The Sheet metal material selection during product design impact the sheet metal part design, manufacturing process, cost, and part performance. In this article, we will discuss sheet metal materials, their advantages, and their limitations. We can divide the Sheet metal material selection into the following two sections.
- Selection of Sheet Thickness
- Type of Material
Factors affecting Sheet Metal Material Selection
Sheet metal material selection is an iterative process. After the material selection, it should be validated and tested according to the product design requirements.
Various types of materials are available on earth. Each material has its advantages, limitations, and applications. Product functional & aesthetic requirements and cost have an impact on the selection of a sheet metal material. You should consider the following factors during the selection of sheet metal thickness and type of material.
- Various external forces acting on the sheet metal part during its complete lifecycle.
- Weight constraints.
- Cost constraints.
- Corrosion resistance requirements.
- Assembly Process.
- Availability of material.
Material Selection Example 1
For example, if you select a 1 mm thick CRCA sheet for an application. After material selection, you should do structural design calculations and structural simulation to validate the material. You can consider the material if the validation results are within acceptable limits.
But if the part weight is not within the acceptable limit. The next step is to find an alternative material with a high weight to strength ratio ( aluminum, stainless steel, titanium, etc.). Afterward, you should perform the validation testing on newly selected material.
You can select the material if validation test results and the cost of the material are within acceptable limits.
Material Selection Example 2
For example, if you select CRCA material. But during validation testing, the product fails in the salt spray test. You can select another material with high corrosion resistance (aluminum, GI, Aluzinc, or steel) or change the surface finish.
Sheet Metal Material Thickness Selection
Sheet metal materials are available in standard sheet thickness. Enclosure sheet thickness depends on selected material properties, product size, weight constraints, and various loads acting on the product. You can perform Structural simulations and manual calculations to find the required sheet thickness.
Since the type of sheet metal material has an impact on material sheet thickness. Selection of sheet-metal material and sheet thickness go in parallel.
Sheet Metal Material Selection
Various sheet metal material grades are available in the market. Product functional requirements and material physical and mechanical properties have an impact on the Material selection. Type of rolling operation (hot rolling or cold rolling operation) also impacts sheet metal material properties. Following are some of the commonly used sheet metal materials in the industry.
- CRCA
- GI
- Aluzinc Steel
- Aluminium
- Stainless Steel
CRCA (Cold Rolled Close Annealed Steel)
CRCA is the cheapest available sheet metal material in the market. It is highly prone to corrosion. After annealing, oil is applied to the CRCA sheets to improve the corrosion resistance for a short duration (2 to 3 weeks).
According to IS 513 (2008) following CRCA grades are available in the market.
Advantages of CRCA Material
Using CRCA material in sheet metal parts has the following advantages.
- Superior surface quality.
- Good strength.
- Excellent weldability and dimensional accuracy.
- Low cost.
- Deep-drawn and Extra deep-drawn grades are also available.
Limitations Of CRCA Material
Using CRCA material in sheet metal parts has the following limitations.
- Highly prone to corrosion.
- The final finish cost to prevent a part from corrosion is high.
- High weight.
Galvanized Iron (GI) Steel
GI sheets are Zinc coated CRCA sheets. Zn coating improves corrosion resistance. GI sheets are available in ordinary (O), drawing (D), deep drawing (DD), extra deep drawing (EDD) grades.
Galvanized steel is available in various zinc plating thicknesses. For example, 120gsm, 200gsm, 300gsm, or 600gsm sheets. 200gsm stands for 200-gram zinc coating in one square meter area. GI sheet grades are available as per IS 277:2003 standard.
Advantages Of Galvanized Iron Sheets
Using GI steel in sheet metal parts has the following advantages.
- Superior surface quality.
- Good Strength.
- Excellent dimensional accuracy.
- Deep drawn and extra deep drawn grades are also available.
- Better corrosion resistance compared to CRCA steel.
Limitations of GI Sheets
GI steel sheet metal parts have the following limitations.
- Not recommended in products where parts are joined using welding operation.
- High weight.
- Higher material cost compared to CRCA.
Aluzinc Steel
Aluzinc steel sheets are aluminum and zinc-coated CRCA steel sheets to improve corrosion resistance. Its microstructure consists of approximately 80% aluminum and 20% zinc‐rich phase with a thin inter-metallic layer.
Aluminum in the aluzinc-coating provides an additional aluminum barrier. Whereas zinc provides sacrificial protection against corrosion at cut edges.
Advantages of Aluzinc Steel Sheets
Alizinc steel has the following advantages.
- High corrosion resistance and strength.
- Superior surface quality and excellent dimensional accuracy.
- Deep drawn and extra deep drawn grades are also available.
Limitations of Aluzinc Steel Sheets
Alizinc steel has the following limitations.
- Welding is not recommended on Aluzinc sheets.
- High Weight.
- Higher cost compared to CRCA and GI sheets.
Aluminium
Aluminum is the second most widely used metal in the world. It is available in various grades. Following aluminum grades are extensively used in the sheet metal industry.
- 5052-H32: Good formability, commonly used sheet grade
- 5052-H34: Fair formability, excellent corrosion resistance & welding characteristics
- 1050-H14: Good weldability
- Al-6061
- 5251-H22: Applications in marine environments.
Advantages of Aluminium Sheets
Aluminum material has the following advantages.
- Low weight.
- High weight to strength ratio.
- Excellent corrosion resistance.
- Good thermal and electrical conductivity.
- Recyclable.
Limitations of Aluminum Sheets
Aluminum material in sheet metal parts has the following limitations.
- The high cost ( 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. Following are the commonly used stainless steel grades in the sheet metal industry.
- SS-304
- SS-304-L
- SS-304-H
- SS-316
Advantages of Stainless Steel
Stainless steel has the following advantages.
- Excellent corrosion resistance.
- Ease of fabrication.
- Food grades are available.
- Good weldability.
Limitations of stainless Steel Sheets
Stainless steel has the following limitations.
- The high cost.
- Limited finish options are available.
Summery of Sheet Metal Material Properties
To sum up, a variety of sheet metal material grades are available. Depending on product functional requirements and cost constraints, the material is finalized. Click this link to know various sheet metal design guidelines.
We will keep updating details on sheet metal materials. Add your comments or questions on sheet metal material selection in the comment box.
Good article that give out an useful information.Thanks a lot!