Volumes of production
At the time of writing the process is more a laboratory project than one for mass-production. However, Sodra will work with designers to help realize products.
Unit price vs. capital investment
The cost of a press-forming tool is in the region of 50,000 US dollars.
Speed
The components have to be left in the press for approximately seven minutes and a fair amount of handwork is required to finish them.
Surface
As expected, the surface looks and feels like ultra-stiff cardboard. Colors, approved for use in children’s products, are impregnated within the paper before the forming takes place.
Types/complexity of shape
Shapes are based on a standard male and female configuration, so undercuts are not feasible.
Scale
At the time of writing the maximum size of the press tool is 20 x 40 inches.
Tolerances
Thickness dimensions are in the range of 1/12 inch to 3/8 inch (although 3/8 inch has yet to be tested).
Relevant materials
DuraPulp is made from paper pulp mixed with PLA.
Typical products
Products currently being tested are in the area of furnishings, such as chairs and lighting.
Similar methods
Molding paper pulp (p.149), paper-based rapid prototyping (p.242).
Sustainability issues
DuraPulp is made using paper pulp and organic plastic both of which are nontoxic and renewable. At the end of its lifespan the material will biodegrade without harming the soil, avoiding landfill disposal. However, the process involves several manufacturing stages and is quite heat intensive, so has high energy use.
Further information
www.sodrapulplabs.com
Bending Plywood
Product |
AP Stool |
Designer |
Shin Azumi |
Materials |
plywood |
Manufacturer |
Lapalma srl |
Country |
Italy |
Date |
2010 |
This elegant, stackable stool is formed from a single sheet of plywood, with the seat and the body of the stool merging seamlessly. The wide spread of the base helps to disperse pressure.
The conversion of a tree into a simple-looking piece of bent plywood furniture involves at least 35 steps. The technique of cross-laminating veneers to produce stable, stiff engineered materials was first understood by the ancient Egyptians, who used the process for making items such as their iconic sarcophagi. The development of modern bent plywood is the result of a range of technological advancements, including the ability to cut the veneers accurately, the presses to laminate them, and the glues to construct them.
The processing of most natural materials tends to be concentrated in the locations where the materials originate, and plywood production takes place mainly in northern Europe, North America, Southeast Asia, and Japan. Starting from the point where the veneers have been sliced or rotary-cut from the logs, these large strips are cut into individual sheets, which are subsequently dried by being passed through a long chamber, at the end of which they are stacked according to quality.
The veneers are fed into rollers that distribute an even layer of glue over each sheet, with the quantity of glue being determined by the porosity of the wood. The various sheets are then stacked, with the grain running in alternate directions, to form an odd number of layers. The assembled sheets are placed over the female part of a mold, with the male part clamped on top. The molds allow for an excess of veneers, which is trimmed to form neat edges once the glue has dried. Depending on the shape, a pressure of several tons is needed to compact the sandwich together. The vertical pressure is aided by horizontal pressure, forcing the molds to come together from all sides, and a combination of heat and pressure cures the glue. The part stays in the mold for about 25 minutes, the exact time depending on the shape. In industrial production, a CNC (computer numerical control) cutter is then used to trim the uneven layers to form a clean edge.
– Can accommodate a range of thicknesses.
– Allows for strong, lightweight components.
– Involves many steps.
– Restricted to bends in a single direction.