How to Choose Sheet Metal

The Difference in Your Sheet Metal Choice…

Sheet metalWhen choosing the correct Carbon Steel sheet metal (Mild Steel) for your manufactured parts, there are several types to pick from and a few basic questions that need answered before choosing the correct material:
1. Will your parts be cut on a laser, plasma or punched?
2. Will your parts be painted?
3. Will your finished parts be an indoor or outdoor part?
All these are factors in choosing the correct sheet metal. Below are some of the common metals used at Metaltech Products, Inc. for fabricated products:

GALVANNEALED STEEL SHEET

Galvannealed sheet is carbon steel sheet coated with zinc on both sides using a continuous hot dip process. The zinc coating is harder than a regular galvanized coating and is more resistant to scratching and manufacturing damage. However, the harder coating is susceptible to powdering if the sheet is severely formed during fabrication.

Galvannealed sheet is specifically designed to be used in the painted condition. When painted with properly selected primers and or paints, the combined paint/galvannealed coating offers excellent resistance to peeling and/or blistering as well as improves corrosion resistance of the paint, compared with conventional galvanized sheet.

Use Galvannealed sheet when the part will be painted and used outdoors. Galvannealed sheet can be laser cut, punched, and formed with excellent results. The surface finish, adhesion, and paint quality is best with galvannealed material.

HOT ROLLED SHEET

Hot rolled sheets are produced at elevated temperatures on rolling mills and generate a material that is resistant to work hardening and exhibits reduced levels of deformation residual stress. Material rolled in the hot rolled condition can require more extensive leveling practices, such as temper passing or stretcher leveling downstream to eliminate coil memory. In addition, hot-rolling may leave surface imperfections such as scale or pits which require additional finishing for a smooth surface.

Use hot rolled steel (HRS) when cost is more important than surface finish. Hot rolled sheet should be punched instead of cut on the laser, as the mill scale affects the quality of the cut. Hot rolled sheet can be formed easily. If painted, any mill scale or pits will show through the paint, resulting in a rough finish.

HOT ROLLED PICKLED AND OILED (HRPO)

This is the same material as Hot Roll Sheet above but it goes through an additional process before it is uncoiled flattened and sheared to specific lengths. The Hot Roll material is uncoiled and ran through a pickling chemical bath that removes all the oxides from the surfaces. Then it is oiled to prevent rusting and recoiled.

Use hot rolled pickled and oiled sheet for a product that will be painted, but used primarily indoors. HRPO sheet is also used as a cost saving alternative to galvannealed. HRPO sheet can be laser cut, punched, and formed with excellent results. The painted surface is typically very good with HRPO.

COLD ROLLED SHEET

Cold rolling is used to further treat hot rolled steel sheet to increase its strength and its strength-to-weight ratio and enable it to hold tighter tolerances during fabricating and machining. The grain structure of hot rolled sheet is compressed during the cold rolling process, which results in a stiffer material, smooth surface, and more consistent metal thickness.

Use cold rolled sheet (CRS) to get better material strength with a good surface finish. Parts made from cold rolled sheet must be painted or otherwise protected immediately to prevent surface rust. Cold rolled sheet can be laser cut, punched, and formed with excellent results. The surface finish of painted parts is usually very good with CRS.

This is only a few of the materials used at Metaltech Products Inc. For more information about selecting or processing carbon steel, stainless steel, copper, and aluminum, contact us at: (417) 426-5577, or email us at: sales@metaltechproductsinc.com. You may also visit our website at: www.MetaltechProductsInc.com.

-Metal descriptions are from O’Neal Metals web page.