Highlights of Laminated Object Manufacturing
•Layers of glue-backed paper form the model.
•Low cost: Raw material is readily available.
•Large parts: Because there is no chemical reaction involved, parts can be made quite large.
•Accuracy in z is less than that for SLA and SLS®. No milling step.
•Outside of model, cross-hatching removes material
•Models should be sealed in order to prohibit moisture.
•Before sealing, models have a wood-like texture.
•Not as prevalent as SLA and SLS®.
Laminated Object Manufacturing
The figure below shows the general arrangement of a Laminated Object Manufacturing (LOM™, registered trademark by Helisys of Torrance, California, USA) cell:
Material is usually a paper sheet laminated with adhesive on one side, but plastic and metal laminates are appearing.
Layer fabrication starts with sheet being adhered to substrate with the heated roller.
The laser then traces out the outline of the layer.
Non-part areas are cross-hatched to facilitate removal of waste material.
Once the laser cutting is complete, the platform moves down and out of the way so that fresh sheet material can be rolled into position.
Once new material is in position, the platform moves back up to one layer below its previous position.
The process can now be repeated.
The excess material supports overhangs and other weak areas of the part during fabrication. The cross-hatching facilitates removal of the excess material. Once completed, the part has a wood-like texture composed of the paper layers. Moisture can be absorbed by the paper, which tends to expand and compromise the dimensional stability. Therefore, most models are sealed with a paint or lacquer to block moisture ingress.
The LOM™ developer continues to improve the process with sheets of stronger materials such as plastic and metal. Now available are sheets of powder metal (bound with adhesive) that can produce a "green" part. The part is then heat treated to sinter the material to its final state.