What Is Laminated Object Manufacturing (LOM)？

Layered object manufacturing is also known as the narrow laminated preparation technology, which uses sheet materials, laser and hot melt adhesive to make laminated structures. The system mainly includes computer, numerical control system, raw material storage and transportation components, thermal adhesive and pressure components, laser cutting system, lifting table and other parts. The laser cutter will cut the film along the contour line of the cross section of the workpiece, and the thermal bonding and pressing part will bond the films in the forming area layer by layer until the workpiece is completely formed. However, few people know about laminated object manufacturing technology in our life. I will introduce some knowledge related to laminated object manufacturing.

 

 

Materials of Laminated Object Manufacturing

The forming material in the manufacturing of layered entities is a thin layer of material coated with hot melt adhesive, and the bonding between layers is ensured by hot melt adhesive. The material generally consists of two parts: sheet material and hot melt adhesive. According to the different performance requirements of prototype parts, sheet materials can be divided into: paper sheet, metal sheet, ceramic sheet, plastic film and composite material sheet. There are the following performance requirements for the base sheet material:

(1) Good moisture resistance is required to ensure that raw materials will not absorb water due to long time.

(2)  Good wettability is required to ensure good gluing performance.

(3)  Good tensile strength is needed to ensure that it will not be broken during processing.

(4)  Low shrinkage is required to ensure no deformation due to partial water loss during hot pressing.

(5)  It is necessary to have good stripping performance so as to make the surface smooth and have better stable parts.

 

The hot melt adhesive used for LOM paper base is divided into matrix resin, mainly including ethylene-vinyl acetate copolymer hot melt adhesive, polyester hot melt adhesive, nylon hot melt adhesive or their mixture. Hot melt adhesive requires the following properties: good hot melt and cold set properties, stable physical and chemical properties under the condition of repeated "melting and curing", good coatability and uniformity with sheet materials in the molten state, sufficient bonding strength, and good waste separation properties.

 

 

Characteristics of Laminated Object Manufacturing

Compared with other rapid prototyping technology, the laminated object manufacturing has the advantages of high precision, high manufacturing efficiency and low cost. This is because when thin materials are selectively cut and formed, only a very thin layer of glue in the raw materials changes state from a solid state to a molten state, while the main base materials remain in the solid state, so the warping deformation is small and the internal stress no longer exists. In layered solid manufacturing, the laser beam only needs to be cut according to the section profile provided by layered information without scanning the whole section, so the manufacturing efficiency is high and the cost is low. Structural parts can withstand temperatures as high as 200℃, have higher hardness and better mechanical properties, and can be used for various cutting processes. However, the disadvantages of laminated object manufacturing are: the tensile property and elasticity of the rapid prototyping parts are not high, they are easy to absorb moisture and expand, and it is difficult to peel off the waste materials of thin-wall parts and thin-column parts. LOM forming process is most suitable for manufacturing large-sized rapid prototyping parts. The mechanical properties of the formed parts are relatively high. The molding materials for LOM molding process are coated with hot melt adhesive and special additives. The formed parts are as hard as bakelite and have good mechanical properties and good mechanical processing properties. The precision of formed parts is high and stable, the price of raw materials is cheaper than other methods, and there is no need to design and manufacture supporting structures.

 

 

Application of Layered Solid Forming

LOM shaped parts are mainly used in the following aspects.

(1) Making paper functional parts directly for appearance evaluation and structural design verification of industrial modeling in new product development.

(2) Making use of the bonding property of materials, large-sized parts can be made, and complex thin-walled parts can also be made.

(3) Making silicone rubber mold through vacuum injection molding machine and trial-producing a small amount of new products.