One of the most common metal forming operations is stretching; this is where the sheet metal is manipulated and curved to create interesting shapes for a number of different structural components. There are a number machines and tools used to stretch sheet metal.
What Tools Are Used to Stretch Metal?
Alongside metal bending machines, there are three main types of tools that are used to effectively and efficiently produce the desired shapes.
Mainly used to form compound curves, English wheels consist of two wheels of which the sheet metal is placed in between. Pressure increases as the two wheels are tightened; as the sheet is moved back and forth, it slowly stretches into the required shape. This tool is well-known for its precision and versatility as it can form curves of various thickness with extreme accuracy.
Shrinkers & Stretchers
Shrinkers and stretchers are essential items for metal fabrication and usually purchased together. Stretchers are understandably tools used for stretching; it is a mechanically operated tool which features serrated jaws. The sheet metal is placed in between these jaws and, when the control lever is pressed, they pull the metal in opposite directions consequently stretching it.
One of the most basic ways to stretch sheet metal is by using planishing hammers. Ultimately, the sheet metal is firmly placed on a hard surface and is beaten using the planishing hammer, forcing the metal to compress and stretch. Only low pressure is required when hitting the metal as the hammers provide complete control; these tools can also be used flatten and smooth metal after it is formed.
Additional Tips to Stretch Metal
Although these are the main types of tool that are used to stretch metal, they can be used in conjunction with other tools to produce quality results. There is no one tool that is the best, you need to find the one that is right for you and your application, so play around and see which one suits you.
Remember: Always use the right die size when using any of these tools as these can affect the end-product. Tailor the die size to the physical properties of the sheet metal to achieve the best results.