Calculating the amount of ink needed for a packaging and label printing job is a complex task – and one that the printer must get right, to protect profits.
Whether nor not you prepare spot colours, there are several mechanical and material factors that determine how much ink is needed for the job. These include:
- The label or package length and width
- The quantity of packages or, for roll-fed printers, the run-length
- The effective coverage of the colour (or ink formula) on the print surface-area of the substrate
- The absorption of the ink – how much ink is needed to reproduce the design in a specific area. This depends on the substrate (papers are porous, while films and coatings repel water), mechanical considerations as well as ink layer thickness
- The percentage of ink transfer – in flexo, a small proportion of ink is left behind after being transferred from the anilox roll cells or the plate
- The ink set – solvent and water-based inks lose weight in the drying process due to evaporation, while UV ink weight is unaffected by curing
- The minimum amount of ink in the printing station – this is the minimum filling amount in the flexo chamber, gravure fountain or rotary screen squeegee needed for the press to operate.
Why informal ink estimations can harm performance
In practice, ink-room staff tend to prepare a little more than is needed for the job. This is principally to avoid the risk of a shortfall, resulting in a costly production stoppage while remaining inks are mixed. Overestimating ink requirements, though, can lead to ink waste – and even if ‘press return’ leftovers can be remixed into new jobs with an ink dispenser, cluttering up the storeroom with press-return inks raises inventory costs.
It’s common for ink makers to determine requirements for packaging artwork based on professional experience. But in the long-term, this can be harmful to performance because the company becomes heavily dependent on key staff to prepare colours – risking disruption in the case of absence.
How ink management software simplifies consumption calculations
Using software, however, provides a faster, more accurate and reliable alternative for calculating how much of each colour is needed for the job.
An example is GSE Article management, a module within GSE Ink manager. Ideal for situations where a customer places repeat orders for printed labels or packaging, the software calculates the required ink weight for each printing station, using job information provided by the customer.
It includes the facility to store details about the user’s printing presses and the fill weight of each press’s printing stations, and the ability to allocate information to a customer and order number for reporting purposes. The steps are as follows:
How to automatically calculate packaging ink consumption with software:
- Choose a print design (known as an ‘article’ in the program) from a menu.
- Select the press you intend to run the job on. The user will have entered this information, together with each printing station’s minimum fill weight, at the setup stage. Note: the press selection can still be changed later, when creating the order at the planning stage.
- Specify the job’s printing length and width
- For each printing position, specify:
- the spot colour ink formula
- absorption (g/sqm, based on experience or information from your suppliers of tools, consumables and materials)
- coverage factor (% of printed area covered by the ink, usually provided by your design software)
- The system then automatically calculates the weight of the ink, expressed (by default) in kilograms per thousand articles or metres of running length.
- Store this as an article so it can be recalled for dispensing or reporting purposes.
Flexibility to override software calculations
It is possible to modify the unit of measurement and scaling factors used for each unit category (length, width, surface area, absorption, and cost). Metric or imperial measurements may be chosen, according to your regional needs.
For some printers, it’s not always necessary to rely on the software’s ink weight calculations. The user may enter desired ink weights for each colour, adjust the software’s calculations, or store all colours , press and printing sequence positions for an order, and let operators manually determine the required weight when it goes into production.
Reports compare estimates with actual consumption
All ink weight data relating to the order may be easily recalled when the time comes to dispense the colours. After production, the program’s reporting function stores ink consumption data, making it easy to compare planned with actual ink requirements. Please note, however, that accurate reporting data depends on booking in any returned inks from the order, using the software program. This requires all operators to strictly follow procedures.
The many performance benefits of automated ink calculations
Overall, using a dedicated software to define ink requirements for a specific job brings a host of performance benefits:
- Reduced ink waste, meaning lower ink spend
- It’s easier to make accurate consumption forecasts – leading to better inventory control
- Calculations are fast and accurate – reducing makeready time
- You can evaluate what is calculated and what is used, using the data to make more accurate calculations the next time the job is repeated – a feedback loop that promoted a culture of ‘continuous improvement’
- Ink consumption and calculation data for all orders are available for all production staff to collectively learn from previous experiences, rather than rely on the expertise of a designated ink maker.
To find out how GSE Article management software could improve your colour preparation processes, contact us at email@example.com.