This image was created with artificial intelligence – marked under Art. 50 of the AI Act, Regulation (EU) 2024/1689. It is a placeholder until the company's photos arrive.FAQ: Frequently asked questions about CNC machining
Answers to the most frequently asked questions about CNC machining: materials, processes, tolerances, programming and online cut-to-size.
CNC machining is the backbone of modern metalworking and plays a central role in almost all industrial sectors. Whether in mechanical engineering, medical technology, the automotive industry or electronics manufacturing – CNC milling and CNC turning stand for the highest precision, repeatability and cost-effective production of complex components. This FAQ article answers in detail the most common questions about CNC technology, materials, tolerances, programming, data formats and processes – explained in a practical and understandable way.
Basics of CNC machining
CNC stands for Computerized Numerical Control and describes the computer-aided control of machine tools. Digital commands are used to precisely coordinate axis movements, feed rates, tool changes and machining parameters. The result is reproducible components of consistent quality, even for high volumes or complex geometries.
CNC technology has revolutionised metalworking: from one-off production to series production, almost all materials can be machined with the highest precision. Particularly in aluminium and stainless steel production, CNC machining is regarded as the standard process for demanding applications.
Typical CNC processes at a glance
- CNC milling: In milling, material is removed layer by layer with rotating tools. The process is ideal for prismatic components, pockets, holes and fits.
- CNC turning: Rotating workpieces are machined with fixed cutting edges. Perfect for shafts, bushes, nuts or cylindrical geometries.
- CNC drilling: Precise holes, countersinks and threads can be produced automatically in a single setup.
- Multi-axis machining: Modern machines with up to 5 axes enable complex free-form surfaces and significantly reduce setup times.
Frequently asked questions about CNC machining (FAQ)
Which materials are suitable for CNC machining?
CNC machines process a wide range of materials – from aluminium, stainless steel and copper to brass and engineering plastics such as POM, PA or PE. Aluminium stands out for its good machinability and low weight, stainless steel for its strength and corrosion resistance. Titanium or tool steels are also used for special applications. The decisive factor is always the material property in combination with the intended area of application.
How precise is a CNC milling machine?
CNC milling is one of the most precise manufacturing processes of all. Depending on the machine and tool, tolerances of ±0.01 mm are achieved. The accuracy depends on machine rigidity, ambient conditions, tool selection and the experience of the operators. Temperature compensation and automatic tool measurement make it possible to achieve consistently exact results – even in series production over many hours.
Which tolerances are usual for CNC parts?
Standard tolerances are based on DIN ISO 2768-mK, although tighter ranges can be manufactured by arrangement for special applications. Online manufacturers such as Martan Metall define clear guidelines for manufacturing tolerances for milled and turned parts so that every component corresponds exactly to customer specifications. Additional measurement reports are often produced for technical functional surfaces.
How does CNC production work in online cut-to-size ordering?
The process is simple and efficient:
- You upload your CAD file (STEP, DXF or IGES) in the online configurator.
- The system automatically checks the geometry, machinability and material utilisation.
- Based on this data, the price is calculated in real time.
- After your approval, CNC programming starts, followed by production, quality inspection and shipping.
These automated processes enable short delivery times, transparent costs and consistent quality.
Which data formats are required?
For precise production, 3D models in STEP format (.stp/.step) or 2D drawings in DXF format are preferred. These files contain exact geometries, hole positions and dimensions. PDF drawings can additionally be used for visual checking or to identify special requirements.
How are CNC parts inspected?
Quality assurance is a central component of CNC production. Modern 3D coordinate measuring machines, profile projectors or optical scans are used to check dimensional accuracy, form and position tolerances. In series production, automated inspection systems are used that detect deviations immediately. Every component passes through several inspection stations before it leaves the premises.
What does CNC machining cost?
The costs result from material, complexity, machining time, tooling effort and quantity. A simple milled aluminium part can cost a few euros, while precise turn-mill combinations with tight tolerances and several machining steps are significantly more expensive. However, automated calculation and digital planning also make it possible to produce small series economically. Martan Metall offers transparent price structures with no hidden additional costs.
How sustainable is CNC machining?
Sustainability is also becoming increasingly important in machining. CNC companies rely on energy efficiency, closed cooling circuits, recycling of chips and optimised material utilisation. Offcuts are either fed back into the production process or processed as recyclable material. The combination of precision and resource efficiency makes CNC production an important part of sustainable industrial processes.
How quickly are CNC parts delivered?
The delivery time depends on the machining effort, material availability and order situation. Standard parts are usually delivered within a few 3–5 working days. Complex assemblies, special materials or tightly toleranced precision parts require somewhat more time. Martan Metall informs you of the expected delivery time at the time of ordering – fully transparent and plannable.
What is the difference between CNC milling and CNC turning?
In milling, the tool rotates while the workpiece is fixed. In turning, it is the other way round: the workpiece rotates, the tool moves linearly. The two processes complement each other ideally – milling for flat or prismatic shapes, turning for round or rotationally symmetrical geometries. Combinations of both processes are common in modern CNC centres.
What role does programming play?
CNC programming is the heart of the process. It translates the CAD model into machine-readable control commands (G-code). Precise programs ensure short machining times and error-free results. At Martan Metall, programming is supported by experienced CAM specialists and simulation tools in order to optimise tool paths and avoid collisions.
CNC machining simply explained
CNC technology stands for precision, efficiency and future viability. It combines digital planning, flexible manufacturing and the highest quality – from prototypes to series production. Anyone who orders CNC parts online benefits from fast processes, transparent calculation, optimal material utilisation and certified quality assurance. Martan Metall offers you tailor-made solutions, expert advice and modern manufacturing technology – for your individual components made of aluminium, stainless steel or plastic. CNC machining is more than just cutting – it is the key to innovation, precision and sustainable production in the industry of tomorrow.
