Roughing and finishing in CNC machining

Roughing and finishing are two key steps in machining that play different but equally important roles.

Definition and Role of Roughing: The main purpose of roughing is to quickly remove a large amount of material to bring the workpiece close to its final shape. With large feed rates and depths of cut, roughing removes excess material in the shortest possible time, setting the stage for subsequent finishing operations. Roughing is typically used in the initial stages of CNC machining, with the goal of reducing machining time and costs while extending tool life and identifying defects in the workpiece more quickly.

Benefits of Roughing

Roughing in machining reduces production time and costs, extends tool life, and easily detects blank defects, making it an integral part of the Manufacturing Process.

Saves time: Roughing is the rapid removal of large amounts of material, thereby reducing the time required for machining. This means the machining process can be completed faster and parts can be produced at a faster rate.

Cost Savings: It can help save money by completing the roughing process in one setup, eliminating the need for additional setups on finishing machines.

Material Savings: Roughing can reduce the volume of material that needs to be extracted in the finishing grade by up to 50%. This saves a significant amount of material and reduces total cost and shipping weight.

Extended tool life: By removing large volumes of material in the roughing stage, cutting tool wear is minimized. This results in less frequent tool changes and reduced tool-related costs.

Easily Identify Blanking Defects: If a machine operator sends a roughly machined part to the finishing process, any defects present in the product, such as air or sand holes, will be quickly seen and identified by the operator. Once material is removed from a specific part of the component, defects or cracks become more visible.

Benefits of Finishing

Improved surface quality: Finishing achieves a smooth surface, reducing friction and wear and improving the durability of the part.

Enhanced corrosion resistance: Finished surfaces are smoother, resulting in improved corrosion resistance.

Aesthetics: Finished parts are not only functional but also smooth and aesthetically pleasing in appearance, meeting demanding product standards.

The difference between roughing and finishing

Expected results: Roughing is designed to remove material quickly while finishing is designed to achieve a precise surface finish.

Tool selection: Roughing tools focus on strength and durability while finishing tools are finer and focus on surface finish.

Feed rates and spindle speeds: Roughing involves higher feed rates while finishing requires lower feed rates and higher spindle speeds.

Material Removal Rate: Roughing removes material faster while finishing is slower but more precise.

Surface finish: Roughing produces a rougher surface while finishing achieves a highly polished surface.

To summarize, roughing and finishing are two integral parts of the manufacturing process. Roughing focuses on rapid material removal while finishing aims to improve surface quality and accuracy. In practice, choosing between these two process steps can dramatically increase productivity, reduce costs, and ensure that product quality meets expected standards.