FAQ.

Our in-house developed smoothing system is specially designed for the chemical smoothing of additively manufactured plastic components. We achieve very good results, for example, with SLS components made of PA2201, PA2200, Alumide, HP PA12, TPU and PA11.

Other plastics and components from other additive manufacturing processes, such as FDM, can also be smoothed depending on the material. One requirement is that the material has sufficient temperature resistance of at least 100 °C.

For unknown or customer-specific materials, we check suitability in advance.

Yes. Depending on the plastic used, chemical smoothing is also possible for FDM components. We have achieved good results with Onyx ESD and various PA6 and PA12 materials, for example.

As FDM materials can vary considerably in composition and additives, we check suitability case by case. We have already tested a wide range of materials – just get in touch about your specific material.

Yes. We also offer chemical smoothing as a contract service for externally manufactured components.

You send us your components and we take care of the surface treatment. On request, further processes such as dyeing, machining, thread cutting or assembly can follow.

For third-party components, we check material, geometry and initial condition before processing.

The smoothing process itself, including the necessary process steps, usually takes about two working days.

Depending on order size, quantity and further post-processing, the component can often be shipped again after about three working days.

We will agree the exact processing time with you when you enquire.

In principle, yes. Multi-part or movable SLS assemblies can also be chemically smoothed.

Whether a component can be smoothed in its assembled state depends on factors such as geometry, gap dimensions, mobility and accessibility. That is why we review such assemblies with you in advance.

Costs are calculated on the basis of the component geometry and CAD data.

In addition, there is a one-off set-up charge of €10 per order. For several components, this is spread across the quantity ordered. On top of this come the component-dependent costs for the actual smoothing process.

For a specific quotation, simply send us your CAD data and the required quantity.

That depends on the cross-section, length and course of the channel and its accessibility.

With sufficiently large and accessible channels, the surface treatment can also take effect inside. With small or complex channels, however, uniform smoothing along the entire channel cannot be expected. Here the effect may be concentrated on the inlet and outlet areas, for example.

For function-critical internal channels, we therefore recommend an individual assessment of the geometry.

The usable process chamber of our smoothing systems is cylindrical and measures:

Ø 470 mm × 390 mm height

Whether a component can actually be processed also depends on its geometry, build orientation and the required suspension points.

Yes. We can reliably smooth suitable components with wall thicknesses from 1 mm.

For particularly delicate structures, suitability also depends on geometry, material, component size and suspension during the process. We therefore check critical geometries before processing.

Yes. We can fully finish and refine additive components beyond the actual 3D printing.

This includes, for example:

Dyeing · Grinding · Polishing · Coating · Flocking · Drilling · Reaming · Thread cutting · Milling · Threaded inserts · Assembly

The individual processes can be combined depending on the application.

Chemical smoothing reduces the typical surface roughness of additively manufactured plastic components and creates a more homogeneous, more closed surface.

This can be particularly beneficial for:

Cleanability · feel · appearance · dirt adhesion · product-contact surfaces · technical functional surfaces

Which benefits are relevant to a specific application depends on material, geometry and operating conditions.

No. The dye can contaminate the smoothing system, which in turn leads to contamination of undyed components.

Here is a video about smoothing.

Yes. Chemical smoothing is mandatory for components in direct contact with food.

Chemical smoothing smooths the rough surface typical of SLS and creates a more homogeneous surface that is easier to clean. For applications with direct food contact, this process step is therefore an integral part of our production.

However, suitability for direct food contact does not result from the smoothed surface alone. What matters is the interplay of material, SLS manufacturing process, component geometry, cleaning, post-processing and the specific operating conditions.

LMD has had corresponding material and process combinations tested using manufactured and post-processed reference test parts.

You can find the associated test reports and certificates here.

As a rule, chemical smoothing does not change component dimensions significantly. An additional allowance therefore does not normally need to be considered in the design.

With pointed or very delicate geometries, the smoothing process can slightly round the contours. The effect depends on component geometry, wall thickness and process duration.

For most components, chemical smoothing therefore has no influence on the design. If required, we check particularly delicate or geometrically critical areas in advance.

During the smoothing process, components are positioned or suspended in a defined way depending on their geometry. At the contact or suspension points, the surface effect may differ from the rest of the component.

Suitable suspension points should therefore be considered at the design stage wherever possible and placed in functionally or visually non-critical areas.

