Compressed air monitoring on a machine tool as a basis for energy efficiency measures
Keeping track of compressed air costs
The production processes of machine tools constantly require compressed air. In sensor production, various devices required to produce the finished product are manufactured in-house. These processes often take place in a machine tool.
In the production process of the machine tool, compressed air is required:
- as “sealing air” to seal a hollow space with the help of overpressure
- for mechanical processes during tool changing
- as “purging air” to clean tools before and after tool changing
- as “purging air” to remove any chips from manufactured parts when removing them from the machine tool
- to cool the tools used for sensitive plastic parts which must not come into contact with coolants
Compressed air production is one of the major cost factors in manufacturing. This is why energy efficiency measures have such a high potential.
The starting position
Compressed air indication without condition-based quantity and cost tracking
By default, every machine tool provides general display instruments to indicate the different operating states. However, the process data of the compressed air consumption in correlation with the associated costs are not monitored.
Consequently, an evaluation in terms of energy management and energy efficiency measures is not possible.
- What are the compressed air costs depending on the state of the machine?
- Where can costs and energy be saved?
Without a database, these questions remain unanswered.
Goal of the project
Assessment of compressed air costs for the purpose of implementing energy saving measures
- Energy-efficient operation of the machine tool
- Calculation of different compressed air costs for the purpose of assessing and organising energy-saving measures
- Identification and visualisation of unnecessary costs in stand-by operation due to leaks
- Reduction of energy and operating costs to become a ‘green factory’
Implementation
Compressed air monitoring with moneo RTM
moneo RTM is centrally installed on a server.
ifm provides a wide range of automation components. In this application, SD6500 compressed air meters were installed at the compressed air supply of the machine tool and upstream of the compressed air gun.
The sensor data is provided to moneo RTM via an IO-Link master of the AL1350 series. The IO-Link master is connected to the server via an internal VLAN.
Data monitoring, threshold management and calculations are carried out with moneo RTM.
Success
moneo RTM visualises energy-saving potential
Data acquisition, visualisation and offsetting of flow values via moneo RTM provide the basis for calculating different compressed air costs.
These data allow dedicated assessment and organisation of energy-saving measures. Unnecessary costs in standby operation were identified, and the machine tool can now be operated more efficiently without wasting compressed air.
Energy and operating costs could be reduced with the goal of becoming a ‘green factory’.
System structure
- SD6500 compressed air meter in the supply line of the machine tool
- SD6500 compressed air meter in the supply line of the compressed air gun
- AL1350 IO-Link master
Wiring diagram
- SD6500 compressed air meter in the supply line of the machine tool
- SD6500 compressed air meter in the supply line of the compressed air gun
- AL1350 IO-Link master
Dashboard
Get the big picture on the moneo dashboard. The dashboard provides the user with an overview of all relevant process values for this plant.
- Current total compressed air - flow (CDS)** (m³/h)*
- Current pressure (bar)
- Total compressed air consumption - totaliser (CDS)** (m³)*
- Current compressed air costs (CDS)** (€/h)*
- Total compressed air costs (CDS)** (€)*
- Machine status “Machine on” (CDS)** (On/Off)
- Machine status “Machine standby” (CDS)** (On/Off)
- Machine status “Machine off” (CDS)** (On/Off)
In the “Compressed air” dashboard, the user sees all relevant compressed air process values for this plant at a glance.
- Machine - current compressed air consumption (m³/h)
- Machine - current pressure (bar)
- Current compressed air temperature (°C)
- Machine - compressed air consumption (m³)*
- Machine - compressed air costs (€)*
- Compressed air gun - current compressed air consumption (m³/h)
- Compressed air gun - current pressure (bar)
- Compressed air gun - current compressed air temperature (°C)
- Compressed air gun - compressed air consumption (m³)*
- Compressed air gun - compressed air costs (CDS)** (€)*
- Current total compressed air - flow (CDS)** (m³/h)*
- Total compressed air consumption - totaliser (CDS)** (m³)*
- Current compressed air costs (CDS)** (€/h)*
- Total compressed air costs (CDS)** (€)*
In the ”Machine status” dashboard, the user can see the current operating status of the machine and the elapsed operating time in the relevant machine status.
- Machine status “Machine on” (CDS)** (On/Off)
- Machine status “Machine standby” (CDS)** (On/Off)
- Machine status “Machine off” (CDS)** (On/Off)
- Time - Machine ON (CDS)** (h)*
- Time - Machine STANDBY (CDS)** (h)*
- Time - Machine OFF (CDS)** (h)*
In the “Process optimization” dashboard, the user can see the energy consumed by machine operating status. The insights gained can be used to optimise the energy consumption.
