Volumes of production
As a form of rapid prototyping the process is ideal for low-volume production.
Unit price vs. capital investment
The process is said to be up to 50 times cheaper than those used for plastics: paper costs very little and is available almost anywhere.
Speed
The cell-phone covers shown here were built in 5–10 hours.
Surface
The surface has the consistency of wood and requires minimal finishing. The Z-axis resolution is 1/250 inch.
Types/complexity of shape
The process is suited to most complex shapes that can be produced by stereo-lithography. The exceptions are thin, spindly shapes.
Scale
The process is based on standard 8½ x 11 inch paper and a maximum stack height of 6 inches.
Tolerances
Currently 1/250 inch on the XY-axis and 1 percent on the Z-axis.
Relevant materials
Standard photocopier paper; Mcor Technologies recommend low-grade paper with a low fiber content for best results.
Typical products
The process is being developed for use in the medical industry, to reproduce X-rays in a physical form to help surgeons to plan ahead of operations, and in dentistry to enable orthodontists to create molds of patients’ teeth much more quickly than can be done using plaster. It is also expected that the process will be introduced for engineering, architectural, and industrial design programs, for use by students as a cheaper alternative to traditional plastic rapid prototyping. It is also a popular choice for architectural models, and as rapid tooling for molds in processes such as vacuum forming, and also investment and sand casting.
Similar methods
Molding paper pulp (p.149), pulp paper composite from Sodra Paper Labs (p.78).
Sustainability
Paper is a rapidly renewable resource, and is also widely recycled. No toxic fumes are released during processing, as they are with some plastic rapid prototyping, and components can be produced in a short timescale to make effective use of energy consumption.
Further information
www.mcortechnologies.com
Contour Crafting
Product |
contour-crafted prototypes and CAD design drawing |
Designer |
developed by Dr. Behrokh Khoshnevis |
Materials |
concrete |
Manufacturer |
Dr. Khoshnevis, under National Science Foundation and Office of Naval Research |
Country |
USA |
These samples, though not on the scale of a building, illustrate the types of forms that can be created through contour crafting. Above is an example of the sort of CAD design that will drive the spraying process.
This is a process that has the potential to revolutionize the construction industry. Dr. Behrokh Khoshnevis, of the University of Southern California, has invented a machine that “prints” houses. As he points out, the automation of the manufacturing industry has been advancing steadily ever since the Industrial Revolution. In comparison, developments in the construction industry have been meager during the same period. However, this is something that Dr. Khoshnevis plans to change with a process he calls “contour crafting,” an advanced form of spraying concrete.
Planned to be commercially available in 2008, the machines that are at the heart of this technology use a method of depositing concrete that is similar to that used in inkjet printers (see p.240) and extrusion (p.96). In this case, however, the technology is on a much larger scale, and it includes the ability of the “printing” head to move in six axes and build up material in layers, based on CAD drawings rather than on two-dimensional graphics.
The “printing” nozzles, which are suspended from an overhanging carriage, deposit quick-drying concrete that is shaped by an integral trowel using a cylinder-and-piston system. A secondary feature of contour crafting is that the system allows utilities, such as conduits for electricity, plumbing, and air-conditioning, to be embedded into the process.
– Allows for rapid construction.
– Plans and designs can be easily altered because they are CAD-driven.
– It is possible to use local materials as reinforcement for the cement.
– Cost-effective.
– Automated process.
– Still in its infancy.