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Start Dates in Production Plans

When you create a Production Plan, each Item will be given a Needed Date. In the case of a Production Plan that you create from a Sales Forecast (i.e. using the 'Create Production Plan' Maintenance function), the Needed Date for each Item will be the first day of the Sales Forecast period (i.e. the first day of a week or month), so that the Items will be in stock ready to sell during the week or month. Each Item will also be given a Start Date. The Start Date is the date when production work should begin in order for work to be complete on the Needed Date. This section describes how Start Dates will be calculated.

The calculation of the Start Date in a Production Plan row requires some or all of the following information:

  1. Fixed Assembly Days, Time to Setup, Days/Hours/Minutes/Seconds to Produce and Number Produced in the Recipe. In more detail, these fields are as follows:
    Days to Produce
    The number of days required to build a single application of the Recipe (i.e. the number of days required to build the Out Qty). One day is 24 hours.

    Hours/Minutes/Seconds to Produce
    The number of hours/minutes/seconds required to build a single application of the Recipe.

    If you specify any combination of Days, Hours, Minutes and Seconds, they will be added together.

    Fixed Assembly Days
    This is a constant figure irrespective of the quantity being built (i.e. it is for work that is carried out once per production run, and so will be the same irrespective of the number of applications of the Recipe). Again, one day is 24 hours.

    Time to Setup
    This is a constant figure irrespective of the quantity being built (i.e. it is for work that is carried out once per production run, and so will be the same irrespective of the number of applications of the Recipe).

    This field uses a time format. For example, if the Time to Setup is two hours, enter "02:00:00". The maximum time is 23:59:59.

    Number Produced
    The Time to Setup, the Days, Hours, Minutes and Seconds to Produce and the Fixed Assembly Days fields above usually refer to one application of the Recipe i.e. they are the times required to produce the Out Qty of the Output Item. If this is not the case, enter the number of applications of the Recipe to which these times refer.
  2. Buffer Days in the Production Settings setting in the Production module.

  3. A record in the Production Item Alternatives register connecting the Recipe to a Machine.

  4. A record in the Machine Hours register for the Machine Group to which the Machine belongs.
For example, five units of an Item are required by November 1. The calculation of the date when production should start will proceed as follows:
  1. The first stage is to calculate the time required to build the five units, using the information in the Recipe, for example:

    Days to Produce (1 day each, from Recipe) 5
    Hours to Produce (12 hours each, from Recipe) 2.5
    Fixed Assembly Days (from Recipe) 2
    Total9.5
    This assumes that the Number Produced in the Recipe is one. If it is more than one, the Days, Hours, Minutes and Seconds to Produce will be divided by the Number Produced. In this example, the Number Produced is 2:

    Days to Produce (1 day each, from Recipe)/Number Produced2.5
    Hours to Produce (12 hours each, from Recipe)/No. Produced1.25
    Fixed Assembly Days (from Recipe) 2
    Total5.75
  2. If the Recipe includes a Time to Setup and/or a Hours/Minutes/Seconds to Produce, and their overall contribution to the calculation is not a whole number of days, the decimal part can be rounded up to one day providing it is greater than one hour. This rounding up will occur if you are using the Round odd Hours to One Day option in the Production Settings setting. Otherwise, the decimal part will be truncated. In this example, the Hours to Produce will be rounded up by the Round odd Hours to One Day option:

    Days to Produce (1 day each, from Recipe)/Number Produced2.5
    Hours to Produce (12 hours each, from Recipe)/No. Produced2
    Fixed Assembly Days (from Recipe) 2
    Total6.5
  3. It will therefore require 6.5 days to produce the five units. This means 6.5 24-hour days, or 156 hours. The next step is to check the working hours of the Machine that will be used to produce the Item.

    The Machine will be established from the Production Item Alternatives record for the Item, as follows:

    1. The Machine will be the Default Machine specified in the header of the Production Item Alternatives record.

    2. If there is no Default Machine in the Production Item Alternatives record, the Machine will be taken from the first row in which the Default Recipe is the Recipe in the Item record.

    The working hours of the Machine will be taken from the record in the Machine Hours register for the Machine Group to which the Machine belongs.

    For example, if the Machine works for eight hours, Monday-Friday, the 156 hours will require 29 calendar days (the calculation will be rounded up to the nearest whole day).

    If there is no record for the Item in the Production Item Alternatives register, or no record for the Machine Group in the Machine Hours register, it will be assumed that the working day for production work is 24 hours.

  4. The final part of the calculation will add in the Buffer Days from the Production Settings setting:

    Total from previous step29
    Buffer Days (from Production Settings) 3
    Total32
  5. The Start Date will therefore be 32 days before the Needed Date, September 30.
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The Calculation Formula in the MRP module:

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