Analyze the principle and characteristics of laser rapid prototyping technology

Knowledge sharing by Guangdong Shunde Teamwork Model Technology Co., Ltd, whom with over 20 years rapid prototyping experience.

Email: ken@gdtwmx.com

Website: www.gdtwmx.com

Most of the traditional industrial forming techniques follow this method, such as turning, milling, drilling, grinding, and planing; others use molds for forming, such as casting and stamping. Laser rapid prototyping uses a new forming principle - layering and superposition. For those who have studied advanced mathematics, this principle is no stranger. In the application of definite integral, it has been said that the busbar is a known volume of the rotating body volume calculation and the parallel section is known to calculate the volume of the solid volume, both of which take a section with a thickness of ΔXi, which is approximately regarded as a flat cylinder. Or curved the cylinder, then add it:

When ‖Δx‖→O, a volume of a known volume of the rotating body or the parallel section is obtained, respectively.

The topography is composed of complex curved surfaces, but as long as we plot the contours of different heights, we can cut the curved planes of different sizes and shapes on the flat plate (of course, the thickness of the board and the adjacent two The height difference between the contour lines should match the scale of the topographic map), and then stack them together. As long as the contour lines are dense enough, they can be made into realistic terrain models.

At present, there are many kinds of laser rapid prototyping machines developed according to the principle of layering processing and superposition forming. Here, the main ones are summarized as follows:

1. Liquid photopolymer selective curing (SLA: Strreolithography pparatus stereo lithography equipment)

In 1902, a patent in the United States proposed the principle of manufacturing plastic parts from photopolymers. In 1986, another patent in the United States proposed a rapid prototyping scheme for layering three-dimensional entities by laser irradiation of liquid photosensitive resin. According to this, 3DSYSTEMS In 1988, the first laser rapid prototyping machine SLA-250 was produced.

The configuration material used in the laser rapid prototyping machine is a liquid photopolymer, which undergoes a polymerization curing reaction under the irradiation of ultraviolet light, and changes from a liquid state to a solid state, and has the advantages of directly obtaining a plastic-like resin member. And the surface roughness is small.

The disadvantages are:

(1) Chemical and physical changes during the forming process make dimensional accuracy difficult to ensure and creep occurs;

(2) The entire section shall be scanned and solidified, the forming time is longer, and further curing after forming;

(3) Since the portion not irradiated by the laser beam is still in a liquid state, the overhang portion is designed in advance, and then removed after curing;

(4) Photosensitive resin is brittle after curing, easy to break, poor processability, working temperature can not exceed 100 ° C, will absorb moisture, corrosion resistance is not strong, and expensive (140-2404 / kg);

(5) The laser tube that produces the ultraviolet laser has a life of about 2000 hours.

2, thin material selective cutting (LOM: Laminatedbjeetanufacturing layered object manufacturing)

The configuration material used in this rapid laser forming is a paper coated with hot melt adhesive in advance, and the forming process is similar to the process of making a topographic model as described above.

The advantages are:

(1) high dimensional accuracy;

(2) It is only necessary to cut the contour line, and the production efficiency is high;

(3) No need to design support;

(4) The prepared sample has the hardness similar to that of wood products, and can be used in a environment below 200 ° C after a slight treatment, and can perform certain cutting processing;

(5) The life of the carbon dioxide laser used is up to 20,000 hours;

(6) The configuration material is cheap (8/kg).

The disadvantages are:

(1) Plastic parts cannot be made directly;

(2) The surface roughness is high, the surface of the workpiece has obvious step marks, and it needs to be polished after molding;

(3) It is easy to absorb moisture and expand, and it should be treated as soon as possible after surface formation;

(4) The workpiece lacks elasticity.