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CNC Machining_FAQs
1.Q: Why we need CNC machining for manufacturing parts?
A:
CNC machining can do various of workpiece with range from simple to complex structure. It offers better and consistency compared to manually operated devices. CNC machines are fully automatic or semi-automatic, once you setup the fixturing, input the programming into the machining, and start the machining system, you are free to do some else work, the machines will create identical parts with the same accuracy and precision.
In one word, precision, quick turn and cost effective is the reason we use CNC machining.
2.Q: What tolerance can you achieve for CNC machined parts?
A:
For plastic parts, we can achieve DIN ISO 2768 (M).
For metal parts, we can achieve DIN ISO 2768 (F).
We can get more accuracy for turning parts and some holes.
3.Q: What’s the maximum size can you machine directly?
A: Generally 1000×600×500mm. It depends on the part structure.
4.Q: Is there any features/details can’t be obtained from CNC machining directly?
A:
1) Hollow parts. e.g. balls, bottles,
2) Tiny gaps, very deep holes.
3) Large undercut.
4) Bend tube
5.Q: How to deal with the parts which is over the maximum size and those features that can’t be machined directly?
A: For large plastic part, we can section the part into 2 or more pieces, and machine them individually, then glue them together with strong adhesive. Similar to the unmachinable features. For metal parts, we also split the parts/ features and machine them separately, then weld them together.
6.Q: Are there any material that can’t be or not available to be sectioned and glued?
A:Some material can’t be glued together after sectioning. For example, PP, POM, PE, Nylon (/with Glass fiber), they are hard to glue because they have "low surface energy". Very crudely, they have little interest in sticking to anything else, including adhesives.
7. What are the advantages of CNC machining compare to 3D Printing?
1) More precise. CNC machines are programmable and every detail of the production process can be fed into the machine, identical parts can made with the highest accuracy levels. Programming the specification and designs into the machine leaves less room for mistake.
2) More material choices. Normally there are only ABS-like, PMMA-like and nylon material for 3D printing, but for CNC machining, we have ABS, PP, POM, PMMA, PC, Nylon, HDPE, PVC, PC+ABS, , Nylon+15% glass fiber, , Nylon6, Nylon 66, PBT+glass fiber, PEEK, PET, PPS, PTFE(Teflon), , UHMW-PE, PEI (Ultem 1000), etc.
3) Better surface finish achievable. 3D printing parts (especially PMMA-like, nylon and metal) usually have rough finish, and difficult to polish, while CNC machined parts can be easily polished and painted with many kinds of surface finish.
8. When we should consider using CNC machining rather than other technologies?
1) Order quantity is range from 1-5 pieces (for plastic parts) or 1-50 pieces (for metal parts), because CNC machining is relative cost-effective
2) Parts with tight tolerance. Because vacuum casting and die casting can’t achieve.
3) Besides small quantity, some special material needs to be machined but cannot casting, such as Peek, Ultem1000, PBT, Fire-resistant material and so on.
