Inappropriate processing refers to the waste of "using a hammer to crack a nut". Thinking in terms of one big machine instead of several smaller ones discourages operator "ownership", leads to pressure to run the machine as often as possible rather than only when needed, and encourages general purpose machines that may not be ideal for the need at hand. It also leads to poor layout, which as we have seen in the previous section, leads to extra transportation and poor communication. So the ideal is to use the smallest machine, capable of producing the required quality, distributed to the points of use.

Inappropriate processing also refers to machines and processes that are not quality capable. In other words, a process that cannot help but make defects. In general, a capable process requires having the correct methods, training, and tools, as well as having the required standards, clearly known. The ideal is to have machines with available capacity exactly matched to demand.

Note that it is important to take the longer-term view. Buying that large machining centre may just jeopardise the possibility of cells for many years to come. Think "small is beautiful". Smaller machines avoid bottlenecks, improve flow lengths, perhaps are more simple, can be maintained at different times (instead of affecting the whole plant), and may improve cashflow and keep up with technology (buying one small machine per year, instead of one big machine every five years).

Examples: variation between operators, variation from standard, having to use a "fast" machine shared between several lines.