Sheet Metal Cutting
Cutting processes within sheet metal fabrication causes the stock to fail or separate – this allows for sheet material to be cut or removed.
Cutting processes can be further divided into:
- Cutting with Shear
- Cutting without Shear
Cutting with Shear
Within fabrication, most cutting processes are achieved by applying a shearing force to the sheet metal material, allowing for a cut to be made.
Shearing force is applied by two tools – one from above and one from below – reaching the material’s ultimate shear strength, which causes the material to fail and cut to be made.
Processes that applies shearing force includes:
Cutting without Shear
Cutting processes in this category do not use shear force, but instead applies forces such as abrasion or thermal energy to form a cut. Some of the common cutting processes here range to include:
- This process entails straight line cuts to separate a piece of sheet metal and is most commonly used to cut sheet stock into smaller sizes for use in other sheet metal fabrication processes.
Used to cut blanks for use in other processes, blanking is capable of cutting out parts in various two-dimensional shapes.
- Conventional Blanking – Using a blanking press, sheet metal stock, blanking punch and blanking die, this method involves the stock to be over the die, which has a cutout of the desired shape, in the blanking press. A hydraulic press now, at a high speed, pushes the blanking punch downwards causing the metal to bend and fracture.
- Fine Blanking – A more specialized method, this process entails the use of three separate forces. A downward holding force (applied to the top of the sheet), a cushion that provides a counterforce (underneath the sheet directly under the punch) and the blanking punch (which impacts the sheet). This method is capable of creating tight tolerances, better flatness and smoother edges with minimal burrs.
- Here, the material being removed from the sheet metal is the scrap (also referred to as the slug), laving behind the desired feature in the sheet. Typically punching involves the use of cylindrical punch tool responsible for piercing the sheet and forming a single hole. Punching can be done by manual press punches or by using CNC punch presses, which can be pneumatically, hydraulically or electrically powered.
- Do not however that punching is capable of creating a number of different features using various operations. Some of these punching operations include cutoff, dinking, slitting, piercing, trimming, nibbling, slotting, shaving, lancing, perforating and notching, to name but a few examples.
- Laser Cutting
- Water Jet Cutting
- Plasma Cutting
- Used to cut blanks for use in other processes, blanking is capable of cutting out parts in various two-dimensional shapes.