Batch machining is defined as manufacturing a minimum of two parts on the machining table at any given time. This section uses the terms “batch machining” and “batch processing” interchangeably. There is no limit to the number of parts that define a batch, but ideally the manufacturer achieves efficiencies by maximizing the space available on the router machine bed and producing as many parts in one run as possible.
When companies produce a quantity of parts, they usually have an operator in front of the machine for an entire shift, producing work-pieces one at a time. The operator takes raw stock, puts it on the router machine bed, mills the part and then removes it repeating the entire process for eight hours. Therefore, the operator is dedicated or “tied” to a single router machine. This procedure is known as “one-up” production.
Based on an 8-hour day, labor costs about $0.40 a minute and a router machine costs about $0.20 a minute to operate. Therefore, if you tie an operator to the router machine with one-up production, your total cost will be $0.60 a minute. If you were to run two shifts, the router machine would cost only $0.10 a minute, while the labor cost remains the same at $0.40 a minute. Although it’s a savings, it falls short of maximizing the impact on a manufacturer’s bottom line and more can actually be saved. By empowering the machine do the work without operator intervention during the second shift, the reduction in the labor cost brings the router machine cost as low as $0.05 a minute.
Batch machining connectors, for example, on a large machine bed reduces operator intervention since it accommodates large sheet material so a full panel batch can have a cycle time that coincides with the length of an operator’s shift. That way, the operator can place a sheet on the machine in the morning and attend to other duties during the day. The automated machine works all day producing the panels. Near the end of the shift, the operator then removes the completed batch of panels, sweeps down the CNC machine, and sets up another sheet to run unattended all night.
When the operator returns to work the next morning, he removes the batch of connectors that the router machine produced overnight and starts up another one. This gets two shifts’ worth of work out of one operator. This is the principle of “lights out” production so named because the machine is left running overnight when everyone has gone home. Bear in mind that the above example reflects the “ideal”, since it keeps the machine operating unattended for most of the workday and at night. This may not fit your exact application but, the closer you can get to that ideal, the more efficient and cost-effective your operation will become.