Texture Analysis in the 3D Printing Industry

In the 3D printing process, a physical object is produced from a 3D digital model. This generally occurs by the laying down of successive thin layers of material to bring the digital model to life.

The steps involved in this process will vary depending on the type of printer and the raw materials involved, but generally they are as follows:

1: A 3D model is created using a modelling package or 3D scanner, saved as a Computer Aided Design (CAD) file

2: The user slices the CAD file and uploads it to the printer

3: The printer reads and creates each 2D slice to form a 3D object

There are many different 3D printing techniques available, and all have their benefits in different industries. The following are some examples of the most commonly-used techniques:

• Stereolithography (SLA) uses a laser to harden liquid photosensitive resin layer by layer to form the 3D shape, putting a process called photopolymerisation to use. Digital Light Processing (DLP) works in a similar way but uses a projector screen instead of a laser.

• In Fused Deposition Modelling (FDM), a melted polymer is extruded through a heated nozzle and each layer is laid down in filaments according to the CAD design.

• Selective Laser Sintering (SLS) uses a laser to sinter layers of polymer powders to bind them and create a solid structure. Selective Laser Melting (SLM) works in a similar way, but fully melts the powders rather than just sintering them.

3D printing is most commonly used for rapid prototyping of plastic parts, but these days can be applied to most groups of materials, in many different industries. Food is frequently 3D printed, taking advantage of its novelty value as well as the customisation available. Syringes are generally used to hold and deposit the printing material, which is laid down layer by layer through a food grade nozzle. Customisation available includes shape, texture, flavour, nutrition and colour.

A Texture Analyser is a very useful tool for the R&D associated with 3D printing. Using food applications as an example, alternative ingredients are often incorporated into food products by use of 3D printing to improve the nutritional profile of that food. A study will be performed to assess the amount of the alternative ingredient that can be added before the texture of the original food is changed significantly. Texture Analysis is performed on samples with varying percentages of additives and acceptability levels used to determine the optimum payoff between high nutritional content and good textural properties.

An example of this process was carried out by researchers from the Indian Institute of Food Processing Technology, who have been investigating the development of fibre-enriched 3D printed snacks from alternative foods, with this study focussing on the button mushroom. The printability of the material supply was optimised by varying levels of mushroom powder in combination with wheat flour. The effect of variations in process variables such as printing speed and nozzle diameter were studied. 

 

They used their TA.HDplus Texture Analyser to measure textural properties of the material supply of the mushroom powder, wheat flour, 20% mushroom powder incorporated material supply and post-processed snack. It was found that it was possible to fabricate 3D printed constructs with good stability using the formulation containing 20% mushroom powder, with a specific set of printing parameters. This work provides insights for the development of foods from sustainable alternative food sources using 3D printing technology, particularly for personalised nutrition. Read more

Another branch of 3D food printing research involves investigation into printing conditions. The texture of the finished food product depends strongly on various parameters involved in the 3D printing process. In this type of study, a range of conditions are used and the texture of the printed product assessed, with the aim of finding the set of variables for a final product with optimum texture.

Researchers from the Indian Institute of Food Processing Technology also carried out a study of this type. The investigated the 3D extrusion printability of rice starch and optimisation of process variables. Three-dimensional extrusion printing is an additive manufacturing approach with numerous emerging applications in the food industry.

In this research, the effect of nozzle size, print speed, and motor speed on the printability of rice starch were studied. Uniformity and ease of extrusion were considered, and the printed constructs were carefully observed for thread quality, binding property, finishing, texture, layer definition, shape, dimensional stability, and appearance. They used their TA.XT2i Texture Analyser to measure the textural characteristics of 3D printed samples including hardness, fracturability, adhesiveness and springiness. 

 

The rheological behaviour of the material supply was studied, and the scientific rationale behind the printability of starch is discussed in detail. Printing rice starch at higher motor speeds with lower printing speeds resulted in better printability. The results of this study would be a foundation for future 3D food printing studies using rice starch. Find out more

The Texture Analysis involved in a food 3D printing study is no different from ordinary food Texture Analysis. The method used is simply suited to the food in question, perhaps with emphasis on a property that could vary the most with the 3D printing process. For example, 3D printed biscuits are frequently used as a novelty food as it is so simple to change their colour or design. However, to show off the capability of the 3D printing process, ornate, lacy, open designs are often used. These are not particularly strong and may break apart in storage or transit. To assess their strength, a standard biscuit bend test is used, putting to use a TA.XTplus Texture Analyser and a Three-Point Bend Rig, HDP/3PB. The fracture strength of various designs can be assessed in this way.

 

Texture Analysis can also be put to use at other stages in the 3D printing process, not just for the measurement of final product properties. For example, the properties of the base powder used in Selective Laser Sintering affect the sintering process as well as the properties of the final product. Powder flow is one of these properties. As each new layer of powder is swept onto the sintering bed, the layer should be uniform and of the correct thickness and distribution. A Powder Flow Analyser (PFA) is a very useful add-on to a Plus Texture Analyser to help measure these flow properties.
 

The PFA proves an accurate and reliable method of measuring the flow characteristics of dry and wet powders, with capability to measure cohesion, caking and speed flow dependence as well as bulk density and other properties.

It can be rapidly fitted to a TA.XTplus Texture Analyser, enabling manufacturers to assess and avoid typical problems such as batch and source variation of ingredients, caking during storage/transportation and problems with discharging from hoppers or bins, as well as 3D printing-specific powder properties. The powder is conditioned at the beginning of each test to eliminate any variations in loading and the precision-engineered, patented blade is then rotated through the sample, causing controlled flow.

A Texture Analyser is a valuable tool to any 3D printing manufacturer, allowing the user to assess textural properties from raw material to final printed product. To find out more, contact Stable Micro Systems today.

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For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.

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