In-Line Annealing Process
In today’s highly competitive market, wire manufacturers ask their suppliers to increase their product quality and production reliability, while at the same time reduce production
costs and scrap rate. For suppliers, the ability to offer high-quality lines for the wire and strand market represents a huge competitive advantage. That is why the Italian company, Sampsistemi,
strongly believes in investing in R&D and focusing product development mainly on two key points:
1. The development of new products.
2. The continuous improvement of existing machinery.
Considering the downstream process from rod to fine wire, be it single or multi-wire production, the in-line annealing process is as important as the wire drawing process itself, because it must ensure the required mechanical and electrical properties (elongation, mechanical strength and conductivity), maintain the wire diameter and roundness defined by the final die, and for metal-plated wires, ensure the integrity of the wire coated surface.
Sampsistemi’s annealing product portfolio is based on three different platforms: AH platform for rod breakdown lines, AN platform for multi-wire lines and AI platform for single wire lines, the last one being completed by annealers integrated with drawing machines into a single frame (MT220/250RC).
These platforms, while referring to different production ranges, are characterized by common technical, technological and commercial features such as:
• Suitability for copper, including FHRC and plated copper, copper alloys, aluminum and relevant alloys;
• Reliability of the DC annealing architecture;
• Availability of both multi-motor technology for all axes, or traditional single-motor and flat belt transmission technology;
• Availability of both L to R and R to L versions, including the application in tandem with extrusion lines;
• Availability of RBD annealers with vertical wire path when low footprint is required.
Over the last few years, Sampsistemi has witnessed a change in the demand for multi-wire drawing machines. In particular, the number of requested wires has increased, the outlet diameter of each wire has become smaller for flexible and conductor class 5 to 6, bigger for stranded circular conductor class 2, and the requested production speed has increased. Sampsistemi’s Multiwire Drawing Line Platform comprises three different product segments (Ultrafine, Flexibility and Heavy-Duty), designed to meet customer requirements depending on their final application (automotive, building wire including regular strand, white/brown goods, electronic wire, etc.), and can be best summarized as follows:
• Number of wires: from 8 to 56. Up to 32 wires, machines are considered standard;
• Inlet wire diameter range of 1.0 to 2.6 mm;
• Final wire diameter range of 0.05 to 1.35 mm;
• Materials: copper (bare and plated), copper alloys, aluminum, aluminum alloys.
To satisfy these technological requirements and customers’ needs in terms of outlet wire diameter range and production capabilities, the Sampsistemi’s multi-wire annealing platform includes a wide range of annealers which can be summarized with the following table:
|Product Segment||Annealer||Contact Rings Ø||Max. Annealing Current||Outlet Ø range||Multimotor Version|
|Heavy Duty||AN 350||350||7000||0.25 ¸ 1.35||—|
|AN 300||300||6000||0.25 ¸ 1.05||Y|
|AN 250||250||5200||0.18 ¸ 1.05||Y|
|AN 200||200||3500||0.15 ¸ 1.05||Y|
|Flexibility||AN 160||160||2000||0.10 – 0.51||Y|
|AN 135||135||1000||0.08 – 0.32||Y|
|Ultrafine||AN 120||120||700||0.05 – 0.20||—|
A Joule effect annealer for in-line annealing of copper and aluminum wire, both connected to a rod breakdown or a multi-wire drawing machine, can be divided into four zones: preheating, annealing, cooling and drying.
The wire path, preheating and annealing length, which design all subsystem elements in contact with the wires, influence the final characteristics of the wire. Therefore, all subsystem elements must be designed considering also an easy string-up process and quick ordinary maintenance operations, such as cleaning, replacement of brushes and contact rings.
This approach has been consolidated over the years, thanks to the experience gained with over 500 installed and operating Sampsistemi multi-wire lines, and has led to the development of several technical features of the utmost importance such as axis electrical insulation system, adjustable pre-heating length, wire walker before contact rings, cleaning device on contact rings, axis and contact ring cooling systems with closed-loop circuit, improved wire cooling and drying system.
For processing aluminium wires, a special design of preheating path including its inertization to avoid wire surface oxidation, has been developed.
The electrical annealing equipment design and construction have a strong impact on the quality of the final annealed wire. In particular, high energy efficiency is required, with stable annealing current and voltage, low ripple and stable annealing quality during ramps, annealing at zero speed to avoid that the wire is over/under annealed during reel change operations.
The design of cooling circuits is also important to guarantee their efficiency. The AN Platform is rounded out by the Annealing Control Equipment, available in two different technologies, traditional and electronic. The Electronic Annealing Equipment, characterized by low current distortion THD-I, represents an important development by Sampsistemi, since it meets the high-quality standards necessary in the production wire and the requested cost reduction in manufacturing as well as the energy efficiency required by our customers today.
The control system of the line is able to set up production parameters including the kinematic parameters for the multi-motor annealer, and to form a production recipe stored in the HMI panel.