Maximum service life and process control through a high-quality surface finish
For critical technical components, surface quality is decisive for performance. Tumag refines the roughness of your moulds and precision mechanical components to the exact specification your process requires.
- Functional precision: eliminating microscopic traces of milling, grinding and spark erosion (EDM).
- Preservation of geometry: manual and mechanical polishing with strict preservation of form and flatness tolerances.
- Optimal range: from technically smooth (Ra 0.8 µm) to ultra-precise mirror finish (< Ra 0.05 µm).
Why technical polishing is essential
Every machining operation leaves irregularities that lead to friction and premature wear. Through controlled polishing, we improve the functional properties of the base material without compromising its technical integrity.
The main benefits at a glance:
- Optimal release: crucial for injection moulds to shorten cycle times and prevent product damage (marks/streaks).
- Extended service life: less material adhesion on stamping tools reduces burr formation and postpones maintenance.
- Minimal friction: essential for moving precision mechanical components to limit heat build-up and mechanical wear.
- Corrosion resistance: a closed, smooth surface offers significantly less grip for oxidation and process contamination.
Surface quality and Ra value: engineering in numbers
At Tumag, we work on the basis of measurable results. The required finish is determined by the application and expressed in the Ra value (average roughness).
| Finish | Application | Indicative Ra value |
| Functionally smooth | Contact surfaces, general mechanical engineering | ± Ra 0,4 – 0,8 µm |
| Finely polished | Mould components, precision components | ± Ra 0,1 – 0,4 µm |
| High gloss | Visible parts, consumer products | ± Ra 0,05 – 0,1 µm |
| Mirror polish | Optical components, transparent parts | < Ra 0,05 µm |
Polishing specialties
Injection moulds and inserts
In injection moulding, the mould is the direct carrier of product quality. Every scratch in the mould cavity is visible on the final product. We polish moulds for both aesthetic high gloss and functional release, making your production process more stable and reducing scrap.
Precision mechanical components
In precision engineering, every micron counts. We polish components that must fit or guide with precision. The focus is on removing micro-burrs and refining surface roughness while strictly preserving form and flatness tolerances.
Stamping dies and cutting tools
A smooth surface on a stamping die ensures better material flow and less friction during the stroke. This results in a cleaner cut and a significantly longer tool life before regrinding becomes necessary.
Your partner for precision finishing
Are you looking for in-depth technical expertise and craftsmanship in surface treatment? Tumag offers the expertise to ensure your critical components perform at their best.
Frequently asked questions about technical polishing (FAQ)
Does polishing affect the dimensions of my component?
At Tumag, we work with the utmost precision. Although polishing removes material, we are talking about fractions of micrometres. Thanks to our experience in mould making, we know exactly how to improve surface quality without exceeding fit tolerances.
Which materials can you polish?
We have extensive experience with various steel grades (hardened and unhardened), stainless steel and tool steel. Each material requires its own technique and polishing compound to achieve an optimal result without an “orange peel” effect.
How does the technical polishing process work?
Polishing is a step-by-step process in which the surface roughness (Ra value) is systematically reduced. We start by levelling the base structure (for example milling or EDM marks) with fine abrasive stones or sandpaper. We then move on to polishing with diamond pastes in decreasing grit sizes, supported by felt, copper or wooden lapping sticks. For complex geometries, we use ultrasonic polishing equipment to ensure consistent quality even in deep recesses.
At Tumag, polishing is a controlled process in multiple stages:
- Inspection: assessment of the base material, hardness and initial roughness.
- Fine sanding: gradual removal of machining marks using controlled grit sizes.
- Polishing: use of specific polishing compounds (often diamond-based) for the final finish.
- Metrology: verification of the achieved Ra value and preservation of critical contours.
When should I choose polishing instead of grinding?
Grinding is primarily used to bring a component to the correct size and geometry within tight tolerances. Polishing is the subsequent operation specifically aimed at the finish. When an extremely low coefficient of friction, improved release from a mould or an optical mirror finish is required, polishing is essential. Polishing refines the surface structure that is still present after grinding (often Ra 0.4–0.8 µm).
Is polishing the same as sanding?
No, although they are closely related. Sanding is a material-removing preparatory operation in which bonded abrasive grains remove the surface “peaks” to create an even base. Polishing is the finishing stage in which the remaining microscopic scratches are rubbed out or smoothed away. Whereas sanding produces a matte surface, polishing creates a closed, reflective surface with much lower roughness.
Do I need to pre-treat the material before polishing?
For an optimal result, the initial condition of the material is crucial. The finer the pre-treatment (such as wire EDM or surface grinding), the more efficient the polishing process will be. Deep grooves or “burn marks” caused by aggressive milling or spark erosion must first be removed mechanically. We are happy to advise you on the ideal delivery specifications to minimise the lead time and cost of the polishing work.