CNC machining is a process in which every minute of downtime directly affects the profitability of production and the unit cost of the finished part.
At SIM Gdynia, based on over 45 years of experience in the mechanical component manufacturing industry, we know that the most critical moment for maintaining operational fluidity is retooling in CNC machining.
It is at the stage of changing the product range that the greatest number of errors can occur, which can result not only in material loss but also in tool damage.
In the following article, we present specific technological solutions that we use in our daily practice to minimise the risk of errors when setting up machines.
Why is changeover a production bottleneck?
From a technical point of view, retooling in CNC machining is the sum of the activities necessary to prepare the machine to produce the first correct part from a new series.
Industry statistics indicate that inefficient setup procedures can consume a significant portion of the machine’s available working time, which we consider to be a structural error in production management.
The most common errors and their technical consequences – know-how from the SIM Gdynia production hall
The table below presents a summary of the problems most commonly faced by operators and the methods of eliminating them that we have implemented at SIM Gdynia as part of our quality optimisation strategy.
| Type of error | Technical cause | Quality effect | SIM Gdynia solution |
| Incorrect tool offset | Manually enter the corrector into the tool table. | Spindle collision or “undersized” workpiece. | Automatic measuring probes. |
| Contamination of the base | Chip residue under the vice or chuck. | Runout error and lack of surface flatness. | High-pressure cleaning procedure. |
| Incorrect choice of tooling | Use of flexible chucks with high cutting force. | Vibrations and poor surface quality. | Selection of rigid, dedicated clamping systems in technology. |
| Error in the NC (Numerical Control) programme | Outdated version of the so-called post-processor (digital translator of instructions for the machine). | Damage to the tool upon first contact with the material. | Mandatory simulation of the tool path in a virtual CAM environment before start-up. |
Eliminating these technical errors allows for the implementation of a rigorous process, which at SIM Gdynia forms the “backbone” of every operation and guarantees the highest quality and precision without unnecessary material losses.
SMED optimisation: How do we reduce machine downtime?
Effective CNC machining requires the division of activities into internal operations (performed when the machine is idle) and external operations (prepared while the spindle is running).
The goal of SMED optimisation is to move as many tasks as possible to the external group.
At SIM Gdynia, the preparation of tools in holders, their measurement and the collection of technical documentation takes place while the machine is still executing the previous order.
Our experience shows that this approach significantly reduces downtime, which directly translates into shorter lead times for our customers.
Key steps in the error reduction process:
- Tool standardisation: Maintaining a permanent tool library in the machine warehouse reduces the need for frequent tool changes.
- Digital setup cards: Each CNC machining changeover has assigned documentation that describes exactly how the part is to be mounted.
- Cleanliness of the workspace: Even a small metal chip under the base can cause a dimensional error, which is unacceptable in the medical or defence industries.
First-Off quality control – a guarantee of repeatability
At SIM Gdynia, we do not start serial production without fully verifying the first piece.
This is a critical moment when we check the linear dimensions and surface roughness, ensuring that the machine settings guarantee a basis for any further processes.
If the parameters are consistent with the documentation, we start the series, confident that each subsequent detail will be perfectly prepared for final refinement.
However, dimensional precision alone is often only half the battle – in the medical or defence industries, the final part must be free of micro-burrs and meet stringent visual standards.
You can read more about the finishing process for mechanical components in our article “Surface finishing after CNC machining“.
Summary and conclusions
Effective CNC machining is a multidimensional process in which attention to detail at the setup stage determines the stability of the entire production. In order to permanently reduce quality losses, it is necessary to focus on three pillars:
- Standardisation and cleanliness: Eliminating chips and automating tool measurements removes the most common causes of failure.
- Virtual verification: Simulations in the CAM environment protect the material and machine from errors in the NC code.
- Rigorous input control: The First-Off procedure is the only way to avoid repeating errors throughout an entire series of parts.
Are you planning to manufacture complex mechanical components and looking for a partner who takes full responsibility for the quality of the process?
Contact us and receive a quote based on optimised manufacturing technologies.