There is the way to ensure the quality of CNC machined brass and copper parts：

l Design for Manufacturability: Design the parts with manufacturability in mind, considering factors such as material properties, machining limitations, and assembly requirements.

l Process Planning: Develop a detailed process plan that outlines the specific machining operations, cutting parameters, tooling, and fixturing requirements.

l Quality Control: Implement a robust quality control system, including in-process inspections and final part inspections, to ensure that the machined parts meet the specified tolerances and surface finish requirements.

l Regular Maintenance: Maintain the CNC machine and tooling in good condition to ensure optimal performance and minimize the risk of errors.

l Operator Training: Provide adequate training to machine operators to ensure that they understand the machining process, can operate the CNC machine effectively, and can identify and resolve potential problems.