Fabrication

Fabrication is the act of taking stock material and turning it into a part for use in an assembly process. There are many different types of fabrication processes. The most common are

1. Cutting. There are many ways to cut nowadays. The old standby is the saw. Others now include plasma torches, water jets, and lasers. There is a wide range of complexity and cost, with some machines costing in the millions.
2. Folding. Some parts need to be bent. The most common method is a press brake (or brake press). It has a set of dies that pinches the metal to form a crease. This operation can only be performed in very specific cases due to the movement of the part and the possible shape of the dies. Designing for Lean manufacturing, though, can help prevent complex shapes that slow down production. Sometimes using two different types of fabrication processes or two different pieces fastened together work better than one complicated piece.
3. Machining. This is the process of removing metal from a piece of material. It might be done on a lathe, where the material rotates against a cutting tool, or in some other cutting machine where a rotating tool is moved in a variety of ways against a stationary piece. Drills fall into this category. The range of motion of the cutting head is defined by the number of axes (i.e. a 3-axis machine).
4. Punching. Punching is the act of a punch and a die forming a ‘scissor’ effect on a piece of metal to make a hole in it. Obviously, the punch and die must be the same shape and size of the desired hole. In some cases, the main piece of material is kept, as in when holes are added for fasteners. In other cases, the piece that is removed is the desired product-this is called ‘blanking’.
5. Shearing. Shearing is the process of making a long cut on a piece of metal. It is, in effect, just like the action of one of those paper cutters with the long chop-handle. This is done on sheet metal.
6. Stamping. Stamping is very similar to punching, except the material is not cut. The die is shaped to make a raised portion of material rather than penetrating.
7. Welding. Welding is the act of joining two pieces of metal together. Different

The are many other types of fabrication that are less common than the ones in the list above. There are also constantly new types of fabrication methods being developed.

One such new type is called additive technology. It is really something like a cross between fabrication and injection molding. In effect, a machine layers materials to form a part-something like a three dimensional printer that prints in plastic.

Fabrication processes are particularly well matched to Lean. The motion of operators, their interaction with machines, and the need to manage inventory are all right in Lean’s power alley.

Fabrication processes are particularly well suited to implementing jidoka (autonomation) and hanedashi devices (autoejectors). Both of those devices are prerequisites of the chaku-chaku line (load-load).

But there is one area where Lean can struggle. Some extremely large machines are well matched to the products they are making. But far too many big machines with too long of a changeover time drive up inventory and promote overproduction. It is best to ‘right-size’ machines and put them into work cells if possible. That helps create flow.

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