transforming surfaces
Made in Germany - since 1984
We take sophisticated products to the next level!
We are experts and innovators for stainless steel surfaces!
Finishing stainless steel small parts
At a glance
INOX COLOR finishes stainless steel small parts and components on a contract basis, chemically and electrochemically. We electropolish, deburr, pickle, passivate and colour by the inoxSPECTRAL process. Small parts such as screws, springs and bolts run as bulk material in drums, larger or delicate components on contact racks. In our small-parts line we handle parts up to 2,000 x 600 x 750 mm (L x W x H), larger components in the same works up to 6 x 2 x 1.2 m. From a single sample part to a running series, in Walldürn (Germany) since 1984, certified to ISO 9001.
Which parts we process
An extract from what runs through our small-parts line on a regular basis:
- Fasteners and standard parts:
screws, bolts, nuts, spring washers, springs, clips, connecting elements - Components and sub-assemblies:
hinges, covers, brackets, sleeves, spray heads, conveyor screws, valve and pump parts - Precision and functional parts:
machined precision parts, parts with threads and fits, components for vacuum and cleanroom applications - Design and consumer parts:
buttons, fittings, motorcycle spokes, trim parts, jewellery components
Why small parts call for different processes
On a sheet the surface lies open. On a small part it does not. A thread has flanks, a spring has coils, a hinge has gaps, a valve body has bores and channels. Mechanical processes cannot reach these surfaces, or reach them only in part.
Chemical and electrochemical processes, by contrast, work through a liquid rather than through a tool: the part is immersed in an electrolyte or a pickling solution, and the effect reaches every wetted surface. That is why we finish small parts by wet chemistry rather than mechanically. The process is controlled through current, time, temperature and electrolyte, which makes it reproducible across many thousands of parts.
Where the parts come from
A large share of our work comes straight out of machining and forming: turned parts, milled parts, CNC parts, stamped parts and bent parts that carry burrs, grooves or manufacturing residues after processing. That is exactly where our processes come in. If you machine parts and they then need to be deburred, cleaned, passivated or visually upgraded, you are in the right place. We are the finishing step after your production, not the turning shop.
The materials are primarily stainless steels such as 304 (1.4301 / V2A) and 316L (1.4404 / V4A), but also numerous further alloys including martensitic and ferritic grades (430 (1.4016)), (316Ti (1.4571)) and duplex stainless steels (318LN (1.4462)). Depending on the process, we handle other metals as well. Which electrolyte and which parameters are right depends on the alloy and the requirement, and is established on a sample.
Our processes for small parts
| Process | What it achieves | Typically used for |
| Electropolishing | smooths in the micro range, provides fine and ultra-fine deburring, passivates. Up to 80 percent less effective surface area | precision parts, threads, springs, valve components, medical and pharmaceutical components |
| Colouring (inoxSPECTRAL) | colour is created within the natural chromium oxide layer, without paint and without pigment, with full corrosion protection | colour coding (screws, rivets, bolts, alloys), buttons, fittings, spokes, design parts |
| Pickling | removes scale, heat tint, extraneous rust and manufacturing residues. Immersion, spray or anodic | welded or machined parts prior to further treatment |
| Chemical deburring | dissolves burrs on geometries that cannot be reached mechanically | bores, cross bores, internal contours |
| Passivation | creates a uniform protective layer under controlled conditions | parts with (high) corrosion requirements |
| Conditioning and cleaning | a defined initial condition, chemically, electrochemically or mechanically | parts carrying oil, swarf or foreign metal residues |
In practice we frequently combine our processes: pickling first, then electropolishing, then passivation. Or electropolishing first, then colouring. Every step takes place in the same works, so your parts never change contractor.
Electropolishing small parts in detail
The part is connected anodically and immersed in an electrolyte. Under direct current the electrolyte removes a thin layer of material, preferentially where the current density is highest: at peaks, burrs and micro-roughness. Material removal is in the micrometre range and is controllable, while the macro geometry is retained. This is why threads, fits and parts with tight tolerances can be treated safely. Removal takes place without mechanical, thermal or chemical stress on the part, which for thin-walled and resilient parts is often the only viable route.
Colouring small parts in detail
In the inoxSPECTRAL process no dye and no paint is applied. We create colour without colour. The existing passive layer is strengthened electrochemically into a transparent chromium oxide layer, at which the colour is produced by interference. The colour is therefore part of the surface itself and cannot flake off. Corrosion protection is fully retained. Standard colours include champagne, gold, bronze, steel blue, cobalt blue and black, with black being particularly scratch-resistant. We recommend red and green for interior applications only.
