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Converting Parts from MRP to JIT Production >
Part Conversion
Part Conversion
Once the above points have been addressed, part conversion can begin. Conversion involves adding and changing information in the Design Engineering module, and rerunning Product Costing, Master Scheduling, and Requirements Planning.
Design Engineering -- Part Master Maintenance
On the Change Description Screen, the Production Type field must be changed from MRP (1) to JIT (2). In addition, the scrap option should be changed to 1 (if scrap should not be accounted for) or 2 (if scrap should be accounted for); option 3 does not apply to JIT parts. The variance option should be set to 1.
Fields that relate specifically to JIT-produced parts may be entered on the Change Productivity Screen. The following fields are necessary for successful JIT production:
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PRODUCTION CENTER
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The main production center where the new JIT-produced part will be scheduled through Master Scheduling and Requirements Planning.
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CONBON CONTROL CODE
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The CONBON system that will be used to control the flow of the part (see the CONBON User Manual for definitions of these methods). The user may select a two-card system (CON and BON cards) to signal production and authorize movement. A single-card system may be chosen when less stringent control is necessary (for example, when production centers are close to one another or when a part is only used by a single cell). If a method other than CONBON is desired to control material flow, the user may select no cards. The field defaults to two cards (2).
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RELIEF TYPE
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The user may track inventory at either the part's point of use or point of production. The default value is point of use (1).
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AUTHORIZED QUANTITY
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The quantity of a JIT part that must be requested before production of that part may begin. Ideally, this number should approach one, indicating that a single part is produced as it is needed. If CONBON is installed, this value is used in CONBON analysis.
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CONTAINER CODE
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The container used to hold this part. If CONBON cards are being used, this code is essential to accurate CONBON analysis. The container must be defined on the Container Master File.
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CONTAINER QUANTITY
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The standard number of parts that the container holds. This quantity defaults from the Container Master File, but may be overridden.
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PRODUCING LOCATION
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Used in the Flow Receipt conversation as the receiving location for parts defined as dual-card or point of production. If a part is defined as point-of-production or point-of-use in a dual-card environment, this value should be defined. This location is also referred to as the outbound stock point for the part's producing cell.
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RELIEF LOCATION
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If the part has components that are defined as point of use, the relief location should be defined. This location is also referred to as the inbound stock point for the part's producing cell.
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Additional fields related to JIT parts are found on the Change Planning Screen:
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STOCK QUEUE DAYS
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The number of days-worth of production that should be kept in a cell. This type of variable buffer stock is consumed when the cell is producing some other part. It is used in CONBON analysis to determine the number of extra containers of inventory to allow. The Requirements Planning module takes stock queue days into account when planning production. The value defaults to zero.
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PLANNING POLICY CODE
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Used in the Master Scheduling and Requirements Planning modules to determine production over the flow interval periods. The default value is partial (6) for JIT parts, but may be changed to averaged (7), fixed time period (2) or fixed quantity (3). Refer to the Requirements Planning User Manual Key Concepts for definitions of these options.
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LEADTIME
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For JIT parts, this field must be manually specified. Lead time is used in the CONBON Analysis Program to determine when cards should be printed. This field should be the greatest of all component offsets (see product structure fields).
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Design Engineering -- Product Structure Maintenance
Fields on the Product Structure File that may need to be changed for converting parts from MRP to JIT production include the following:
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COMPONENT OFFSET
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The number of days from the issue of the component part to the receipt of its parent part.
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DELIVERY FREQUENCY
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The number of times a component part is delivered to the parent part during a day in a JIT environment.
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DEDUCT OPERATION
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The step in the routing of the parent part where the component is issued through the Deduct Issues Program.
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BON SAFETY STOCK
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The quantity of the component part that is reserved for the parent. This field is used in the calculation of BON cards in the CONBON Analysis Program. It is defined in the stockkeeping unit of measure.
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Product Costing
Once the new JIT routing has been established and the product structure and part master fields have been modified to contain the desired values, Product Costing should be rerun for the part, because JIT parts are costed differently than MRP parts.
Master Scheduling and Requirements Planning
After all fields necessary for converting parts from MRP to JIT production have been entered or changed, Master Scheduling and Requirements Planning must be rerun. Existing manufacturing orders are handled as follows:
· Open manufacturing orders are left unchanged. They are handled exactly as they were when the part was an MRP part. When MS and RP are run, action messages for the order are still being given. If, however, additional requirements occur for the time period spanned by a manufacturing order, the additional demand will be satisfied by new flow authorizations.
· Firm manufacturing orders are left unchanged. After the transition from MRP to JIT production, firm manufacturing orders may be opened and maintained in the same manner as open manufacturing orders. They may also be manually closed.
· Planned manufacturing orders are converted into flow authorizations once MS and RP are run to reflect the part's new status as a JIT-produced part.