CNC Machining

1. Strategic Selection of CNC Equipment

Choosing the right machine is the foundation of economic production. At Ever Power, we categorize machine selection into two scenarios: selecting a machine based on existing part drawings, or selecting appropriate workpieces for an existing fleet of CNC machines. Regardless of the direction, our selection criteria hinge on three primary pillars:

• Technical Compliance: Ensuring the machine's accuracy and envelope can handle the part's geometry and tolerance requirements.
• Productivity Optimization: Selecting machines with rapid tool change times and high-speed spindles for volume production.
• Cost Management: Minimizing the “cost-per-part” by matching the part complexity to the machine's axis capabilities.

2. Enhancing Part Processability for CNC Efficiency

Processability analysis bridges the gap between design intent and manufacturing reality. We focus on two critical dimensions: the convenience of programming and the physical possibility of machining.

Dimensional Logic in Programming

To reduce cumulative errors, drawings should utilize a unified datum. Traditional scattered dimensioning often ignores assembly characteristics, leading to coordination issues. CNC machining thrives on coordinate-based dimensions, which align design, process, and inspection datums seamlessly with the programming origin.

Geometric Integrity

A frequent hurdle in automated programming is “insufficient geometric definition.” If a line and an arc are meant to be tangential but the provided coordinates result in an intersection or gap, manual intervention becomes necessary. Ensuring consistent internal radii (cavity corners) allows for fewer tool changes and prevents localized stress concentrations.

3. Determining Machining Schemes and Precision Grades

The selection of machining methods must guarantee the surface finish and tolerance specified. For instance, high-precision holes are often classified under IT7 precision grades. While boring, reaming, and grinding can all achieve IT7, the choice depends on the material and part size.

Boring vs. Reaming: For standard industrial gearboxes or housings, reaming is preferred for smaller IT7 holes, whereas larger diameters or those requiring high positional accuracy demand boring. Precision is a tiered process: an IT7 hole typically evolves from Drilling → Expanding → Rough Reaming → Fine Reaming.

4. Logical Division of Processes and Steps

To maximize the rigidity of the setup and the accuracy of the finished part, Ever Power follows a strict hierarchy of operations:

Sequence Logic

1. Roughing to Finishing: Always complete heavy material removal before moving to semi-finishing and final precision passes.
2. Face Milling Before Boring: On parts requiring both face milling and boring, mill the faces first. This provides a stable surface for the boring tool to enter, reducing deflection and vibration.
3. Tool-Based Steps: In high-speed machining centers, grouping steps by tool usage often proves more efficient than grouping by surface, as tool changes can be slower than table rotations.

5. Advanced Tooling Technology and Cutting Data

Modern CNC machining demands high rigidity, durability, and stable dimensions. We utilize the TSG Tool System, featuring both straight and tapered shanks across 16 specialized tool types. Selecting the correct cutter material is paramount:

• Carbide Inserts: Preferred for milling high-strength stainless steel (SUS304/316) to resist work-hardening.
• HSS (High-Speed Steel) End Mills: Ideal for machining complex profiles or internal slots in softer alloys.
• Ball-Head & Ring Cutters: Essential for curved 3D surfaces. When machining flatter curved regions, ring cutters offer superior efficiency compared to ball-head mills.

Cutting Parameters: Determining the Spindle Speed (RPM), Feed Rate, and Depth of Cut (Back Engagement) is a balance of productivity and cost. For roughing, we prioritize high material removal rates; for finishing, we prioritize surface integrity and dimensional stability.

6. Precision Control: Tool Setting and Change Points

The “Tool Setting Point” (Program Start) is where the digital world meets the physical material. At Ever Power, we recommend aligning the tool setting point with the part's design datum to minimize calculation errors. For batch production, repeatability is key—we verify this by measuring the coordinate distance from the machine origin.

Safety First: Tool change points must be set outside the work envelope to prevent collisions with the fixture or the part. This is particularly crucial on 5-axis machines where rotational movements can be unpredictable.

7. Optimizing the Machining Path

The tool path dictates the surface finish. To avoid visible tool marks and scratches:

• Tangential Lead-in/Lead-out: When milling external profiles, always enter and exit the material along the tangential extension of the curve. Direct normal entry causes localized pressure spikes and visible “witness marks.”
• Internal Contours: If tangential entry is impossible, utilize normal entry at the intersection of two geometric elements to hide transitions.
• Thread Cutting: For CNC threading, maintain a strict lead-in distance ($\delta_1$) of 2–5mm and a lead-out distance ($\delta_2$) of approximately 1/4 the pitch to ensure the feed rate is stable before the tool engages the material.

Ever Power Custom Machining Solutions

Whether you require high-precision stainless steel fasteners or complex CNC-machined components, Ever Power combines decades of process expertise with state-of-the-art technology to deliver excellence. Our engineering team is ready to analyze your drawings and optimize your production workflow.

Contact us today for a technical consultation or high-precision fastener inquiry.