Anatomy of a job

  • Printing

    • Press allocation
      Using a Device ID, a JDF file can define which press is allocated to print a job or a part of a job. A fundamental flow in JDF-based workflow is that sales often use cost as the only parameter to decide on press allocation. The press that could print a particular job the cheapest is selected and this choice is reflected in the JDF file sent to prepress and press management systems. Afterwards that choice frequently changes based on press availability, final paper selection or particular issues with the content of a job. Since the press selection also determines prepress specific settings such as dotgain or screen ruling, last minute press changes might lead to having to rerender jobs in prepress.
    • Ink key settings
      Since JDF is the successor to PPF (CIP3), it can also be used to send ink key settings to a press management system. Function wise, the result is similar to using PPF.
  • Finishing

    • Trimming
      more information to be added
    • Folding
      more information to be added
    • Binding
      more information to be added

JDF & cost accounting data

One of the key advantages of JDF is the ability to provide cost accounting feedback to MIS systems. This information can include:

  • the number of proofs made
  • the number of plates made
  • the actual run length and the time needed to print the job

JDF is one way of collecting such data, the alternative is called SFDC or Shop Floor Data Collection. This is a technique in which barcode readers, manual data entry & proprietary links are used to provide feedback to an MIS system.

When using JDF, there are two mechanisms available to report such data.

  • JMF: using the Job Messaging Format a system can provide interactive feedback to an MIS system. Each time a plat or proof is made, a prepress system can send a related Status Signal. A press management system can provide continuous updates about the number of impressions of a job. JMF offers instant feedback but it requires a continuous connection between systems.
  • Systems can collect accounting information in a job and send these data back to an MIS system when they have finished processing the job.This mechanism is called ‘Returned JDF’. Logging data re recorded in the JDF Audit Pool.

Some MIS systems support JMF, some only support Returned JDF & others can handle both mechanisms. The same is true for the systems that need to report these data.

18 January 2015

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