The best use of 3D printing is not always obvious. In designing objects for 3D printing, the limitations and benefits of the process must be kept in mind. These techniques will help any designer make full use of 3D printing services.
I. No use of existing designs
The design of each part should take into account the expected manufacturing process. Many designers and engineers are surprised to find that, even in small batches or one-off situations, using 3D printing to produce existing part designs is not always so cheap.
For example, consider existing parts designed for CNC processing. This part needs to produce 100 pieces of SS 304L, which can be printed in 3D by DMLS and SLM. When the part is manufactured by numerical control, the production cost is $35 per piece. But if the manufacturing process is changed to 3D printing, the cost will increase to more than $70 per unit.
This is because economies of scale are not suitable for 3D printing, to the same extent as CNC processing services and injection moulding. The most cost-effective type of production depends on the number of application and production units.
Here are some rules of thumb to guide you in the selection process of plastic parts.
· Select less than 100 units for 3D printing
· Selection of NC Machining under 500 Sets
· Injection Molding Selecting More than 500 Units
Note that there is a grey area between 100 and 500 units. Any of these three technologies may be economically viable, depending on the geometry, material and application of the parts.
Metal is another matter. Even in one-off prototype or low-production operation (< 100 units), parts that are not specifically designed for 3D printing are always manufactured more economically and efficiently using CNC processing. Here are some examples of using metal 3D printing.
II. Elimination of support structures
All 3D printing designers need to follow a simple rule: minimizing the need for supporting structures. 3D printing is a manufacturing process of augmented materials. Each layer of new material is deposited on the first layer and cannot be deposited in thin air. Supporting structures are usually used to print cantilevers and bridges; these structures are subsequently removed during later processing. Removal of supporting structures always increases production costs and time. This is especially suitable for metal 3D printing, which is very expensive for later production.
There are several simple ways to reduce the support structure required for design:
· Keep the cantilever less than 45 degrees.
· Cantilever with slight angle usually does not need support.
· Consider the direction of printing when designing.
For example, unlike other 3D printing processes, SLS and MJF printing do not require support structures.
III. Consideration of post-processing
Powder removal and bracket are the necessary forms of post-treatment, and articles need to be cleaned and repaired before use. Other forms of post-processing can be used for aesthetic and functional applications. Objects printed in metal 3D can undergo heat treatment, surface treatment, and even additional numerical control processing to achieve ideal results. Plastic 3D printing objects can be dyed, smoothed, or watertight.
Understand post-processing options in the initial design phase. Processing will increase production costs, but it can also be a good way to produce 3D printing components for specific applications.
Satellite module with lattice structure and internal cooling channel. The initial assembly consisted of 100 different parts, which were redesigned into one part.
V. Increasing Design Functions
3D printing has a unique ability to produce products with internal channels. No other manufacturing technology can effectively produce pore structure, grid structure or porous structure with the same quality level. This design function has several common applications.
Heat exchangers: Heat exchangers require two fluids or gases to pass through an area while maintaining separation. The 3D printing channel makes it easy to design complex heat exchangers for various applications.
Air duct: 3D printing duct is usually used in automobile or other industrial applications. Complex surface meshes are used to create variable wall thickness; this level of structural design is almost impossible to create using traditional manufacturing methods.
Organic structure: From honeycomb hexagonal stacking to honeycomb plant structure, 3D printing can simulate almost any complex natural design. One of the designs was used to provide scaffolding to repair spinal injuries.
Adding channels and complex structures to 3D printing design will not increase manufacturing costs. Use this to design parts that could not have been created. In order to make full use of the benefits of 3D printing, it is important to consider the process limitations when designing each part. Minimize the amount of material to be used and create an object that is superior to the selected production method.