Our technology

The 3D-printed last from Dreve offers outstanding properties for the production of custom shoes. It is available for you at short notice without long delivery times and is manufactured by us in an energy- and resource-saving way. At the same time, it is in no way inferior to traditionally manufactured lasts. Thanks to the digital workflow, you always receive a highly accurate product that can be reproduced at any time.

Properties

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Resilience
An important requirement for the shoe last is its resistance to mechanical stress. This is especially enormous when molding the sole. The 3D-printed last from Dreve can convince here with maximum stability, even under punctual load. The internal honeycomb structure ensures that stability is provided and the last remains pleasantly light.
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Sanding
If adjustments to individual lasts are necessary, the removal of material is an important step. Belt or flap sanders are used to remove material by means of machine power, which results in high material removal and heat. Both are factors for which Dreve's 3D-printed last has been optimized. The material has very low thermoplastic properties, allows grinding without lubrication, without rapid clogging of the abrasives. Sufficient wall thickness prevents exposure of the internal structure during grinding.
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Filling and bonding
The best possible, individualized fitting for each patient is the goal of every orthopedic custom shoe. To ensure this and provide the patient with a comfortable wearing experience, the last may need to be adjusted in the early stages of the production process. Despite highly accurate scans, possible pressure points that only become visible when a trial shoe is tried on are not always predictable: the last can then be built up and shaped using putty or glued-on cork strips. These common materials are fully compatible with Dreve's 3D-printed last. Both putty and cork strips bond perfectly to the plastic and can be machined and sanded down to an imperceptible, seamless transition to the rest of the molding.
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Thermoforming
In order to be able to make a perfectly fitting custom shoe, a fitting with a trial shoe is an established procedure. Transparency allows the orthopedic shoe technician to see if there are any pressure points and to assess the general fit. Traditionally, the trial shoe is produced using the thermoforming process. For this purpose, the foil used is heated and thus made very flexible. The foil is then pulled over the last in the thermoforming unit and applied perfectly to the last by means of a vacuum. The heat transferred to the last in this process is easily absorbed and dissipated by the Dreve 3D-printed last. Once the material has cooled, the last can be easily removed from the mold and used directly for further shoe production.
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Tacking
Working with compressed air-driven tackers on the last is essential for rapid work progress. In order to be able to optimally insert tacker needles into a component, the material properties must be such that the needles can be inserted as easily as possible on the one hand, but can also be removed again without too much effort on the other. Optimally, the material should still be stable enough after the staples have been removed to allow further needles to be inserted, for example for the production of another shoe. Dreve's 3D-printed last can guarantee all this. The optimized material properties in combination with a standard wall thickness of 8 mm ensure ideal retention of the needles in the last at all times.
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Nailing
Custom shoes should meet the highest quality standards for optimal patient care. High-quality fabrics and leathers in particular are therefore used to make the custom shoes. When shaping the shoe upper, the chosen material is pulled over the last and fastened to the underside of the last with nails. These nails must be easy to insert and remove, but hold the upper material securely in place. Dreve's 3D-printed molding meets this requirement. The adapted wall thickness ensures that the nails always find enough hold in the last. Material parameters optimized for this additionally support simple and low-damage removal of the nails.
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Highly resilient connection
The dimensional accuracy of the last during the production process in the manufacture of customized shoes is elementary for the optimum fitting of the patient's foot. To ensure that the multi-part last remains absolutely stable at its connection points, Dreve's 3D-printed last is equipped with a heavy-duty connection mechanism consisting of two elements. The first element is the inserted staircase-shaped separating cut, which ensures that loading forces are transmitted over a large area between the two parts of the last. The second element is the bolting element inserted into the internal honeycomb structure, which is introduced during the modeling of the last and holds the last parts securely together. We usually insert two stainless steel threaded inserts in the front section of the strip, which are engaged by M8 screws, also made of stainless steel, when the two parts are screwed together. For a taller, three-piece leg moulding, the same screwing technique is used again. The combination between the two fasteners provides a positive, heavy-duty connection. Nothing stands in the way of wear-free opening and closing of the connection thanks to the stainless steel design!
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Absolutely stable
The long-term stability and durability of lasts is an important aspect of being able to produce several pairs of customized shoes of consistent quality over a longer period of time. Wood is subject to slight fluctuations due to fluctuations in temperature and humidity, 3D printed lasts from other manufacturing processes also tend to absorb water and then have reduced mechanical characteristics. The Dreve last made of light-curing plastic does not exhibit these deficits and is just as resilient and dimensionally accurate after years as on the first day.
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Reprinting and new printing
All lasts that Dreve produces using 3D printing processes must be available in digital form for production. The digital data can be generated in a variety of ways. A direct digital impression using a scanner, scanning a plaster cast or creating a last by taking measurements are the most common methods. The advantages of the digital last are obvious: easy storage for decades without having to store the last in physical form, immediate reprinting or new printing in the event of loss, damage or necessary major changes to the last, or the simple adjustment of individual areas. All this speaks for the digital last and simplifies and streamlines the handling of the large amount of patient data.