- Total compressed air costs (CDS)** (€)*
- Compressed air costs machine (CDS)** (€)*
- Compressed air costs machine in standby (CDS)** (€)*
* Counting start was the set-up of the sensor. A reset can be performed via the sensor or via moneo configure.
** NOTE! A reset also resets all values calculated so far! CDS (Calculated Data Source) stands for a value calculated via the moneo Dataflow Modeler
Analysis
The analysis function can be used to view further details. The screenshot shows how the operating status of the machine tool can easily be identified via the flow value of the compressed air.
- Machine status “Machine off” (0m³/h)***
- Machine status “Machine standby” (approx. 19m³/h)***
- Machine status “Machine on” (>20m³/h)***
*** To be determined individually depending on the application
Settings & rules: Manage thresholds
Tasks & tickets
As soon as a defined limit value has been exceeded or not reached, a ticket will be created for the corresponding process value. A red traffic light and a pop-up alert message indicate that a pressure threshold was violated.
The ticket can be taken over and processed by the responsible employee. Via the comment function, implemented measures and descriptions of solutions can be documented immediately. The following notification options are available:
- SAP integration
Calculated values
Using moneo, much more information can be calculated from the process values of the sensors. The ‘Dataflow Modeler’ enables custom creation of calculated values, e.g. by combining and offsetting data sources from sensors in a data flow model.
Calculation of total compressed air consumption:
- Totaliser of the SD6500 compressed air meter in front of the machine tool (m³)
- Totaliser of the SD6500 compressed air meter in front of the compressed air gun (m³)
- Function block “Addition” - calculation of total compressed air consumption
- Result - total consumption (m³)
Calculation of compressed air costs of the machine tool:
- Totaliser of the SD6500 compressed air meter in front of the machine tool (m³)
- Energy price for 1m³ of compressed air - must be determined individually depending on the application (€/cent)
- Constant “100” for cent to euro conversion
- Function block “Division” - cent to euro conversion
- Function block “Multiplication” - calculation of energy costs
- Function block “Round” - the energy costs are rounded to two decimal places
- Result - compressed air costs of the machine tool (€)
Determination of the machine tool status “Machine on”:
- Flow value of SD6500 compressed air meter (m³/h)
- Constant “20” for determining the machine status “Machine on” - must be determined individually depending on the application (m³/h)
- Function block “Comparison” - output is true if A is greater than B
- Function block “Boolean to double” - conversion of the Bool value into a numerical value: true = 1 / false = 0
- Result - machine tool operating status = on (true = 1 / false = 0)
Determination of the machine tool status “Machine off”:
- Flow value of SD6500 compressed air meter (m³/h)
- Constant “1” for determining the machine status “Machine off” - must be determined individually depending on the application (m³/h)
- Function block “Comparison” - output is true if A is less than B
- Function block “Boolean to double” - conversion of the Bool value into a numerical value: true = 1 / false = 0
- Result - machine tool operating status = off (true = 1 / false = 0)
Determination of the machine tool status “Machine standby”:
- Flow value of SD6500 compressed air meter (m³/h)
- Constant “1” for determining the machine status “Machine off” - must be determined individually depending on the application (m³/h)
- Constant “20” for determining the machine status “Machine on” - must be determined individually depending on the application (m³/h)
- Function block “Comparison” - output is true if A is greater than B
- Function block “Comparison” - output is true if A is less than B
- Function block “And” - output is true if A and B are true
- Function block “Boolean to double” - conversion of the Bool value into a numerical value: true = 1 / false = 0
- Result - machine tool operating status = off (true = 1 / false = 0)
Calculation of the production time of the machine tool:
- Calculated machine status “Machine on” (true = 1 / false = 0)
- Function block “Double to boolean” - conversion of a numerical value to a Bool value 1 = true / 0 = false
- Function block “Time counter” - counts as soon as trigger input 1 = true
- Function block “Round” - the counter value is rounded to two decimal places
- Result - time of the machine tool in the “On” state (h)
Calculation of standby energy costs:
- Calculated value Machine tool standby time (h)
- Constant “19” Average standby consumption of the machine - must be determined individually depending on the application (m³/h)
- Energy price for 1m³ of compressed air - must be determined individually depending on the application (€/cent)
- Constant “100” for cent to euro conversion
- Function block “Division” - cent to euro conversion
- Function block “Multiplication” - calculation of average standby energy costs
- Function block “Multiplication” - calculation of energy costs
- Function block “Round” - the energy costs are rounded to two decimal places
- Result - compressed air costs of the machine tool in standby (€)
