Curriculum - Hands on manufacturing

Allowing materials and processes to help guide design is critical in understanding mass customization. Industrial equipment cutting flat panels is nothing new, but understanding how process effects efficiency and then makes objects easier and less expensive to produce is critical. Below is an example of Context Furniture’s material handling for the Truss Occasional Table and Kids Chairs.
Lumber and Laminator
Sheets of 18mm (3/4”) Baltic birch plywood are sent to the laminator. The laminator needs the wood, the color laminate (which the client can spec from any color available) material backer, masking paper and glue. The masking paper is applied to the laminate via a pinch roller. The stacks of material are set on a glue spreader conveyor; the boards are glued together in the appropriate order and cold pressed in a large hydraulic press. The panels needed for the Truss Kids chair and Occasional Table are one 36mm x 5 x 5 panel with laminate on both sides, and one 18mm x 5 x 5 panel with laminate on one side and paper backer on the other side. These two panels are then sent on to the CNC router.
CNC Router
The router operator needs to pre program the digital files from CAD software into CAM software. The panels are placed upon a large vacuum hold down bed, and the router cuts the interior shapes, the exterior shapes and drills any surface holes that are necessary. The size of the bit determines the size tolerence the cut path needs, so parts must be nested a certain distance away from each other. Profile furniture parts are cut from the 36mm panel, and surfaces such as tabletops and seats are cut from the 18mm panel.

When the parts are removed from the CNC router bed, the surface edges have been cut smooth, which eliminates the need for sanding. The sharp edges do need to be softened, so the parts are run along a table router to chamfer the edges. Any secondary drilling or boring also takes place. Connection hardware is inserted and the parts move to finishing.

Finish/Ship
A large conveyor, spray booth and oven accomplish the finishing. Each part is sealed, sanded, coated, sanded and then top coated. The entire process takes several days. After finishing the parts are ready for quality control inspection, removing of the masking paper protecting the laminate, cleaning and test fitting. If everything passes inspection the parts are packed with instructions and hardware, either in a box for shipping or blanket wrapped for an installation. The packing of parts is as critical a step as any other; since damage due to transportation is the part of the process that is most out of the company’s control. The finished product arrives on the client’s doorstep ready to assemble.

CNC
The advancement of computer numerical controlled, or CNC, cutting machines has helped make mass customization a reality. There are a few common types of CNC cutting tools: Routers, Laser and WaterJet machines. A commonality in these machines is material lays on a flat bed with a hold down system that keeps the material in place while cutting. This can be as advanced as a vacuum hold down system or as simples as clamps. The cutter head is attached to a mechanical arm, or gantry, that travels along the x and y axes in relation to the material it’s cutting. In some instances the machine can also engrave along the z-axis.
Router
Router machines use bits that rotate at high speeds to abrade and cut the material away. These router bits can have a variety of shapes and sizes for not only cutting through material, but also for cutting relief patterns and shapes into the material. Advanced versions of these machines can cut on 5-axis and may have specialty fixtures or jigs system to hold complicated or curved parts. Routers are best for cutting wood and non-ferrous metals, plastics and composites. An advantage of the router is the ability to cut thicker materials by making several passes. Disadvantages are the equipment is limited by tool size and the number of tool changes and cutting paths increase cost.
WaterJet
A Water Jet uses a pump to force water through the cutting head that generate high pressure so the resulting water stream can cut surfaces like plastics, foam, wood, rubber and vinyl. The jet stream is pinpoint small, allowing extremely intricate cutting. An aggregate can be added to the water jet stream to create a more abrasive cutting action. This allows metals, stone, ceramic and glass to be cut as well. The ability of this machine to cut through very hard and thick material sometimes makes it the only option. The process does not generate heat, so it won’t distort metals. However, it is a wet environment so materials like wood, fiber and fabrics may not be best suited for water jet cutting.
Laser
Laser cutting uses a high power laser that melts, burns or vaporizes material away. Thin gauge metals, fabrics and paper are well suited to laser cutting. Plastics, wood and thicker gauge metals can also be cut. The laser leaves a high quality edge surface (aluminum and steel) but also a visible burned edge on some materials (like wood). The intricacy and finite precision of the laser make it a good fit for small detailed jobs.
Carvewright
When CNC cutting technology was introduced the cost of the equipment was high and the scale was large. As advances in technology have been made, access to the equipment has increased, making tools more available and not as cost prohibitive as they once were. A good example of this is a do-it-yourself Carvewright machine, which sells at Sears for less than $1800.
http://www.sears.com/shc/s/p_10153_12605_00921754000P