Why DLP Printing?

Waste and sustainability are growing and important issues in today's world. Wood moldings fit ideally into this profile of requirements, but are manufactured by machining and therefore come with a high amount of wood waste not directly used for the application. Additive manufacturing meshes precisely with this approach. In the manufacturing process generally referred to as 3D printing, the component is built up layer by layer, i.e. material is gradually layered on top of one another, and only in the area that will later constitute the component. The material used is therefore incorporated into the final component almost completely and without waste.

In the FDM printing process, the material used is heated and recorded layer by layer with a nozzle in the form of a melted plastic strand. Two things in particular are disadvantageous here: Firstly, the nozzle has to approach each individual point within a layer once, which means high production times for large components. Secondly, the material cools after deposition, which means that the next layer, again hot and molten when extruded from the nozzle, is deposited on a cold layer. Stresses and a less than ideal layer bond, leading to mechanical weak points, are the result.

In 3D printing with light-curing plastics, material is cured by means of UV light and thus chemically shaped by molecular bonds. The bond between the layers is also based on cross-linking of the molecules, which makes the layer bond very stable and gives the finished component almost anistropic properties - the component can be loaded equally in all directions.

The combination of these advantages is united in Dreve's 3D-printed last.

Sustainability

In today's world, awareness of sustainability and ecological products continues to grow. This idea affects both the private and commercial sectors - and thus also the work of the orthopedic shoe technician in his workshop. Shoe lasts are no exception, even if the aim should always be to use the last for as long as possible and for as many pairs of shoes as possible for reasons of efficiency alone, provided that the patient's foot does not change significantly. However, if this is the case, the disposal of the last must be resolved. The traditional way of manufacturing shoe lasts from wood is already a good solution due to the use of a renewable raw material.

However, since the wood lath is rarely optimized with filler or materials applied with adhesives, classic recycling of the wood is no longer possible. Its use as a secondary raw material for the production of chipboard or similar is therefore no longer possible. The only possible use is then thermal recycling. Our 3D-printed lath is in no way inferior to wooden lath in this respect. The plastic does not contain any toxic substances, which means that the lath can be disposed of with normal household waste. Thermal recycling for the generation of heat or electricity is also possible without any problems. Alternatively, the last can of course be returned to us and recycled by Dreve!

Disposal options of the 3D-printed last from Dreve:

✓ Disposal via household waste 
✓ Thermal recycling possible without any problems
✓ Return to Dreve for free disposal

Our experts

Choosing 3D printing is an innovative step in your overall workflow. But sometimes especially the start and the implementation can be a challenge, not only for beginners. Ouradditive manufacturing and 3D printing experts are happy to support you on your way. We'll be pleased to guide you expertly through the process. For more than seventy years, Dreve has stood for high-quality and reliable products in medical applications. 

As a supplier of medical products, one thing is most important to us: the complete satisfaction of ourcustomers. Our experts therefore offer real added value for you - whether you are an experienced user of digital technologies or an ambitious newcomer. Feel free to contact us at any time!

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