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Sheet Metal Material Selection
Sheet metal material selection process is a crucial part of product design. It affects part design, cost, manufacturing process and part performance. In this article we will discuss sheet metal materials their advantages and limitations.
Sheet metal material selection process can be divided into two parts.
Selection of Sheet Thickness
Type of Material
Following Factors affect the selection of sheet thickness and type of material.
Required Product Strength
Weight Constraints
Cost Constraints
Required Corrosion Resistance
Assembly Process
Material Availability
Sheet Thickness
Sheet metal materials are available in standard sheet thickness. Enclosure sheet thickness depends on product size, weight and loads acting on it. Structural simulation is performed to calculate required sheet thickness.
Sheet Metal Material
Various sheet metal material grades are available in the market. Sheets are manufactured using hot rolling or cold rolling operation. Type of rolling operation also affect sheet metal properties Material selection is done based on product requirements. This article covers commonly used sheet metal materials.
CRCA (Cold Rolled Close Annealed Steel)
CRCA is cheapest available sheet metal material. It is highly prone to corrosion. After annealing oil is applied on CRCA sheet to improve corrosion resistance for short duration (2 to 3 weeks).
As per IS 513 (2008) various CRCA grades are given below.
Advantages of CRCA Material
Superior Surface Quality
Good Strength
Excellent Weld-ability and Dimensional accuracy
Low Cost
Deep Drawn and Extra deep drawn grades are also available
Limitations of CRCA Material
Highly prone to corrosion
Final finish cost is high
High weight
Galvanized Iron (GI) Steel
GI sheets are Zinc coated CRCA sheets. Zn coating improves the corrosion resistance. GI sheets are available in ordinary (O), drawing (D), deep drawing (DD), and extra deep drawing (EDD) grades.
Galvanized steel are available in various zinc plating thickness. For example 120gsm, 200gsm, 300gsm or 600gsm sheets. 200gsm stands for 200 gram zinc coating in one square meter area. GI sheets are available as per IS 277:2003 standard.
Advantages of Galvanized Iron Sheets
Superior Surface Quality
Good Strength
Excellent Dimensional accuracy
Deep Drawn and Extra deep drawn grades are also available
Better corrosion resistance compared to CRCA sheets.
Limitations of GI Sheets
Not recommended if welding is used as assembly operation.
High Weight
Higher cost compared to CRCA sheets
Aluzinc Steel
Aluzinc is Aluminium and Zinc coated steel sheets. AlZn coating improves corrosion resistance. Its micro-structure consists of approx. 80 % aluminium and 20 % zinc‐rich phase with a thin inter-metallic layer.
Aluminium in Aluzinc coating provides additional aluminium barrier. Whereas zinc‐provides sacrificial protection against corrosion at cut edges.
Advantages of Aluzinc Steel Sheets
High Corrosion resistance and Strength
Superior Surface Quality and Excellent Dimensional accuracy
Deep Drawn and Extra deep drawn grades are also available
Limitations of GI Sheets
Welding is not recommended on Aluzinc sheets
High Weight
Higher cost compared to CRCA and GI sheets
Aluminium
Aluminium is second most widely used metal in the world. It is available in various grades.
Commonly used Aluminium grades is sheet metal industry.
5052-H32 : Good Formability, commonly used sheet grade
5052-H34 : Fair Formability, excellent corrosion resistance & Welding characteristics
1050-H14 : Good Weldability
6061
5251-H22 : Applications in marine environments
Advantages of Aluminium Sheets
Low Weight
High weight to Strength ratio
Excellent corrosion resistance
Good Thermal and Electrical Conductivity
Recyclable
Limitations of Aluminium Sheets
Aluminium is three times costlier than CRCA
Weldability is not good
Stainless Steel Sheets (SS)
SS is a corrosion resistant alloy steel containing more than 10.5% chromium. Stainless steel offers good corrosion resistance due to naturally occurring chromium-rich oxide film formed on the surface of the steel.
Commonly used stainless steel grades in sheet metal industry:
SS-304
SS-304-L
SS-304-H
SS-316
Advantages of Stainless Steel
Excellent corrosion resistance
Ease of fabrication
Food grades are available
Good Weldability
Limitations of stainless Steel Sheets
High Cost
Limited finish options are available
