Electrostatic Waxer for Metal Sheet

Electrostatic Waxer for Metal Sheet

    I. Introduction

After exterior and interior coating of metal sheets/ coiled materials, a layer of wax needs to be sprayed as lubricant to avoid damage during in subsequent processing like stretching and bending. The electrostatic waxer is especially designed for this working procedure.

Compared with traditional waxers, the electrostatic waxer has the following prominent advantages.

1.   Excellent Coating Uniformity

 (1) Traditional waxers: Pulverize melted wax via nozzle using compressed air and spray it directly on metal surface, which results in inevitable uneven wax layer.

A. Wax mist is sprayed on metal surface via the nozzle in a circle or oval. When metal sheets/coil materials go through mist area and area B, more wax than that of area A will be attached, resulting in unevenness. 

B. To spray on a big area of metal surface, a group of nozzles is required. To ensure wax cover on metal surface, the spraying areas of each nozzle must have partial overlap with those of neighboring nozzles. Therefore, the overlapped sections will have two times of wax attachment compared with that of non-overlapped areas.

             Due to this design defect, customers using traditional waxers have been unsatisfied with the uniformity of wax coating.

           C. Traditional waxers use universal nozzles to generate wax mist of a diameter of about 30 microns and cannot avoid big wax drops, therefore the wax coating on material surface is very thick and separated wax grains and many big wax drops with a poor sectional uniformity. 

(2) Electrostatic Waxer

A. With a completely different working principle from that of traditionalers, the electrostatic waxer first pulverizes melted wax and distributes the wax mist in a coating box evenly and makes the wax mist have negative charge. When metal sheets/coil materials with zero potential pass the coating box, wax mist with negative charge is absorbed on the sheets/ materials. Areas with higher potential have faster wax mist aggregation, which means areas with thinner wax coating have higher potential and adsorb more wax mist and on the contrary less wax mist is adsorbed. Finally, wax mist will be attached evenly on the surface of metal sheets/coil materials, solving the problem of uneven wax coating.

B. The electrostatic waxer adopts ultrafine pulverizing nozzles. The diameter of wax grains is only 1~8 microns. Wax mist entering the working area is very refined after grade 1 sedimentation and grade 1 separation. Wax mist attached on material surface is like a thin layer of condensed mist of expiration on glass in winter with a very high uniformity and the grain state is invisible. 

2.   Little Wax Pollution

A. Traditional waxers use compressed air to pulverize melted wax via nozzles and spray on metal surface. During pulverization some big-diameter wax drops are generated and are more easily adsorbed on the surface of sheets/coil materials compared with small-diameter ones, resulting in wax pollution. Meanwhile, collected wax around nozzles drop on materials, brining more serious pollution. Wax shortage for sheet/coil materials and wax drop pollution is unavoidable due to nozzle blockage. 

B. During wax pulverization of the electrostatic waxer, wax mist is not allowed to enter the coating box directly. Large-diameter wax drops are obstructed from the coating box through grade 1 sedimentation and grade 1 separation, while those entering the coating box are of a diameter of 1~8 microns. Meanwhile, the pulverizing nozzle module stays in heating state and is separated from the coating box, and no residual wax at the nozzle will drop on sheets and there will be no wax shortage due to nozzle blockage.

3.   High Spraying Thickness (Wax Quantity)

As the electrostatic waxer introduces high-tension electrostatic charge on wax mist to generate very high absorbability to metal sheets/coil materials with zero potential. Even regulating variable of wax coating in large area can be easily obtained through adjusting wax feeding, which is difficult to realize on traditional waxers using compulsive spraying. 

4.   High Production Rate

As the introduction of high-tension electrostatic charge on wax mist for high absorbability for metal sheets with zero potential, the electrostatic waxer can spray a wax layer of enough thickness on metal sheet in very short time, which means that metal sheets can pass the at a very high speed while guaranteeing quality wax coating to ensure high-speed production of the whole production line. In comparison, traditional waxers depend on wax mist grains and sheet adhesion. Therefore, to ensure coating thickness, sheets must stay in mist area for an enough period, being difficult to realize high production speed.

5.   Reducing Pollution to Improve Working Environment and Save Wax

  The specially designed recovery system of the electrostatic waxer recovers residual wax mist to reduce pollution as much as possible and to provide better working environment for operators. Meanwhile, recovered wax can be reused.

II. Scope of Application

  The product is suitable for the wax coating of all metal sheets/coil materials

III. Equipment Parameters

 i. Sheets

1. Maximum suitable sheet width: 42”(1,067mm) (electrostatic waxers of bigger dimensions are customizable.)

 (The maximum suitable sheet width of existing electrostatic waxers: 1250mm)

2. Production rate: 9-90 m/min (higher speeds are customizable.) 

 (The highest production rate of existing electrostatic waxers: 110 m/min)

3. Wax coating thickness: 40~100mg/m² (related to the operation speed)

 (The largest wax coating thickness of existing electrostatic waxers: 130mg/m²)

4. Suitable material thickness: 0.13~0.76mm

5. Equipment dimensions: 

Length ~2,400mm

 Width ~2,060mm

Height ~1,400mm-Operation mode; 1,800mm-Non-operation mode with uncovered coating box.

ii. Coil Materials

1. The maximum suitable coil material thickness: 42”(1,067mm) (electrostatic waxers of bigger dimensions are customizable)

(The maximum suitable coil material width of existing electrostatic waxers: 1,600mm)

2. Production rate: 70 m/min （the highest production rate is customizable）

 (The highest production rate of existing electrostatic waxers: 70 m/min. A waxer for coil materials of 110m/min will be designed and manufactured for a customer from southwest China)

3. Wax coating thickness: 40~100mg/m² (related to the operation speed)

 (The largest wax coating thickness of existing electrostatic waxers: 100mg/m²)

4. Suitable material thickness: 0.13-0.76mm

5. Suitable material thickness:    

Length ~2,400mm

Width ~1,800mm

Height ~1,400mm- Operation mode; 1,800mm-Non-operation mode with uncovered coating box.