Fitted holes are particularly suitable as suspension points if they are reamed to their final size after smoothing anyway. Alternatively, additional eyelets or auxiliary geometries can be provided and removed after smoothing.

For components without a suitable suspension option, we agree the positioning individually before smoothing.

No. Chemical smoothing always treats the entire component. Selectively smoothing individual surfaces or areas is not possible with this process.

Areas that should not be smoothed therefore cannot simply be excluded from the process.

With our standard smoothing programme, surface roughness values down to approx. Ra 1.6 µm are possible. However, the surface quality actually achievable always depends on material, component geometry, build orientation and initial surface.

As a rule: the smoother and more uniform the surface before smoothing, the better the result after smoothing. Stepping caused by the layer-by-layer build or an unfavourable build orientation for the surface in question may remain visible even after smoothing.

Additional mechanical pre-treatment, such as grinding, can further improve the initial surface and thus the final smoothing result.

In addition to our standard process, components can also be smoothed more lightly or more intensively. This allows the surface appearance and roughness to be adjusted. However, more intensive smoothing has a greater effect on fine geometries: delicate structures, sharp edges or tapered areas may become more rounded or lose their original contour.

In short: chemical smoothing can significantly reduce roughness, but it cannot completely “smooth away” geometric irregularities or steps. For particularly high surface requirements, the initial surface should therefore be designed or pre-treated accordingly.

Yes. A few points should be considered at the design stage so that the component can be hung securely and smoothed evenly:

• Provide suitable suspension points and mark them clearly in the finishing drawing. Areas that will be machined afterwards anyway, such as fitted holes, are particularly suitable. Alternatively, additional eyelets can be added and removed after smoothing.

• Specify chemical smoothing as the required surface treatment in the finishing drawing.

• Fitted holes are only reamed to final size after smoothing. Design these holes correspondingly smaller in CAD. As a guide, we use approx. 0.2 mm undersize. For critical fits, we recommend consulting LMD.

• Provide radii and smooth transitions. Very sharp edges, points and delicate geometries may become more rounded during smoothing.

Our dyeing system specialises in dyeing SLS-printed plastic parts such as PA2201, PA2200, Alumide, HP PA12, TPU and PA11. Other materials are possible on request.

In addition to our standard colours – natural (white), black, grey, light grey, blue, orange, green, yellow, pink and red – we also offer individual custom colours. Custom colours require individual coordination and, if necessary, test parts for colour matching.

We use RAL colours as a guide, but due to material and geometry influences we cannot guarantee exact or binding RAL values. Thick- and thin-walled areas may show slightly different colour depths.

Yes, we also offer contract dyeing. You send us your SLS-printed parts and we take care of the dyeing and, on request, further post-processing (e.g. smoothing, polishing or assembly).

The processing time depends on the scope and the service required. The dyeing process takes about one hour in the rack, so you will have your part back after 2–3 days. For components manufactured at LMD, dyeing has no effect on the delivery time due to the short process duration (for standard colours). For custom colours or additional finishing, we agree the delivery time with you individually.

Our colour treatments are permanently bonded approx. 0.2 – 0.3mm into the component surface. They are abrasion-resistant under normal use. As is usual with plastic parts, the colour will change slightly over time. With dyed components, this process is somewhat slower than with undyed components. For applications with particularly high UV exposure, we offer post-treatment with Dichtol.

Individual dyeing is no problem. We handle one-off parts and prototypes as well as series in various quantities.

Yes, for custom colours or larger projects we recommend producing sample or test parts for colour matching. This lets you assess the result before series production.

We calculate the cost of dyeing from the CAD file, which we need for production anyway. Dyeing in our standard colours usually costs between €2–8 per part. 

Yes, dyeing takes place in a pressure vessel in a water bath, so the dye reaches every part of your component.

No, dyeing takes place in a water bath in which the component is completely immersed. If components are to have different colours, we recommend splitting the component in the design and then dyeing the parts separately.

The usable space of our dyeing systems is cylindrical and measures:

Standard dyeing systems: Ø 350 mm, height 260 mm

High-pressure dyeing systems (black): Ø 300 mm, height 400 mm

In individual cases, larger components can be treated in two dyeing runs:

Black: up to 800 mm

Other colours: up to 520 mm

Please note that with all colours except black, turning the components may cause visible colour differences in the transition area.