Posted on: June 29, 2018, | By Candy, WayKen Marketing Manager
Rapid prototyping services are owning a large scale of technologies, how engineers and designers achieve the final production goals by using rapid prototyping?
1. What is Rapid Prototyping Manufacturing?
Rapid Prototyping Manufacturing (RP&M).
In the automotive applications industry called RP samples.
RP technology is integrated and developed on the basis of modern technology, including CAD/CAM, laser, CNC prototyping, precision servo drive and new material.
Different types of rapid prototyping systems have different forming principles and system characteristics due to the different forming materials used. Among the more mature methods are SLA, SLS, FDM, and LOM.
However, the basic principles are the same, that is, “layered manufacturing, layer by layer stacking” is similar to the mathematical integration process. Graphically speaking, the rapid prototyping system is like a "3D printer." We visually call it "additive manufacturing."
2. CNC Machining
CNC is the abbreviation of Computer Numerical Control (CNC) and is an automatic machine controlled by a program.
Comprehensive computer-aided design, auxiliary manufacturing, digital control and other advanced technologies, the three-dimensional data model formed on the computer, in the machining center machine tool from the cutting material mining and mining.
After the workpiece is clamped one time, the digital control system can regulate the machine tool to automatically select and change the tool according to different processes, and automatically change the spindle speed, feed amount, tool trajectory and other auxiliary functions of the tool spindle, and complete several workpieces in turn. On multi-process processing, the entire process is automatically controlled by the program, without the operator's human. Compared to RP molding "additive manufacturing", CNC can visually be called machining as "subtractive manufacturing."
2.1 CNC machining precautions
- CNC machining in order to make product size tolerances smaller and more precise, in order to ensure product quality, we generally consider from the aspects of machine tools, tool holders, tool selection, machining methods, and CNC operator requirements.
- Make sure that the machine's X, Y, Z triaxial accuracy is controlled in the 0.005MM range.
- Arbor accuracy is controlled in the 0.003MM range. Tool wear control.
- The preparation of the processing method should consider the characteristics of the material, the structure of the part, the rigidity of the part, the application of the tool, etc., the rough finish machining should be separated, and the positioning of the part clamp should be reasonable.
- Before machining parts, the operator must ensure that the wear of the tool wears the tool in the range of 0.01mm to ensure that each step of the part is correct in the process of clamping or centering.
3. Rapid Mold
Rapid Tooling is based on rapid prototyping--a new type of manufacturing technology that has been developed in order to shorten the development cycle of new products and to introduce to the market, as soon as possible, multi-species and small-volume products that are customized according to customer intent. It has the characteristics of a short cycle and low cost.
The current rapid application of mold manufacturing technology:
- Silicone rubber mold for vacuum injection molding process;
- For reaction injection molding aluminum alloy, ABS mold or epoxy mold;
- Aluminum mold or simple steel mold for injection molding.
3.1 What should be paid attention to in rapid die?
- Positioning ring of mold
It must be checked whether the size of the positioning ring has reached the requirements of 2D drawings.
- Screw processing requirements
Each screw hole is strictly processed according to the theory. The depth of the screw hole requires more than 2 times the diameter of the drill screw, and the tapping depth is more than 1.5 times the screw diameter. Of course, if you have to transport water below, you must be careful. The depth of the screw countersunk head will sink into the mold surface and the screw head will be lower than the die surface 1-2mm.
All molds, molds, fixtures, fixtures, non-use surface or sealant surface must be all chamfered, large mold chamfer C45 degrees X2, small mold chamfer C45 degrees X1 - 1.5MM.
- Inclined top and small inserts must be hardened
All inclined tops and small inserts must be hardened before using.
4. SLS/SLA Technology
4.1 SLS printing technology
SLS (Selective Laser Sintering). This technique uses powder coating to lay a layer of powder material on the top surface of the molded part and heats it to a temperature just below the sintering point of the powder. The control system regulates the laser beam to follow the cross-sectional profile of the layer on the powder layer. Scan the powder and raise the temperature of to the melting point, sinter it, and bond it to the molded part below. After the first layer is completed, the workbench is lowered by a layer of thickness. The spreader roller is covered with a layer of uniform dense powder and a new layer of the cross-section is sintered until the entire model is completed.
- A variety of materials are available. The available materials include a variety of powder materials such as polymers, metals, ceramics, gypsum, and nylon. Especially the metal powder material is one of the most popular development directions in the current 3D printing technology.
- The manufacturing process is simple. Due to a large number of materials available, the process can directly produce complex-shaped prototypes, three-dimensional constructions of cavity molds, or parts and tools, depending on the materials.
- High precision. It is generally possible to achieve a tolerance of (0.05-2.5) mm within the overall range of the workpiece.
- No support structure required. The suspended layer that occurs during the lamination process can be directly supported by the unsintered powder.
- High material utilization. As there is no need for support, unnecessary to add a pedestal. This is the most commonly used material in several 3D printing technologies, and the price is relatively low.
4.2 SLA printing technology
SLA (Stereo Lithography Apparatus). The liquid bath is filled with a liquid photosensitive resin that cures rapidly under the ultraviolet laser beam emitted by the laser (SLA is different from the laser used by SLS. SLA uses ultraviolet laser, while SLS uses an infrared laser). At the beginning of the molding, the lifting table is below the liquid surface, just at the height of section thickness. The laser beam focused by the lens scans the profile along the liquid surface according to the machine instructions. The resin in the scanning area is rapidly cured, thereby completing a layer of cross-section processing process to obtain a layer of plastic sheet. Then, the workbench descends the height of the cross-sectional layer and solidifies the other cross-section. In this way, layers are stacked to construct a three-dimensional entity.
- The longest period of development, the most mature process, and the most extensive application. In the rapid prototyping machines installed all over the world, about 60% of photocuring molding systems are used.
- The molding speed is faster and the system is stable.
- Highly flexible.
- The accuracy is very high and can be done in micron level, such as 0.025mm.
- The surface quality is good and relatively smooth: it is suitable for fine parts.
4.3 What Should SLS/SLA Pay Attention to?
- When you print a new item, you may want to do to experiment quickly with the printer's low settings (ie, high speed, low accuracy), because you do not want to spend too much time finding the size of the item or what is wrong, after the completion of the print
- If you are printing with ABS plastic, be sure to preheat your printing platform to its high temperature, as higher temperatures prevent ABS material from curling up during printing.
- If you use PLA plastic to print, you can use a heated printing platform to stick a layer of blue painter's cloth tape on your platform. It is also cheaper than the legendary tape.
- Kapton tape is the most suitable for heated printing platforms because it has better heat resistance and heat dissipation than Blue Painter Tape fabric tape.
- Learn more about the properties of the print material you have chosen. The two main plastics used in personal 3D printing are ABS and PLA. Each has its own characteristics, such as melting temperature and discharge speed. Make sure that the printer data you set up supports the printed materials you use.