on the spooler 21,0 m/sec

Average efficiency 80 %

Lubricant wear about 1,00 Kg / 1.000 Kg

Low carbon rod for nails production.

Low carbon rod B.M.Z. SAE 1010 type - Ø 5,5mm having the following characteristics:

C Mn Si Tensile strength

0,10 % 0,70 ÷ 0,90 % <= 0,10 % 400 N/mm2

Rod tested at Lisciani plant to produce - by dry drawing - bright wires for nails included in the range Ø 3,0 mm - Ø 2,5mm.

Rod before descaling and cleaning.

- Scale thickness: 0,03mm (about 1% of the rod weight)

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- Scale chemical composition: Fe3O4 - On the rod surface they are visible areas where the scale falls by the minimum bending. The rust,

even if high in some points, can be considered into allowable limits.

Fig.8

Fig.9

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Fig.10

Rod after descaling and cleaning.

Fig.11

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Fig.12

Fig.13

The analyzed sample presents negligible residual scale values, as usual found into the groves where the roughness of the interface metal-scale is accentuated (max. value not available). Maximum roughness 0,12mm.

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Wire after lubricant application and first drawing step.

- First die on the Mechanical Descaler SC55b: Ø 4,60mm / pressure die - Life of the Ø 4,60mm die: over 200 Tons - Lubricant on first drawing step: sodium or calcium - sodium mix

Two parts A and B from the same wire sample:

Data A B

Wire diameter in exit (mm) 4,58 4,58

Residual lubricant (g/m2) 2,54 2,86

Residual lubricant (g/Ton) 267,73 301,50

See previous notes about the Cartridge that equips the Rotary Dieholder of the Descaler.

Main data of the following drawing process.

Bright wire fit for nails production:

Min. outlet wire 2,50 mm

Drawing steps Up to 6

Inlet speed into the descaler 3 ÷ 4 m/sec

Final speed on the spooler about 15,0 m/sec

Average efficiency 80 %

Residual lubricant on final wire 0,4 ÷ 0,8 g/m2

Lubricant wear 1,00 ÷ 1,2 Kg / 1.000 Kg

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Advantages of the Lisciani rod preparation.

Main characteristics of the SC55b and SC90b design.

The main characteristics of the Lisciani Rod Mechanical Descalers SC55b and SC90b, designed for the most simple and effective rod preparation at lower operating costs, can be resumed as follows: - Modular design. - Efficient scale breaking by correctly dimensioned integral tungsten carbide bending rolls. - Efficient scale removal by a patented system that utilizes low cost commercial abrasives. - Efficient and simple lubricant pick-up - adequate also for following deep drawing processes - by

special lubricant-holder box and a patented Lisciani Rotary Dieholder. - Optional systems that collect the scale removed from the rod surface. - Low energy costs. - Easy-to-use and fast restoring operations. - Minimum maintenance.

Decisive reduction of the rod preparation costs.

Thanks to the above characteristics, the Lisciani Rod Mechanical Descalers SC55b and SC90b prepare the rod with a decisive reduction of costs as resumed in the following schedule:

Steel wool wear variable according to the abrasive used but ever

below 0,25 Euro/Ton (2)

Electric Power required below 10 Kw/h - 8 hours of operation (3)

Pressured Air Supply (6 bar) about 200 lt/min

Incidence of other factors as Maintenance, Scale Breaking Rolls wear, etc

Variable according to the production requirements, but ever below 0,50 Euro/Ton (4)

(2) Overestimated value (our production data is about 0,15 Euro/Ton). (3) Descalers equipped by the one static press plus two rotary presses. (4) Life of the integral tungsten carbide bending rolls above 15.000 Tons of rod.

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antaac jan. 2009 · 2019. 11. 16. · - 4 - antaac jan. 2009 the lisciani rod preparation system....

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