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Formability of Coating Material

Over a range of industries it is standard practice to coat sheet metal before it is formed to the final shape. This is a proven and widely used procedure to prevent corrosion during transportation and storage. There are well known examples where it would now be unthinkable not to use pre-coated sheet metal. The initial coating remains on the sheet material even after the parts have been formed to the final shape and becomes the base for subsequent coatings. It is thus a decisive factor for the quality of the finished product.


Over a range of industries it is standard practice to coat sheet metal before it is formed to the final shape. This is a proven and widely used procedure to prevent corrosion during transportation and storage. There are well known examples where it would now be unthinkable not to use pre-coated sheet metal. The initial coating remains on the sheet material even after the parts have been formed to the final shape and becomes the base for subsequent coatings. It is thus a decisive factor for the quality of the finished product.

The formability of this first coating depends on good adhesion as well as adequate elasticity. These properties can be tested in the laboratory and monitored alongside production under standardised conditions using ERICHSEN Sheet Metal Testing machines. The pioneer and inventor for this basic procedure, which remains the established test method worldwide, was AM Erichsen, founder of the Erichsen company.

Product Examples:

Lacquer and Paint Testing Machine, Model 200

The painted or otherwise coated sheet metal specimen is drawn into a die using a spherical nose punch, thus stretching the material until the coating cracks or peels off. The depth to which the material has been drawn by the punch when the coating fails is the measure of the quality of the paint or coating material and relates to the elongation and adhesive properties. This simple hand operated Testing Machine is particularly suitable for quality control on lacquers, paints, plastic coatings and enamels in smaller establishments.

Model 200 is used for the ERICHSEN CUPPING TEST in accordance with DIN ISO 1520, ISO 1520, BS 3900 : Part E4, NF T 30-019 und SIS 18 41 77 on coated sheet metal, with a tensile strength of 400 N/mm², up to 1.25 mm thick and from 70 - 90 mm wide.

 

Lacquer and Paint Testing Machine, Model 202 EM

This simple to operate Lacquer and Paint Testing Machine is used for rapid and accurate measurement of the elongation and adhesion properties of protective paints and other coatings of all types using the ERICHSEN CUPPING TEST in accordance with DIN EN ISO 1520, BS 3900 : Part E4, NF T 30-019, SIS 18 41 77 on sheet metal specimens up to 1.5 mm thick and max. 100 mm width. The ERICHSEN Cupping Test provides valuable information on the suitability of a coating material for application in practise. Low cupping test values mean that the coated product may not withstand elongation stresses arising, resulting in corrosion of the substrate. Model 202 EM is versatile and can be further enhanced by the various accessories available. The machine is a valuable tool for the quality control both for producers of paints and coating materials and for users .

Cupping and Deep-drawing Cup Test Machine, Model 242-Basic

When manufacturing deep-drawn products the ingoing material is deformed in all three coordinating planes. Thereby the surface coating should not become defect to avoid subsequent corrosion. For the standard controls and proofs required for the purposes of quality assurance Model 242-Basic is particularly suitable to conduct cupping and deep drawing cup tests within the sheet metal thickness range of 0.2 mm to 4.0 mm. To intensify the tests by further special investigations, it is possible to carry out without any problem a redraw (a second deep drawing operation conducted on the standard cup using a smaller drawing die and drawing punch). Furthermore the Bead Test Instrument, Model 227, can be used to form a bead into the cylindrical wall of a standard cup until a mechanic destruction of the coating is achieved. This is another possibility to intensify the test. The above mentioned sheet thickness range of 0.2 mm to 4.0 mm is based on material with a tensile strength of 400 N/mm². In case of a higher/lower tensile strength the values mentioned concerning the maximum sheet thickness that can be drawn, are to be reduced/increased.