CNC machining of small core clamping challenges
The "small" of small parts not only refers to the physical size, but also means that its section inertia moment is low, its stiffness is high, but its toughness reserve is small. Under the action of high speed cutting force, the following three types of problems are the most typical:- Gripping deformation: Small diameter shaft parts in the chuck jaw, if the clamping force is too large, remove the external force after elastic recovery caused by roundness error; if too small, it will occur movement.
- Reference blur: Small excircle or end face is often used as the positioning reference for subsequent processes. If the indentation during clamping is located on the reference surface, it will directly lead to subsequent assembly errors.
- Interference and Collision: In 5-axis machining, the clamping tools for small shell parts (such as vacuum cups and vacuum fixtures) themselves may block the tool path, resulting in a sharp increase in tool collision risk.
Comparison of clamping methods: balance between accuracy and efficiency
For batch production, the choice of clamping method directly determines the rhythm and consistency. The following is a comparison of the characteristics of the three mainstream solutions in small parts processing:| clamping method | Applicable parts form | Positioning accuracy (repeatability) | Main risks and avoidance measures |
|---|---|---|---|
| Soft jaw/mechanical jaw | Shafts and cylinders (Φ 5 μ m) need to be polished. ShowyMetal will conduct 100% full inspection on the appearance surface before shipment to ensure no scratches and defects.
FAQ: Technical Q & A on CNC machining small partsWhat is the minimum quantity of CNC machining small parts?Usually 1 piece is supported for prototyping, and it is recommended that a single batch of more than 500 pieces be produced to reduce unit cost. For extremely small parts (such as optical lens holders), due to the high cost of tooling development, it is recommended to optimize the combination of clamping surfaces by design to improve economy.How to avoid clamping marks affecting the appearance of small parts processing?The core lies in clamping force control and soft contact. Use V-groove soft claws or customized silicone/copper gaskets to change point contact into surface contact and disperse pressure. In addition, 0.05mm fine turning allowance is reserved on the key appearance surface, and finally the fine cutter cuts out, which can effectively eliminate the residual stress of the previous process.Which materials are suitable for batch processing of micro-structural parts?Aluminum alloy (6061/7075) is preferred due to its excellent cutting performance and light weight. Stainless steel 303 is also suitable for precision small parts due to its good cutting toughness. Engineering plastics such as PEEK and POM are suitable for insulation and wear scenarios. The selection of materials should be evaluated in combination with the temperature resistance and corrosion resistance of the final use environment.How much surface roughness can small parts be machined?By optimizing tool coating, feed speed and coolant, conventional CNC machining of small parts can be stable to Ra 0.4 μ m. If mirror effect (Ra) is required
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