5 Axis CNC Finishing Processes / /
After CNC machining, a part may need to be finished by utilizing various finishing processes. Finishing a part may include powder coating, assembly, drilling, polishing or EDM. Some of the finishing processes offered by Fathom include:
After powder coating, the part has a thin protective layer that adds strength and wear resistance. During the powder coating process, the part is first primed using a chromating or phosphating coat. Next, the part receives a dry powder coating from an electrostatic spray gun. Lastly, the part is cured in an oven.
Assembly is required when the unit manufactured is part of a larger piece. During the assembly step, the workpiece is bonded together with other parts to create the final product. Fasteners or bonding procedures may be used to fuse the parts temporarily or permanently.
Drilling is used to add a round hole to a part. Drilling may be performed using a drill press, tapping, or milling machine. Different types of drills may be used, such as spotting or peck drills, depending on the mark that must be made.
Gear cutting is used to make gears. Broaching, milling, hobbing, grinding, and shaping are some of the methods used in gear cutting. Gears may be made of metal, wood or plastic.
Jig grinding adds complex geometrical shapes onto parts. The process uses a jig grinder to grind complex shapes and holes with a high level of accuracy. Grinding removes a thin layer of material from the workpiece. During grinding, the workpiece is pressed against a rotating abrasive wheel that removes a thin layer.
EDM is often used when sharp corners or curves are needed that cannot be formed using conventional manufacturing processes. Often, a part is made first using CNC machining and then special features are added using EDM. Electrical discharge machining uses electrical discharges to subtract material from a workpiece.
The polishing technique can improve the dimensions and accuracy of a part while producing a mirror gloss finish. Polishing tools and abrasive materials are used to achieve a smooth surface.
When two metal pieces must be joined together, arc welding may be used. Arc welding uses the power from an electric current to fuse two pieces of metal. Generally, direct current arc welding is preferred as DC uses electrons that move in a single direction, resulting in a stable arc.
Laser welding joins metal or thermoplastic parts together. During laser welding, a laser beam applies heat that melts both pieces’ material to form a joint. As the heat is concentrated to a specific area, the surrounding material is not damaged and there is minimal stress on the part.
Oxyfuel Welding & Cutting
Oxyfuel welding and cutting are often used to reduce the thickness of a metal piece. Commonly used on steel, oxyfuel welding and cutting use a torch with a mix of fuel and oxygen. The workpiece is first pre-heated to its kindling temperature, then pierced and cut by an oxygen stream.
Deburring is used to remove any raised edges or unwanted material known as burrs. Deburring may be achieved using several methods, including electrochemical deburring, thermal deburring, and abrasive flow deburring. Electrochemical deburring uses an anodic metal dissolution to remove unwanted material. Thermal deburring uses a combustible gas in a pressurized chamber to deburr a part. Abrasive deburring uses an abrasive slurry to deburr the part.