Integral Logistics Management — Operations Management and Supply Chain Management Within and Across Companies

1.2.5 Rough-Cut Product Structure, Rough-Cut Work Center, Rough-Cut Operation, Rough-Cut Process Plan: Rough-Cut Business Objects

Intended learning outcomes: Identify reasons and principles for defining rough-cut business objects. Disclose the rough-cut product structure, the rough-cut work center, the rough-cut operation, and the rough-cut process plan. Explain a way to derive a rough-cut process plan from a detailed process plan.

To estimate the requirements for goods and capacity quickly, planning cannot reach the detail of the precise number of screws or the minutest task. Sometimes only partial data are needed, because

  • Only relatively few purchased items, such as raw materials or semifinished goods, are expensive or difficult to procure (have very long procurement lead times).
  • For a great percentage of work centers, load is not critical, because for technical reasons, over­capacity is the rule (for example, replacement machines or special machines that are not available with low capacity).
  • Various processes are very short and do not affect the total load of a work center.

Furthermore, it can suffice to use item families or product families as the business object rather than individual items or products. In analogous fashion, the following rough-cut business objects may be defined:

Rough-cut product structure is the structured makeup of the product from its components, whereby both product and components may be an item or product family. For convergent product structure (see Section 4.4.2), the term rough-cut bill of material is also used.

A rough-cut work center is composed of the total of work centers that do not have to be further differentiated by rough-cut planning & control.

A rough-cut operation is composed of the total of operations, not further differentiated by rough-cut planning & control.

A rough-cut routing sheet for a product (family) is the overall chain of operations, not broken down further by rough-cut planning & control.

The rough-cut production structure of a product (family) is the combination of its rough-cut product structure and the rough-cut routing sheets of the product or product family itself, as well as associated (rough-cut) assemblies and single parts.

The rough-cut process plan of a product is the rough-cut production structure plotted on the time axis.

One way to derive a rough-cut process plan from a detailed process plan involves three steps:

  1. Determine an item’s item family. Determine the item families to be included for the rough-cut product structure.
  2. Determine the work centers or rough-cut work centers to be included and assign the work centers to the rough-cut work center. Determine a time length for operation time under which a (rough-cut) operation can be omitted in a rough-cut structure. Instead, determine a percentage for the reduction of capacity that will be caused by these short operation times, and use this percentage to take these into account.
  3. Determine rough-cut product structure (rough-cut bill of material) and the rough-cut routing sheet for each product or product family, often by contraction of several structure levels into one.

Example: The following list contains measures that allow, departing from the detailed process plan in Figure, the formulation of the rough-cut process plan. The numbered steps refer to steps 1 and 2. Figure shows the result.

  • 1a. Purchased components X, Y, and Z form a single item family Y’.
  • 1b. Component E is not included in the rough-cut structure.
  • 1c. Components G and B form the single item family B’.
  • 2a. Work center 6 is not included in the rough-cut structure.
  • 2b. Work centers 5 and 7 join to form a single rough-cut work center 7’.
  • 2c. All operations having an operation time of less than 0.1 hours are not included in the rough-cut structure.

Fig.        Rough-cut process plan for product P.

The rough-cut process plan must, of course, include (rough-cut) inter­operation times, which are no longer apparent once individual (rough-cut) operations have been excluded. Other­wise, lead-time calculation will be wrong. Every (rough-cut) component gains the correct lead-time offset in relation to the completion date of the product. Setup time and setup load are divided by a norm batch size and added to run time and run load. The lead-time offset then refers to that batch size.

Continuation in next subsection (1.2.5b).

Course section 1.2: Subsections and their intended learning outcomes