Bulk material in drums or parts on racks
Surface finishing distinguishes between two routes, and we offer both: barrel processing and rack processing.
| Bulk material in drums (barrel processing) | Contact racks (rack processing) | |
| Suitable for | screws, springs, bolts, spring washers, buttons, fasteners | hinges, covers, brackets, larger precision parts, sleeves, tubes and profiles |
| Quantity | medium to large batches | single piece to medium series |
| Advantage | economical, because parts are not handled individually | defined electrical contact, no part-on-part contact |
| Limitation | parts that interlock or damage one another belong on the rack | can mean higher handling effort per piece |
Which route is right is something we decide on your actual part. Mass-produced and series parts normally run as bulk material, because the parts do not have to be handled individually. For delicate, very thin or visually critical parts, the rack is the better choice despite the potentially higher effort.
Formats and limits
- Small-parts line: up to 2,000 x 600 x 750 mm (L x W x H)
- Large plants in the same works: up to 6 x 2 x 1.2 m
- Batch sizes: from a sample part through small series to a running series
Because several plants, and therefore several workable sizes, are located on the same site, an assembly and its associated small parts can be finished within a single process chain. That is the practical advantage when a component consists of large and small parts that need to match visually.
We tell you the limits in advance
In colouring, shades can vary depending on the alloy or the batch, which is why we colour these separately in order to match the shades to one another. Weld seams and burrs are removed before colouring. The shades red and green are intended for interior applications. And because the colour is an interference effect, the same shade appears different on a polished surface than on a blasted one. This is why we work on the basis of samples.
Electropolishing or coating?
Many enquiries reach us asking about galvanising, chrome plating, powder coating or anodising. For stainless steel small parts the comparison is worth making:
| Electropolishing | inoxSPECTRAL colouring | Powder coating / painting | Galvanising | Anodising | |
| Principle | material removal | strengthening of the passive layer | a layer bonded on top | a layer applied on top | conversion, aluminium only |
| Can it flake off | no, nothing is applied | no | yes | abrasion possible | no |
| Dimensional change | micrometres, controllable | nanometres, controllable | layer thickness is added, seals and builds up | layer thickness is added, seals and builds up | micrometres, controllable |
| Threads and fits | suitable | suitable | critical | critical | critical |
| Corrosion protection | increased | increased | depends on the layer | sacrificial protection | increased |
| For stainless steel | yes | yes | possible for interior use, but a coating on stainless steel | unusual | no |
In short: coating processes add material and therefore change dimensions and tolerances. Electropolishing and inoxSPECTRAL colouring work within the surface itself. For stainless steel small parts with threads, fits or hygiene requirements, that is usually the decisive difference.
The industries we work for
-
Pharmaceutical, food and beverage technology:
components in product contact, where cleanability and low microbial adhesion decide on approval -
Medical and laboratory technology:
precision parts with requirements for freedom from particles and for deburring -
Mechanical and plant engineering:
fasteners, springs and assembly parts that must be corrosion-resistant and fatigue-resistant; visual upgrading, quality feature, differentiator -
Vacuum and cleanroom technology:
reduced outgassing, metallically clean surfaces -
Design, interiors and consumer goods:
fittings, buttons, spokes and trim parts, where colour and finish carry the product
How your order works
We work exclusively on a contract basis, in other words as a service provider working on your parts. Contract finishing, contract pickling, contract electropolishing and contract polishing all run under one roof, in one order and with one point of contact, and have done for more than 40 years.
- Send us your requirement
Part drawing or photograph, material, quantity and the result you are looking for. If you are unsure which process is right, describe the problem or the solution rather than the process. - Advice on material and process
We tell you which process, or which combination of processes, suits the component, and where the limits are. - Sample part
The most meaningful basis is a real part from your production. We treat it and you assess the result on the object, not on a data sheet. - Quotation and series approval
Once the sample is approved, we fix the parameters so that the result stays reproducible across the series. - Series
Flexible batch sizes, processing as bulk material or on racks, return shipping as agreed.
Our works is located in Walldürn in Baden-Württemberg, between Würzburg, Heilbronn and the Rhine-Neckar metropolitan region. Batches of small parts are easy to ship, which is why we work for customers throughout Germany, Austria and Switzerland as well as across Europe and even worldwide.
Quality and documentation
INOX COLOR is certified to ISO 9001. For small parts this means in practice that the process parameters are defined and maintained per part and per batch, so that the result stays reproducible across the series.
If your industry requires documentation, we agree the scope before the order: details of the batch, of the process and of the parameters maintained. What is possible in an individual case depends on the process and on the evidence required. Talk to us before you send the parts, and we can carry the documentation from the outset.
